Part 31 - cd3wd431.zip - Offline
A project of Volunteers in Asia
Photovoltair:s.
.
. A aurde
fo rdevelog;nent
wo
By: Anthony Derrick, Catherine Francis, & Varis Bokalders
Published by: Intermediate Technology Publications
103/l 05 Southampton Row
London WCIB 4HH
U.K.
In association with: The Swedish Missionary Council and the
Stockholm Environment Institute 1991
Available from: Intermediate Technology Publications
103/l 05 Southampton Row
London WCIB 4HH
U.K.
Reproduced with permission.
Reproduction of this microfiche document in any form is subject to the same
restrictions as those of the original docunsnt.
AnthonyDe&k, CatherineFrancisandVarisBokalders
The StockholmEnvironmentInstitute
SwedishMissionaryCouncil
SOLAR PHQTOVQLTAIC
PRODUCTS
NOTICE
Neither the publishers nor I T Power, the Stockholm Environment Institute, the
Swedish Missionary Council or the Swedish International Development Agency make
any warranty expressed or implied, or asssumes any legal liability or rE:s;?onsibility
for the ;xccuracy, completeness or usefulness of any information, apparz?us, product,
or process disclosed, or represent that its use would not infringe privately owned
rights. Reference herein to any specific commercial products, process, or service by
trade-name, mark, manufacture, or otherwise, does not necessarily eanstitute or imply
its endorsement,
recommendations,
or favouring by the authors, sponsors and
publishers of this guide.
This Guide presents technical and price information on the photavoltaic products of
Inclusion of the specific manufacturers
or
some manufacturers
and suppliers.
suppliers 2nd their products does not constitute or imply endorsement nor should an
omission of a manufacturer
or supplier or produci. be considered indicative or
significant in any respect. Price data where given ydere obtainined in 1990 and will
be approximate only. As 2 result of exchange r%e fluctuations and price revision
by suppliers, comparisons of the prices of products from different suppliers would be
incorrect and should not be undertaken.
The authors, sponsors and publishers assume no responsibility for any personal
injury or property damage or other loss suffered in activities related to information
presented in this book.
Published by intermediate Technology Publications Ltd
103/105 Southampton Row, London, WC1 8 4HH, UK
0 Intermediate Technology Publications 2nd IT Power 1991
ISBN 1-85339-002-X
Printed by the Russe!! Press Ltd., Radford Mill,
Norton Street, Nottingham NG7 3HN.
LAR PH
A
guide
VOLTAIC
for
development
P
workers
Anthony Derrick, Catherine Francis
and Varis Bokalders
REVBSED EDITION
Intermediate Technology Publications in association with The Swedish
Missionary Council and the Stockholm Environment Institute 1991
This book is the result of a cooperative project involving I.T. Power Ltd, the Stockholm
Environment Institute and SMC, the Swedish Missionary Councii, 2nd is sponsored by
SIDA, the Swedish Internationsl Development Authority.
Its origin stems from the
needs of SMC fieid staff who ha re found much of the information currently available
on photovoltaics to be fragmented 2nd often incompatible.
This book is an updated version of the 1988 publication with the same name,
produced jointly by IT-Power, the Beijer Institute 2nd the Swedish Missionary Council.
During 1989, the Beijer institute was integrated into the new Stockholm Environment
Institute .
The Stockholm Environment Institute, which has close working contacts with the SMC
in the field of renewable energy, runs an inform2tion programme on renewable energy
for development which has resulted in a series of publications 2nd seminars.
I.T.
Power has substantial experience of renewable energy matters and for many years has
taken a particular interest in photovoltaics.
Photovoltaics (PV) were a natural choice 2s the subject of the first cooperative project.
PV is 2 mature technology which has already proven its reliability in several important
niches, not least in many small scale applications in developing countries such as
Large numbers of PV
water pumping, refrigeration, lighting and telecommunications.
systems are currently being installed. This proliferation of the tech!:ology has, however,
created a need for accurate, reliable and objective information amc;ng field workers who
seldom have time to grasp the intricacies of all the various gadgets offered to them by
PV thus differs from several other renewable energy
manufacturers and agents.
technologies in that it has already been proven under widely varying circumstances,
and that 2 major bottleneck to its dissemination is not connected tc the technology as
such (2s is the case with many other renewable energy sourc@ but rather to the
lack of availability
of reliable information
on i3 operation, Gost and range of
applications.
This book aims at addressing this shortfall cf infor,nation, and we hope that the
combined experience of clJr three organizations will be of assistance to other workers
in the field.
Stockholm
Lars Krlstoferson
Environment Institute
December
1990
CONTENTS
Page
PREFACE
ACKNOWLEDGEMENTS
1. lNTRODUCTlON
1.1
1.2
What is Photovoltaics?
Why Photovoltaics?
2. OVERVIEW OF PHOTOVOLTAICS
2.1
2.2
2.3
2.4
2.5
Brief History
The Photovoltaic Process
Modules and Arrays
Systems
Overview of the Economics
3. IMPLEMENTATION
3.1
3.2
3.3
3.4
3
6
7
10
13
CONSlDERATlONS
The Solar Resource
System Sizing
Procurement
Safety
15
21
24
27
4. BATTERIES, POWER CONTROL UNITS AND
BATTERY CHARGING SYSTEMS
4.1
4.2
4.3
4.4
4.5
Batteries
Power Control Units
Battery Charging Systems
Implementation Considerations
Product Information Sheets
28
34
36
37
39
5. WATER PUMPING
5.1
5.2
5.3
5.4
5.5
5.6
Experiences
Relative Merits
Commercially Available Equipment
Procurement
Implementation Considerations
Product Information Sheets
42
44
47
53
59
60
6a VACCINE REFRIGERATION
6.1
6.2
6.3
6.4
6.5
6.6
FOR HEALTH CARE
65
68
70
72
73
76
Experiences
Relative Merits
Commercially Available Equipment
Procurement
Implementation
Product Information Sheets
7. LIGHTING
7.1
7.2
7.3
7.4
7.5
7.6
79
80
83
86
88
90
Experiences
Relative Merits
Commercially Available Equipment
Procurement
Implementation
Product Information Sheets
8. RURAL TELECOMMUNICATIONS
8.1
8.2
8.3
8.4
8.5
8.6
Expsriences
Relative Merits
Commercially Available Systems
Procurement
Implementation
Product Information Sheets
.*
94
95
95
96
96
98
9. OTHER APPLICATIONS
9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.8
9.9
Introduction
Water Treatment
Agricultural Applications
Fisheries Applications
Transport
Security Systems
Corrosion
Domestic Appliances
Product Information Sheets
! 0. FREQUENTLY
ASKED QUESTIONS
105
106
GLOSSARY
APPENDIX I
APPENDIX 2
APPENDIX 3
99
99
100
100
100
101
101
101
102
Life Cycle Costing
Suppliers Name and Addresses
Tender Document Format
109
113
123
PREFACE
This handbaok aims to assist anyone with a little technical experience, but probab!y no
previous knowledge of photovoltaic (PV) systems to decide:
8
if a power supply is suitable for the purpose in mind
@
the type of equipment needed;
e
how to proceed in implementing a project using PV products
This guidebook has been prepared by I.T. Power Ltd of Eversley, UK and the
Stockholm Environment Institute, Sweden for the Swedish Missionary Council Office for
International Development Cooperation.
Contact persons at these Institutions are:
International Development
The Warren
Bramshill Road
Eversiey, Hants
RG27 OPR, UK
Tel: +44-734-730073
Tlx: 846852
Fax: +44-734-730820
Tegnergatan 34 n.b.
113 59 Stockholm
S-l 0314 Stockholm
Tel: -1-46-8-16 04 90
Tel: +46-8-30 60 50
Fax: +46-8-7230348
Fax: +46-8-31 58 28
ACKNOWLEDGEMENTS
The authors wish to thank the Swedish International Development Authority for
supporting this guide and gratefully acknowledge the information provided by the
photovoltaic systems industry. The authors also wish to thank their colleagues at I.T.
Power and Stockholm Environment Institute for useful comments received. Particular
thanks are due to Mr Karl-Erik Lundgren of the Swedish Missionary Council.
1.1 WHAT IS PHOTOVOLTAICS?
Photovoltaics is a technology that can convert light directly into electricity. (The term
photovoltaic is often abbreviated to PV.)
The sunniest regions of the world receive a vast amount of energy from the sun every
day. At the peak of the day the power from the sunshine falling over one square
kilometre of Kenya is equivalent to the total being supplied by the ca:!ritry’s electric
grid. Solar energy can be converted directly into electricity. The techn?j>gy used to
do it is called photovoltaics.
Photovoltaic systems are being used in developing countries to provide power for water
I: Amping, lighting. vaccine refrigeration, electrified livestock fencing, telecommunications
cathodic protection, water treatment and many other applications.
Some tens of thousands of systems are currently in use yet this number is insignificant
compared to the vast potential for PV applications.
Installing the Solar Array of a Solar Powered Refrigeration and Lighting System for a
Health C&ntre in Zaire ( I T Power)
1
WHY PHOTOVOLTAICS?
1.2
The majority of the pxmlaiiott In developing countries live in dispersed ccmmunities in
rural areas. The prI&ior, pi an electricity supply tu these areas IS difficult and costly;
extension of the mains ~:i;l o\‘er difficult terrain is generally not economic for small
power loads and the use 3.f diesel generator sets relies on the availability of fuel
supplies and maintenance skills.
Photovoltaic modules provide an independent, reliable electrical power source at the
point of use making it particularly suited to remote or inaccessible locations. PV
systems are technically and economically viable. Their principal advantages are:
a
PV systems have no fuel requirements:
In remote areas diesel or kerosene fuel supplies are erratic and
often very expensive. The recurrent costs of operating and
maintaining PV systems are small.
l
PV systems are modular:
A solar array is composed of individual PV modules so each
system can be sized to meet the particular demand.
a
PV systems can be used to improve quality of life:
For example, the provision of lighting in a rural school allows
evening educational or community activities. Refri,leration at a
health centre improves effectiveness of immunization programmes.
e
PV systems are highly reliable:
The reliability of PV modules is significantly higher than of diesel
generators or wind generators.
m
PV systems are easy to maintain:
Operation and routine maintenance requirements are simple.
0
PV modules have a long Ilfe:
There is little degradation in performance over 15 years.
a
PV systems provide national economic benefits:
Reliance on imported fuels such as coal and oil is reduced.
0
PV systems are environmentally benign:
There is no harmful pollution through the use of a PV system
and no contribution to “greenhouse gases”.
e
PV systems are economically viable:
On a life cycle cost basis and taking into cons’deration the higher
reliability of PV, many small scale applications “an be more
economically powered by PV than with diesel systems, or other
small power supplies.
2
-
2.1
BRIEF HISTORY
Until recently, price has been the main barrier to the widespread use of photovoltaics.
In 1975, this was over $30/W&t. Since then, improvements in manufacturing
technology and production volumes have reduced prices to their present 1991 level of
around $4 per Watt. This has resulted in making photovoltaic power economic in
areas remote from mains electricity grids.
The photovoltaic effect was first observed by the French scientist Becquerel in 1839
who noticed that when light ,was directed onto one side of a simple battery cell, the
generated current could be increased.
The first practical photovoltaic devices were selenium and cuprous oxide cells used for
photographic exposure meters and light sensors. Light to electricity efficiencies of
about 1 per cent were achieved in the early 1940s.
It was not until the late 1950s however, that crystalline silicon solar cells were
developed with high enough conversion efficiencies to be used for power generators.
A major impetus for the development of these cells was the space programme. The
first solar-powered satellite, Vanguard I, was launched by the USA in 1958. The
output for terrestrial PV modules matured in 1983 with the introduction of automated
PV production plants (see Figure 2.1).
60
1
76
77
78
79
80
81
82
83
84
85
86
87
88
Year
Figure 2.1 PV Module Production in Recent Years
3
89
90
2.1.:
Technoloay and Prices
Over the last ten years, the price of photovoltaic modules and systems has been
steadily falling in real terms. Module prices for both forms of crystalline silicon are
currently around $4/Wp (exclusive of delivery or taxes;) for large orders. Bearing in
mind that the cells account for about 60 per cent of the module price, some further
price reductions, possibly down to about $2-$3/Wp, are foreseen through the
introduction of cheaper silicon and larger, fully automated manufacturing plants. Much
lower costs, even down to $l/Wp or less, are potentially attainable with thin film cells.
In view of the large efforts being made world-wide to develop different thin lilm
technologies including Cadmium Telluride, CIS ar,d Multijunction devices, it is probable
that large-area thin film cells will become available with much improved efficiency and
stability compared with current products. Some researchers maintain that crystalline
silicon cells could continGe to be compatitive with thin film processes for several years.
Figure 2.2
PV Price Hlstory
2.12
The Future Market
Market prospects are largely dependent on prices of photovoltaics in relation to
alternative energy sources, but other factors are important, such as government
incentives, availability of finance and the general perception of the technology held by
YEAR
1990
1995
2000
LOW PRICE SCENARIO
Modules
wP
Systems
$JWP
4.0
2.0
1.5
8-i5
3-7
2.5-5
Sales
MWp/yr
52
700
1000
HIGH PRICE SCENARIO
Modules
$NP
Systems
$MP
4.0
3.0
3.0
8-I 5
6-10
5-9
Table 2.1 Projection of PV Prices and Sales to - 2000 (1990 US$)
Sales
MWplyr
52
100
200
potential customers. Although it is not passible to predict with precision what the
future market will be, Table 2.1 indicates what the future sales of photovoltaic systems
worldwide might be for two scenarios. The low price scenario assumes that large area
thin film cells with adequate performance are utilised for power applications within the
next two to three years: the high price scenario is based on the assumption that the
technical or cost targets for thin film cells remain elusive, leaving crystalline silicon as
the dominant technology for power applications.
For the low price scenario, with module prices falling to around $1.5/Wp, total annual
sales are projected to grow rapidly, from the 1990 level of about 52 MWp to as high
as 1000 MWp by AD2000, with continued expansion thereafter. Most of the output
would be in and for developing countries for rural off-grid applications using stand-alone
systems, but there would also be many applications in industrialized countries for
consumer systems, professional systems and remote houses and villages. Gridconnected applications (central power and distributed) could begin to become a
significant market in some countries by the late 1990s.
For the high price scenario (now increasingly looking a pessimistic scenario), with
crystalline silicon modules prices falling to about $3/Wp and thin film cells not able to
compete for power applications, the total market would grow much more slowly,
possibly levelling out at about 200 MWp per annum by AD2000. Most of the sales
would be for consumer systems and professional systems, with relatively little going to
rural electrification, because of the high capital costs invofved. However, in some
countries, there would be good markets among more wealthy private customers for
powering isolated houses and for consumer systems, particularly for the tourist and
leisure markets. This scenario also assumes systems installed by national governments
and public utilities would be relatively limited, probably only a few megawatts per
annum.
2.1.3
Market Develonment
Developing countries have always been considered as a very large potential market
but, due to financing problems, actual commercial sales in these countries are at
present very small
In fact, the greater part of the systems installed to date in
developing countries has been assisted by foreign governments and/or the international
aid agencies. Developing countries are rightly concerned to ensure that at the right
time photovoltaic technology is transferred to them, rather than find themselves
dependent yet again on an imported energy technology. In due course, it is likely tha!
most developing countries will have their own PV industry, but this will take many
years to establish, during which time there will be a need to import systems for
demonstration projects, professional applications and key community applications. At
present photovoltaics are manufactured in Brazil, China and India on a commercial
scale in the developing world.
Significant markets can be expected to develop for professional systems, particularly for
telecommunications, viliage water supplies and generators for police posts and health
centres If system costs can be brought down to about $5/Wp rural electrification
using photovoltaics will become a viable option in many situations, with market potential
reckoned in many hundreds of megawatts per annum.
5
2.2
THE PHOTOVOLTAIC PROCESS
When light falls on the active surface, the photons in a solar cell become energised,
in proportion to the intensity and spectral distribution of the light. When their energy
level exceeds a certain point a potential difference, or open circuit voltage (Voc), is
established across the cell. This is then capable of driving a current through an
external load.
Most modern photovoltaic devices use silicon as the base material mainly as monocrystalline or multi-crystalline cells but recently also in amorphous form.
The main features of a mono-crystalline silicon cell are shown in Figure
made from a thin wafer of a high purity silicon crystal, doped with a minute
boron. Phosphorus is diffused into the active surface of the wafer.
electrical contact is made by a metallic grid and the back contact usually
whole surface. An anti-reflective coating is applied to the front surface.
2.3. It is
quantity of
The front
covers the
The process of producing efficient solar cells is costly due to the use of expensive
pure silicon and the energy consumed. Research work to develop new manufacturing
technologies continues.
Sunlight
-\
\
\
\
ElectronFlow
c
~
,r
Comntionol
DirectionOf
Current
lilt01
I
..,.,-..
’
Antireflection Coating
Thickness
250-350pm
Figure 2.3
$
Cell Junction
Metal Base@te
[Features of a Mom-Crystalline
6
Silicon Solar Cell
2.3
MODULES AND ARRAYS
Solar cells are interconnected in series and in parallel to achiqv,? the desired operating
voltage and current. They are then protected by encapsuiation between glass and a
tough resin back. This is all held together by a stainlecc steel or aluminium frame to
These modules form the basic building block of a solar array.
form a module.
Modules may be connected in series or parallel to achieve the required solar array
characteristics.
Thus, with no moving parts and all
delicate surfaces protected, the modulas
can be expected to provide power fGi
15 years or more. Many suppliers @‘.le
warranties of 10 years or more.
Toughened
transmission
Typically
saries connected
1OOmm cells
Commercially available modu!Ps fall into
four types based on the solar cells
used. These are:
% mono-crystalline cell modules where
highest cell eftlclericies of around 16O/o
are Gbtaine.d. Figure 2.4 shows the
construrzon of a mono-crystalline
silicon W module. The cells are cut
from a mono-crystalline silicon crystal.
high
glass
Junction
box
/
.
S~liconc
(EVA) Ethylene
vinyl acetate
(5 multi-crystalline cell modules where
the cell manufacturing process is of
lower cost but cell efficiencies Gf only
around 13% are achieved. A multicrystalline cell is cut from a cast ingot
of multi-crystalline
silicon and is
generally square in shape.
Tedlark?lumlnium
sandwich
Figure 2.4
Construction of
Mono-crystalline
PV Module (BP Solar)
amorphous
silicon modules are
made from thin films of amorphous
silicon where efficiency is much lower
(5-g%) but the process uses less
material.
The potential for cost
reduction is greatest for this type.
Unlike mono-crystalline
and multicrystalline cells with amorphous silicon
there is some degradation of power
output with time.
multi/unction
types where different
‘layers of thin film photovoltaic material
are used with each layer receptive to
a particular part of the solar spectrum
therby achieving higher efficiencies.
Figure 2.5
7
Amorphous Silicon
Modules
The current-voltage relationship (I-V) for a typical module is dependent on solar
irradiance and temperature. As the level of solar irradiance increases so the output
current will increase proportionately. Conversely, as cell temperature increases, the
current will increase slightly but the voltage will decrease significantly, resulting in a
decrease in power. Figure 2.6 illustrates these characteristics.
The main importance of Figure 2.6 is to show that:
@ It is desirable to operate the cells at as low a temperature as possible.
@ The maximum power output realisable from a PV cells is when the opera?ing
conditions are at the “knee” of the I-V curve. This is referred to as the “Watt
Peak” - Wp - of the cell. For comparative purposes, this is measured at an
irraCiance level of 1000 W/m2 and a temperature of 25OC.
An array can vary from one or two modules with an output of 1OW or less, to a vast
bank of severai kilowatts. Figure 2.7 shows a typical installation for a remote dwelling
with a few modules on the roof to charge a battery typically for lighting use. This can
be compared to the array shown in Figure 2.8 which provides the needs of a
community and requires large battery storage, power conditioning equipment and a
mini-grid distribution system.
NOCT = Nominal Operating Cell Temperature
Figure 2.6
Electrical Characteristics of a Typical PV ModLile
8
Figure 2.8
Figure 2.7 Individual Dwelling
Electrifiction
Flat plate arrays which are held fixed at a
tilted angle and face towards the equator
The angie of tilt
are most common.
should be approximately equal to the angle
of latitude for the site. A steeper angle
increases the output in winter; a shallower
angle gives more outpui in summer. It
should be at least 10 degrees to allow for
rain runoff (Figure 2.9).
Figure 2.9
Photovaltaic
Array Supplying
a “Mini - Grid”
Fixed Flat
Plate Array
Tracking arrays follow the path of the sun
during the day and thus theoretically
capture more sun. However, the increased
complexity and cost of the equipment rarely
makes it worthwhile.
Mobile (portable) arrays (Figure 2.10) can
be of use if the equipment being operated
is required in different locations such as
with some lighting systems or small
irrigation pumping systems.
9
Figure 2.10
Mobile Array
2.4
SYSTEMS
The term “system” is used to describe the complete set of equipm(ent used in
converting solar energy to the final requirement, eg light, pumped water or refrigeration.
PV systems are mainly used as stand-alone systems to provide a power supply
independent of any grid. They are the main concern of this guide. However, PV
arrays may also be used as a central generator connected to a local grid network or
as a power station for a mains grid.
A stand-alone system can notionally be divided into three parts:
The PV array (comprising the photovoltaic
modules and support structure) which
converts solar energy to d.c. electricity.
The power conditioning equipment which
is optional, but typically includes:
0
e
0
e
e
PV System Without Batteries
(Solar Pump)
cabling
controller which may include battery
overcharge protectior! to pt dvent
gassing and loss of electrolyte from
the battery, an automatic load
disconnect facility for when battery
voltage is low (to prevent damage to
the load) and maximum power point
tracking
(array/load
impendence
matching).
batteries:
these should only be
included when storage of electrical
energy is required, eg,for lighting.
When not essential batteries should
be avoided due to the additional cost
maintenance
requirements
and
batteries impose.
PV System with Battery
PV System with lnverter
an inverter: to convert d.c. to a.c.
electricity.
As significant energy
losses are always incurred in the
cor:version process it is preferable to
use d.c. appliances and avoid the
need for an inverter.
Load or end use equipment, eg lights,
pumps and refrigerators. Most commercial
suppliers now prefer to supply complete
systems rather than individual components.
These are sized for the specific location
and energy demand required.
10
PV System wit9 Multiple Load
and Diesel Back-up
Applications of Photovoltaics
RURAL ELECTRIFICATION
lighting and power supplies for remote
buildings (mosques, farms, schools,
mountain refuge huts)
a power supplies for remote villages
0 battery charging stations
0 portable power for nomads
0
WATER PUMPING AND TREATMENT SYSTEMS
PV lighting for a Community
Building
0 pumping for drinking water
i pumping for irrigation
o de-watering and drainage
o ice production
0 saltwater desalination systems
0 water purification
o water circulation in fish farms
HEALTH CARE SYSTEMS
lighting in rural clinics
@ UHF transceivers between health centres
0 vaccine refrigeration
0 ice pack freezing for vaccine carriers
0 sterilisers
b blood storage refrigerators
0
Floating Solar Powered Pump
COMMUNICATIONS
0 radio repeaters
0 remote TV & radio receivers
0 remote weather measuring
@ mobile radios
0 rural telephone kiosks
0 data acquisition and transmission
(river levels, seismographs)
0 emergency telephones
PV Refrlgerator for Vaccine
Storage
AGRICULTURE
0
0
0
0
livestock watering
irrigation pumping
electrical livestock fencing
stock tank ice prevention
PV Power for a Radio-Telephone
Systems
11
TRANSPORT AIDS
0
0
0
a
0
0
0
0
road sign lighting
railway crossings and signals
hazard and warning lights
navigation buoys
fog horns
runway lights
terrain avoidance lights
road markers
SECURITY SYSTEMS
0
0
securi;g lighting
remote alarm system
PV Powered Navigation Buoy
CORROSION PROTECTION SYSTEMS
0
0
0
0
e
cathodic protection for bridges
pipeline protection
well-head protection
lock gate protection
steel structure protection
MISCELLANEOUS
0
0
0
0
0
0
0
0
0
0
0
0
0
ventilation systems
camper and recreational vehicle power
calculators
automated feeding systems on fish farms
solar water heater circulation pumps
path lights
yacht/boat power
vehicle battery trickle chargers
earthquake monitoring systems
battery charging
fountains
emergency power for disaster relief
aeration systems in stagnant lakes
PV Street Lamp
INCOME GENERATION
0
0
0
0
battery charging stations
TV and video pay stations
village industry power
refrigeration services
PV Powered Ventilator
12
2.5
OVERVIEW OF THE ECONOMICS
In Ln analysis of a potential PV system its viability must bs assessed relative to
In general, PV is most competitive where relatively small
the alternatives.
amounts of energy are required in areas remote from the grid. Typical viable
demands are less than 50 kWh/day.
In undertaking an economic evaluation,
the following parameters should be
considered:
The economic characteristics
of PV
systems are different to that of most
small power systems in that:
0
the initial outlay on purchasing
the equipment (the capital cost) is
high
0
there are no fuel costs
e
maintenance costs are low
0
reliabtlity
is high such
replacement costs are low
*
the output of a system depends on
its location, so its economic viability
has to be assessed, for each
case.
0
the life cycle costs-which are the
sum of the costs and benefits of
the system accrued over its
lifetime, expressed in present day
value
a
payback period - which is the
length of time it takes for the total
costs to be “paid for” by the value
of benefits gained from the system
0
rate of return - which is the value
of the benefits gained from the
system compared to the initial
investment made.
that
The viable applications for photovoltaics include village water supplies, and livestock
water pumping, lighting and refrigeration. The relative economics will, however, be
dependent on local conditions including the solar resource at the site, local fuel costs
and the particular application. Figure 2.11 shows how the comparative costs of P!!,
diesel generator and grid supplied electricity vary with solar energy received, fuel cost,
demand and remoteness, frorn a grid.
Life cycle costing is the most complete analysis and normally undertaken to
determine if an application is economic. A brief description of how to undertake life
cycle costing is given in jpendix 1.
In practice, it is necessary to take into account the availability of funds. Larger
amounts of money are required initially for PV systems to cover capital costs but then
recurrent costs are lower. Hence, if there is uncertain funding in the future for fuel or
maintenance, PV has an advantage. The World Health Organisation for example is
promoting the use of PV to provide income generation for sustaining rural health care.
PV also offers less financially quantifiable advantages arising from its high reliability
such as improved immunisation programmes (from more reliable vaccine refrigeration).
A brief description of the economic viability of each ap@cation is covered in the
applications sections of this book.
13
PV SYSTEM
0.8-
OFs5,wp
-l
/
DIESEL GENERAT
Fuet cost in S4itre
0.4
-
0.2
-QtWp-
-
source:
Adapted from M.R. Starr, 1987
ii
t0
$0
43
160
3od
AVERAGE DAILY LOAD ikWh/day)
Figure 2.11
Comparative Costs of PV and Diesel Power
,,’
Figure 2.12
An Economic Application:
14
,’
Household Electricity in Mongolia
3.1
THE SOLAR RESOURCE
The output of a solar array depends on the amount of sunlight or solar
irradiance, falling on It, so it is Important to determine how much solar energy is
available at the site. Solar irradiance levels vary during the day with the angle
of the sun, with season, with latitude and with climate.
Of most interest to potential users of
photovoltaic systems is not, however, the
instantaneous solar irradiance at a site
but the total solar energy received in a
day over a specific area. This is known
as the daily solar irradiation or insolation.
On the horizontal surface, this is typically
5 to 7 kWh per square metre per day
in the tropics but can be less than 0.5
kWh per square metre per day on a
winter’s day in northern Europe. An
example of the variation in the solar
resource from month to month and day
to day is shown in Figures 3.1 and 3.2.
The solar irradiance at ground level is
made up of a direct component and a
diffuse component. The sum of these
two components on a horizontal plane is
termed the ‘global irradiance’.
The
diffuse component can vary from about
20 per cent of the global on a clear
day, to 100 per cent in heavily overcast
conditions.
On a clear day in the
tropics, with the sun high overhead, the
global irradiance can exceed 1000 W/
mz, but in northern Europe it rarely
exceeds 900 W/m*, falling to less than
100 W/m* on a cloudy day.
3 20
1
4
-r
2
.: 15
t
e
z
f 10
::
z
?i
2
5
0
5
2 0
J
I
I
I
J
A
Arid Equatorial
Figure 3.1
0
N 0
Months
bvlAMJ
AS;;;;
Months
Location
Aumid Tropical
Location
Typical Monthly Variations of Solar Energy Availability
15
It must be emphasised that ail leading
and reputable suppliers of PV systems
have detailed data files on the solar
resources throughout the world. Thus, it
is only necessary to specify to a
supplier where you wish to use the PV
system. However, it is important that
the location should be specified quite
accurately as the solar resource can
vary within some countries quite
significantly between, for example, the
coastal, inland or highland areas.
As discussed earlier, it is normal to tilt a
solar array to maximize the solar energy
received. The world distribution of solar
energy received on an array tilted at
latitude angle is shown in Figures 3.3 to
3.6. In order to determine the required
size of a PV system, it is necessary to
know the levels of solar irradiation and
temperatures that can be expected
throughout the year. This is specified in
tern\\\ of the average daily insolation and
average ambient temperature for each
month.
L-J
0
I
4
I
8
I
12
I,
16
20
1
24
B.
%
0
,I
28
0
Days
looof
MAY8
Davs
1
1
800
67
sg 400
$
E
p 200
2
3
0
4
0
4
8
12
Arid Equatorial
16
20
24
Time (hours)
Time (hours)
Location
Humid Tropical
Location
Figure 3.2 Typical Hourly and Daily Variations in Solar Energy Availability
16
I
I
I
I I I
II
t i i
F3
0
;
8
Figure 3.3
8
0
%
Solar Energy Distribution In Summer (June to August)
17
I
I
8
0
s
8
8
0
0
0
Figure 3.3
Solar Energy Distribution in Autumn (September to Novemh
18
I
Figure 3.5
Solar Energy Distribution In Winter (December to February)
19
I
i
\I1
IW\
III
KY!/
%-.
I
I
8
Figure 3.6
I
I
i il
c)
I
I
0
t
I ,
I
8
Solar Energy Distribution in Spring (March to May)
20
SYSTEM SIZING
3.2
3.2.1 How Bia a PV Solar Arrav do I Need?
Normally when you buy a PV system the supplier will determine the size and
power of PV array you require using a computer based mode!. This is a service
which should be -taken advantage of.
A general nomogram for estimating the
array size required for a given daily load
energy demand is shown in Figure 3.7.
You will be asked to supply information
regarding the intended location of the
equipment and user’s needs, eg quantity
of water or hours of light required per
day. Satisfactory performance of the
final system will depend on it being
correctly sized at this stage.
It is
therefore important to provide as full and
accurate details as possible regarding
the proposed site and use of the
required systems.
To use the nomogram:
determine the average daily energy
demand for the month being
assessed and locate it on the axis
OB
W trace a line horizontally from the
point on 08 to intercept with the
line which corresponds to the
average daily efficiency of your
load equipment
An appreciation of system sizing is
valuable in order to check supplier’s
recommendations. It is also useful to
obtain recommended sizes from several
suppliers for comparison. Suggestion by
any one supplier that the load can be
met with a small PV array would
indicate that their sizing assumptions
may be too optimistic.
;..
.I”,
~.‘:);”
.,,-,
__ -,
‘:..,_
I
:.
:,;-:
~,: ;
,:
:.;,.;~I;‘r::.Q
.i.,:‘,
cl
move from this point vertically
upwards to intercept the average
daily insolation in the month
d)
move from this point horizontally to
intercept the line OA from which
the approximate PV array size in
watts peak is derived.
e)
repeat the procedure for each
month. The array size required is
the highest value derived from the
twelve monthly assessments.
_~ ~
. .../. ‘L,
~~:,;p’
“T’
The nomogram can be used in the
reverse mode to determine the monthly
system output if the array size, insolation
and sub-system efficiency are known.
Figure 3.6
Note also that the nomogram can be
used for large or small values of daily
energy demand by factoring by 10 on
axis OB and then factoring the array
size indicated also.
420 Wp Array for a PV
Pump In Brazil
(Heliodlnamica)
21
Averagedaily
solar irradiation
for design month
2000
Z
s
F
‘L;
i!
1500
5
::
(0
u
E
‘5
/
1000
g
nE
500
0
z
E
ii
2
cUJ
‘si
4
5
-0
fi 4
E
G
>
P
P
w
f
I
7
2
1
Figure 3.7
Nomogram for System Sizing
22
3.2.2 Assessina the End Use Requirementa
In general, to size arrays it is necessary to determine the daily energy demand in
kWh/day to fulfill the requirements of the user(s). This will have to take account of
the power rating of the equipment to be used and estimated daily hours of operation.
Where there are seasonal variations in demand the period with the highest ratio of
energy demand to solar energy availability should be used.
w
A SOLAR PUMP
l
WATER SOURCE TYPE (well, river, canal,
borehole)
l
WELVBOREHOLECHARACTERISTICS
(diameter,yield)
l
HEAD (total static lift in metres)
e WATER DEMAND (month by month
average daily demand and peak requirements).
A SOLAR REFRIGERATOR
l
WATER STORAGEAND DISTRIBUTIONSYSTEM
l
INTERNALVOLUME REQUIRED
e MAXIMUMAMOUNTOF ICE OR GOODSTO BE
FROZENPER DAY
* THE NORMAL AMBIENTTEMPERATURE
LIGHT (S)
a NUMBEROF LIGHTS REQUIRED
l
WATTAGEOF EACH LIGHT
0 AVERAGEHOURLY USAGE OF EACH LAMP
TELECOMMUNICATIONS
e coNTirwous STANDBYPOWER FOR THE
EQUIPMENT.
l
TRANSMITTING/RECEIVING
POWER
l
NUMBEROF HOURSOF TRANSMITTING/
RECEIVING.
Table 3.1 Load Parameters Needed to Determine System Size
A summary of the load parameters to be specified when ordering PV systems is given
in Table 3.1. The appropriate application chapters have more detailed information on
assessing the load requirements for each application.
23
3.3
PROCUREMENT
Ill
3.3.1 Where to Obtain Photovoltak Svs&ms * (see Abnendix
_
Solar photovoltaic systems are commercially available from many companies throughout
the world. There are some indigineous companies manufacturing or assembling PV
systems in Brazil, China, India, Indonesia, Senegal, Thailand, Vietnam and Zimbabwe
though the majority are based in Europe, USA, Japan and Australia. Many of the
latter group have agents and representatives in the Developing World.. A summary of
the areas of particular experience for some leading companies is given in Table 3.2.
3.3.2 Selectina Equipment
Equipment should be selected on the basis of technical vlabllity, cost, experience
of the manufacturer and supplier and ease of implementatlon.
A cost comparison
of all systems
which fulfill the technical requirements
should be made taking account of initial
purchase, transport to site, installation,
operation and maintenance of the
system.
Technical viability - the system should
have the capability to perform the
required function in the specified location.
Field experience has shown the actual
load (ie, kilowatt-hours consumed) is
often greater than anticipated. A safety
margin of 20% should be added to
allow for this. Ensure it is clear exactly
which components are included in the
which
and
necessary
system,
components are not included and hence
are assumed to be readily available
locally (eg, pipework in a solar pumping
system}. Check these components are
available locally.
The experience of the manufacturer
and supplier should be considered.
Much information can be gained by an
examination of other units already
operating in a similar situation.
Practical
considerations
of procurement, transportation and installation
should be made. Determine if after
sales service is available locally for
spares supply and repair. Enquire if
training courses in the operation and
maintenance of the equipment are
available.
Simplicity of the system is often a
major factor in obtaining reliable and
etiective performance in the field. This
is particularly so in rural areas of
developing countries.
Figure 3.8
Delivering a PV System to a Health Clinic in Zaire
24
Nav-Aids, CP, CT
:hlorlde Solar
ilhc
iitachl
ioxan
+@as3l
ntersolar/Solarpak
UK
Japan
PC
sofoton
USA
lalSOlW
G.B.
<yocera
00
Japan
00
USA
UK
0
Neste
Portsol
Ras
Rade Koncar
SE. I.
SE. T.
l
l
Spain
ltalv
Germany
Japar
*a
Finland/Sweden
Norway
USA
FraIlCe
USA
Portugal
Netherlands
Yugoslavla
0
Germany
USAlAustralla
Australia
FWlCe
Belgium
swanks
Sun Frost
Suryovonlcs
Suntfon
Telefunken
USA
USA
lndla
Australle
Germany
Total Energie
Transcoast
FMa,
Belgium
l
00
*a
0
l
0
l
l
Educational Kits
CT, Fans
0
Nav.Aids, CP, Fans, CT
Moblle Power, Towable Arraj
CT, Home Power Kits
CT, NavAids
*
a
l
0
0
0
0
NW-Aids, CP, CT
l
l
e
e
l
Tunnel
LlQhUnQ,lV
FendhQ
l
@
a
em
l
l
*
o
l
l
l
0
0
a
e
NavAlds, CT
Alr cooler
0
l
l
*
l
Fans, Sterlllzers
.0
0
0
l
0
Home Power Kits, Fencing
Nav-Alds, Home Power Kits
Home Power Kits
l
**
0
l
W
Germany
Slemens
Solerex
SOlarWatt
Solems
Soltech
0
0
0
MB0
Germany
McOanald A.Y, Co USA
Mitsulblshl Elec.
Japan
MObeS
Genany
Mono Pumps
UK, Austmlla
Noack Solar
Photocomm
Photowatt
Polar Pmducts
0
a
l
l
e*
0
00
00
0
*
*a
l
0
0
0
o
00
cb*
l
TV, Fans
0
*
0
l
l
l
0
0
Home Power Kits
00
l
oe
TV, Nav-Alds, CT
Nav-Aids, CT
Home Power Kits
0
0
l
o
l
o
l
l
*
00
0
Home Power Kits
o
00
l
0
o
0
0
l
Table 3.2 Principal Suppliers of Photovoltaic Systems
25
3.3.3 Tender Procedure and Evaluation
Here are some things you should think of during the tender procedure.
e Assess the viability of using PV with regard to technical, social, institutional,
cost and practical considerations. If PV appears to be sensible then:
a Prepare site details including location, factors which may affect installation and
if available, local meteorological data.
@ Prepare details of load requirements for each month. These should be
expressed as monthly average daily values with any specific peak demands
noted.
e Prepare a tender document to send to potential suppliers. Allow adequate time
for suppliers to respond (4 weeks typically).
@ Undertake preliminary assessment of tenders for
-
completeness of tender including spares, tools, manuals
delivery period
warranty
a Undertake a detailed assessment for
compliance with the specification and estimate of the safety margin
in the array size over the wo:st case daily load
the extent and credibility of the information supplied
suppliers credibility and availability of back-up services
cost competitiveness
0 Select th,? preferred supplier and ensure you have answers to all queries on
the equipment before ordering.
Figure 3.9
Carrying a PV Array onto
a Roof
Figure 3.10 Installing a Roof
Mounted Array
26
3.4
SAFETY
Although photovoltaics modules and systems are no more dangerous than any
other small-scale
power source, users must always take the following
precautions:
Solar Arrav
Photovoltaic modules have a
glass cover; always carry and
transport them carefully.
There is a risk of receiving
an electric shock from a solar
array. Although most modules
have output voltages of less
than 20 volts, if several
modules are connected together
such that the voltage is greater
an electric shock risk is present.
Always take the following
precautions when undertaking
servicing or repair work on PV
systems:
cj
I0
Batteries contain acid which
can cause acid burns on skin or
blindness if in contact with the
eye. The acid will also damage
clothes.
avoid spilling or splashing
battery acid especially in
transport.
A
0 always keep the batteries
upright.
0 carry batteries carefully (do
not carry
head).
A
them
on your
a always use a funnel or plastic
bottle with a spout to add
distilled water.
0 cover the solar array with a
sheet or cloth
a do not let children
e disconnect the array from the
load
near
batteries and keep batteries in
locked, ventilated containers.
a us9 insulated tools.
Batteries also give off gases
which are explosive
Solar arrays may need regular
cleaning. With roof mounted
arrays there is a risk of falling
off a roof or ladder.
make sure that the battery
containers provided are well
ventilated and that they are
placed in a well ventilated
room.
0 make sure that the user has
easy and safe access to
clean the array.
position them firmly.
keep naked flames and
lighted cigarettes well away
from batteries.
use crawling boards when
walking on roofs.
use insulated tools to prevent
sparks.
a always use good ladders and
l
27
4.1
BATTERIES
4.1.1 The Case for Batteries
The amount of electricity produced by a photovoltaic array will vary throughout
the day and be zero at night. Some applications need an electric supply at
times when no electricity Is being produced by the module, for example night
Ilghtlng. In these Instances, batteries are used to store the electricity for use at
a later time.
For some applications, batteries are not
important. For example, if water is being
pumped into a starage tank it is not
critical when it happens only that
sufficient water is pumped to meet the
day’s demand. Batteries are thus not
needed in this type of system.
In many countries, particularly in Asia,
batteries are routinely used in rural areas to
power lights, fans and radios. PV systems
may be used to recharge these systems
which otherwise have to be undertaken by
transporting the batteries to urban areas,
Battery charging is a source of employment
and economic activity in many rural areas
and is being promoted as a source of income
for health centres, for example.
In other cases the supply of electricity
needs to be constantly available, for
example, for refrigerator or telecommunications loads.
Vent Plug
Terminals
Large
Electrolyte
Reservoir
Low Antimony
Lead Plates
/
Clear CaseFor Inspection
-
Figure 4.1
Space Below
Plates
Desirable Features of a Battery for Photovoltaic Use
28
4.1.2 Batteries for Photovoltaic Sysk~~
Batteries come in all shapes and sizes, each designed to suit a particular use. The
characteristics of most importance for use with PV are: ability to be repeatedly charged
and discharged without damage, the storage capacity of the battery, the ability to hold
charge when not in use, a need to be charged and discharged with minimum loss of
electrical energy and a requirement to operate for long periods with little or no
maintenance.
DOD is expressed as a percentage of
the rated battery capacity, and typically
varies from 50 to 100% depending upon
type of battery. Those with a high DOD
are called deep-cycle batteries and are
most suitable for use with PV systems.
These characteristics, (described in terms
used by manufacturers), are discussed
below. Actual data should be requested
from the suppliers.
0 Cycle Life - is the number of times
a battery can be discharged and
This is happening
recharged.
continuously in a PV system so it is
essential that the battery has a high
cycle life. Some types of batteries
are designed with a longer cycle life
than others.
For any type of battery, the DOD is
affected by operating temperature. In low
ambient temperatures, the allowable DOD
will be significantly reduced.
NbkmlCahnbm
The cycle life for any particular type
of battery will depend on the extent
to which it is discharged. If only a
small amount of power is taken from
the battery before recharging, the
cycle life will be much longer (see
Figure 4.2).
14
- - - -- 0rll.d l l.- . . . . .. . . ..,, b&akbm
9
08- 12
\
Ti?
kd-m&i
bdaid
-.-.-
Ledalltllmny(B%)
-..-..-
Mvltknaycr#)
a Rated Storage Capacity - a battery’s
size is expressed by the amount of
charge it can hold and is measured
in terms of Ampere-hours (Ah). A
battery of 100 Ah used to run a light
which consumes a 2A current will
operate for 50 hours.
The actual, or available, storage
capacity can be significantly less than
rated and depends on battery type,
manufacture and operating conditior?s.
0
20 40 60 80 -IO0
Depth of Discharge (%)
a Depth of Discharge (DOD) - is the
extent to which a battery should be
allowed to discharge in normal
operation.
Beyond the maximum
permissible DOD permanent damage
will be caused to the battery.
Figure 4.2 Variation in Battery
Cycle Llfe with Depth
of Discharge
29
l Self-Discharge
Rate - if left unused,
all batteries will slowly lose their
charge but some types self-discharge
faster than others, as shown in Figure
4.3.
A loss of 0.1 to 0.3% of
capacity per day is typical. This can
be greater
at high ambient
temperatures.
l
Charge Rate - charging a battery
with a high current causes excessive
heat to build up and can cause
damage. Normally a battery can be
safely charged with a current equal to
one tenth of its amp hour capacity or
less. The lower the charge current,
the greater
the efficiency
of
recharging.
0 Temperature - a battery’s capacity is
usually quoted at 25OC. Above this
the available capacity will be greater
but beyond 40°C the capacity will
decrease again. Temperature below
25°C will also increasingly reduce
battery capacity to 75-90% of rated
capacity.
At O°C freezing of
electrolyte particularly in lead-acid
batteries can casue permanent
damage. Temperature also affects
battery cycle life.
Continuous
operation above 25°C will cause a
significant reduction in life.
TYPO
Figure 4.3 Self Discharge Rate
by Battery Type
0 Discharge Rate is the period of time
in which a battery is designed to
deliver its full storage capacity. A
100Ah battery with a discharge rate
of 50 hours is designed to deliver a
current of 2A. The available storage
capacity of a battery will be greater if
it is discharged over a longer pe:iod
or less if the discharge rate is
increased.
@ Maintenance - the battery is often
the component of a PV system with
highest maintenance requirements. If
sited at remote locations or without
frequent maintenance services, a low
maintenance
battery shouid be
chosen. Maintenance requirements
vary with the battery type and
operating conditions.
Volts pe: cell
2.11
0
2
4
8
I
8
TknrN-1
Figure 4.4 Effect of Discharge
Rate on Battery Voltage
4.1.3 Commerciallv Available Batteries
Two principal battery types are used with PV systems.
batteiies and nickel-&admium batteries.
These are lead acid
Sealed Batteries - both lead antimony
and lead calcium are available in sealed
casings. They require no topping up
throughout their life so maintenance
requirements are low. This is achieved
by a large electrolyte reserve and a
catalytic recombination
plug which
reabsorbs the gasses back into the
battery as water.
LEAFi &CID BAlTERlES can be further
divided into:
Lead Calcium
- they are most
automotive
used for
commonly
applications. Calcium is added to the
lead plates to increase their strength.
The result is a battery able to deliver a
high current, but with a poor cvcle l& .
Self-discharge rate and water loss is
low.
NICKEL CADMIUM BATTERIES have
very different characteristics. They are
not liable to sudden failure because
plates are not “used up” in chemical
reactions. They can be fully discharged
without damage and they have a high
tolerance to being overcharged. Nickel
cadmium batteries can operate for long
periods without replenishment
of
electrolyte and they ha\ :r a long cycle
life, if shallow discharged.
Lead Antlmony - these have a small
amount of antimony in the lead plates to
improve the deep cycle characteristics.
They can tolerate repeated discharging
to 50-80% of rated capacity.
The
presence of antimony in the battery
increases both its rate of water loss and
self-discharge rate. The extent of these
effects are proportional to the amount of
antimony used. High water loss can be
counteracted by a large electrolyte
reserve. These batteries are commonly
used as traction batteries for electric
vehicles.
This gives nickel cadmium (ni-cd)
batteries advantages for use with PV
systems because the depth of discharge
is maximised. A battery with a smaller
rated capacity than that necessary with
a lead-acid type may be chosen
whereby
easing
storage
and
transportation requirements. They can
operate successfully without sophisticated
voltage regulation units.
Lead-alloy with gelled electrolyte - have
been developed to provide a sealed,
spill-proof battery. The internal design
minimises gassing and eliminates water
loss. They require no topping up and
hence maintenance requirements are
minimal. Cycle life is variable depending
on the design. Certain types have no
antimony in the plate alloy in which
case, cycle life can be poor.
However, nickel cadmium batteries have
not been as widely used in PV systems
as lead acid types because of higher
initial cost and poor availability in
developing countries.
When greater
depth-of-discharge
and longer life
expectancy are taken into account, their
life cycle costs are however often
comparable with lead-acid batteries.
Those with a medium to long cycle life
are suited to use in PV systems,
however, their cost is high and will limit
their widespread use. Similarly, the
number of manufacturers producing this
type of battery is very small.
31
PLATE TYPE
LEAD-CALCIUM
LEAD
ANTIMONY
CALCIUM
(6%)
LEAD-CALCIUM
ANTIMONY
(42%)
ELECTROLYTE
Liquid
Liquid
Liquid
Liquid
TYPICAL DOD
50%
80%
80%
100%
DESIGN USE
Automotive
Traction
Emergency
Power supplies
and PV
Low
Maintenance
Needs, PV
SELF-DISCH
RATE
Low
Medium
Low
Low
CYCLE LIFE
Low
MediumLong
Long
Long
SEAL
Vented
Vented
Vented
Vented
TOPPING-UP
REQUIRED
Infrequent
Frequently
Infrequently
Minimal
CAP ITAL
COST
Low
Mid-range
Mid-range
Very High
SUITABILITY
TO PV USE
Not
Recommended
Recommended Recommended
Highly
Recommended
Highly
NICKEL
CADMIUM
Table 4.1 Comparison of Battery Types Commonly Useel with PV Systems
I= Small
Ni-CB Battery
2~ Automotive
Type Battery
3= Community TV from
Rrcbufl~
d1 batllrlls
p”
EDW#I
PV
Recharging
Charged Battery
COmmunity TV Hall
SOWI
Figure 4.5
Recharging
Commercial Battery Charging in Zaire
32
4.1.4 Batterv Sizinq
A storage battery is the balancing factor between the pattern of energy
production from the array and the pattern of energy used by the consumer. If
too small, the battery will be completely discharged at times and overcharged at
others. (A lead acid battery will suffer permanent damage If used in this way.)
Determining the correct size of battery to
use can be complex due to the range
of factors which should be considered.
The two methods commonly used are by
deciding either:
Batteries
0 the number of days or hours of
autonomous operation required, ie
the length of time the energy stored
in the battery will operate the load
when no power is produced by the
array.
l
in Parallel
--I
12v
12v
lOOah
lOOah
ZE..ax;lliiL
the required availability
of the
power supply
(expressed as a
percentage of time when there is low
probability of a power failure). For
high value loads, such as vaccine
refrigerators
or commercial telecommunication equipment, very high
availability is required.
For nonessential services such as lighting or
household electrification,
a lower
availability can be tolerated. Lower
availability will result in a smaller
array and battery size along with
lower cost. Typical battery sizes for
equatorial regions have 3-5 days
storage capacity for low status loads
and 5 to 10 days where high
reliability is required.
TWO 6V Batteries
12v
lOOah
in Series
I
,
+-
o6V
ZOOah
6V
200ah
12v
ZOOah
I
Four 6V Batteries
and Parallel
,
in both Series
.
I
J
Lead acid batteries are made up of 2
volt cells connected in series to create
6, 12 or 24 volt units. Ni-Cd batteries
contain 1.2 volt cells connected together.
They may be connected in series or
parallel configurations to achieve the
required operating voltage and current
conditions. Figure 4.6 illustrates typical
wiring configurations.
Figure 4.6 Wiring of Batteries
33
12v
300ah
4.2
POWER CONTROL UNITS (PCU)
As already said, the power produced by a PV array is continually varying. Most
electrical equipment will only tolerate small variations inthe voltage and requency
of the electrlcal supply. Power control units essentially manage and refine the
system to enable smooth snd efficient operation.
The principal functions of a PCU will
depend on the type of system.
Commonly used PCUs are:
Charge Regulators - are required for
battery charging systems, particularly
those using lead acid batteries. Their
main purpose is to prevent damage to
the battery by over charging or
discharging. Initially the regulator will
allow all the power from the PV array to
be used to charge the batteries. As the
L attery voltage approaches a fully
charged level the charge from the array
will be cut to a float or ‘top-up’ charge
level. This is just sufficient to maintain
full charge, but will prevent gassing and
subsequent loss of water. If a battery
is near the fully discharged voltage the
regulator will cut the supply to the
equipment - or warning lights are
illuminated to indicate the low state of
charge of the battery.
These regulators operate on the voltage
level of the battery.
However, the
available capacity of a battery depends
In low
on its operating temperature.
temperatures, the battery voltage can be
relatively high yet the available charge
will be substantially reduced. Similarly,
battery voltage can be temporarily
reduced if a large current is being
drawn to power equipment.
Figure 4.7
Charge Regulator and
Blocking Diode Positions
Blocking Diodes - are used in battery
charging systems. They are connected
in line between the array and the
bbttery to prevent discharge of the
battery through the array. This would
otinerwise occur when the battery voltage
is greater than that produced by the
array (such as night).
Good quality charge regulators will
therefore include temperature and current
“compensation” features. It should be
noted that the better the quality of
regulator, the longer the batteries are
likely to last.
34
lnverters - are necessary only when a.c.
electrical appliances - eg, normal
domestic appliances and some pump
types. They convert the direct current
(d.c.) electricity produced by the array,
or stored in the battery, into alternating
(a.c.) current. lnverters are expensive
and introduce power losses, so where
possible the use of d.c. appliances is
preferred, eg, d.c. lights, fan units, etc.
n
Figure 4.8
Typical 400 W lnverter
Figure 4.9
A Charge Controller
System Indicators - display how the
system is functioning. This may be a
light to show power is being produced in
the array, or state of charge of the
batteries. It may include a voltmeter to
show battery voltage and an ammeter to
indicate the array output.
Junction Box - the control unit can
provide a useful point to join Gables at
installation of the system. A terminal
block is usually provided.
Maxlmum Power Polnt Trackers - are
quite sophisticated controllers used to
maximize the amount of power produced
by the array by optimising
the
impedance match between the array and
the load. They usually employ a microprocessor which looks at the array
power output (typically
every 30
milliseconds) and steps up the array
output voltage by means of impedance
adjustment.
If the power output has
increased since the last sample, the
array voltage is increased again. If the
array power has decreased,
the
controller will decrease the voltage.
Hence the controller hunts for a point of
maximum power output.
MPPT’S are sometimes used in PV
pumping systems. The controller itself
consumes power and has an associated
cost so only in a few Systems are they
cost-effective. In general, power control
units should be used with discretion.
Sophisticated electronic controllers can
be self-defeating if their unreliability
disrupts the system to the extent of
outweighting th benefits of improved
efficiency. This is particularly relevant in
areas where regular maintenance or
electronic repair services are not readily
available.
The choice of PCU will usually be
dictated by the system supplier. Whilst
their advice should not be ignored, the
information given in this chapter should
enable a qualitative evaluation of the
types available and their appropriateness
for the intended application.
4.3
BATTERY CHARGING SYSTEMS
In many remote locations or countries where the extent of grid electricity supply
is very Iimlted, batteries are used as a source of power. PV systems are now
betng increasingly considered as a means of recharging batteries, either at
battery charging stations or in dedicated systems. In Zaire the income from PV
battery charging stattons is used to maintain health centres.
The conventional methods of battery
charging in rural areas are periodically
transporting the batteries to a mains
supply or by using diesel or gasolene
generators.
The use of PV for battery charging has
the advantage that local charging points
can be established remote from the grid
network, there are no inherent fuel costs
or fuel supply problems, and unattended
operation of equipment at remote sites is
possible.
from
When
comparing
systems
Plternative suppliers, it is necessary to
look at array size, battery size and type,
charge rate specifjed for a given level
of insolation and which components are
supplied with the system.
Some
suppliers include batteries in their
systems, others leave this for local
purchase.
The inclusion of a power control unit will
depend on supplier and type of battery
used. Reliability is an important factor
as electronic controls have proved the
least reliable part of many PV systems.
For unattended operation, particularly with
lead acid batteries, a control unit with
voltage regulation is essential. Simple
units from suppliers
with proven
experience and reliable back-up services
are the safest choice.
It can be considered suitable in areas of
medium to high levels of insolation
(above about 3.0 kWh/m*/day). When
assessing economic viability of PV
battery charging compared to its
alternatives, associated operational and
should
be
factors
maintenance
considered as well as capital cost and
These will vary
output.
relative
considerably ’ for each site and
application.
Typical system costs range from US$lO20 per Wp of array rating.
KYOCERa
Figure 4.10 A 1400 Wp Battery Charging Station
36
4.4
IMPLEMENTATION CONSIDERATIONS
4.4.1
Procurement
YOU
will need to specify to the supplier:
*
the site location (country, nearest town, latitude and longitude)
l
your month by month daily charge required in Ampere hours
a
full details of the load on the battery
a
the type of batteries you intend to charge
0
which type of batteries you prefer to buy with the PV battery charger and
your preference for either high quality (and high cost), long life batteries
and controllers or for lower cost equipment which will require more frequent
maintenance and replacement.
4.42
‘JransportatioQ
If batteries are being transported over long distances and/or kept in storage before use,
this should be done in a “dry” condition (without electrolyte). It is then important to
ensure the supplier provides both acid and distilled water to fill the batteries prior to
use.
4.4.3 Sitinq
Batteries should be sited in a dry, well-ventilated position. This should not be in a
living EiiSZL
They should be protected from unwanted interference especially from
children and animals. Always keep them upright.
4.4.4 Maintenance
Regular checks are necessary to ensure that:
l
the electrolyte level is sufficient to cover the internal plates
l
batteries are clean and dry to prevent losses from the terminals
al
there is no build up of corrosion around the terminals
a
casing is sound without cracks or leakage
The amount of charge in each cell of a battery can be checked by measuring the
specific gravity of the electrolyte with a hydrometer (see Figure 4.12). It is important
that the battery cell is kept at a good state of charge. Any discrepancy can be
rectified by boost charging the battery - ie, maintaining a high charge rate until full
charge level is reached in all cells.
37
Q
j3Docifia
statm
ctmrgo
100
90
80
70
60
50
40
30
20
10
0
Gravitv
of
Z
1’
1
erature
at 1%
spaaifia
Gravity
Press
1.225
1.216
1.207
1.198
1.189
1.180
1.171
1.162
1.153
1.144
1.135
55
50
45
40
35
30
25
20
15
10
5
Release
Corroctisg
*C
Spmaifia
to
Gravity
+0.028
+0.024
*0.021
+0.017
+0.014
+0.010
*0.007
+o. 003
0.000
-0.003
-0.007
STATS OF CHARGE VS SPSCSFIC GRAVITY TABLE
Figure 4.11 Checking the Battery State of Charge
38
IS*
from
Correotion
Elmctrolyto
Tompor8ture
and
I
Product:
BATTERY CHARGINGSYSTEM
Includes:
Self regulating module, support
structure, wiring and connectors
Product:
BATTERY CHARGING KIT AND POWER SUPPLY
Indudes:
PV module, charge controller, discharge controller, warning light
circuit breaker, connectors and manual.
MODEL NO.
SPC
SPC
SPC
SPC
ARRAY Wp
15
60
120
160
5
18
88
60
OUTPUT WNday
15
60
120
180
PRICE U.S. $
180
370
880
880
Product:
BATTERY CHARGINGSTATION
Indudes:
PV array 8 support structure, charge controller and multiple
battery charging facility for 8, 12, or 24V batteries
MODEL NO.
ARRAY Wp
1440
c~rge
station
I
OUTPUT WNday
PRICE U.S. $
charge rate:
ten 1OOAh 12v
batteries
In
- .
3 days
refer
to
EL’-&+;
EXAMPLES OF PRODUCTS AVAILABLE - BATTERY CHARGERS
Product:
VEHICLE BATTERY CHARGING SYSTEM
Indudes:
PV Module and Connectors
PRICE U.S. $
OUTPUT Wh’day
MODEL NO.
Refer
to
supplier
1SWhIday
at
5kWhlm2/day
RK-PV
Product:
BATTERY CHARGINGSYSTEM
Indudes:
Module 8 mounting bracket. battery charge regulator with
overcharge protection, manual, all necessary tools & installation
materials. Does not include battery. optional low battery
voltage protection
ARRAY Wp
MODEL NO.
45
SOLARC I
OUTPUT WNday
PRICE U.S. $
340
180
@ 5 kWNm2/d
Product:
DOMESTIC BATTERY CHARGING STATION
Indudes:
PV module, 1OOAhbattery, charge controller, cable
junction box, instruction manual and optional array
support and battery box.
MODEL NO.
SGl
802
SG3
SG4
SG6
ARRAY Wp
35
70
105
140
210
OUTPUT WNday
approx Q5kWi-J ml/d
140
280
420
560
820
Product:
PORTABLE BATTERY CHARGING SYSTEMS
Includes:
PV modules, carrying case and charge regulator
MODEL NO.
ARRAY Wp
I
OUTPUT Whlday
!
PRlCEU.S.$
1
afw~x
HDS
portapak
t Chargeabout
106
250 - 350
I
1,700
10.8
30-50
I
800
40
I
The most versatile of solapak’s
portable power range, the solar
Chargeabout is supplied in a folding
canvas pouch which may be carried
on a beit or a back pack.
EXAMPLES OF PRODUCTS AVAILABLE - BATTERY CHARGERS
Product:
BATTERY CHARGING SYSTEM
Includes:
PV Modules and support structure, battery
and charge controller
ARRAY Wp
MODEL NO.
1SM55/12V
4SM55/12V
8SM55124V
53
212
424
BATTERY CHARGING SYSTEMS
Includes:
FET switching, battery charge controllers for
PVapplications
SP 102
SP 105
SPllO
ARRAY Wp
I
PRICE U.S. $
265
1060
2120
Product:
MODEL NO.
I
OUTPUT WWday
OUTPUTWhIday
2
6
12
554
1,760
3,376
PRICE U.S. $
refer
to
supplier
10
25
50
Product:
BATTERY CHARGING SYSTEMS
Includes:
FET switching, battery charge controllers for PV applications
MODEL NO.
OUTPUT
BCC1203
BCC1230
BCC2424
12 volt, 3 Amp
12 volt 30 Amp
24 volt 24 Amp
PRICE U.S. $
refer
to supplier
Product:
BATTERY CHARGING SYSTEMS
Includes:
Module and support structure, battery box charge controller with
battery overcharge & discharge protection. Optional kit form s
upport structure. (TGK series).
MODEL NO
TGP
TGP
TGP
TGP
TGP
45
180
270
360
540
ARRAY Wp
45
180
270
360
540
OUTPUTWhIday
@6kWhlm2ld
PRICE U.S. $
170 Whlday
700 Whfday
10001 Wh/day
1400 Wday
2100 Whfday
1,690
4,900
7,200
9,200
11,800
41
5.1
EXPERIENCES
More than 10,000 PV pumps are known to be operating throughout the world and
experiences have been good. Solar pumps are used to pump from boreholes, open
wells, rivers and canals to provide rural water and irrigation supplies. Less common
applications include de-watering drainage pumping and water circulation for fish farms.
With technical problems now largely
resolved, experience suggests that
reports of poor performance are largely
caused by incorrectly specified solar,
water resource and water demand data.
Proper consideration must be given to
these parameter and also the well
characteristics (yield and draw down) to
ensure correct system operation.
submerged
a.c. motor/pump
sets
because of their lower maintenance
costs. Reliability of the equipment in
the harsh Sahelian environment has
been good with the solar pumping
systems operating for more than 99% of
the time. Most recent installations have
operated faultlessly and effectively since
being commissioned. Monitoring of over
70 pumps for 8 years showed mean
time between failures of greater than 12
years.
A comprehensive UNDP and world Bank
study, completed in 1983 included testing
of systems in Egypt, Mali, Philippines
This did much to
and the Sudan
demonstrate
that solar pumps are
technically and economically viable and
ready tomeet the pumping needs of rural
areas.
Particular project experience includes:
Mali: provides a good example of solar
pumping experience. Over the past 11
years more than 150 PV pumping
systems have been installed, mainly
under the auspices of Mali Aqua Viva, a
charitable organisation. A high degree
of local involvement has been insisted
upon, especia!ly with construction work
on water tanks, foundations, access, etc.
This has provided up to 25% of the
initial cost of any one project and
generated a high level of enthusiasm
within the locality,
Borehole centrifugal pumps have been
the type most widely used in Mali,
originally coupled to surface mounted
d.c. motors. More recent installations
have changed to using pumps with
Figure 5.1
42
A Solar Pump in Mali
India:
the largest number of solar
pumps in one country is in India, where
more than 500 systems have been
installed for viilage water supplies.
Good responses have been reported
along with wide user acceptance. The
modules and systems have been
manufactured by Central Electronics
Limited (GEL) in India. The potential
of PV in India is so great that other
companies have started PV production
including Bharat Heavy Efectricals Limited
(BHEL), Rajasthan Electronics and
Instruments Limited (REIL), Tata-BP
Solar and Sutyovonics.
Bolivia: in co-operation with the World
Bank and the Government of Bolivia, the
US Department of Energy has installed
three pumping systems in the altiplano
region of Bolivia near Lake Titicaca.
The systems have operated flawlessly in
providing a potable water supply, since
A submerged
installation in 1986.
centrifugal pump/motor combination is
used with photovoltaic arrays ranging
from 160 to 320 Watts. Acceptance by
the users was immediate, resulting in a
higher usage than that originally
anticipated and considerable interest for
further system in the area.
Heliodinamica (Brazil)
Grundfos (Denmark)
KSB (Germany)
Typical Commercially Available Products
43
5.2
RELATIVE MERITS
Water pumping has a long history so many methods have been developed to pump
water with a minimum of effort. These have utilised a variety of power sources, namely
human energy, animal power, hydro power, wind, solar and fossil fuels (diesel and
gasoline) for small generators.
The relative merits of these are laid out in Table 5.1.
Plsadvantw
Hand pumps
l local manufacture
@ loss of human productivity
a often an inefficient use of
boreholes
@ only low flow rates are
achievable
is possible
I) easy to maintain
l low capital cost
l no fuel costs
Animal
driven pumps
e more powerful than
humans
l lower wages than
human power
e dung may be used
for cooking fuel
l animals require feeding all
Hydraulic
pumps
(eg. rams)
l unattended
0 require specific site
conditions
* low output
Wind pumps
9 unattended
operation
* easy maintenance
8 long life
a suited to local
manufacture
a no fuel requirements
l water storage is required for
Solar PV
@ Unattended
operation
* low maintenance
@ easy installation
a long life
8 high capital costs
0 water storage is required for
cloudy periods
@ repairs often require skilled
technicians
Diesel
and
Gasoline
Pumps
0 quick and easy
to install
a low capital costs
@ widely used
l can be portable
9 fuel supplies erratic and
expensive
0 high maintenance costs
8 short life expectancy
* noise and pollution
year round
0 often diverted to other
activities at crucial
irrigation periods
operation
0 easy to maintain
0 low cost
@ long life
@ high reliability
Table 5.1
low wind periods
l high system design and
project planning needs
6) not easy to install
Comparison of Pumping Techniques
44
The wind, solar and water powered stand-alone systems will operate without input from
other resources. This makes them most applicable to very remote or inaccessible sites
- BUT they involve the introduction of a new technology so time is required for:
e
assessing the availability of the resource
0
acquiring the equipment
0
familiarisation and training in operation and maintenance.
I,
Handpumps
- are the most
common type of water pumping
device because of their low cost
and relative simplicity. They are
appropriate for low lifts (c20m) and
where the demand is smell.
Handpumps do have hidden costs,
namely the time spent by people
queuing and pumping water and
the limitation on the output of a
borehole they impose.
a
Animal powered pumps - Some
200 million draft animals are in use
in developing countries mainly in
South East Asia. Many of these
are used for powering Persian
wheels, Mohtes, Sakias and other
animal driven pump designs. In
many countries these devices are
gradually being replaced by diesel
pumps.
0
Q
Windpumps
are
considered
appropriate in relatively windy
locations where aver;iGi wind
speeds are over 2.5m/s m thu
least windy month. Windpump
performance is very site specific.
The output is dependent upon the
wind availability
and often the
windy areas are not where the
water resources are, ie wind is
generally more available on hills
while water is in the valleys.
Windpumps almost always utilize
reciprocating positive displacement
pumps and can pump from
boreholes and wells and lift water
more than 200 metres.
a
Photovoltaic
pumping systems
should be considered in sunny
locations (where worst month
insolation exceeds 2.& kWh/m2/day
and in areas where supply of other
fuels is difficult. Solar pumps are
not normally economic for very
large pumping needs (where a
3 kWp or more PV array is
required).
l
If diesel or gasoline engine pump
sets are to be considered (ie, if
the wind or solar resource is poor)
then it is essential that fuel and
spare parts supplies are reliable.
Water powered pumps - can be
used in one of two forms, to drive
small hydro-electric plant which can
then be used to power electric
pumps or for water driven pumps hydraulic rams or river current
turbines. The use of water power
is also very site specific - there
has to be a sufficient amount of
water in the right place and with
reasonable access. Generally, if
these conditions are fulfilled, the
use of hydraulic powered pumps is
often very appropriate.
A decision chart to assist in
identifying the appropriate water
pumping option is shown in Figure
5.2.
45
0
RURAL
SUPPLY
Figure 5.2
Decision Charts for an Appraisal of Solar Pump Appropriateness
46
5.3
COMMERCIALLY AVAILABLE EQUIPMENT
5.3.1 AbDllcatloag
Solar pumps are used principally for two applications,
(Including livestock water supply) and irrigation.
A solar pump for village water supply
is shown schematically in Figure 5.3.
With village water supply a constant
water demand throughout the year
occurs although there is need to store
water for periods of low insolation.
Typically in Sahelian Africa the storage
would be 3 to 5 days of water demand.
In environments where rainy seasons
occur the reduced output of the solar
pump during this period can be offset by
rain water harvesting. The majority of
solar pumping systems installed to date
are for village water supply or livestock
watering. Systems typically have arrays
of less than 3 kWp and pump at heads
of 20 - 60m.
Village
Water Supply
A solar irrigation ~ystsrn needs to take
account of the fact that demand for
irrigation water will vary throughout the
year. Peak demand during the irrigation
seasons is often more than twice the
average demand. This means that solar
pumps for irrigation are underutilized for
most of the year. Attention should be
paid to the system of water distribution
and application to the crops.
The
system should minimize water losses
without imposing significant additional
head on the pumping system, and be of
low cost.
The suitability of major irrigation systems
for use with solar pumps is shown in
Table 5.1.
wotering
Point
Ai
I+
Rgure 5.3
c
Schematic of A Solar Powered Village Water Supply System
47
Distribution
Method
I
Typical
Application
Efficiency
Typical
Head
50 - 60%
0.5 - Im
Suitability
for use with
Solar Pumps?
Yes
I
IO-20m
Sprinkler
65%
Trickle
I
Yos
1-2m
40 - 50%
Table 5.2
Suitability of Major irrigation Methods for use with Solar Pumps
*r
P
1
/V&r
-Flouting
Figure 5.4
Level
Motor/PulQ
Sat
Schematic of A Solar irrigation Pumping System
48
5.3.2 The Technoioay
Systems are broadly configured into 5
types as described below:
Submerged
multistage
centrifugal
motor pumpset (Figure 5.5).
This type is probably the most common
type of solar pump used for village
water supply. The advantages of this
configuration are that it is easy to install
often with lay-flat flexible pipework and
the motor pumpset is submerged away
from potential damage.
Waterhblc 1
Submerged
Pump&
Motor
4
Either a.~. or d.c. motors can be
incorporated into the pumpset although
an inverter would be needed for a.c.
systems. If a brushed d.c. motor is
used then the equipment will need to be
pulled up from the well (approximately
every 2 years) to replace brushes. If
brushless d.c. motors are incorporated
then electronic commutation will be
required. The most commonly employed
system consists of an a.c. pump and
inverter with a PV array of less than
1500 wp.
Submerged
pump
with
mounted motor (Figure 5.6).
Figure 5.5
:
:
Submerged Centrifugal
Pumpset Configuration
surface
ifecic J
This configuration was widely installed
with turbine pumps in the Sahelian West
Africa during the 1970s. It gives easy
access to the motor for brush changing
and other maintenance.
IHIII
‘Submerged
Pump
The low efficiency from power losses in
the shaft bearings and the high cost of
installation have been disadvantages.
In general, this configuration is largely
being replaced by the submersible motor
and pumpset.
Figure 5.6
49
Surface Motor-Submerged
Pump Configuration
Reciprocating
positive
pump (Figure 5.7).
displacement
The reciprocating positive displacement
pump (often known as the jack or
nodding donkey} is very suitable for high
head. low flow applications.
PumpDriv
‘itloft \
The output is proportional to the speed
At high heads the
of the pump.
frictional forces are low compared to the
hydrostatic forces, often making positive
displacement pumps more efficient than
centrifugal pumps for this situation.
Reciprocating
positive displacement
pumps create a cyclic load on the motor
which, for efficient operation, needs to
be balanced. Hence the above ground
components of the solar pump are often
heavy and robust and power Controllers
for Impedance matching often used.
9
Figure 5.7
Positive Displacement
‘Jack’ pump
Rlrt0bt2
PVArray,
Floating motor-pump sets (Figure 5.8).
The versatility of the floating unit set
makes it ideal for irrigation pumping from
canals and open wells. The pumpset is
easily portable and there is a negligible
chance of the pump running dry.
Electric
WotN
Outlet
Most of theso types use a single stage
submersed centrigual pump. The most
common type utilize a brushless
(electronically commutated) d.c. motor.
Often
the
solar
array
support
incorporates a handle or ‘wheel barrow’
type trolley to enable transportation.
Surface
suction
Figure 5.8
Floating Motor-pump
Configuration
F+V
&my
T
pumpsets (Figure 5.9)
of pumpset
is not
This
type
recommended except where an operator
will always be in attendance. Although
the use of priming chambers and nonreturn valves can prevent loss of prime,
in practice self start and priming
It is
problems are experienced.
impractical to have suction heads of
more than 8 metres.
Figure 5.9
50
Surface Suction
Configuration
5.3.3 PefFormance
The performance of some commerciaiiy available products is shown in Figure
5.10 it can be seen that solar pumps are available to pump from anywhere in
the range of 1.5m to 200m head and with outputs of up to 250mYday.
Solar pumping technology continues to
improve. In the early 1980s the typical
solar energy to hydraulic (pumped water)
energy efficiency was around two per
cent with the photovoltaic array being six
to eight per cent efficient and the motor
pumpset typically 25 per cent efficient.
Today, an efficient solar pump has an
average daily solar energy to hydraulic
efficiency of more than four per cent.
Photovoltaic
modules
of
the
now
monocrystalline
have
type
efficiencies in excess of 15 per cent
and more efficient motor and pumpsets
are available. A good sub-system (that
is the motor, pump and any power
conditioning) should have an average
daily energy throughput efficiency of at
least 30% or ideally more than 40%.
Typical Products Available
MultistaDeContrifuSal
Vertical Turbine
PUmDS
Volumetric
Pump8
(Pas$ive Displacamenll
\
Oaily Output Im’iDayl
Single Stage
Centrilugel Pumps
Figure 5.10
Performance of Commercially Available Solar Pumping Systems
51
A PV pumping system to pump 25mVday through 20m head requires a solar array of
Such a pump would cost
approximately
800 Wp in the Sahelian regions.
Other
example
costs
are
shown
in Table 5.2.
approximately $9,000 FOB.
A range of prices is to be sxpected,
since the total system comprises the
cost of modules, pump, motor, pipework,
wiring, control system, array support
structure and packaging. Systems with
larger array sizes generally have a lower
Motor Pump/configuration
The cost of the motor
cost/Wp.
pumpsets varies according to application
and duties; a low lift suction pump may
a
cosi less than $800 whereas
submersible borehole pumpset costs
$1500 or more.
Output (maIday)
@ SkWhm*/day
Head
(m)
Solar
AW%y
System Price
US$ FOB
12,000 - 15,000
9,000 - 10,000
b) Surface motor /
submerged pump
60
7
840
8,000 - 9,000
c) Reciprocating positive
displacement pump
6
100
1200
9,500 - 11,000
d) Floating motor/pumpset
100
10
40
3
3
4
530
85
350
5,500 - 7,500
2,000 - 2,500
3,500 - 4,500
e) Surface suction pump
Table 5.2 Typical PV Pumping Systems
A life cycle cost analysis of a solar pumping system is shown in Table 5.3
Location
Array Size
Head
Annual Output
System Cost
:
:
:
:
:
Transpottion
and Installation
: $8,300
Total Installed:
cost
:
: $24,800
Sahel
1400wp
10m
27,20Cm3
$16,500
Period of Analysis
Discount Rate
: 15years
: 10%
Replacement Costs (2 spare pumps)
- present worth (bought wih system)
: $3,500
: $3,500
Recurrent Costs (Maintenance)
- present worth
Total Present worth of life cyc;le cpsts
Annual&d Life Cycle Costs
Unit Water Cost
If 100% of Output utilised
If 50% of Output utilised
:
:
:
:
..
:
:
Table 5.3 Life Cycle Cost Analysis for Solar Pumps
52
$250/yr
$1,902
$30,202
$3,960
$0.15 per ti
$0.29 per m3
5.4
PROCUREMENT
5.4.1 jhsessina
Requirements
The output of a solar pumping system is very dependent on good system design
derived from accurate site and demand data. It is therefore essential that accurate
assumptions are made regarding water demand and pattern of use and water
availability including well yield and expected drawdown.
Domestic water use per capita tends to
vary greatly depending on availability.
The long term aim is to provide people
with water in sufficient quantities to meet
all requirements for drinking, washing
and sanitation. Present short term goals
aim for a per capita provision of 40
litres per day, thus a village of 500
people has a requirement of 20 cubic
metres per day. Most villages have a
need for combined domestic and
livestock watering.
Irrigation requirements depend upon crop
water requirements, effective rainfall,
groundwater contributions and efficiency
of the distribution and field application
system. Irrigation requirements can be
determined by consultation with local
experts and agronomists or by reference
to
FAO
document
“Cropwater
requirements“ (J Doorenbos, W 0 Pruitt,
FAO, Rome, 1977). Typical figures are
given in Table 5.4.
Generally accepted water requirements for community water supply, livestock and
irrigation are given in Table 5.4.
litres/day/animal
litres/day/person
To survive
8
Subsistence
20
don keys/camels
mYday/hectare
cultivated
20
Present aims 40
Table 5.4
Typical Daily Water Requirements
Figure 5.12
PV Irrigation System in Egypt
54
5.4.2 Assessing Water Availability
Several water source parameters need to be taken into account and where
possible measured. These are the depth of the water source below ground level,
height of the storage tank or water outlet point above ground level and seasonal
variations In water level, The draw-down or (drop in water level after pumping
has commenced) also needs to be considered for well and borehole supplies.
This will depend on the ratio between pumping rate and the rate of refill of the
It is useful to present site details to the supplier In the format
water source.
laid out in Figure 5.13. The pattern of water use should also be considered in
relation to system design and storage requirements.
Water supply systems
should Include sufficient covered water storage to provide for daily water
requirements and short periods of cloudy weather. Generally two to five days
water demand is stored.
Surface Water Supply
Ground Water Supply
Height of storage
Height of storage
A: .................................
A: ......................................tank ................................
tank ................................
Suction
B: ......................................
Depth of well ...............
elevation
B.
..... ..................................
(surface mounted
pump only)
Distance oftank
C: .....................................
from pump ...............
Distance of tank
Diameter of well
C: .................................
from pump ...............
D’. . ...................................
or borehole ..............
Pipe diameter .......................
Depth of water level E: .....................................
Seasonal variation
F: ......................................
Drawdown ......................
ofAorB(+or-)
. ....................................
Pipe diameter ...........................................................
Figure 5.13
Pro-forma Speclficatlon for PV Pumping System Layout
55
5.4.3 S&ction
1.
of Equipmen
Determine the Viability of Solar Pumps
Using the decision chart on page 46, determine if, on economic grounds, solar
pumps are appropriate. Consideration should then be given to associated social
and institutional factors, such as the present systems being used for water
pumping in the vicinity and compliance with national standardisation plans,
Different systems will affect existing patterns of water supply and use. f-low
these fit in with the local skill levels and experience should be considered.
2.
Prepare Pro-forma Specification
Sheets
Complete the site layout and water demand pro-forma sheets (Figures 5.13 and
5.14 respectively).
3.
Issue Request for Tender
By reviewing the product information sheets listed at the end of this chapter,
select five or so companies to send a request for tender. Also take into
consideration companies that are known to have representation in the region
where the equipment is to be installed (see Appendix 2).
A general tender document is given in Annex 3. This can be modif!ed to suit
particular applications and specifications. Figure 5.15 shows a performance sheet
which should be completed by the supplier. Forward the tender document, the
two pro-forma specification sheets you have prepared, plus a blank performance
sheet to each company selected.
4.
Compare the Costs with Alternative Pumping Systems
When quotations have been received from the manufacturers, it is necessary to
check that buying a solar pump will be a sensible use for development funds.
In almost all cases, a solar pump will cost more on an initial capital cost basis,
but will have lower running costs than a diesel pumpset. Ideally, life cycle
costing should be undertaken using present worth analysis of future costs anti
benefits. This is described in Appendix Ill. An example shown in Table 5.5
compares life cycle costs for a solar and a diesel pump. It can be seen that
although the solar pump costs more to buy, over its life the unit cost of pumping
water is less expensive than if a diesel pump is used.
5.
Place the Order
Select the most appropriate solar pump to meet your requirements and budget.
Ensure you are satisfied that solar pumping is the most aprorpriate use of funds
available, that satisfactory answers have been received from the manufacturers on
all queries relating to the equipment, that all the necessary components, special
tools and accessories necessary to complete the installation have been ordered
and that spare parts sufficient for 5 years’ operation have been ordered.
56
Pro Forma Specification
Sheet -To
.- be completed
Longitude:
Latitude:
Location:
by user
Water source:
Application
water supply or irrigation:
no. of users or area to irrigate:
Site Details: (Complete layout information
Month:
on next page also):
1 Jan 1 Feb 1 Mar 1 Apr ( May 1 Jun ( Jul
Figure 5.14
Aug
Sep
Ott
Nov
Dee
Water Demand Pro-Forma Sheet: To be Completed by User
System Details and Performance
-To Be Completed
By Supplier
System specification
Arrav Wp: .................................................................... Pipe diameter: ................................................ mm
Pipe lengths supplied: ........................... ...... m
Tilt angle: ...._................................................................
Volts... Motor Type: ....._............................................................
Motor Voltage: .._....._..............................
Pump Type: ..........._...._...............................................
Type* . ...................................................................................
Water Store* . ..,................................. ............ m3 ...
Distribution
System Details and Type: ......._............................................................................................
.......................... ............................................... ,........................................I............................................,..................................
Month:
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Ott
Nov
Dee
Dynamic
Head
(ml
Insolation
Assumed
MJlmzld
Avarags Oaily
Water
Output (maI
Figure 5.15
Performance Specification Sheet: To be Compieted by Supplier
57
DIESEL
Rb?P
tN7ZOXlS
@ NEL
USr = SO.ZS/lite+
e FUEL Q3sr = Sl.SO/litrer
/
/
PVPUVWIT
/
'a!ers
e lNsxmxN=
4 kwhlm2/&y
I.?anJma=
6 kuhh2/daY
HEAD = 25m
10
PV PUMP SYSTEM CHARACTERlSTlCS
Depth of Water Supply, Head
Annual Average Daily Water Demand
Annual Max Daily Water Demand
Insolation
PV Array Peak Power
PV Pumping System Capital Cost
PV Pumping System Availability
PV Array Life
Pump Life
Normal Discount Rate
Inflation Rate
PV Annualised Life Cycle Cost
25m
20 m3 /day
30 m3 /day
5 .OkW h/m 2/day
1.11 kWp
12.OO$/Wp
95%
20 yrs
5Yf-S
10%
DIESEL PUMP CHARACTERISTICS
Depth of Water Supply, Head
Annual Average Daily Water Demand
Annuai Max Daily Water Demand
Diesel Generator Power Rating
Average Load Factor
Diesel Fuel Cost
Diesel Gen-Set pump Capital Cost
Diesel Pump Availability
Diesel Gen-Set Life
Pump Life
Diesel Annualised Life Cycle Cost
Table 5.5
25m
20 m3/day
30 m3 /day
3.0 kW
45.4%
$0.75 /litre
$1.59/W
90%
9yrs
5 yrs
$0.28 /m3
Example of Comparative Life Cycle Costs of Solar and Diesel Pumps
5.5
IMPLEMENTATION CONSIDERATIONS
5.5.1
Installatiorj
When installing the equipment, ensure:
l
manufacturers’ instructions are followed accurately
l
the array is kept covered throughout installation of the system
l
the solar array faces towards the equator and is tilted at the angle of latitude
plus 10 degree or as recommended by the supplier
a the solar array cannot be shaded by trees or buildings during the day except
before 0730 or after 1630
there is safe access to the array for cleaning
l
0 all cable lengths are kept to a minimum in order to reduce power losses
0 power controllers
penetration
and junction boxes are shaded and protected from rain
you position the motor-pumpset in the well to allow for drawdown and possible
long term water table drop
l
0 pipe lengths and number of bends and restrictions in the pipework are kept to a
minimum to reduce head losses
water storage tank and stand pipe configurations do not impose high static lifts
(or shade the array)
l
0 pipe diameters are sufficiently large so as not to impose additional head losses
l
any paint or sealants used are safe and do not contain harmful additives.
5.5.2 Maintenance
Regular maintenance will help ensure maximum performance is obtained from a solar
pump. The following should be undertaken as often as possible:
l
clean the solar array with water and a cloth
@ clear the pump inlet filter and strainer of leaves and other particles that may
impede the flow into the pump
0 check cables for evidence of damage or loose connections
l
commutator brushes of d-c. motors may need changing every 2-5 years
0 Routine maintenance as specified by the supplier must be undertaken.
59
Product:
SUBMERSIBLE BOREHOLE PUMPING SYSTEM -TYPE SPTP
includes:
PV anray and support structure. MPPT control unit, inverter, flexible
riser pipe, submersible a.c. motor pumpset, cable and necessary
fittings
Applications: Boreholes and rivers. Head range 1O-l 20m
MODEL
NO.
PERFORMANCE
@ 5.0 kWhfm%w .
WATTS
PEAK
HEAD RANGE m
BPSPl
BP SP2
BP SP3
BP SP4
BP SP5
BP SP6
I
100
50
20
15
8
6
60-120
30-60
5-35
8-20
5-11
5-80
1225
1225
1225
1225
1225
HEAD m
U.S.$
m%ay
5
15
36
52
86
130
P.O.A.
18,000
15,300
12,000
9,500
6,700
Product:
SUBMERSIBLESOLARPUMPINGSYSTEM
Indudes:
8 PV modules, support structure, cables, pumpset and instruction
manual
Applications: Boreholes and rivers. Head range 10 - 80m
MODEL
No.
PERFORMANCE
@ 5.0 kWh/m”day
WATTS
PEAK
HEAD
1 ESPOIR 1
88
1
10
ml/day
1 1.8
HEAD m
j 6.0
PRICE
U.S.$
m%ay
1 0.7
1 2,300
1
Product:
SUBMERSIBLE SOLAR PUMPING SYSTEM
Includes:
Subsystems for submersible water pumping, submersible pump/motor, x7-77DC-AC inverter and accessories.
Applications: Boreholes and rivers. Heads up to 120 m, flow up to 250 md/day
MODEL
NO
SPl-28
SP2- 18
SP 4-8
SP 8-4
SP27-1
bx.)
SP2- 18
SP 4-8
SP!6-2
PERFORMANCE
@ 5.0 kWhlm2lday
WATTS
PEAK
1484
1484
1464
PRICE
U.S.$
HEAD m
Watts Peak
80-120
30-80
5-40
8-20
5-8
750 - 1500
500 - 1500
250 - 1500
500-150
750 - 1500
20
10
46,7m3/day
99,2m3/day
Refer
to
Supplier
_-_--_exampI
s _____-__-----65
14.5m3/day
t
Product:
SUBMERSIBLESOLAR
Includes:
PV array with support structure and DC submersible pumpset
PUMPING SYSTEM
Applications: Boreholes, wells and rivers
MODEL
NO.
PERFORMANCE
@ 5.0 kWhimz/day
WATTS
PEAK
HEAD
SB 37
SB 46
SB 47
SB 56
735
840
980
1050
14
14
14
15
m’/da:f
HEAD
39
42
45
45
38
54
58
63
PRICE
U.S.$
m%fay
13
10
10
10
11,600
13,400
15,000
15,800
-+-I==
EXAMPLES OF PRODUCTS AVAILABLE - BOREHOLE PUMPING SYSTEMS
Froduct:
SUBMERSIBLESOLARPUMPINGSYSTEM
Indudes:
PVarray, support structure, cable submersible motor pumpset
Applications: Boreholes smali volume - high head
Product:
SUBMERSIBLE BOREHOLE PUMPING SYSTEM
Indudes:
PV array, steel support structure, invetter submersible a.c pumpset,
dry run protection
Applications: Boreholes, wells and rivers
PERFORMANCE
@ 5.0 kWm2lday
ma/day
21 - 3161-28
21 - 3126-28
21 - 3146-l 8
28 - 412-18
56 - 414-15
70 - 514-19
1050
1050
1050
1400
2800
3500
4.5
18
47
24
32
32
80
30
10
30
40
50
HEAD
PR!CE
U.S.%
m’/day
120
80
40
80
75
95
Refer
to
Supplier
Product:
SUBMERSIBLE BOREHOLE PUMPING SYSTEMS - TYPETSP
Includes:
PV array, anodised alumlnium support structures, control box,
with inverter, centrifugal submersible a.c. pumpset and fitting accessories
Appllcatfons: Wells or boreholes, heads from 10 - 120m. output from 10 to 150 mWay
x
PERFORMANCE
Low head
I
MODEL
NO.
WATTS
PEAK
HEAD m
TSP 720
TSP 1080
TSP 1440
TSP 1800
TSP 2160
TSP 2520
TSP 2880
TSP 3240
TSP 3600
TSP 3960
720
1080
1440
1800
2!60
2520
2880
3240
3600
3960
10
10
10
10
10
10
10
20
20
20
I
ms/day
36
60
75
115
133
148
162
99
107
113
25
45
80
60
100
120
120
120
120
120
15
12
18
20
11
8
11
15
18
21
17,400
23,000
28,000
31,400
42,300
46,800
51,000
55,500
60,600
63,rJoo
1
EXAMPLES OF PRODUCTS AVAILABLE
FLOATING AND SUBMERSIBLE SYSTEMS FOR OPEN WELLS/RIVERS
Product:
FLOATING PUMP SYSTEM
lndudes:
PV array, on mobile support structure, floating motor pumpset
with centrifugal pump and integral brushless DC motor
Applications: Open channels or wells, low liff, irrigation
MODEL
NO.
BP FM
BP FL
Product:
FLOATING PUMPING SYSTEM
Includes:
Floating pumpset, PV array and support structure 20m of cable
and connectors
Applications: Open wells or rivers, low lift Irrigation
MODEL
NO.
HF450 - 160
HF450-110
HF - 800
HF- 1080
Product:
SUBMERSIBLE DC SOLAR PllMPlNG SYSTEM
Indudes:
PV array, support StNCtUtl3,
cable submersible pump
Applications: Open wells or rivers, low lift irrigation
MODEL
NO.
WATTS
PEAK
PERFORMANCE
Q GkWh/m*/day
-HEADm
m3iday
HEAD m
PRICE
U.S.$
m%lay
SMB - 50
96
6
5
10
2
SMB - 200
384
3
50
6
30
SMD - 750
864
9
40
32
10
SMD - 750
1344
12
50
35
20
63
Refer
to
supplier
EXAMPLES OF PRODUCTS AVAILABLE
SURFACE MOUNTED SYSTEMS
Product:
SURFACE MOUNTED PORTABLE PUMP SYSTEM
Indudes:
PDI: Surface mounted double-acting posive displacement pump,
PV array mounted on mobile trolley, pre-wired with plug and socket
connections, d-c. electgniccontrol unit, riser pipe and intake filter.
Utility: Module, support, pumpset and hose.
Applications: Open channels, wells, mobile applications, low volume requirements,
low-medium head
MODEL
NO.
WA-f-f!3
PEAK
BP PDl
uti1itv
Product:
SURFACE MOUNTED PISTON PUMP
Indudes:
Surafce mounted piston pump, permanent magnet d.c. motor,
PV array with concentrating reflectors mounted on tracking
support structure, MPPT control unit
Applications: Low head, irrigation medium output
Product:
SURFACEMOUNTEDPRESSURISEDPUMPINGSYSTEM
Includes:
PV arrav. surface mounted oumowith oermanent maanet d.c. motor
and 1O&h battery, Jet ejector provides pressurised titer supply
Applications: Ooen wells rivers and boreholes with water source withln 7m
of ground level
I
I
MODEL
NO.
WATTS 1
PERFORMANCE
I
I
Q 6 kWh/m*/day
Low head
Hiah head
810108DS
610268DS
64
I
PRICE
1
6.1
EXPERIENCES
6.1.l .Why PV Ref riaerators?
Extensive immunization programmes are in progress throughout the developing
world in the fight against the six common communicable
diseases.
To be
effective, these programmes must provide immunization services to rural areas.
Solar power for refrigerators has great
potential for lower running costs, greater
reliability and longer working life than
kerosene
refrigerators
or diesel
generators. Over the past five years, at
least 3000
photovoltaic
medical
refrigerators have been installed.
of refrigeration for this, known as the
Vaccine “Cold Chain”, is a major
logistical undertaking in areas where
electricity supplies are non-existent or
erratic. The performance of refrigerators
fuelled by kerosene and bottled gas is
often inadequate.
Diesel powered
systems frequently suffer fuel supply
problems. Solar power is therefore of
great importance to health care.
All vaccines used have to be kept within
a limited temperature range throughout
transportation and storage. The provision
Figure 6.1 The Vaccine “Cold Chain”
65
6.1.2 mtfonal
Field Testina and Evaluation Pro-
Much work has been carried out on the field testing and evaluation of PV refrigerators,
the most significant being under the World Health Organization’s Expanded Programme
on Immunization and USAID/NASA/CDC Programmes. These have involved field
testing of over 50 systems in more than 30 countries - the first systems being instailed
in 1981.
Figure 6.2
Qne of more than 850 PV Refrigeration and / or Lightlng Systems being
Manufactured and Installed in Zaire
Field trials organised by the NASA Lewis Research Centre in the USA reported
favourable user reaction and that correct operating temperature was achieved for at
least 83% of the time. Reasons cited for temperature deviating outside the specified
limits were:
0 defective components - temperature controls, voltage regulators.
e excessive amounts of warm material being placed in the unit at one time.
@ incorrect setting of the thermostat.
6 shadowing of the array.
The performance of these early units exceeded the reliability of kerosene refrigerators
but was poor in comparison to recently installed systems. Correct operation for over
98% of the time is now routine.
66
6.1.3 Project Experience
Major programmes to utilize solar refrigerators are underway notably in:
Zaire - The Department of Public Health
and Social Affairs in Zaire, with the
technical and financial assistance of the
European Economic Community (EEC),
is carrying out a programme of installing
100 photovoltaic refrigerators (and 750
lighting systems) in rural hospitals and
health centres. This operation will equip
roughly 400 health establishments spread
out over more than 20% of Zaire’s
territory. A Zairian firm FNMA designed
and now produces the refrigerator
utilizing imported compressors and
batteries.
Mali - over six years of trials have
taken place in Mali leading to the
conclusion
by the Laborataire
de
I’Energie Solare that with periodic
maintenance
checks, the rate of
equipment failure is negligible.
Uganda - a project to install initially 100
solar refrigerators and eventually more
than 400 systems in Uganda is
underway.
Africa - Projects involving significant
numbers of solar refrigerators are also
now undeway in Chad, Ghana, Kenya,
Mozambique and Sudan.
User reaction has been good, and the
systems have demonstrated greater
reliability than kerosene fridges.
In
1986, the World Health Organization
undertook
an evaluation
of the
installations.
Their conclusions were
very supportive.
Pakistan - In the desert town of Diplo
in the Thar desert region of Sind
province, a solar refrigerator
was
installed by UNICEF in 1987. With the
enthusiastic support of the health centre
staff, the total installation time was less
than 5 hours. In addition to UNICEF,
other agencies such as the Aga Khan
Foundation are using solar refrigerators
in Pakistan.
Indonesia
: More than 100 solar
refrigerators are being installed in Sudan
as part of a world bank health
programme
Figure 6.3
PV Refrigerator Assembly in Zaire
(FNMA)
67
RELATIVE MERITS OF USING PV REFRIGERATORS
6.2
6.2.1 Advantages of PV Refrlgeratolg
Compared to kerosene or bottled gas fuelled refrigerators, PV systems have the
following advantages:
Improved vaccine storage facilities as a result of:
a
a
*
e
elimination of fuel supply problems
elimination of fuel quality problems
greater refrigerator reliability
better refrigerator performance (and temperature control).
Reduced running costs as a result of:
e
d)
+
m
a
elimination of kerosene fuel costs
elimination of kerosene transportation costs
reduced vaccine losses
lower refrigerator maintenance costs
reduced need for back-up refrigerators where there are fuel
supply or repair problems.
Cold chain management benefits due to:
longer equipment life (PV array 15 years, battery 5 years, refrigerator 10
years)
a
reduced logistical problems arising from non-availability
refrigerators and associated vaccine losses.
of working
The above operational advantages of introducing solar refrigerators into the cold chain
indicate that solar refrigerators can provide a more sustainable vaccine cold chain.
6.2.2 Bs
of PV refriaeratorg
Failure of a main component, such as
the compressor control unit, requires
repair or replacement
by skilled
technicians.
As each system is site specific, more
time is necessary for planning and
implementing
a project with solar
refrigerators.
User training dems”-’
overln-A’
6.2.3 Comparative Caste
A true comparison of solar refrigerators and comparable kerosene and bottled gas
fuelled refrigerators can only be made through a life cycle cost analysis. A solar
photovoltaic refrigerator is likely to cost around $3000 to $6000 and will cost more to
install than a kerosene unit.
vaccine solar refrigerators
are the
preferred option. Table 6.1 shows the
relative costs of utilizing a PV or
kerosene refrigerator in a health centre
in Pakistan, serving a population of
12,000 with a crude birth rate of 4.5%.
It can be seen that a PV refrigerator is
the most economic option.
A kerosene refrigerator will cost only
$600~$800 but will use 0.5 to 1 .O litres
of fuel per day, require frequent
maintenance and have a shorter life. In
general life cycle costs are approximately
the same for solar and kerosene
refrigerators, but because of their greater
reliability and resultant savings in wasted
KEROSENE
Rs
-
PHOTOVOLTAIC
Rs
Array (125 Wp - 15 yr life)
Battery (2400 Wh - 5 yr life)
Refrigerator
Installation Costs
10,400
2,880
13,047
5,107
22,409
7,219
Total Installed Cost
13,280
47,864
Annual Maintenance Costs
Annual Fuel Costs (3.08 Rs/Litre)
1,400
675
479
Annualised Refrigerator Life Cycle Cost
(ALCC)
5,579
8,894
Refrigerator Reliability/Availability
Potent Vaccine Doses Available
60%
3,600
97%
5,820
1.55
21,300
5.92
1.53
21,300
3.66
ALCC per potent vaccine dose
EPI Programme Cost per outlet
Programme Cost per Potent Vaccine Dose
.
Total Cost oer Effectrve Dose (Rs)
Table 6.1
Costs of Photovoltalcs vs Kerosene Refrigerators for Vaccine Storage On
Paklstan (6,000 Doses/year required at a Health Centre)
69
6.3
COMMERCIALLY AVAILABLE EQUIPMENT
6.3.1 The Technolosy
The Refrigerator
- Photovoltaic
refrigerators
operate on the same
principle
as normal compression
refrigerators but incorporate low voltage
(12 or 24 v) d.c. compressors and
motors, rather than mains voltage a.c,
types. A PV refrigerator has higher
levels of insulation around the storage
compartments
to maximise energy
efficiency, a battery bank for electricity
storage, a battery charge controller and
a compressor controller which converts
the power from the battery to a form
required by the compressor motor.
Figure 6.6 PV Array on Rural
Health Clinic
Charge Regulator - The regulator
maintains the power supply within the
current and voltage range tolerated by
the refrigerator and prevents overcharge
of the battery. Some models include an
audible alarm or warning light to signal
when battery voltage becomes low.
Lightning surge protection must be
provided for tropical areas.
Typical refrigerator components are
shown in Figure 6.6. Most refrigerators
include a freezer compartment for ice
Other systems have
pack freezing.
separate units to provide solely for
refrigeration or freezing. Sizes available
range between 10 and 200 litres of
vaccine storage capacity with ice
production rates of up to 5 kg per 24
hours.
Array and Support Structure - The
solar array can be for roof (Figure 6.5)
or ground mounting. The array size for
a refrigeration system is calculated to
meet the power requirements for the
proposed site. The typical requirement
is 150 to 200 Wp of photovoltaic
modules.
Batteries - The type most commonly
used are lead acid batteries. Long life,
deep cycle batteries are preferred. A
capacity to run the refrigerator for 5
days without sun is recommended.
Figure 6.6 A Typical Solar Refrigerator (R 86)
70
6.3.2 Performance
Vaccine refrigerators are required to maintain vaccine between +O% and +8% at
all times, In addition, there Is normally a requirement for a separate freezer
compartment to freeze ice packs which are used for transporting vaccines in
cold boxes.
The performance of a refrigerator or
freezer is dependent on the ambient
temperature, therefore specifications are
usually defined at 32OC and/or 43OC.
The following criteria are used to assess
performance:
a
internal temperature distribution and
variation within the permissible
range of +OaC to +8OC.
e
the rate of icepack freezing
kilograms per 24 hours.
a
holdover time during loss of power.
This is the length of time for which
the internal temperature of the
refrigerator will remain below 8%
when the power supply has been
disconnected.
in
For system
sizing,
the energy
consumption per 24 hours in kilowatt
hours, whilst freezing icepacks and/or
without icepack freezing is required.
The energy consumption
of a PV
vaccine refrigerator is typically 300 to
500 Watt hours per 24 hours for a 100
litre refrigerator without icepack freezing
and at +32OC ambient temperature. At
+43OC ambient tmperature and freezing 2
kg of icepacks per 24 hours, the energy
consumption of the same refrigerator
would rise to about 600 to 1200 Watt
hours per 24 hrurs. It is very important
not to overload a solar refrigerator as
this increases energy consumption
considerably.
vaccine
A good (well insulated)
refrigerator should be able to maintain
correct internal temperatures for at least
ten hours in the event of it being
disconnected from the battery and solar
array.
6.3.3 Costs
The output of a PV array will vary according to the location at which it is to be
installed and the refrigerator energy consumption will depend on local climate.
Therefore the size of the solar array, the battery storage capacity and hence system
cost will vary depending on location. Typical system costs are in the range of US
$3000-$6000 excluding transport and installation.
6.3.4 products
Availably
At the end of this chapter, product information sheets are listed presenting brief details
of some commercially available products. The World Health Organization, in its EPI
Technical Series, publishes a document entitled ‘The Cold Chain Product Information
Sheets”. This catalogues equipment which have undergone tests to verify the
performance is of a standard acceptable to the WHO and UNICEF. The document
may be obtained from:
The Cold Chain Unit, Expanded Programme
Organization, 1211 Geneva 27, Switzerland.
on Immunization,
World Health
PROCUREMENT
6.4
6.4.1 /iAssessing Requlrementg
The points below should be considered when estimating the required refrigerator
capacity. Full details are given in the WHO document EPI/CCIS/86.3 - “A Guide to
Estimating Capacity of Equipment for Storing and Transporting EPI Vaccines”.
It is necessary to delineate the functions required of the system to fulfill the
immunization programme. This should take account of:
0
the type of vaccine to be used and its required storage temperature
0
the population figure targeted for immunization in the area allowing
approximately 4 litres storage capacity to fully immunize 150 infants and
their mothers
a
the frequency at which vaccines are likely to be delivered
a
the requirements for icepack freezing (for use in cold boxes)
0
storage space required for other medical supplies, eg blood bags
e
likely future requirements for approximately 10 years.
From these can be determined:
0
vaccine storage capacity required
l
ice pack freezing capability required
6.4.2 Selection of Eauipmenj
Selection of the model of solar refrigerator should be made with regard to:
a
required vaccine storage capacity and ice production capability
m
cost competitiveness
0
operating experience of local health sector personnel with the type of
equipment being considered
a
the local availability of backup services for spares and repairs.
Some technical points to look for are:
a
thermostat position (this may be better concealed to prevent unauthorised
tampering) and indicators supplied
0
batteries - are they sealed? If not, will distilled water be available?
do they come with a lockable ventilated battery box or do they fit within
the refrigerator cabinet?
72
6.4.3 Placina the Order
When placing the order, the type of number of spare parts should be specified. The
recommended spare parts (per 10 systems) are given below.
QUANTR=Y/ 10 SYSTEMS
SPARE PARTS REQUIRED
Photovoltaic modules
Battery charge regulators
Battery sets
Array cables
Compressor or complete cooling unit, as
recommended by the manufacturer
Spare electronic control cards
Thermostat or temperature control cards
Condenser fans (if used)
1.
2.
3.
4.
5.
6.
7.
8.
3
3
2
Ensure also that instruction manuals for the user and technician are ordered for the
correct language for the country of use.
Purchase of comDlete svstem from WHO awroved suppliers alven in the WHO[
UNICEF Cold Chain Product Information Sheets is recommended,
IMPLEMENTATION
6.5
Documents are available from WHO, Geneva, which are of direct use in implementing
a solar refrigeration project. They include:
P4
WI
(8)
“A User’s Handbook for PV Refrigerators”
“Fault Finding and Repair of PV Refrigerators”
“Installation of PV Refrigerators”
“Instructor’s Notes for PV Refrigerators” (for training courses).
“Guide to Infrastructure requirements for PV Refrigerators”
Training courses for solar refrigerator technicians are periodically organised by WHO.
For information on these contact your local WHO office or WHO, Geneva.
6.5.1 bstallation
Ensure:
0
l
l
0
l
a
l
the solar array is not likely to be shaded
the solar array can be easily and safely cleaned
cable lengths are reduced to a minimum
the refrigerator is located in the coolest room of the clinic
there is good air circulation around the refrigerator
the sun does not shine on the refrigerator
the batteries are mounted in a well ventilated protective case
from the reach of children.
73
QUALIFIED REFRIGERATORS
Model
Country
BP Solar VR50
Dulas V50
Dulas I50
Electrolux RCW42
Electrolux RCW42
FNMA 75
NESTE - NAPS
Polar Products
SASA 60
SET KTI 80/24
Sunfrost RFV - 4
UM Tropic
U.K.
U.K.
U.K.
Luxembourg
Luxembourg
Zaire
Norway
USA
Australia
Germany
USA
Germany
Net Vaccine
Capacity (litres)
Gross Freezer
Volume (litres)
5
38
37
54
14
27
30
80
26
56
17.5
30
27
63
2
27
11
55
34
20
Noack Solar
Polar Products
Rand S
Solapak
Solarex
Telefunken
Soltech
Norway
USA
Netherlands
U.K.
USA
Germany
Belgium
APPROVED SYSTEM SUPPLIERS
Ansaldo
Budimex/FNMA
BP Solar
Chloride Solar
FNMA
Italsolar
Nest8 - NAPS
Table
Italy
Belguim
*
E:
Zairo
Italy
Norway
6.2 WHO Qualified Refrigerators and System Suppliers
74
,... ..
:‘: _-
I
,_
.-,
:
6.5.2 M&&&mfZ
Each day:
e
0
0
record the temperature in a log book each morning and afternoon
check the indicator lights for correct opera?ion
check the ventilation grill is not obstructed.
Each week:
check the freezer evaporator for build up of ice - defrost if more
than 5 mm thick
clean the solar array.
l
l
Each month:
a
a
clean the condenser and compressor with a soft brush
check for shadowing of array early in the morning and afternoon.
Six monthly:
l
a
a
check the level of acid electrolyte mixture in the batteries and top up
with distilled water if necessary
check all mountings, fixtures and cables for loose connections
check the lid seal - if there is a gap between the seal and lid or
refrigerator, replace it or glue it back on.
6.5.3 Fault Findina and Repak
It is outside the scope of this handbook to give detailed fault-finding procedures but:
If the refrigerator will not run:
a
9
check the fuse in the compressor controller
check the array cables
If the refrigerator is too warm but does run:
0
a
a
l
adjust the thermostat setting
check battery state of charge with a voltmeter or hydrometer
check the refrigerator is not overloaded or that there has been an
exceptional persistance of cloud
check the array is not shaded at times.
If the refrigerator is too cold:
l
0
adjust the thermostat
check the freezer/refrigerator thermal barrier is not damaged or missing.
75
EXAMPLES OF PRODUCTS AVAILABLE
VACCINE REFRIGERATORS
Product:
REFRIGERATOWICEPACK
FREEZERSYSTEM
Includes:
PVanay and support sbucture, cable battery, charge
regulator, BP VR50 refrigerator/freezer unit, controller
and alarms, instruction manual, tools and spares kit.
Peformance: @ 32 deg.C emblent temp.:
Ice pack freezing
Internal temp. range
Holdover time
2.6
2-7
4
kg/l0 hrs
deg. C
hours
38
5
likes
lltres
Vaccine Storage Capacity:
Refrigerator
Freezer
Price: US$ - depending on Insolation and ice needs
Product:
MS3:
Indudes:
PVarray (288Wp), support structure, FNMA 75 refrigerator
/freezer unit, minimum-maintenance (3OOAh+ 12OAh) batteries,
control unit. 8 x 8 Watt fluorescent lights, cables, accessories and
installationhandbook
COMBINED VACCINE REFRlGERATlON AND LIGHTING SYSTEM
Perfonnance:Q 5kWh/m2/Day, and 32%. ambient temperature:
Ice pack freezing
internal temp raige
Holdover time
2.7ka24ht.s
1 -7-c.
5.6 hrs
Vaccine Storage Capacity:
Refrfgerator
Freezer
27 litms
13 litres (gross)
Lighting:
Up to 3 hrs per night from each of the eight lights depending on
the refrigerator usage
Price:
u!3$5.740.00
Product:
REFRIGERATOFUICEPACK FREEZERSYSTEM
Indudes:
PV array (120 - 160 Wp) and support structure, cable,
batttery, charge regulator, FNMA 75 refrigerator/freezer
unit and instruction manual
Peformance: @p32 deg.C ambient temp.:
Ice pack freezing
Internal temp. range
Holdover time
2.7
l-7
5.6
kg/24 hrs
deg. c
27
13
libes
litres (gross)
hOUR?
Vacdne Storage Capacity:
Refrigerator
Freezer
Price: US$ - depending on insolation and ice needs
$3,500 - $5,000
76
EXAMPLES OF PRODUCTS AVAILABLE
VACCINE REFRIGERATORS
I
Product:
MOBILEPVVACCINEREFRIGERATORSYSTEM
Includes:
PV array (3 x 48Wp). special array structure for mobile use.
Sealed batteries in a special box, which includes charge
controller Mobile refrigerator CFM49,49 litre gross internal volume
I
Peformance: @ 32 deg.C ambient temp.:
Ice peck freezing
Internal temp. range
Holdover time
2.4
1-8
6 -8
kg/t2 hrs
deg. C (max)
hours
With std solar day of SkWh/m2Afay, it can operate
ccntinously
at ambient temperatures of upto 41 deg C (no or occasional
i-making), or up to 25 Deg C with 2.4kg icemaking every day
Vaccine Storage Capacity:
Refrfgerator
Freezer
20
7
litres
litres (gross)
Price: US!J
$4.720 (3 module system as above)
Product:
REFRIGERATOWFREEZERSYSTEM
Includes:
PV array (235 - 282 Wp) and stipport structure, cable,
battery, charge regulator, Polar Products refrigerator
freezer unit, manuals and thermometer
Performance: Q 32 deg. C ambient temperature:
Ice pack freezing
Internal temp range
Holdover time
2.1
4-7
4
Kg/ 24hrs
deg. C
hrs
80
20
litres
Vaccine Storage Capacity:
Refrigerator
Freezer
IittSS
Price: US8 depending on insolation and ice needs. Refer to supplier
Pmduct:
REFRIGERATIONSYSTEM
Indudes:
PV array (135 - !80 Wp) and support structure, cable,
batttery, charge regulator, with low battery alarm and
Electmlux RCW42DC refrigerator,
Pefonnance: Q 32 deg.C ambient temp.:
Ice pack freezing
Internal temp. range
Holdover time
2.1
3-6
4
kg/24 hrs
deg.C
hours
14
7
litres
litres (gross)
Vaccine Storage Capacity:
Refrigerator
Freezer
P&3:
us$
$3,200 - $4,296
77
EXAMPLES OF PRODUCTS AVAILABLE
VACCINE REFRIGERATORS
Product:
REFRIGERATOWFREEZERSYSTEM
Includes:
PV array (168 - 208 Wp) and support strutwe, cable, battery,
charge regulator, Polar Products refrlgomtor unit, manual,
and alarms
Pefomance: Q 32 deg.C ambient tamp.:
Ice pack freezing
Internal temp. range
Holdover time
2.1
4 -7
4
kg/l 2 hrs
deg. C (max)
hours
80
2oe
litres
litres (gross)
Vaccine Storage Capacity:
Refrigerator
Freezer
Prfce: US$
Depending on Insolation and ice needs
Refer to supder
Pmduct:
REFRIGERATORIFREEZERSYSTEM
Indudes:
PV array cable, battery, charge regulator, SET KT 180 (24V)
refrigerator/freezer unit two 1OOAhbatteries, array support
and instruction manual
Performerwe: Q 32 deg. C ambient temperature:
Ice pack freezing
Internal tamp range
Holdover time
2.4
l-8
3.9
kg 24hrs
deg. C
hrs
56
35
litres
litres (gross)
Vaccine Storage Capacity:
Refrigerator
Freezer
Price: US$
Depending on Insolation and Ice needs.
$2,600 - $3,400
Product:
VACCINE REFRIGERATOR SCS 20C
Indudes:
PV array (180 - 4OOWp) incl. support structure and
cabling, refrigerator/freezer, electronictemperature
regulator, lead acid battery, charge regulator
Pefomtance: Q 32 deg.C ambient temp.:
Ice pack freezing
Internal temp. range
Holdover time
2.4
2-7
3
kg&?4hrs
deg.C
hDUrS
56
55
litres
litres (gloss)
Vaccine Storage Capacity:
Refrfgerator
Freezer
Price: US$
Refer to supplier
78
7.1
EXPERIENCE
In terms of number of installations, lighting is presently the biggest appllcatlon of
photovoltaics with tens of thousands of units Installed worldwide.
They are
mainly used to provlde lighting for domestic or community buildings, such as
PV llghting Is also being Increasingly used for
schools or health centres.
security, street and tunnel Ilghtlng.
User experiences have been excellent
with increasing
demand for more
systems in the locality where a PV light
is installed. Specific examples of lighting
experience include:
Zaire - Here the Departement de la
Sante Publique has been installing 850
PV lighting systems in health centtes
and clinics, in conjunction with 100
refrigerators.
One side effect of the
project is that the provision of lighting
has given medical staff a significant
incentive to work or to continue to work
in rural areas, thereby contributing to
improved health care services.
French Polynesia - Where mere than
1000 homes on the islands have been
PV powered with anything from 2 to 20
roof mounted modules. The scheme
had a 25% grant from the government
with the remainder coming from private
resources or loans. As a commercial
project, the extent of uptake has been
high with favourable responses. The
users reported PV to be less expensive
than diesel.
Dominican Republic - Approximately
70% of the rural population have no
access to the utility grid in the
Dominican Republic.
In 1984, a PV
based rural electrification project was set
up, using USAID seed money to install
PV lighting systems. The income from
charging for these systems has allowed
further equipment to be bought and the
project is now self-financing, with more
than 1000 systems now installed.
Figure 7.1
Thailand - In many villages in Thailand,
lighting
is achieved
by sending
automotive batteries into towns for
charging and then running 12 volt lamps
from the batteries. With Japanese seed
funding,
the
ministry
of Rural
Electrifications has installed 500 Wp PV
battery charging stations,
Due to
savings on replacement battery, and
transportation costs, a PV system will
pay for itself in three years or less.
PV Light Assembly in
Mongolia
Lighting is taken for granted in the
industrial countries and in most of the
urban areas of developing countries. In
areas without access to mains electricity,
lighting is restricted to candles or
kerosene lamps. Torches (or flashlights) powered by expensive, throw-away
dry-cells are used intermittently as a
portable source of light.
79
7.2
RELATIVE MERITS
Common means of lighting where mains electricity does not exist, or is impractical,
include:
candle
kerosene lamp
kerosene hurrican lamp
diesel generator for electric lamps
@ automotive batteries for electric
lamps
l
l
l
l
Kerosene lamps and candles have the
obvious drawback of producing only a
low light output and being a fire hazard.
They do, however, have the lowest
purchase price, but are expensive and
inefficient to run. In comparison the
convenience,
relative
safety and
brightness of the electric light is
generaliy accepted as preferable. The
use of fluorescent lamps rather than
filament lamps is necessary for efficient
use of the electricity.
Figure 7.2
PV Lighting Kit
The output and power use efficiency of lamps are summarised in Table 7.1.
TYPE OF LIGHT
ENERGY SOURCE
candle
kerosenelamp (wick)
hurricanelamp (wick)
oil lamp (mantle)
gas lamp (mantle)
filamentlamp
3W
filamentlamp
4ow
flourescent
15w
mercury
sodiumSOX
2ow
80W
35w
INTENSITY
(LUMENS)
parraffinwax
kerosene
kerosene
Kerosene
butane
dry batteries
POWER USE
EFFICIENCY
(LUMENDiVAn)
1
.a1
10
.l
.2
100
electricity
electricity
electricity
electricity
electricity
1000
1
1000
10
1
3
400
600
1000
3200
4500
40
50
40
128
Table 7.1 Lamps: Power and Eff iclency
80
10
USE
PV?
/:
NO
NO
NO
NO
NO
YES
YES
YES
YES
The relative
photovoltaics
merits of providing light by diesel
is given in Table 7.2.
System
Diesel
Generators
Automotive
Battery
Recharging
generators,
battery
recharging
Advantages
Disadvantages
(b widespread operating
and maintenance
experience
l creates noise and fume pollution
pollution
0 moderate capital
cost
0 require a reliable
fuel supply
l easy to install
a high running costs
0 can be combined
power supply for
additional uses
@ high maintenance costs
0 low capital cost
8 relies on transporting
to charging stations
and
l low operating efficiency often achieved
0 easy to install
l high charging fees often apply
0 batteries locally
available
Photovoltaics
Table 7.2
l short battery lifetimes
0 high reliability
l involves the introduction of a new and
often poorly understood technology
l low maintenance
requirements
l high capital cost
l low running costs
0 spares not widely available
l suited to most locations
@ not physically robust so
vulnerable to damage
l long life expectancy
for main components
l specialised batteries
not widely available
Comparison
of Power Sources for Electric Lightlng
Even though individual PV lamps may be more expensive to buy initially, in general
they are cost-effective on a life-cycle cost basis, compared to kerosene lighting and in
addition provide a better quality light. The relative economics of PV versus kerosene
lighting is shown in Table 7.3.
Kerosene Pressure Lamp = 2.8 litres
Hurricane lamp
Fluorescent Lamps
2x8W
=64Wh
But battery charging efficiency is only
80%, hence requirements
=80Wh
Weekly Energy Costs:
Kerosene at $0.3 Litre
Average Daily Insolation 5 kWh/m2
Required Array Size 18 Wp
$150.00
Annual Total
Capital costs:
Pressure lamp
Hurricane Lamp
Battery (100 Ah x 12 v)
Flourescent Lights (2)
Voltage Regulator
$140.00
$ 34.00
$ 50.00
$374.00
Total
Recurrent Costs:
Recurrent Co&:
Present Worth of Fuel
Discounted at 10% over
15 yrs = $62.4 x 7.61
Battery (replace 5 years) PW = $141 .OO
Tubes (replace 2 yrs) PW
= $ 28.00
Voltage Regulator
PW = $ 24.00
Lamps are replaced every 2 years.
Present Worth Of Replacements
Total Life Cycle Costs (15 years)
= $25.00 + $475.00 + $95.00
Annualised LC Cost
Total Life Cycle Costs (15 years)
= $374.00 + $193.00
= $567.00
Annualised LC Cost
= $ 74.00
Table 7.3 Life Cycle Cost Comparison of Conventional and PV System
The use of photovoltaic systems for lighting should therefore be considered where:
e
kerosene fuel supplies are erratic or expensive;
l
good quality lighting is required (eg, in schools and home industries such as needlework)
l
solar irradiation levels are moderate to high (~3 kWh/m*/day).
82
COMMERCIALLY AVAILABLE EQUIPMENT
7.3
7.3.1 lions
PV lighting systems can broadly be categorised as suitable for use in one of the
following applications:
l
0
l
domestic or community building lighting (homes, schools, community centres,
mosques, churches)
street, area or security lighting (car parks, industrial areas, warehouses)
portable light units.
Specialised commercial lighting such as terrain avoidance lighting for aircraft and other
navigational aids are briefly described in Chapter 9.
7.3.2 Jhe Technoloay
The main difference between photovoltaic and other electric lighting systems Is
that a d.c. supply is produced, thus the use of d.c. lights is preferred. A.c.
lights may be used by Incorporating an inverter into the system, but this will
introduce significant addltlonal electrical losses, hence a larger array will be
needed.
Many d.c. lights are now commercially
produced, but the most efficient in terms
of light output (lumens) per watt of
power consumed are low voltage
fluorescent tubes.
If these are not
available, conversion of ax. tubes is
possible by changing the a.c. starter and
ballast components to produce a d.c.
version.
Figure 7.3 shows common
types of d.c. lights for use with PV
systems.
Domestic or Community Building Lighting
Usually systems are dedicated for use in
one building, normally providing one or
two lights, but often up to about eight
lights. Complete system packages are
available, comprising of:
0 PV array including one or two
modules and mounting structure;
l
fluorescent lights usually 8 W, 13 W,
16 W or 20 W;
0 battery
l
charge control regulator;
l
cabling, installation tools.
Figure 7.3 12 Volt Fluorescent
lamps
83
Figure 7.4 Typical PV Lighting System
Street, Area or Security Lightlng
Specific systems, usually pole mounted,
have been developed for this purpose
and typically include:
8
PV modules; (typically 40 - 120 Wp)
8
support structure
mounted);
8
battery;
8
lamp - generally d.c. fluorescent
tubes, low pressure sodium or
mercury vapour lamps;
8
controller - including charge regulation
and optional automatic on/off switching
(set by timer or light sensitive switch).
- (usually
pole-
Figure 7.5
Area or Security Light
Figure 7.6
Portable Light with
Integral PV Cells
Portable Llghting Systems
Small systems have been designed to
be easily carried by hand. One model
developed with user acceptability in mind
has a hand lamp based on the
conventional kerosene lamp design, but
fitted internally with a fluorescent tube.
Many systems combine PV module,
battery and lamp in an integral unit,
whilst others have a detachable PV
module.
Typical specifications:
array size:
lamp:
performance:
4-10 wp
4-8 Watts
3-5 hours/day
84
7.3.3
costg
Typical costs for the three applications of lighting considered are shown below. It
should be noted that in all cases, although the PV option is higher capital cost, the
life cycle cost is lower than in comparison to kerosene systems.
INITIAL CAPITAL
APPLlCATlONS
Home or Community
1 x 20 Wp PV Module
2 x 8 Wp fluor. lamps
Security Light
2 x 40 Wp PV module
Portable Light
5 Wp of PV module
15 Wh sealed battery
Figure
7.7
Portable
PV Lighting
Systems
85
(Suryovonics,
India)
73.4
proc&cts Available
There are many types of PV lighting products available. Details of some typical
products are given at the end for this section. In fact, almost all the suppliers listed
in this book are able to supply lighting systems.
7.4
PROCUREMENT
7.4.1 Assesslna
Require-
The requirements of a lighting system should be appraised in terms of:
a quality and intensity of light required
l number of lights and their proposed location
9 daily hours of operation
a the anticipated pattern of use of the lighting system
0 how requirements may change and future demands.
It is preferable to over-estimate demand but financial resources often prove to be the
limiting factor. It is important to look at the overall system and operating procedure
when designing the system configuration, eg:
if several lights are required in dispersed locations, it may be better to use
several small systems rather than one large;
@ portabiiity of lights may be a requirement;
l automatic switching of outside lighting or timers may be required.
l
l
A pro-forma sheet for determining the approximate system sizing required is given in
Table 7.6. An example is shown below in Table 7.5. If specific component
efficiencies are not available, battery and regulator efficiencies of 0.8 and 0.9
respectively should be used.
Requirements:
Insolationlevel:
Systemnominalvoltage:
MaximumBatteryDischarge
=
t
=
=
one 8 W lamp plus one 20 W lamp for 4 hoursper day
4 kWhfm2/day
12v
20%
Energyconsumption
=
=
(8Wx 4h) + (20 W x 4h)
1j 2 WWday
Array Load
r
x
=
112/ (batteryand regulatorefficiency)
112/(0.8x 0.9)
155Wh/day
Array Size
m
z
=
Array Load/(lnsolationx mismatchfactor)
155/ (4 x 0.85)
46 Wp
BatterySize
=:
Dailylamp consumption
Max.dischargex nominalvoltage
i
x
112/(0.20 x 12)
47 Ah
Table 7.5
Example of Simple System Sizing
86
.
SIZING PV LIGHTING SYSTEMS
........................
1.
How many and what size of lights are required?
2..
How many hours of lighting are required each day? .........................
3.
Calculate daily energy consumption:
a)
W
c)
............ lamps at
.....*...... lamps at
............ lamps at
........... Watts, for
........... Watts, for
........... Watts, for
........... hours = ......... Wh
........... hours = ......... Wh
........... hours = ......... Wh
Total daily energy consumption = ..... Wh
4.
Calculate PV array daily energy load:
Array load
=
daily energy consumption
battery effic. x charge regulator effic.
=
.......*........ Wh
5.
What is the average daily insolation in the lease sunny month?
6.
Calculate PV array size required from:
array size
7.
=
Array load
insolation x mismatch factor (mismatch factor = 0.85)
Calculate minimum battery capacity
Battery Capacity =
=
Table 7.6
daily energy consumption
max. allOWmle Urscharge (%) x nominal voltage
.......... Ah
Pro Forma for PV Llghtlng Systems
67
.’
I
7.4.2 Eg&mqIt
SelectlQn
Unless there is good reason for doing otherwise, equipment should be purchased as a
complete package from one supplier. The components included in the package will
vary from supplier to supplier. Points to look for when comparing systems include:
l
array size in Wp;
l
number of lights provided;
l
the output (in lumens) of the lights per Watt of energy consumption and
estimated hours of use per day;
e if switching for the lights is included;
e type of support structure, if included, and its suitability for proposed site;
l
ease of installation with toots and facilities available;
@ battery capacity in ampere hours;
0 maximum permissible depth of discharge of the battery;
0 controller functions (automatic load disconnection at low battery voltage is
recommended and lighting protection is essential for tropical regions);
0 sufficient cable lengths and wall fixings.
7.5
IMPLEMENTATION
7.5.1 )nstallatlo~
PV lighting systems are generally easy to install because normally they only require
one or two modules, which may be roof mounted, pole mounted, or, for small systems,
hung on walls or porches. The module should face the equator and be tilted at an
angle recommended by the supplier (approximately latitude plus 10 degrees).
This ease of installation presents one major problem in that they are easy to remove
and hence vulnerable to theft (if not integral in a lantern). Except for portable systems,
a secure roof mounting fixture is thus preferred.
The battery should be located in a ventilated locked battery box. It should be out of
the reach of children. This is very important in a domestic installation.
7.5.2 Maintenance
The principal maintenance requirements will be to:
0 clean the PV module(s) each week (if accessible)
0 check cables and connections weekly
F check the battery electrolyte level monthly.
If the battery electrolyte requires topping up, it is essential to use distilled water.
7.5.3 Fault Flndlna and Rew&
If the light does not work at all:
0 check the fluorescent tube on another 12 volt battery.
If the light comes on but for fewer hours than expected:
l
check the battery state of charge
0 check for loose connections.
If the battery is completely discharged, check the fuse in the charge regulator (if fitted).
The battery may be recharged by disconnecting the lamp for a few days (to allow the
battery to be recharged by the modules). Alternately, the battery can be taken to the
nearest town for commercial recharging.
89
EXAMPLES OF PRODUCTS AVAILABLE
DQMESTIC AND COMMUNITY LIGHTING SYSTEMS
Product:
DOMESTlCOR COMMUNITY LIGHTING
Indudes:
A complete kit with self regulating 4OWp PV module, support
structure for roof or ground mounting, 4 x 6W fluorescent
lights with 10m of cable, pre-wired plug and socket connections,
distribution box, installation fasteningsand instruction manual
MODELNO.
1 ARRAY Wp
40
d
1 PRICE U.S.$
16hr @ 5kWWm2id
560
Product:
DOMESTICOR COMMUNITY UGHTING
Indudes:
Acomplete package with 45W module, support structure for roof
or ground munting, 3 x 15W and 1 x 9W lights, 10m of cable,
acoessorles and manual
I?
MODEL
NO.
ARRAY Wp
L-PAK
I
1 LIGHTHOURS/DAY
45
LIGHT HOURS/DAY
PRICE U.S. $
4.5 hrs @ 5kWh Im2Iday
6.0 hrs @ 7kWh/m*/day
insolation
720
Product:
DOMESTlCANDCOMMUNlTYLlGHTINGSYSTEM
Indudes:
Self regulating 49 Wp PV module, support structure, 105Ah battery
and home lighting kit comprising 3 x 6W fluorescent lights,
distribution box with three light switches and low voltage cut our,
plugs, connectors, 2 x 5m cables, 3 x 10m cables, 1.5m battery
cable, fuse, terminals, clips and screws
Product:
DOMESTICOR COMMUNITY LlGHTfNG SYSTEM
Includes:
One PV module, control unit, 4 x fluorescent lamps,
!oOAh battery, Installation fittings and handbook
EXAMPLES OF PRODUCTS AVAILABLE
DOMESTIC AND COMMUNITY LIGHTING SYSTEMS
DOMESTICLIGHTINGSYSTEM
Complete kit with PV module, supportstructure,2 x 8 W fluorescent
lights, 15m cables, 12v, 50Ah battery, switch, junction box, fittings
and manual
Product:
COMMUNITY BUILDING LIGHTING SYSTEM
Indudes:
PV Module, structure, battery, controller 2 x 20W fluorescent
lamps and manual
MODEL
NO.
ARRAY Wp
KLK 41
PERFORMANCE
4 hrs @ 4kWNm2/day
7 hrs @ 5kWNm2Iday
8 hrs @p6kWhlm2/day
96
PRICE U.S. $
2,500
Product:
LIGHTING SYSTEMS
Indudes:
PV module s mounting brackets, control unit, battery,
switches and cables plus 4 x 13W fluorescent lamps and
one 1OW spotlamp gQuu&k
MODEL
NO.
1 ARRAY Wp
1
LK 1
1 module
LK2
2 modules
LK3
3 modules
48
180 Wh available per day
630
86
360 Wh available per day
1050
540 Wh available per day
1475
144
LIGHT HOURS/DAY
1 PRICE U.S.$
t-i
Product:
DOMESTICOR COMMUNITY LlGHTfNG SYSTEM
Indudes:
Modules, support structure, regulator, 60Ah battery and
enclosure, 1058 Lumen fluorescent lamp(s)
MODEL NO.
A53-1 lamp
A106-1 lamp
B106-21amps
ARRA” Wp
53
106
106
LIGHT HOURS /DAY
1 PR;CEl
@ 5 kWhlm2/d insolation
4hrs
8hrs
4hrs
800
1,300
1,400
91
-
EXAMPLES OF PRODUCTS AVAILABLE
STREET AND AREA LIGHTS
Product:
STREET LIGHTING SYSTEM
Indudes:
2 PV rodules, 4.5m pole, 200 Ah battery, electronic control unit,
8W or 35W sodium lamps
I
MODEL NO.
LIGHTHOURSIDAY
ARRAY Wp
SL 90
.SLllO
90
110
10 hrs @ 4kWh/m21d
10 hrs Q 4kWhlm*/d
PRICE U.S. $
2,765
3,259
i
,
I
Product:
STREET LIGHTING SYSTEM
Indudes:
2 PV modules, 5 m pole. 100 Ah battery, electronic control unit,
18W sodium lamp.
MODEL
NO.
ARRAY Wp
PERFORMANCE
96
12 hrs Q 5kWhlm*/day
4080
;._‘T
PRICE U.S. $
2,289
Product:
SOLAR LAMP POST
!ndudes:
2 PV modules, 3.5m aluminium pole, 200Ah battery electronic
control unit, 11W fluorescent lampor 18W sodium on LP 90-s)
MODEL NO.
LP45
LP90
LPSO-s
I
EXAMPLES OF PRODUCTS AVAILABLE
PORTABLE LAMPS
Product:
PORTABLE
LANTERN
Includes:
10 Wp PV panel, nickel-cadmium battery and 8W fluorescent
light all in a moulded plastic case. The total weight is 4 kg
MODEL
NO.
ARRAY
LIGHT HOURS I DAY
SL48
10
5.0 Q 7kWNm2/d
PRICE
U.S. $
300
Product:
PORTABLE
LANTERN
Includes:
9W PV moldule, 9w fluorescent lamp and battery in conventionally
styled lantern with rugged case
MODEL
NO.
ARRAY Wp
LIGHT HOURS/DAY
PRICE U.S. $
AFRICA
9
5 hours @ 5kWNm*/day
130
Product:
PORTABLE
LANTERN
Indudes:
Detachable 5W PV module, light and battery in robust container
with 12V output socket for other devices
1
MODEL NO.
BEDOUIN
ARRAY Wp
5
LIGHT HOURS DAY
PRICE U.S. $
5hrs @ 3.3 kWh/m2/d
170
Product:
PORTABLE
LAMP
Includes:
10 Wp PV module, 6Ah battery with charge controller and two
flourescent lamps In a conventlnally styled lantern
\
MODEL NO.
lAntern
ARRAY Wp
10
LIGHT HOURS / DAY
4-8
PRICE U.S. $
Hours
309
93
0.1
EXPERIENCE
.
Small scale communications
systems can play an important role in rural
development, those of most relevance are radio transceivers, radio telephone
links, radio receivers, community television and public address systems.
To
operate they need a small, but reliable power supply. Photovoltaics is an ideal
A significant number of systems have
power supply for these applications.
already been installed almost always with good user responses.
In fact, the
level of use of the equipment has often far exceeded expectations.
Specific examples include:The Jungle
Aviation
and Radio
Service (JARS):
USA has shipped
more than 1000 PV systems to
development workers throughout the
developing world.
Panama: At Boca del Monte, a radio
station is powered by a 180 Wpk array.
The cost of the PV modules, transmitter,
studio equipment, fan and lights was
less than $3000.
Ll beri a: At ELRB radio station in
Monrovia, a 360 Wp PV array provides
power for lighting, ventilation and standby
transmitters.
Figure 8.1
Indla:
More than 250 community
television systms have been installed in
India, under the National Solar PV
Energy Demonstration
Programme.
b,,ny of the systems were combined
with community lighting to provide a
range of educational activities.
Gambia:
In the Gambia, VHF
transceivers are being used to provide
communication of urgent information
between health centres.
Pan Africa: The Panaftel telecommunications network has seen increased
availability since the introduction of PV
on key repeators.
Community Centre with PV Operated Television
8.2
RELATIVE MERITS
PV has several attributes which make it particularly suited to telecommunications
applications. They include:
l
reliability - PV systems are the most reliable power source;
l
size - PV systems can be sized to provide the relatively small amounts required
for transmission and receipt of signals;
l
unattended operation - PV systems will operate for long periods with little or no
maintenance;
8.3
COMMERCIALLY AVAILABLE SYSTEMS
8.3.1 The
Suppliers are packaging systems for use in a range of applications, namely:
Radio receivers - radios of 1.5 to 20
Watts output are available. The solar
module typically
l-2 Wp may be
incorporated into the side of the radio or
more commonly a separate module is
used with connection via an extendible
lead. The battery and charge regulator
are integrated into the radio.
Television receivers - comprising array,
batteries, charge regulator and TV.
Public address loud speaker systems pole mounted array and loud speaker
with battery, charge controller, amplifier
and microphone.
Radio Transceivers - typical systems
incorporate a 100 W transmitter, 30-50
Wp PV array, 105 Ah 12 volt battery
and transceiver equipment. The solar
array is sometimes pole mounted on the
antennae of the transmitter.
Figure 8.2 PV Powered F?adlo
Telephone System
Due to the wide range of different receivers and transmitters available or specified by
users, it is common for PV companies to offer solar powered battery charging systems
suitable for 12 Volt telecommunication equipment.
95
8.3.2 Costa
Typical complete system costs are given in Table 8.1.
System
Performance
Radio:
1.5 Watts output
20 Watts output
Transceiver:
TV System:
Public Address System:
100 Watts
100 Watts
Price $
75
500
3000
2000
3000
Table 8.1 Typical Costs of Small PV Telecommunlcatlons
Systems
PROCUREMENT
8.4
8.4.1 Assesslna RequlrementS
This should principally cover two areas, the telecommunication functions required of the
equipment, taking account of likely changes in future needs and the daily usage levels
in operating hours per day and number of users.
It should be noted that some equipment will have different power consumption levels
when receiving, transmitting and on standby. Hence, if it is necessary to source the
telecommunications equipment separately from the photovoltaic power supply, careful
consideration of daily energy consumption should be made.
Having determined the average daily energy load in watt-hours, the PV array and
battery sizes can be determined in the same manner as for a lighting load (steps 6
and 7 on Table 7.6).
IMPLEMENTATION
8.5
8.5
P=~llatioq
The principal considerations to be given which are specific to the installation of PV
powered telecommunication equipment are:
0
adequate lightning protection for the telecommunications equipment;
a
ensure the antennae of the transmitter (or anything else) does not
shade the array.
96
Maintenance
The recommended maintenance of PV powered telecommunications equipment includes:
0 clean the solar array weekly (if accessible)
l check battery electrolyte level monthly and top up with distilled water,
if necessary.
Fault Findina and Repair
The suggested fault finding and repair of the PV array and battery power supply is the
same as that described for lighting systems in Section 7.5 of this guide.
Figure 8.3
PV Telecommunications
97
Repeater (NAPS - Sweden)
EXAMPLES OF PRODUCTS AVAILABLE
T.V. VIDEO AND BROADCASTERS
Product:
SOLAR POWERED TRANSCEIVER
Indudes:
30 W SSB transmitter and receiver, 2 channels. steel case,
microphone and 1OWp PV mOdUl8 for 6Ah battery pack.
Applications:
Health centres, schools and outposts
,
MODEL NO.
10
69248
PRICE U.S. $
PERFORMA%CE
ARRAY Wp
3,500
30W SSBTRANSMITTER
Product:
LOUD SPEAKER
SYSTEM
includes:
PV module, control unit with Charge regulator battery, amplifier
(2OW), microphone, cassette player and two 15W Speak8rS
Applications:
Schools, parks, mosques and campsites
Product:
EDUCATION
Includes:
PV mOdUl8S,control unit, 3 fluorescent lights, TV receiver,
Video recorder, inverter and cabling, battery (150 Ah)
Applications:
Remote educational viewing
MODEL
NO.
Array Wp
I
PRICE (USD)
PERFORMANCE
96
EC-2
SYSTEM
360 whlday aVallabl8
I
2,160
I
I
TV SYSTEM
PVarray, charge regulator, t8l8tiSiOn, battery, module SUppOrt
98
9.1
INTRODUCTION
Photovoltaics can be used as a power source whenever small amounts of energy are
required in a rural or remote location. The range of applications are thus numerous.
Those of principal interest to development workers are described here.
9.2
WATER TREATMENT
Water Purification
Desalination
In ma,ny parts of the world, drinking
water is taken from polluted water
sources. In fact, it is estimated that
more than half the illnesses in the
developing world are attributable to water
related infection.
PV Desalination equipment to remove
Ihe salt from water is available
commercially, but costs are very high
due to the high energy consumption of
the desalination process.
Desalination is of particular interest to
island communities with no fresh water
sources.
Thus demonstrations have
been set up in the Asia and Pacific
regions. In Japan a 25 kWp system is
installed on Ohshima Island where
approximately 5 cubic metres per day of
clean water is produced, from the sea
water. The salt content is reduced from
35,GO0 mg/!itre to 400 mg/litre.
Solar powered water treatment plants are
in operation in Kenya, Nigeria, Indonesia
and several other countries. Although
chemical
dosing
and ultraviolet
sterikzation are technically feasible
practices, a simpler approach is to
combine a solar-powered water pump
with slow-sand filtration where inany of
the components, particularly the storage
and settlement tanks, can be obtained
and assembled locally. Such installations
are found in Indonesia, Kenya and
Nigeria
CXirer installations of PV desalination can
be found in Austrialia, Indonesia and the
Middle East.
Figure 9.1 PV Water Purification Plant in Nigeria (Satec)
99
AGRlCULTURAL APPLICATIONS
9.3
In addition to irrigation pumping covered
in Chapter 5, PV can be used for:
0
l
a
l
Within the fisheries industries,
principal applications for PV are:
A PV powered grain mill has been
operatin sijcs>ssfuIly for eight years in
Faso. It forms ,\art of
Tangays: ,C)JUrzi;ii?
a 3.6 k-‘&p ?V system whicn also
includes a water pump. The overall
availability has been reported as over
A similar unit is operating
909c.
successfully in Tanfa, Mali. PV powered
grain mills are not a commercially
available “off-the-shelf” product.
the
0 shore-based navigational aids
for fishing boats;
0 lights on fishing boats:
l aeration and circulation pumps
at fish farms;
l ice production for transporting
fish;
0 insect traps.
electrified cattle fencing
grain milling
produce cooling.
freeze protection in stock
tanks
PV powered electric fence systems are
in widespread use with several thousand
systems installed. A small PV array of
10 Wp with battery can electrify several
kilometres of fence.
FISHERIES APPLICATIONS
9.4
The main products being sold for the
fisheries
industry
are lights and
circulation pumps which can be used in
fish farms. Suspended lights are used
to attract insects thereby providing a
concentration of insects for the fish to
catch.
Ice production requires iarge amounts of
energy and hence few photovoltaic
products are available commercially. A
PV-diesel hybrid system has been
installed on the Red Sea Coast in Egypt
for demonstration purposes.
PV powered cold stores are a rarity with
only a few demonstration units operating
such as the 45 kWp 275 m3 cold store
on Giglio Islano, Italy. Generally, these
units are also not “off-the-shelf” items
and are very expensive because of the
high energy consumption.
9.5
TRANSPORT AIDS
has
become
well
Photovoltaics
established for powering transport aids
particularly in:
l
l
l
l
0
e
0
0
0
a
railway crossings and
signalling
obstacle lights
terrain avoidance lights
navigational buoys
navigational lights on coasts
runway lights
highway signalling
tunnel lighting
navigational lights
emergency phones
In Zambia and Zimbabwe, photovoltaics
are used for railway signalling and
communications.
The Sudan Civil
Aviation Authortity uses PV power
navigation aid equipment in Sudan:
Figure 9.2 PV Powered Electrical
Fencing
100
9.7
CORROSION
SYSTEMS
PROTECTION
Photovoltaics has been utilised in many
developing countries to protect steelwork
from corrosion. In Pakistan, PV protects
pipelines in the Badin gas fields. In
China, lock gates are protected by PV
and in India PV is used for off-shore
platform protection. Photovoltaics is also
being used to protected well-heads in
n;any oil and gas fields and has recently
been applied to the protection of bridge
structures.
9.8
Several domestic appliances can now be
obtained to operate from a 12 volt
power supply and thus are suitable for a
solar-powered battery charging system.
In addition to lighting covered in chapter
7, these include:
Figure 9.3 Rural Airfield Lighting
(Total Energie)
circulation pumps for solar water
heating systems
domestic refrigerators
PV fan powered evaporative coolers
fans and ventilation systems
television, radios and video
machines
air compressors
chain saws, drills, soldering irons
and other tools.
Of particular relevance to development
workers are the new range of runway
lighting and airfield equip-ernt such as
illuminated windsocks f,:: ;ise at small
airfields.
Solar power is recognised as the best
option for off-shore navigational aids
because the need to make refuelling
visits is thus eliminated. Not only are
these devices used in the equatorial
countries, but also throughout the coast
of Europe and North America, even at
high latitudes. Some 3000 systems are
installed in Canada.
9.6
DOMESTIC APPLIANCES
It is important, when selecting any of
these appliances, to consider its rated
power consumption. Equipment with the
lowest power consumption is preferred to
minimise the load on the PV system.
SECURITY SYSTEMS
As described in Chapter 7, the total
daily load of all appliances should be
calculated in watt-hours to determine the
PV array and battery size required.
Alternatively, for a given PV array and
battery combination, it is possible to
calculate the maximum time available to
operate the appliances for a particular
location and season.
Photovoltaics is used to power both
lighting and also remote alarm systems
using infra-red detectors. In Pakistan, a
PV alarm system in use at a rural
agricultural engineering training centre
successfully alerted a night watchman
that an intruder had entered the area
where expensive agricultural equipment
was stored (including PV pumps!).
101
EXAMPLES OF PRODUCTS AVAILABLE
WATER TREATMENT SYSTEMS
Product:
SAND FILTRATION WATERTREATMENT
SYSTEM
Description:
A PV pump lifts water which feeds through a slow sand
filter plant providing clean water to W.H.0 standards.
System supplied ready to assemble
indudes:
PV pumping unit, raw water storage tank, filtration tank,
clean water tank, control unit
PRICE U.S. $
WATER OUTPUT &/day
MODEL NO.
Refer
to
Supplier
12.5
25
50
BPP 250
BPP 500
BPP 1000
Product:
WATERTREATMENTSYSTEM
Description:
A containerised (Wasoi) water treatment system of sand
filtration and ultra-violet light sterilisation
Indudes:
PV pumping unit, sand and carbon filters, U.V. sterilizer, clean
water storage tank, batteries, controller, dlstributlon system
MODEL
r---
A:Wp
1 WATE(RRrn,
/ PRl;gE53.$
/
HOME POWER (A.C.) SYSTEMS
Product:
HOME UTILITY KIT (22OV, 50Hz)
Indudes:
4PV modules, charge contmller, 300 VA inverter. 78 Ah battery,
support structures and wiring.
Applications:
Where a.c power is required
MODEL
NO.
Utility Klt
I
supplier
102
I
.’
EXAMPLES OF PRODUCTS AVAILABLE
AGRICULTURAL SYSTEMS
Product:
ELECTRIC FENCE
indudes:
PV module, battery, fence electrifer support structure, cables
Applications:
Llvestockfencing
MODEL
NO.
ARRAY Wp
PERFORMANCE
for 1Okm fence
9
EF
PRICE
U.S. $
380
Product:
ELECTRIC FENCING UNIT
Description:
A range of electric fencing system;
of locations
Includes:
Pole Mounted PV module, fence energiser
sealed battery and voltmeter display
MODEL
NO.
r use In a variety
PERFORMANCE
PRICE U.S. $
I
W4OOOGNi
For medium -high sunshine
areas, larger fences .
W4000 CNI
refer
to
supplier
For abundent sunshine areas
smaller fexes.
Product:
ELECTRIC FENCE
includes:
PV module, battery, fence electrifier for (30W) support structure,
cables
MODEL NO.
346
ARRA’! Wp
30
PERFORMANCE
PRICE U.S. $
for 40km of fence
990
PIdUCt:
STOCK TANK ICE BREAKER
Indudes:
PV module, module mount, pipe. pole air lift pump. nozzle,
endosure.
Applications:
Stock tank and trough ice breaking
MODEL NO.
l?aicer
ARRAY Wp
16
PERFORMANCE
PRICE U.S. $
up to 60 cm6 ice prevented
650
103
EXAMPLES OF PRODUCTS AVAILABLE
MISCELLANEOUS
rI
Product:
EDUCATIONALPRODUCTS
Indudes:
Ranges of kits, cells, small motors, fans, battery chargers, clock,
elc for school projects
Product:
EXTRACTOR FANS
Description:
An extractor fan unit with integral PV ceil for surface mounting
in glass or wail structure. Complete unit ready for installation
Automatic or manual operation. Optional battery for night time
U68.
MODEL
PRICE U.S. $
output alr c.hanges/day
I
21
22
20-40
15-30
64
Type 25
40-60
20-50
60
76
Type
Type
Type
26
I
50
I
Product:
SOLAR VENTILATOR
Description:
A free-standing ventilation fan with PV module for direct
operation duiing daylight hours
indudes:
I MODEL NO.
KB- 1502
PV module. ventilator fan and motor unit
ARRAY Wp
9
OUTPUT
12W Fan
PRICE U.S. $
refer to
supplier
Product:
AIR CONDITIONING UNIT
Description:
Evaporative cooler with PV powered fan
Indudes:
PV module, support structure, 12Vevaporkive cooler Unit
with fan and pump. Battery optional for night time cooling
MODEL NO
New Breeze
ARRAY Wp
30-40
PERFORMANCE
PRICE U.S. $
refer to
supplier
suitable for areas
with relat&z humidity ~75%
104
1.
How long will a PV system last?
PV modules will last twenty years or more and many suppliers will give a five to
ten year warranty. Generally, the component with the shortest life will be the
battery which may have to be replaced each three to five years.
2.
is there enough sun in my area - I often have cloudy days?
In general, PV can be economically applied to all regions between the latitudes
of 40° N and 40” S. Having cloudy days or rain is not necessarily a problems
because batteries can store electricity for these days. In the case of solar pumps
water can be stored in storage tanks. With many applications, there is good
correlation between supply and demand. For example, a solar irrigation pump is
not needed if it is raining!
3.
Is the application
I’m considering
likely to be economic for PV power?
If the average daily energy consumption of your application equipment (motor/
pump, refrigerator, lights, etc) is less than 50 kWh per day, PV is likely to be
economic.
4.
Snould PV be used only where there is no electric grid?
In general .. yes. If you have access to grid electricity it is more economic to
connect to the grid. If the grid electricity is unreliable it may be less expensive
to buy a mains battery charger and batteries for the power cut periods rather
than buy PV.
5.
Can I get an electric shock from a PV array?
Yes, treat PV arrays as potentially dangerous as any other electricity supply.
6.
I cannot run my lights and other
can I do?
app!iances
as often as I want to.
What
Most PV systems are modular. You can add more PV modules to increase the
energy available and add additional battery capacity if necessary. Seek advice
from your supplier before doing this.
7.
is PV an ‘*appropriate technology”
for countries?
Yes, Just because it’s considered advanced technology dosn’t make it
inappropriate.
PV is reliable, has a long life, Is environmentally clean and
economic for small scale applications. PV systems are now being manufactured in
Brazil, China, India, Mongolia, Tunisia, Vietnam, Zimbabwe and other developing
countries.
105
Alternating current (AC.) - Electric current in which the direction of flow is reversed
at frequent intervals. Opposite of direct current (D.C.).
Amorphous - The condition of a solid in which the atoms are not arranged in an
orderiy pattern; not crystalline.
Annual equivalent life cycle cost (ALCC) - The total life time costs of a system
express34 as a sum of annual payments.
Balance of system (BOS) - Parts of a photovoltaic system other than the array.
Cathodic protection - A method of preventing oxidation (rusting) of exposed metal
structures such as bridges by imposing between the structure and ground a small
electrical voltage that opposes the flow of electrons, and is greater than the voltage
that is present during oxidation.
Clearness index - The ratio of global solar irradiation to extraterrestrial solar irradiation.
Concentrator - A photovoltaic array which includes an optical component such as a
lens or focusing mirror to direct incident sunlight onto a solar cell of small area.
Conversion efficiency (cell). The ratio of the electric energy produced by a solar cell
(under full sun conditions) to the energy from sunlight incident upon the cell.
Czochralski process - Method of growing a perfect crystal of large size by slowly
lifting a seed crystal from a molten bath of the material under careful conditions of
cooling.
Deep discharge - Discharging a battery to 20 per cent or less of its full charge.
Design month - For the purpose of sizing a solar photovoltaic system, it is necessary
to choose a ‘worst month’ in relation to the solar resource for which the system must
meet the load requirements. This month is termed the design month.
Diffuse radiation - Solar radiation scattered by the atmosphere.
Direct radiation - Solar radiation transmitted directly through the atmosphere.
Direct current (D.C.) - Electric current in which electrons are flowing in one direction.
Opposite of alternating current (AX.).
Dynamic head - The head loss in pipes caused by the flow of water through the
pipes.
Extra-terrestrial Irradiation - The solar energy received outside the earth’s atmosphere.
106
Fill factor - The ratio of maximum output of a PV cell under reference conditions to
the product of open circuit voltage and short circuit current/under the same conditions.
Flat plate (module or array) - An arrangement of solar cells in which the cells are
exposed directly to normal incident sunlight. Opposite of concentrator.
Global irradlance - The sum of diffuse and direct solar irradiance incident on a
horizontal surface.
Hydraulic energy - The energy necessary to lift water.
Impedance matching - The process of matching the output of one device to the input
of another device such that there is a maximum transfer of power between the two.
lnsolation - Sunlight, direct or diffuse (not to be confused with insulation).
lnverter - Device that converts D.C. to A.C.
I
I-V curve - A graphical presentation of the current versus the voltage from a
photovoltaic cell as the load is increased from the short circuit (no load) condition to
the open circuit (maximum voltage) condition. The shape of the curve characterises
cell or module performance.
Kilowatt (kW) - 1,000 Watts.
Kilowatt hour (kWh) - 1,000 Watt hours.
Life Cycle Costs (LCC) - The lifetime costs associated with a pumping system
expressed in terms of today’s money.
Load - Any device or appliance that is using power.
Maximum Power Point Tracker (MPPT) - Impedance matching electronics used to
hold the output of the PV array at its maximum value.
Parallel connection - A method of interconnecting two or more electricity-producing
devices, or power-using devices, such that the voltage produced, or required, is not
increased, but the current is additive. Opposite of series connection.
I
Peak Watt or Watt peak - The approximate amount of power a photovoltaic device
will produce at noon on a clear day (insolation at 1000 Watts per square metre) when
the cell is faced directly toward the sun.
Photovoltaic - Pertaining to the direct conversion of light into electricity.
Photovoltaic array - An interconnected system of photovoltaic modules that functions
as a single electricity-producing unit. The modules are assembled as a discrete
structure, with common support or mounting.
Photovoltaic cell - A device that converts light directly into electricity. A solar
photovoltaic cell, or solar cell, is designed for use in sunlight. All photovoltaic cells
produce direct current (D.C.).
107
Photovoltaic collector - A photovoltaic module or array which receives sunlight and
converts it into electricity.
Photovoltaic module - A number of photovoltaic cells electrically interconnected and
mounted together, usually in a common sealed unit or panel of convenient size for
shipping, handling and assembling into arrays.
Photovoltaic system - A complete set of components for converting sunlight into
electricity by the photovoltaic process, including array and balance-of-system
components.
Polycrystalline silicon; polysilicon - Silicon which has solidified at such a rate that
many small crystals have formed. The atoms within a single crystal are symmetrically
arrayed, whereas in polysilicon crystals they are jumbled together.
Power conditioner
- The electrical equipment used to convert power from a
photovoltaic array into a form suitable for subsequent use, as in supplying a
household. Loosely, a collective term for inverter, transformer, voltage regulator,
meters, switches and controls.
Present worth - The vaiue of a future cost or benefit expressed in present day
money.
Prime mover - The power source for a system.
PV - Abbreviation for photovoltaic.
Serles connection - A method of interconnecting devices that generate or use
electricity so that the voltage, but not the current, is additive one to the other.
Opposite of parallel connection.
Short circuit current - Of a PV cell, module or array is the current that flows when
the output terminals of the device are joined together.
Solar irradiance - The power received per unit area from the sun.
Solar irradiation or insolation - The energy received per unit area from the sun in a
specified time period. In this handbook, the time period is generaliy taken to be a
day and the solar irradiation is expressed in MJ per m2 per day or kWh per m2 per
day (1 kWh = 3.6 MJ).
Stand alone - An isolated photovoltaic system not connected to a grid; may or may
not have storage, but most stand-alone applications require a battery or other form of
storage.
Tilt factor - The ratio of solar irradiation incident on a tilted PV array to global
irradiation.
Watt, wattage - A measure of electric power, or amount of work done in a unit of
time. One amp of current flowing at a potential of one volt produces one Watt of
power.
Watt hour (Wh, Whr) - A quantity of electrical energy (electricity). One Watt hour is
consumed when one Watt of power is used for a period of one hour.
106
1.
Introduction
Economic considerations are important when comparing Photovoltaics with other
power sources. PV systems are technically viable but where alternatives exist
the evaluation of the alternatives must include economic and technical and
envrronmental considerations.
When economic viability is considered, a distinction should be made between
economic and financial assessment. The economic approach seeks to make a
true comparison of the value to siciety as a whole, and as such must use costs
and benefits that are free from taxes, subsidies, interest payments, etc.
Conversely, a financial assessment is an evaluation from the purchaser’s
viewpoint; so taxes, subsidies and the effect of spreading the capital cost over
several years by means of a loan, are all taken into account.
2.
Methodology
The most complete approach to economic appraisal is to use life cycle costing
because all future expenses are than taken into account. In this method, all the
future costs and benefits are discounted to “present day” values. The underlying
concept in this approach is that investors would be indifferent as to whether they
had $100 now or $110 in a years time if the $100 could be invested at an
interest rate of 10%. Hence the Present Worth (PW) of an expenditure of $110
in one years time would be $100 when discounted at a rate of 10%.
The calculation of PW involves the use of a discount rate which reflects the
opportunit;L! cost of capital. Values of discount rate that are used for other
projects in the country concerned can usually be taken as a guide, typical values
are 1O-l 2%. High discount rates mean that a low value is placed on future
costs and benefits. For example, at a discount rate of 50%, an expenditure of
$100 in one years time has a PW of only $66.67.
However it should b8 noted that such economic analysis doesn,t take into
consideration such factors as environmental benefits (PV doesn’t add to Global
Warming like diesel engines) nor the benefits of superior service (e.g. higher
reliability of PV).
3.
Calculation of Present Worth
For a future cost or benefit (Cr), payable in N years, which is inflating at a fixed
percentage 9” each year and discounted at a rate “d”, the Present Worth is given
by:
with
PW = Cr.Pr
Pr
+ i)
+ d)
109
N
1
For a payment or benefit Ca ($) occurring annually for a period of N years which is
inflating at a rate ‘3” per year and discounted at a rate d, the Present Worth is
PW =
with
Ca.Pa
Pa
U+i)
U+d)
-1
Tables 1 and 2 give the factor Pr and Pa respectively for selected values of N, i and
d.
4.
Examples
(a)
To find the PW of a single cost of $10,000 occurring in 5 years time at an
inflation rate of 5% per annum and discounted at a rate of 10% per annum.
The factor Pr from Table 1 for d = 0.1, i = 0.05 and N = 5 is found to be
0.79. Hence the PW = (10,000 x 0.79) = $7900.
(b)
To find the PW of an annual benefit of $2000 occurring for a period of 10 years
which has an annual inflation rate of 5% per annum and is discounted at a rate
of 15% per annum. The factor Pa from Table 2 for d = 15%, i = 5%, N = 10
is found to be 6.27. Hence the PW = $2,000 x 6.27 = $12,540
It is usual to carry out economic evarrtations in real terms; the interest rates and
discount rates used should be relatk. to general inflation. Hence costs are only
assumed to inflate or deflate if their prices are changing relative to all other prices.
However, as long as both discount and inflation rates are expressed in the same way
(ie, both excluding general inflation or both including general inflation) the resulting
Present Worth will be the same. Hence, normally inflation rates in Table 1 and 2 are
assumed to be zero (general inflation excluded).
5.
Considerations
When undertaking an economic comparison of different technologies it is important to
consider if, some costs have subsidies, taxes or duties included. For example if diesel
fuel is subsidised in a country then a solar photovoltaic pump may not appear to be
competitive to the user on a life cycle cost basis compared to a diesel pump (if the
subsidised diesel fuel price is used). However if the unsubsidised cost of the fuel is
used the use of solar pumps may be found to be economic for the country.
110
Discount
Rate (dl
0.00
Inflation
Rate (i)
56-y:
7:75
8.93
7.72
10.00
13.03
17.06
0.20
10.38
15.00
22.21
33.51
51.29
12.46
0.05
0.10
0.15
4.33
5.00
5.76
6.62
7.60
0.00
3.79
6.14
7.81
7.61
10.55
15.00
21.80
32.26
8.51
12.72
9.43
15.80
20.00
32.95
56.38
E;
151:24
0.15
0.05
0.10
0.15
22.41
4.36
5.00
10.00
12.87
16.65
5.02
6.27
0.00
0.05
0.10
0.15
7.90
10.00
0.20
12.73
0.00
0.20
3
15.00
22.66
34.95
54.72
86.44
5.00
0.20
0.15
20
13.21
17.53
23.35
31.15
0.00
0.10
xi
a
10.00
0.00
0.05
0.10
0.20
0.05
Factor Pa for given number of years
0.05
0.10
0.15
0.20
2.99
3.41
3.88
4.41
5.00
4.19
5.16
6.39
7.97
10.00
30.00
34.72
69.76
63.00 180.94
117.81 499.96
224.03 1418.26
20.00
20.00
15.37
30.00
66.82
164.68
431.39
5.85
7.82
10.71
15.00
21.44
6.26
8.80
12.96
6.57
9.81
16.20
20.00
32.22
2Ei.
4.68
6.06
8.02
10.85
15.00
4.87
6.52
9.07
13.18
20.00
4.98
6.87
10.19
16.58
30.00
Table 2 Selected Values of Present Worth Factors Pa for an Annually Recurring Cost
111
Discount
Rate (d)
Factor Pr for given number of years
Inflation
Rate (i)
5
0.00
0.05
0.00
0.05
0.10
0.15
0.20
0.00
0.05
0.15
0.20
1.00
1.28
1.61
2.01
2.49
1.00
1.63
..ll
1.00
-L
70
1.00
2.59
ix.;
.
2.08
4.18
8.14
15.41
2.65
6.73
3.6.37
38.34
0.78
0.61
0.48
0.38
1.00
1.00
1.00
1.00
30
1.00
4.32
17.45
66.21
237.38
0.23
1.00
0.10
O.i5
1.26
1.58
1.95
1.59
2.48
3.80
2.01
3.91
7.41
2.54
6.17
14.45
4.04
15.32
54.92
0.00
0.05
0.10
0.15
0.62
0.79
0.39
0.63
0.24
0.50
0.15
0.39
0.06
0.25
1.00
1.00
0.20
1.25
1.55
1.56
2.39
1.00
.1.g5
1.00
2.43
5.70
3.79
13.60
0.00
0.05
0.50
0.63
0.80
0.25
0.40
0.64
0.12
0.26
0.51
0.06
0.16
0.41
0.02
0.07
0.26
0.20
0.10
a
0.10
0.15
3.69
1.00
1.00
1.00
1.00
1.00
1.00
0.20
1.24
1.53
1.89
2.34
3.59
o.co
0.05
0.40
0.51
0.65
0.81
0.16
0.26
0.42
0.65
0.06
0.13
0.27
0.53
0.03
0.07
0.18
0.43
0.00
0.02
0.07
0.28
0.10
0.15
0.20
1.00
1.00
1.00
1.00
1.00
Table 1 Selected Values of Present Worth Factor Pr for a Cost in N Years Time.
112
EUROPE
Atersa
Fernando Poo, 6
28045 Madrid
SPAIN
Tel: + 34-1.4747211
Fax: + 34-1.4647467
Chronar Ltd
Waterton Ind.1Est.
Bridgend
Wales
CF313YN
Tel: +44 - 656.61211
Fax: +44 - 656.63182
BP Solar Ltd
36 Bridge Street
Leatherhead
Surrey KT22 882
UK
Tel: +44 - 372 377899
Tlx: 263320 BPSIL
Fax: +44 - 372 377750
Codan (UK) Ltd
6 Grove park
Mill Lane
Alton
Hants
GU34 2QG
UK
Tel: +44 - 420 80121
Fax: +44 - 420 541098
BP Solar Espana
Poligono Industrial de Valporfillo
Calle Primera 5
Alcobendas, Madrid
SPAIN
Tel:’ +34 - 1.6534422
Fax: +34 - 1.6535771
Duba NV.
Kasteeldreff 1
89201; Wetteren
BELGIUM
Tel: +32 - 91.893496
Fax: +32 - 91.695752
Benelux Solar
Gagelveld 7-A
4844 Re Therheijden
THE NETHERLANDS
Tel: +31 - 16. - 934143
Fax: +31 - 16.934138
Dulas Engineering
Old School House
Eylwystach
Machynlleth
Wales SY20 8SX
UK
Tel: +44 - 654.74332
Fax: +44 - 654.74390
Budimex
Rue Van Eyck, 11C
1050 Brussels
BELGUIM
Tel: +32 - 2.647 8515
Fax: +32 - 2.647 8788
Dynhelios
2A Du Buisson
76350 Oissel
FRANCE
Tel: 35 64 9747
Tlx: 770204
Fax: 35 64 0818
Chloride Solar Ltd
Lansbuty Estate
Lower Guildford Road
Knaphill
Woking GU21 2EW
UK
Tel: +44 - 483.797773
Tlx: 589791
Fax: +44 - 483.797269
Ecosolaire
19 Rue pavee
75004 Paris
FRANCE
Tel: +33 - 1.48 87 4360
Fax: +31 -1.48 87 8827
Chronar France
3 Allee Edme Lheureux
lmmeuble Vancouver
94340
Joinville - Le - Pont
FRANCE
Tet: +33 1.4885 1333
Fax:+331.48852&!
ENE
Avenue van der Meerschen 108
B-l 150
Brussels
BELGIUM
Tel: +32 - 2.771 13 28
I!3
Flachglas Solar Technik
Muhlengasse 7
D-5000 Koln 1
GERMANY
Tel: +49 - 221 235191
Tlx: 172214258
Fax: +49 221 243811
Fluxinos
Viate Europa 6/b
20060 Bussere, MI
ITALY
Tel: +39 - 2.95039089
Ttx: 500433
Fax: +39 - 2.95039089
IBC
POBox1107
D-8623 Staffelstein
GERMANY
Tel: +49 - 9573 3066
Fax: +49 - 9573.3832
ICPE PV Co.
T Vladimirescu Bd
45 - 47,
79623 Bucharest
ROMANIA
Tel: +40 - 0.314100
Tlx: 010486
Intersolar Ltd
Unit Two
Cock Lane
High Wycombe
Bucks HP13 7DE
UK
Tel: +44 - 494.452945
Tlx: 837383
Fax: +44 - 494 - 437045
Grundfos
DK-8850
Bjerringbro
DENMARK
Tel: +45 - 86.68 1400
Tlx: 60731 GFOS DK
Fax: i-45 - 86.68 4472
Helios Technology
Via PO 8
Galliera l-3501 5
Veneta (Padova)
ITALY
Tel: + 39 - 59 65655
Fax: i39 - 59 58255
lsofoton S.A
Miguel Angel, 16
28010 Madrid
SPAIN
Tel: +34 - 1.4012354
Tlx: 49944
Fax: +34 - 1.4105989
Hittec
Unit 24 D
North Tyne Industrial Estate
Whitley Road
Longbenton
Newcastle-Upon - Tyne
UK
Tel: +44 - 91.2663478
Fax: i-44 - 91.2818430
ltalsolar
Via A. D’Andrea, 6
Nettuno 00048 (RM)
ITALY
Tel: +39 - 6.9850246
Tlx: 612441
Fax: +39 - 6.9850269
Hydrasol
lndustriestrasse 100
6919 Bammental
GERMANY
Tel: +49 6223 47532
Fax: i-49 6223 48159
MBB
Energie und Protesstechnik
Postfach 801109
D-8000
GERMANY
Tel: +49 - 89 46005357
Tlx: 5287117
Fax: +49 - 89 46005332
IDEA
Via G. Rossi 1313
40138 Bologna
ITALY
Tel: +39 - 51.393639
Fax: +39 - 51.394839
Mobes Nach, GmbH
Bergiusstrasse 40-44
1000 Berlin 44
GERMANY
Tel: +49 - 30.684 8094
Tlx: 183432
114
Portsol
Rua Polincarpo
Anjos 62
Lisbon
PORTUGAL
Tel: 4198523
Tlx: 63668
Mono Pumps Ltd
Cromwell Trading Estate
Cromwell Road
Bredbury
Stockport SK6 2RF
UK
Tel: +44 61.494 6999
Tlx: 668762
Fax: -14461.494 5802
Pumpen Fabrik Wangen GmbH
Ampata18
D-8049 Unterbruck
W. GERMANY
Tel: 08133 2071
Tlx: 5270504 PULE D
NAPS-UK
PO Box 83
Abingdon
Oxon OX14 2TB
UK
Tel: +44 - 235 529749
fax: +44 - 235 553450
Rade Koncar
Tezacki put bb
58000 Split
YUGOSLAVIA
Tel: +38 - 58.512 299
Fax: -1-38- 58.512 138
NAPS Sweden
Stensatravagen
S-l 27 35 Skarholmen
SWEDEN
Tel: +46 - 8.979 565
Fax: +46 - 8.463 205
R & S Renewable Energy Systems
PO Box 45
5600 AA Eindhoven
THE NETHERLANDS
Tel: -131 - 40.520155
Tlx: 59030 RES NL
Fax: +31 - 40.550625
NAPS Finland
Ralssitie 7
SF - 01510 Vantaa
FINLAND
Tel: +358 - 0.8701611
Fax: + 358 - 0.826 301
SAB Nife
Box 515
S-261 -24 Landskrona
SWEDEN
Tel: 46 418 16280
Tlx: 72416
NAPS Norway
PO Box 96
Rislokka
N-0516Oslo5
NORWAY
Tel: +47 - 2.723012
fax: +47 - 2.722435
Siemens Solar GmbH
Buchenallee 3
D-5060, Bergisch Gladbach
GERMANY
Tel: 49 - 89 - 3500
Tlx: 884 891 SSOL
Fax: 49 - 89 - 35002573
Noack Solar
Kjelsaavelen 160
Box 79
Kjelsaas
0411 Oslo 4
NORWAY
Tel:+ 47-2.227460
Tlx: 71128 NOACK N
Fax:+47-2151808
Sistemi Energetici lntegrati
Via S Jacopo
32-50047 Prato
ITALY
Tel: 0574 24051
Tlx 570045
Photronics
Hermann-Oberth Str 9
D-801 1 Putzbrunn
GERMANY
Solar Energie Technik
Postfach 1180
D/6822 Altlussheim
GERMANY
Tel: +49 - 6205.3525
Tlx: 465 849
Fax: +49 - 6205.3528
Photowatt Intn! S.A
65, Av du Mont Valerien
92500 Rueil-Malmaison
FRANCE
Tel: +47 - 080505
Tlx: 202084
115
Vergnet SA
66, rue Hoche
92240 Malakoff
FRANCE
Tel: +33 - 1.47461616
Fax: +33 - 1.47460686
Solems
3 rue Leon-Blum
Z.I Les Glaises
1120 Palaiseau
FRANCE
Tel: 1 60 133440
Tlx: 604549
Fax: 1 60 133743
VIESH
1st Veschnjakovskij Str, 2
109456 Moscow
USSR
Soltech
Boekteerheide 30
3550
Zolder
BELGIUM
Tel: +32 - 11.530181
Fax: +32 - 11.539574
Windsol
18 Chatzopoulou St
17671 kallithea
GREECE
Tel: +30 - 9232943
Tlx: 226551
Sunpower
tocalita Pannellia
33030 Sedegliano
ITALY
Tel: +39 - 434.571760
Fax: +39 - 434.571554
AFRICA
Animatics Ltd
PO Box 72011
Nairobi
KENYA
Tel: +254 - 2.331 722
Tlx: 22233
Telefunken System Technik
lndustriestrasse 23-33
D-2000 Wedel (Holstein)
GERMANY
Tel: +49 - 4103.600
Fax: +49 - 4103.604700
BP Solar East Africa Ltd
Fedha Tower
Muindi Mbingu St
Nairobi
KENYA
Tel: +254 - 2.336396
Fax: +254 - 2.331756
Total Energie
7 Chemin du Plateau
Z.I. Le Tronchon
69570 Dardilly
FRANCE
Tel: +33 - 78 47 4455
Fax:+33-78 649100
BP Solar Zambia
PO Box 31999
Mutaba House
Cairo Road
Lusaka
ZAMBIA
Tel: +260 - 1.215390
Tlx: 41180
Textronica
Av.Colegio Militare 153-B
1500 Lisboa
PORTUGAL
Tel: +351 - 1.715 5684
Fax:+351 -1.7152123
CDK Engineering Ltd
29 Nassar Road
POBox 1173
Kampala
UGANDA
Tel: +256 - 41.259902
Transcoast Ltd
Ave de Gaulle 28
1050 Brussels
BELGIUM
Tel: +32 2 647 7504
Transelektro
1394 Budapest
POB377
HUNGARY
Tfx: 224571
Ecological Designs
PO Box 780
Masvinga
ZIMBABWE
Fax: +263 - 39.2215
116
FNMA
14me Rue Limete
BP 1967
Kinshasa 1
ZAIRE
Tel: +243 - 12.77264123482
Tlx: 22080
Somafrec
Rue Enseigne Froger
BP800
Bumako
Mali
Tel: +223 - 225584
Tlx: 425
Inter% Contracting
(C Africa) Ltd
PO Box 409
Blantyre
MALAWI
Tel: 636825
Tlx: 4544 INTEC Ml
West African Batteries
16 Keffi Street
S/W Ikoyi,
PO Box 2341
Lagos
NIGERIA
Tel: +234 - 1.685095
Fax: +234 - 1.685182
Kensid
Abcon House
Baricho Road
PO Box 18511
KENYA
Tel: 555622
Tlx: 22774
WSG Hitech
PO Box ST 319
Southetton
Harare
ZIMBABWE
Tel: +263 - 0.64320
Tlx: 2386
Kenital Solar Electricity
Elgeyo Marakwet Close 381
Nairobi
KENYA
Fax: +254 - 2.562295
INDIA & PAKISTAN
BHEL
PV Division
Vikasnagar
Mysore Road
INDIA
NORD lndustrie
26 Avenue Kheireddine Pacha
Tunis
TUNISA
Tel: +216 - 1.288746
Tlx: +14906
CEL
4 Industrial Area
Sahibabad 201010
UP
INDIA
Tel: 869157/201071
Tlx: 592203
Scan African Trading Ltd
PO Box 40490
Gabarone
BOTSWANA
Tel: 313638
Tlx: 2638 SCANT BD
HMA Investments Ltd
11 West Wharf Road
PO Box 5266
Karachi 2
PAKISTAN
Tel: 202737
Tlx: 25499 HMAI PLC
SEI Nairobi
PO Box 47384
Nairobi
KENYA
Tel: 335056
Tlx: 22347 PANELAER
Hydrasol Ltd
7-2-21 A Begumpet
Hyderabad 500 016
INDIA
Tel: +91- 842.33827
Fax: +91 - 842.222483
Solarcomm
PO Box ST31 9
Southerton
Harare
ZIMBABWE
Tel: +263 - 0.64341
TN: 26482
IMFA
Therubali Dist
Koraput Orissa 765018
INDIA
117
China PV Centre
91 Huang Cheng Xi Lu Road
Hangzhou
CHINA P.R.
Tlx: 35069
REIL
D-37 Madho Singh Road
Bani Park
Jaipur 302006
INDIA
Tel: 62601
Tlx: 365403
NAPS East Asia
Room 808 Wingon Plaza
62 Mody Rd
Tsimshatsui E.
Kowloon
Hong Kong
Tel: +852 - 739 6565
Fax: +852 - 3115289
Suryovonics Ltd
7 - 1 - 21A Begumpet
Hyderabad 500 016
INDIA
Tel: +91 - 842.33827
Fax: +91 - 842.222483
Neimeng Gu Solar Factory
Park Road,
Donghe Di Triet
Bao Tou Neimenggu
CHINA P.R.
Tata-BP Solar
A101 Block II
KSSIDC Multistorey Blocks
Electronic City
Hebbagodi
Hosur Road
Bangalore 562 158
INDIA
Fax: +91 - 8114.2417
Tlx: 8408 224
Ningbo - Solar
590 Xijiao
Road
Ningbo
Zehejiang
CHINA P.R
SE ASIA
Solarex Electric Ltc!
18th Floor, Sincere Insurance Bldg
4 Hennessey Road
HONG KONG
Tel: 852 5 285717
Tlx: 780 61254
Fax: 852 5 279704
AWA Ltd
47 Forster Road
Walu Bay
Suva
FIJI
BP Solar Malaysia
37th Floor
Menara Maybank
100 Jalan Tun Pesak
50734 Kuala Lumpur
MALAYSIA
Tel: +60 - 3.232 6322
Fax: +60 - 3.232 7642
Solarindo
PT Centronix
Jl Matraman Raya 36
Jakarta 13150
INDONESIA
Tel: +62 - 21.884187
Tlx: 48216
BP Solar Papua New Guinea
PO Box 569
Speybank Street
Lae
PAPUA NEW GUINEA
Tel: e675 - 422200
Fax: +675 - 424401
Showa Arco Solar
10 Anson Road 18-24
International Plaza
SINGAPORE 0207
Tel: 2212 433
Tlx: RS 20061 ASIS PR
Fax: 22 58002
BP Thai Solar Corporation Ltd
13th Floor
Sitthivorakil Building
5, Soi Pipat
Silom Road
Bangkok
THAILAND
Tel: +66 - 2.2368160
Fax: +66 - 2.2368169
Solar Lab
Trung Tam Vat Ly
01 Mac Dinh Chi
Ql.TP
Ho Chi Minh City
VIETNAM
Tel: 22028
118
Kyocera
Chiba-Sakura Plant
4-3 Ohsaku 1-Chome Sakura-Shi
Chiba - Pref 285
JAPAN
Tel: +81 - 434.981231
Fax: +81- 434 982215
Solar Power Division
PT Kemenangan
JL Gunung Sahari, 75
PO Box 2628
Jakarta
INDONESIA
Te!: +62 - 21.420 0823
Fax: +62 - 21.420 0052
Mitsuibishi Electric
2-3 marunouchi
2-Cho, Chiyoda-Ku
Tokyo 100
JAPAN
Tel: 031 218 3535
Tlx: 24532
WEST ASIA
AL Jazirah Solar Energy
Riyadh
SAUDI ARABIA
Tel: +966 - 1.464.0050
Fax: +966 -! .464.0053
Showa Shell
Tokyo Bldg
7-3 Marunouchi 2-Chome
Chiyoda - Ku
Tokyo 100
JAPAN
Tel: 3 215 9661
Tlx: 22373
BP Solar Arabia
PO Box 85652
Riyandh 11612
SAUDI ARABIA
Tel: +966 - 1.498 4864
Fax: +966 - 1.498 4796
Gtundfos Gulf
Jebel Ali Free Port
Dubai
UAE
Tel: +84 55166
Fax: +84 55135
AUSTRALASIA
BMK
PO BOX 92
Fortitude Valley
Qld 4006
AUSTRALIA
Tel: 07 52 7600
Tlx: 1846
Fax: 07 525505
JAPAN
Hitachi Ltd
6 Kanda-Surugadai
4-Chome
Chiyoda-Ku
JAPAN
Tel: +81 - 3.258 1111
Tlx: 22395.
BP Solar Australia
98 Old Pittwater Road
Brookvale
NSW 2100
AUSTRALIA
Tel: +61 - 2.938 5111
Fax: +61- 2.939 1548
Hoxan
13-l 2 Ginza
S-Chome Chuo-Ku
Tokyo 104
JAPAN
Tel: +81 - 3.543 2017
Tlx. 02524470
Fax: +81- 3.546 1637
Mono Pumps Pty Ltd
338-348 Lower Catidenong Road
Mordialloc
Vii 3195
AUSTRALIA
Tel: +61 - 3 580 5211
Fax: +61 - 3 580 6659
Komatsu Electronics
2612 Shinomiya
Hiratsuka
Kanagawa
JAPAN
Tel: +91- 463 231301
Tlx: 47995 KEMS
Rankin Solar
2A Gatwick Road
Bayswater North
Victoria 3153
AUSTRALIA
Tel: 03 729 5177
Tlx: 37489
Fax: 03 729 9234
119
SAB NIFE
Jungnergatan
Box 3,
S57201 Oskarshumn
SWEDEN
Tel: +46 - 491.16000
Tlx: 43982
Chronar Corporation
POBox 177
Princeton
NJ 08542
USA
Tel: 609 587 8000
Tlx: 843 394
Solarex Pty Ltd
78 Biloela Streeet 2163
Villawood
PO Box 204,
Chester Hill 2162
NSW
AUSTRALIA
Tel: +61- 2.727 4455
Fax: +61 - 2.727 7447
Currin Corporation
POBox 1191
Midland
Ml 48641
USA
Tel: +l - 517.835 7387
Dinh Compnay
Box 999
Alachua
Florida 32615
USA
Te!: +l - 904.462 3464
Fax: +l - 904.462 2041
Solarwatt
Box 379
Hamilton Central 4007
Queensland
AUSTRALIA
Tel: 617 8541053
Tlx: 41846 AA
Fax: 617 525505
ECD/Sovonics Canon
1100 W Maple Road
Troy Ml 48084
USA
Tel: +l - 313.362 4170
Tlx: 230648
Fax: +l - 313.362 4442
Southern Cross
PO Box 155
Darra
Qld 4076
AUSTRALIA
Tel: +61 - 7.375 3944
fax: +61 - 7.375 4553
Hydrasol Corp
1001 Alt AIA
Jupiter
Florida 33477 USA
Tel: +l-407 747 3388
Fax:: +l -407.746 1055
Suntron
2/861 Doncaster Road
Doncaster East
Victoria 3109
AUSTRALIA
Tel: +61 - 3.848 8944
Tlx: 151224
Fax: +61 - 3.848 4873
Intergrated Power Corporation
7524 Standish Place
Rockville
Maryland 20855
USA
Tel: +l - 301294 9133
Tlx: 79 7799
Fax: +l - 301 294 0809
USA
Armech
PO Box 7906
Atlanta
Georgia 30309
USA
Automatic Power Inc
PO Box 18738
Houston
Texas 77223
USA
InterSol Power Corporation
11901 W Cedar Avenue
Lakewccd
Colorado 80228
USA
Tel: 303 989 8710
Tlx: 45 4592
120
JadeMountain
PO Box 4616
Boulder Co 80306
USA
Jonco Pump Inc
100 Waldron Drive
Durant
Oklahoma 74702
USA
Tel: +l - 405.920 2473
A Y Mcdonald Manufacturing co
4800 Chavenelle Road
Dubuque
Iowa 52001
USA
Tel: +1 - 319 583 7311
Tlx: 43 9020 AYMCE DUQU
Fax: +l - 319.588 0720
Midway Labs
2255 E 75th Street
Chicago IL 60649
USA
Tel: +l - 312.9332027
Photocomm Inc
930 Idaho Maryland Road
Grass Valley
CA 95945
USA
Tel: +l - 916.477 5121
Fax: +l - 916.477 5751
Photron Inc
77 W. Commercial Street
Willits
CA 95490
USA
Tel: 707 459 3211
Fax: 707 459 2165
Polar Products
2808 Oregon Court
Bldg K-4
Torrance
CA 90503
USA
Tel: +l - 213 320 3514
Tix: 4940451 POLAR LSA
h
Real Goods
966 Mazzoni St
Ukiah
CA 95482
USA
Tel: +l - 707 468 9214
Fax: +l - 707 463 0301
Siemens Solar Inc
PO Box 6032
Camarillo
CA 93010
USA
Tel: +l - 805 388 6335
Tlx: 6716260
Solarex Corporation
1335 Piccard Drive
Rockville
MD 20850
USA
Tel: +l - 301.948 0202
Tlx: 64358
Fax: +l - 301.948 7148
Solar Engineering Ltd
1210 Homann Drive SE
Lacey
WA 98503
USA
Tel: +l - 206.438 2110
Fax: +l - 206.438 2115
Solarjack
13901 North 73rd St
Scottsdale
AZ 85260
USA
Tel: +l - 602.443 - 3655
Fax: +l - 602.443 - 3657
Speciality Concepts Inc.
9025 Eton Avenue
Suite A
Canoga Park
CA91 304
USA
Tel: +l - 818.998 5238
Tlx: 662914 SCU CNPK UD
Fax: +l - 818.998 5253
Sunfrost
POBox 1101
Arcata CA 95521
USA
Tel: +l - 707.822 9095
Fax: +l - 707.822 6213
Zome Works Corporation
PO Box 25805
Albuquerque
NM 87125
USA
Tel: +1 - 505.242 5354
Fax: +l - 505.243 5147
121
CANADA
CENTRAL AND SOUTH AMERICA
Candian Agtech
5037 50th Street
PO Box 2457
Olds AB TOM IPO
CANADA
Tel: +l - 403.556
Fax: +l - 403 556 7799
BP Solar
Apartado Aereo 59824
Bagata
COLOMBIA
Tel: +57 1 218 3029
Tlx: 45822 BPCO
Enerssin
PO Box 90880
Bogota
COLOMBIA
Photron Canada
PO Box 136
Colinton
Alberta TOG OR0
CANADA
Tel: +l - 403.675 2586
Heliodinamica
Rodovia Raposa Tavares KM 41
Caixa Postal 111
06730 Vargem Grande Paulista (SP)
BRAZIL
Tel: +55 - 11.790 0888
Fax: +55 - 11.790 1280
Intersolar Group Canada
4044 Aberdeen Road
Beamsville
Ontario
LOR 1B6
CANADA
Fax: +l - 416 563 - 0539
Repprice
Calle 13 Etre Carrera 23Y
24 No. 23 - 66 Barquisimetro
VENEZUELA
Tel: +58 - 51 51250
Fax:+58-51 518016
SolarPac
1535 Meyerside Drive
Misissanga
LST 1MG
CANADA
Tel: +l - 416 674 1616
122
1. tNSTRUCTlONS TO TENDER
Tenders are required for a complete solar photovoitaic system as described In the specification.
The Schedule for the purchase of system is as follows:
Tender forms issued by
............(day).,....,.....(month)............(year)
Completed tenders to be returned by
...........(day)............(month)............(year)
Tenders awarded by
............(day)............(month)............(year)
Systemsto be delivered by
............(day)............(month)............(year)
The origlnal tender shall be in the .........,.......... language and shall be filled out in Ink or typewrltten and
will be made a part of the awarded contract.
1.2 Adludic&ton Process
Tenders will be primarily considered for:
Performance
Durability
1 Cost effectiveness
l
Experience of the tender
l
l
The purchaser will not be bound to award a contract to the lowest, or any Tender.
2. SPEClRCATtON
2.1 &QQQ
This specification is for the design, manufacture, supply and delivery of:
The system to be supplied shall include:
l
Photovoltaic modules and array support structure
9 Load equipment to be specified
l
All control equipment and wiring
l
All fixlngs and ancillaries necessary for complete construction and commisslonlng
l
Tools needed for assembly and maintenance
l
Spare
l
Documentation
parts
The complete system shall be robust, and capable of withstanding hard usage in a harsh environment. lt shall be resistant to damage from accidental misuse and reasonably resistant to vandalism and the attentions of animals, wild
or domestic.
123
The system shall be designed for assembly, operation and servicing by unskilled personnel under the guidance of a
trained technician. The requirement for special tools or instruments to install and maintain the system shall be minimlsed and all tools needed for installation shall be supplied with the system. Foundations or other preparatory work
shall be as simple as practicable.
The system shall be designed for assembly from units which can be packed In containers small enough to be easily
man-handled and transported on small vehicles. The maximum permltted dimensions for any one unit are:
The systems shall be designed to operate for a long lifetime with minimum deterioration of performance. The design
life of the whole system shall be a least ten years with a minimal need for replacement of components. Routine malntenance shall be minlmised and mairuenance work necessary shall be a simple as possible, requiring only a few basic
tools for its execution.
Tne system shall be deslgndd to meet the requirements of this Specification under the following environmental
conditions:
0)
(ii)
(iii)
(iv)
Ambient air temperature between ...... and ...... (eg: 5OCand 45OC).
Relative humidity up to .... at an ambient temperature of .... (eg: 90% and 45C).
Wind speed up to ..... kmlhr (eg: 150 km/hr) (for fixed installations).
A maximum altitude above sea level of ..... m (eg: 2000m).
The system should also be resistant to the following extremes of environment eg:
(1)
(ii)
(iii)
Sand storms
Typhoon or hurricane winds
Overnight freezing temperatures
The Contractor shall state the limits of environmental conditions under which the system Is designed to operate.
2.4 Standards
Photovoltalc modules shall comply with the test requirements of the current Photovoltalc Module Control Test Specifications of the Commission of the European Communities Joint Research Centre (Ispra Establishment).
2.5 Perfarmance
2.5.1 Location
The system to be supplied is to be located as detailed below:
.
.
.
.
2.5.2
Name of nearest village/town:
Country:
Latitude:
Longitude:
Required Performance
The required performance of the system is summarizedin Table 1, along with the typical environmental conditions for
the locations. The system should provkfe average daily output as specified in Table 1 for each month, provided that
the specified monthly mean average daily solar irradiation for the month is met orexceeded. The tenderer shall state
the output of the system expected for each month of the year. (The user should supply Table 1).
2.5.3 Installation
Details
The sketch of the site is shown in Figure 1. (The user should add this).
124
TheContractorshallsupplyw~hthesystemsufficisntconsumab!eitems(such asmotorbrushesandfuses)whichmay
need replacementto last for 2 years of operation. Space nuts, bolts, washers etc, likely to be lost during shipment and
erection shall also be supplied at the time of shipment.
2.7 &&j~~$forShlDment
All equipment shall be carefully and suitably packed for the specific means of transportation to be used, so that it is
protected against all weather and other conditions to whicn lt may become subject.
Complete assembly and operating instructions are to be included in packing.
2.8 Documem
Prior to shipment of the equipment, the Contractor shall submit to the Purchaser the following documents: (Copies
also should be shipped with system).
(I)
A list of components and assemblies to be shipped Including ail spare parts andtools
01)
The size, weight and packing list for each package In !he shipment
(ill)
Assembly instructions
(Iv)
Operating Instructions
(4
lnstructionsforall maintenance operationsandtheschedule forany routine maintenance requirements
(vi)
Sufficient descriptions of spare parts andcomponents to permit ldentlficatlons for ordering ieplacement
(vii)
Revised drawings of the equipment as built lf different from the approved proposals
All documents shall be In the ................... language.
2.9 Tools
The Contractor shall provide two sets of any special tools and other equipment that are required for erecting, operating, maintaining and repairing the equipment. Special tools shall include such items as Allen or socket keys, box
spannera, feeler gauges, grease guns etc. A single set of all other tools required for erection shall also be supplied.
The contractor shall arrange for the equipment to be comprehensively insured for its full value from the time it !eaves
his premises until clearance from customs at the point of entry into the country of installation.
2.11
w
The contractor shall specify the period of the warranty together with a list of items covered under the warranty.
3. QUESTIONNAIRE FOR TENDERS
Tenders are asked to supply the following information to demonstrate their ability to meet the requirements of !he
project. All info-nation will remain confidential.
125
3.1 General
Name of Company:
Individual Contract:
Address:
Telex:
Tel:
Fax:
Legal status (eg: limited company)
Country In which registered:
Total number of employees:
3.2 merlence
of Tend=
Number of years of experience with photovottalc (PV) system:
Product Experience (list number In use of each main product type eg: pumps, lights, refrigerators etc):
3.3 ws
of Sugplv for m
Ten-
items manufactured by Contractor:
Items bought in from Suppliers:
3.4 m’.
.lance
3.5 A&r
Sales SW
(de-
Tenderers to list names, addresses,telex and telephone number of persons and organisatlon who may be contacted
for advice during the period of installation and operation of the equipment.
126
4. PRICE AND DELIVERY
Terms of payment
3.
............
% on order
.. .. ..... ,. .
% on delivery
............
% on satisfactory operation
Item
Description
1.
Equipment
2.
Transportation (from place of
manufacture to point of entry)
of complete pumping system,
including insurance by air/ship
Other
Total Contract Price
4.
Price
Currency
Total:
Spare parts (list prices of spare parts:
.
.
.
.
.
.
Delivery of complete system to be ............ weeks from receipt of order.
127
II
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.
Small sol&&k&
~~~~~~v~~i~).powe&f~dewi~e$are gradually being introduti4nto
developing ~u~~~~~f~~~~te~ pumping, vaccine refrigeration, lighting, battery ‘~@arf$ng
and ,oth.erimy#lrt@ .d~v~lp~~e~?-appkations,.. Most of these have been pumhaskdih
small numbe~~‘hyin~~,~~~als’i,p~‘iiatevoluntqry organizations and do& agenQk,-The
number of systesmsc~~~~y~~:~~,~:~(a/though numbering tens of thousands) is
extremely -srn~4,‘~mrp;~t..11Qt~~~pbte;nti~l
dema.nd. ‘A,major re.a8on.for this -is a.laok of
and using.these devikes and a soarcity of
awarene@%ofht?w tc? :& ~~~~,~~~~~~8~~
information dn’.~3d~~:~~~~lalatein a form s@table fQr d,evelopment “f &er&,-,
‘:,;
Racognking this ~a~~of-‘~~~.~,~~~~~
the .Swedkh Mi88ionary Counoil; !T:Power $nd:.t@
Stockholm ~n~ronmonti!iu~~thjs 2i y I
guide.
: / :+. ji : -~:1.__‘. _ :.~‘.,’ :,/ : “..
.i :;. :
.i,
<‘.:
The auttKJ[gof this bo0k.a~~‘~h~~vG~i.G#pp~&.&f@ $Jpci&$& && i+f$&&& ‘&,th~
Stockholm Environment lit&u&. IT Powet 4sm iiitkqdi~rr@irrg of ~~~i.~ee~~,~~~,~~
_-,_’ : ‘1:
consu~tants.~~~~hspecializ‘e~in the implsment&tion ef new and rertew&&energy~~~< ;:I. ‘_- :’
k?ohnologie8fof rui’ai deveiopment. For further information contact I-TPavVer Ltd., The
.,
Warren, Branshill Fig&f, Evereley~idant FEW OPR, UK.
1.
.
:
The Stockholm -EnvironmentInstitute(SE1) is an international reseamh organization: .
specializing in ~n~ror~rnen+~ltechnology and management, The main the-masof
activities are at present gimbal energy futures, climatechmge,~~t~h~o~y in ‘ag~~ul~r~” and the areas of econe?mlos,&hi& and environmental value. A,rn&jor
component of SEl’s energy pfogrirmme is related to Third World-snergy,titilraticjn &nd. :
technologies. The Institute’s headquarters are in Stockholm, with branch offic&rsin
Boston (USA) and York (UK).
The Swedish !vksionary Council is an organization dedicated to sustainable progress in
less developed countries through missionary work and project support,
ISRN “I 85339 091 7
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3909 13
The lnterm~iate T%hnok)gy Development Group wa$ founded by
the taps Dr E.F.Sohumachsr. inte~ed~te Technology enables
e in the Third Worid to dsvetop and use t~hnul~~~s
Fro0
ds which Qivethem more control over their lives and
and
which contribute to the long-term development of their
CGmmuniti~s
.
Intermediate Technology sublimations is the publishing arm of the Intermediate
Technology Development Group and is based at 1’03/105Southampto.? Row, London
wci R 4HH, UK.
,.
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