Smart PV and Hybrid Mini-grids
Hybrid Micro Grids for rural
electrification: Developing
Appropriate Technology
Antoine Graillot, TTA
TRAMA TECNOAMBIENTAL, S.L.
Avda. Meridiana 153
08026 Barcelona
Tel: + 34 934 463 234
Fax: + 34 934 566 948
tta@tramatecnoambiental.es
AIE Event
Maputo, June 10th 2009
Relevant aspects in rural electrification
 Cost-effectiveness
 The needs: demand analysis and segmentation
 The technologies and design practice
 Ownership and operational scheme
 User and operator training/capacity building
 Monitoring and performance assessment
 Lessons learned in demonstration projects
What is a Hybrid Mini Grid with RE?
 A combination of different but complementary energy generation
systems based on renewable energies or mixed (RES- genset)
 Hybrid powered mini-grids can provide steady community-level
electricity service, such as village electrification, offering also the
possibility to be upgraded through grid connection in the future
 Total installed power up to 100 kW (according to IEC)
 Distribution line in Low Voltage (up to 1.000V) (only distribution)
 Single or 3-phases
PV Hybrid Mini Grid in West Bank, Palestine
Classification of Hybrid Mini Grids
DC coupling
~
=
~
AC loads can be optionally
supplied by an inverter.
Genset
=
The battery, controlled and
protected from over charge
and discharge by a charge
controller, then supplies power
to the DC loads in response to
the demand.
Wind Energy
Hydro Power
~
AC generating components
need an AC/DC converter.
Photovoltaics
=
All electricity generating
components are connected to
a DC bus line from which the
battery is charged.
AC/DC Converters
Charge Controllers
DC bus
linebar
DC Loads
Optional
Battery
Inverter
AC Loads
Classification of Hybrid Mini Grids
AC coupling
Genset
=
~
In both options, a bidirectional
master inverter controls the
energy supply for the AC loads
and the battery charging.
Wind Energy
Hydro Power
~
AC generating
components may be directly
connected to the AC bus line or
may need a AC/AC converter
to enable stable coupling of the
components.
Photovoltaics
=
All electricity generating
components are connected to
an AC bus line.
AC/DC Converters
Inverters
AC bus line 230 or 400 V
Master Inverter
and
Battery charger
AC Loads
Optional
DC loads can be optionally
supplied by the battery.
Battery
DC Loads
Classification of Hybrid Mini Grids
DC and AC coupling
Wind Energy
~
Photovoltaics
DC loads can be optionally
supplied by the battery.
=
DC and AC electricity
generating components are
connected at both sides of a
master inverter, which controls
the energy supply of the AC
loads.
Genset
Hydro Power
AC/DC Converter
AC bus line 230 or 400 V
Charge Controllers
On the AC bus line, AC
generating components may
be directly connected to the AC
bus line or may need a AC/AC
converter to enable stable
coupling of the components.
AC Loads
Master Inverter
and
Battery charger
DC bus
linebar
DC Loads
MILES DE EUROS
PV cheaper than grid extension for
remote areas
100
90
80
70
Red Media Tensión
60
50
40
FV autónoma 6325 Wh/día (3,2-4,0 HSP)
30
20
FV autónoma 3300 Wh/día (3,2 -4,0 HSP)
10
FV autónoma 2200 Wh/día (3,2 -4,0 HSP)
Red Baja Tensión
0
0
0,5
1
1,5
2
2,5
3
3,5
Kilómetros
Comparison of investment costs between grid extension and off-grid PV in Spain
PV more sustainable than fossil
fuelled Gensets
1,00
Combustible
G&O&M
Inversión microrred
20,0
0,80
16,0
€/kWh
0,70
0,60
12,0
0,50
0,40
8,0
0,30
0,20
€/mes usuario medio
0,90
4,0
0,10
0,00
0,0
Grupo electrógeno
directo
Grupo electrógeno +
baterías
FV híbrida (25%
fracción solar)
FV híbrida (80%
fracción solar)
FV (100% fracción
solar)
Levelized costs for PV and Diesel technologies in microgrid for 340 users in Peru
(D.R. 5%, Diesel: 0,57 €/l)
Source: http://www.esmap.org/filez/pubs/620200785630_Peru_Solar-Diesel_Amazon_111-07.pdf
PV more sustainable than fossil
fuelled Gensets
1,00
Combustible
G&O&M
Inversión (microplanta + microrred)
20
0,90
16
€/kWh
0,70
0,60
12
0,50
0,40
8
0,30
0,20
€/mes usuario medio
0,80
4
0,10
0
0,00
Grupo electrógeno Grupo electrógeno
directo
+ baterías
FV híbrida (25%
fracción solar)
FV híbrida (80%
fracción solar)
FV (100% fracción
solar)
Levelized costs for PV and Diesel technologies in microgrid for 340 users in Peru
(D.R. 5%, Diesel: 1 €/l)
Source: http://www.esmap.org/filez/pubs/620200785630_Peru_Solar-Diesel_Amazon_111-07.pdf
VISION: Universal electrification-individual plants
and micro grids under one operational scheme
MSG
MSG
Individual Micro-Power Plants
From individual PV autonomous power
plants to microgrids
Application types
Types of uses
Home applications
Lighting
Audio/video
Refrigerator(s)
Small household appliances
Washing machine
Irons
Freezer(s)
Odd jobs
Individual PV micro
plants in Europe
Public areas applications
(places of collective life: worship
halls, community centre, health
centre, etc.)
The same appliances as above are
used, but more and more powerful.
Multi-user
microgrids in
Public lighting.
Developping
Countries
Village water pumping.
Economic activities applications
Process equipment supply (mainly
motors)
Comparison of PV Individual and Micro grids
Advantages
Disadvantages
Individual
Electrification
Micro plants
• Consumption is user managed on
a day to day basis.
• System black outs affect just one
user.
• Systems can be easily moved to a
new location.
• Limited surge power capacity.
• Monitoring individual systems can
be expensive and difficult.
• Maintenance and repair service
complex to organize in rural areas.
Multiuser Solar
Grids (MSG)
• Improved quality (surge power,
load shedding, etc).
• Lower investment for compact
villages.
• Energy saving can be practiced
using improved management tools.
• Lower maintenance costs.
• Telemetry can be economic for
monitoring system status.
• If the power plant fails, everybody is
cut off.
• Social rules required to distribute
energy availability.
• Local management required.
• Systems generally need to be
serviced on site.
 Challenge: sharing the energy available without conflicts

Energy distribution and metering problem!
Energy Availability
 General scheme for tariff: users pay for consumed kWh
 In stand-alone electrification with RE, Key aspect is the available
energy and not the installed power
 Tariffs must reflect this idea
 Tariff based on the Energy Availability (similar to fee for service ≠
prepayment)
 Clearer and easier financial planning and vision
BACKGROUND: Typical Design approach
 Experience in Design and Project management of PV-hybrid micropower plants in rural areas of southern Europe, Africa, Latin America,
Pacific …
 Technical specification for PV-hybrid micro-power plants (<100 kW, LV)
partially adapted from IEC 62257 TS series
 Demand analysis and segmentation
 Standardized technical solutions with high PV penetration
 10 yr. Service horizon with local operator and local capacity building
 Monitoring of systems to validate technology and the service
BACKGROUND: Typical Technical Specification
 DC coupled topology, high fraction of Renewable Energy generation
 System bus-bar voltage: < 75V DC (SELV)
 Battery: Pb-tubular, vented, DODmax=75%, A>3 days, 48V
 PV Charge controller: MPPT
 Inverter: sinusoidal > 85% +25W pilot inverter
 PV modules: crystalline CEI 61215 - 2
 Data logging: based on CEI 61724 (JRC guidelines)
 Load electrical supply: Mainly standard AC quality single phase
 Load Management: user interface, automatic load disconnect
 Etc.
From single user to villages: MSG (Multi user
Solar Grid) up to 150 kW.h/day
Typical layout (DC bus-bar micro power plant+AC single phase grid )
Typical load profiles
Profile 1- Daily Cycle rigid slim loads
Profile 2- Base Load
MODULABLE
LOAD
INTERRUPT.
PROFILE
2c- Base Load- Stand-by
DEFERABLE
2b- Base Load Interruptible
AVOIDABLE
2a-Base Load
TYPIC AL DAILY
RANGE
(Wh/ da y)
2a
A
NO
NO
NO
275
275
550
1100
NO
2b
A
NO
NO
YES
NO
550
1100
YES
NO
YES
YES
0
1100
2c
Typical load profiles
Profile 3- Daily Deferrable load
Profile 4- Periodical Deferrable load
Profile 5- “ Dump or ballast” load
Two key points

The main actor for
load management is the user
•
Training needed

Load management requires measurement and
broadcast of information on system status
•
Power and Energy generation
•
Power and Energy consumption
•
Energy availability
•
Battery status
Load management tools

User information interface + training

Automatic total load disconnect

Automatic selective load switching

Individual Energy limitation (multi user
system)
User interface
 Active display
 Remote display
 Data logging
RESULTS OF INDIVIDUAL LOAD SENSITIVITY
ANALYSIS (careful user: good operator)
SL05028
Wh/d
2600
2400
2200
2000
1800
1600
1400
1200
1000
0
Spring
Spring-06
1
2
Summer
Summer-06
3
4
Autum
Autum-06
Hp
5
6
Winter
Winter-07
7
8
DD (Wh)
Electricity Dispenser / meter
 Metering and invoicing interface
 Energy and power limitation and guidance
according to tariff contracted and generation
status
 User pays for availability of energy, not for the
consumed energy
Sharing of energy among users
Progressive tariff scheme
1
Tariff variable charge (€/kWh)
• Application and control of new
tariff systems (progressive
tariffs, EDA,...)
• Energy limitation according
to tariff contracted
• Low consumption energy
meters
• Incentives for active load
management
• Flexibility in energy use –
sharing of energy between
neighbours
0,8
0,6
0,4
0,2
0
17
33
66
134
Consumption blocks (kWh/month)
>134
Sharing of energy among users
Monitoring
Combination of user questionnaires and data logger
• User records:
– Satisfaction ??
– Electrolyte level in battery
– Black outs ?
Data logger:
built-in device in power conditioner
Hourly Data Storage (1 year):
Average and total hourly values
Parameters:
all relevant energy flows
solar irradiance
information on battery (voltage, SOC, etc.)
others
Typical monitoring data
Examples MSG
Akkan, Morocco
PV HYBRID POWER PLANT
PV GENERATOR
Installed PV capacity
5.760 Wp
Module type
80 Wp 36 cell – mono crystalline
Number of modules
72
Inclination / orientation
43º / +5º S
PV CHARGE CONTROLLER
Rated power
6.000 Wp
Control algorithm
MPPT - Boost
BACK UP GENSET
Rated power
8,2 kVA single phase
Fuel
Diesel
BATTERY
Number of elements (voltage)
24 (48V)
Model
Hawker 2AT1500
Capacity (C100)
1.500 Ah
Autonomy
4 days
INVERTER
Voltage input / output
48 V DC / 230 V AC
Rated power
7.200 W
Harmonic distortion
< 2,5%
DATA LOGGER
Memory / log frequency
300 kbyte / hourly
Type of data
Energy, voltage, radiation, etc.
ELECTRICITY DISPENSER – METER
Input
230 V AC 50 Hz
Maximum current
10 A
Algorithm
Configurable Daily Energy Deliverability
STREET LIGHTING
Number of lamps
13
Type
70 W hp sodium / 2 level electronic ballast
Total power - high
910 W
Total power - low
683 W
INDIVIDUAL LOADS
Akkan, Morocco
Households 275 Wh/day
23
Households 550 Wh/day
3
School 550 Wh/day
1
Mosque 550 Wh/day
1
Technology-PV hybrid power plant
San Lorenzo, Ecuador (LA)
Technology-distribution microgrid
Typical household
San Lorenzo, Ecuador (LA)
User interface and loads
San Lorenzo, Ecuador (LA)
Diakha Madina, Senegal
PV ARRAY
PV installed power
3.150 Wp
PV Module model
PW750 75 Wp 12V
Nº PV modules
42
Orientation/Inclination
0º S / 10º S
PV Area
46 m2
AVAILABLE ENERGY
Available Energy (Wh/day)
4.803
Irradiation (ḠpHp)
5 HPS
Month of design
December
BATTERY
Nº elements
24
Battery type
Tudor 6 OPzS 420
Capacity (C100)
672 Ah
Day of autonomy
4 days
CHARGE CONTROLLER
Regulation capacity
4.000 Wp
Mode of charge control
MPP Tracker
INVERTER
Input / Output voltage
48 V DC / 230 V AC
Nominal Power
3.600 W
DC/DC Converter (12 V)
10A máxima de corriente
Harmonic distorsion
< 2%
DATA LOGGING
Memory / freq. of logging
300 kbyte / hourly
PUBLIC LIGHTING
Number
Type of lamp
2
70 W / electronic ballast
PUMPING SYSTEM
Power of the pump
1.100 W
Flow
5m3/h
Deep
49 m
Height of the tank
7m
Tank capacity
20 m3
BACK-UP GENSET
Diakha Madina, Senegal
Nominal power
4,2 kW single phase
Fuel
Diesel
Current situation in SSA
Current situation in SSA
 Low population density
 Remoteness from the public grid
 Low demand in electricity
 High energy losses on the transmission lines
 High costs of grid extension and connection
 High Operation and Maintenance costs
Current situation in SSA
 Many villages and households and villages not connected to the grid
 Existing mini grids running with Genset (many are not working)
But essential to bring electricity, even basic needs (high value for the
first kWh)
Present and future potential
Short-term (0-2 years)
 Villages not connected to the grid, where the grid extension is too
expensive and not cost effective: micro-grid for basic needs (health,
school, water, etc)
 Villages with obsolete diesel generator because of the high running
costs (Operation and Maintenance): refurbishing distribution grid,
electrical installations, etc
Medium-term (5-6 years)
 Villages not connected to the grid: extension of the mini-grid to private
applications and productive uses
Long-term (10 years onwards)
 Villages not connected to the grid: interconnection of several mini-grids
between them or/and the national grid
Constraints and limitations
 Training and capacity building
 High costs of investment
 Critical number for maintenance
 Management of accumulated money
 Social organization may be a critical issue depending of the
management model

Unfair regulation (unfair regulations that discriminate against
technologies that are especially suited to rural areas)
LESSONS LEARNED in 15 years of practice
 PV-hybrid micro grids are an acceptable long term option and
expanding market
 Public subsidies in rural electrification must be technology neutral
 Typical average energy consumption is low but very valuable to users
 Demand limitation not a problem if EE appliances available
 Generation technology more and more reliable and adequate but...
• Load management is an important issue
• Stand-by loads in appliances dramatically increasing !!
 Operator recommended for long term security. Fixed user fees better
 User interface is critical !
antoine.graillot@tta.com.es
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