Basics of Photovoltaic (PV) - Pacific Gas and Electric Company

Basics of Photovoltaic (PV) - Pacific Gas and Electric Company
Basics of Photovoltaic (PV) Systems
for Grid-Tied Applications
Pacific Energy Center
Energy Training Center
851 Howard St.
1129 Enterprise St.
San Francisco, CA 94103
Stockton, CA 95204
Courtesy of DOE/NREL
instructor
Pete Shoemaker
Basics of Photovoltaic (PV) Systems
for Grid-Tied Applications
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PG&E Solar Information
www.pge.com/solar
Pacific Energy Center (San Francisco)
www.pge.com/pec
Energy Training Center (Stockton)
http://www.pge.com/myhome/edusafety/workshopstraining/stockton
Contact Information
Pete Shoemaker
Pacific Energy Center
851 Howard St.
San Francisco, CA 94103
(415) 973-8850
[email protected]
Some images displayed may not be in the printed booklet because of copyright restrictions.
Agenda
1.
2.
3.
4.
5.
6.
7.
Big picture: Team California
Electricity Fundamentals
PV Technology
Feasibility
Finances
Sales & Installation Process
Jobs Overview and Future Trends
5
One Minute Summary
Rent a portion of utility grid output
Buy your own power plant
Same
electricity
CURRENT
POSSIBLE
RENT
Courtesy of DOE/NREL
Your home needs
electricity
Pacific Energy Center
San Francisco
OWN
Source: Pete Shoemaker
The basic economics are
just like the “rent vs. buy”
of purchasing a home.
6
The Big Picture:
Team California
Pacific Energy Center
San Francisco
7
The California Regulated Utility
Financial Structure
How the utilities make money,
and why they can support energy
efficiency and conservation.
California’s regulated utilities cover most
of the state.
PG&E
San Diego Gas &
Electric (SDG&E)
Southern California
Edison (SCE)
Southern California
Gas (SoCalGas)
They are essentially monopolies in their
respective territories, and so need to be
regulated.
CPUC
The California Public Utilities Commission is
the regulatory body.
30 years ago, the utilities made money like most
businesses: on profits from sales.
Profits
Energy Sales
The more energy they sold, the more profit
they made.
Also 30 years ago, California’s power
consumption was rising rapidly, along with the
rest of the country.
Per-capita power
consumption.
U.S.
California
Projecting this into the future made people
realize that it was not sustainable, and that
something needed to be done.
Very high utility bills
Many more new power plants
Serious environmental consequences
We needed to lower people’s energy usage,
but how?
The utility companies had to be involved, but
how could you require them to encourage
less energy usage, since their profits and
business model depended on more sales?
Conclusion:
The utility financial structure must change.
DECOUPLING
Separating profits from sales.
Profits
Energy Sales
Energy Sales
Profits
Since 1978 (gas) and 1982 (electricity)
California’s regulated utilities have made
profits on INVESTMENTS, not SALES.
These investments are directed by the CPUC
and include energy efficiency and
conservation.
Example of EE investment and target:
1. The CPUC authorizes PG&E to spend the
money to give away 1,000,000 CFLs.
2. The target over 3 years is to reduce electric
consumption [xx] mWh.
3. If PG&E makes the target they can set rates
so that they earn [x]% for their
shareholders.
4. If they exceed the target they can earn
more, if they miss the target they earn less
or even get penalized.
California utilities have NO incentive to
increase energy usage.
They DO have mandates and incentives for
energy efficiency, conservation, and
renewables.
The result?
California, and PG&E, is the leader in
energy efficiency and renewable
generation.
Solar Electric Trends
PG&E Electrical Power Mix 2009
U.S. Electrical Power Mix June 2011
Bioenergy4%
Geothermal 4%
Other
1%
Coal
1%
Unspecified
Wind 3%
Small Hydro 3%
Solar <1%
(market purchases)
15%
Large Hydro
13%
Natural Gas
35%
Source: PG&E
Nuclear
20%
Source: U.S. Energy Information Administration,
Electric Power Monthly
.
Portfolio: Past, Present, and Future
2002 Actual
10.6% of total bundled retail sales
2010 Actual
16% of total bundled retail sales
2020 Projected
33% of total bundled retail sales
-- --
.,,.
11--W
Solar Thermal
19%
Wind
24%
Solor FV
35%
Total RPS-Eligible Procurement
Total RPS-Eligible Procurement
Projected RPS-Bigible Procuren1ent
7,504 GWh
12,34-0 GWh
· 27,000 GWh
Source: PG&E'• 2002 Corporate Env1roomental Report and PG&E's August 2011 RPS Compliance Report.
Note: 2020 delr.eries are based on current and projected future contractual commitments
Solar Thermal Technologies
Under Contract
I
·-~~
IO!
~t-
- -
Parabolic Trough
Dish Engine
(SCE/SDG&E)
. '""'
··""
··--==--·
I
Compact Linear Fresnel
Reflector
Power Tower (SCE)
Power Tower
Trough/B ion1ass Hybrid
Courtesy PG&E
...
Solar PV Technologies
Under Contract
Fixed Thin Film (a-Si)
Fixed Thin Film (Cd
Tel) (SCE)
Unspecified CPV
(illustrative)
Tracking Crystalline Silicon
Concentrating PV
Courtesy PG&E
..
Other Renewable Technologies
Under Contract
Biomass Energy
Wind Energy
Geothermal Energy
Small Hydropower (<30MW)
BioGas
Ocean Power
Courtesy PG&E
The Big Picture
California Public Utilities Commission
(CPUC) “Loading Order”
How we fill in new supply in California
1. Energy Efficiency/Demand response
2. Renewables
3. Distributed Generation (such as CHP)
4. Conventional efficient fossil generation
U.S. Electricity Generation 2008
Source: Energy Information Administration / Annual Energy Rev iew 2008
Total energy consumed = 40.67
Delivered for end use = 13.21 (32%)
Over 2/3 of the energy is wasted.
Energy Conservation
Energy Conservation
3 times the value!
That’s leverage!
PG&E as a Partner and Solutions Provider
PG&E Portfolio Solution
1) Reduce consumption as
much as possible.
3) Offset any
remaining
carbon
emissions.
Reduce
Energy
Use
2) Get the
“greenest”
power you
can.
Partnership
Education
Outreach
ClimateSmart
Renewable
Power
Supply
Electricity Fundamentals
Electricity Fundamentals
Watts
Volts
Elec.
pressure
Water
pressure
Amps
Output
Amount of flow
Amount of flow
Output
(work done)
Electricity Fundamentals
Watt (W) = Basic unit of Power
In generator: Capacity to do work
In appliance (load): Requirement for work to be done
Electrical terms:
•Amps x Volts = Watts
• 5A x 12V = 60 W
• 0.5A x 120V = 60 W
Kilowatt (kW), Megawatt (MW)
•1 kW = 1,000 Watts
•2.5 kW = 2,500 Watts
•1 MW = 1,000,000 Watts
•500 MW = 500,000,000 Watts
Electricity Fundamentals
Power over time = Work
Watts over time = Watt-hours (Wh)
Power x Time
1 sec.
1 hour
Instantaneous
power: 20 W
Power over
time: 20 Wh
Electricity Fundamentals
Watt-hour (Wh) x 1000 = Kilowatt-hour (kWh)
In a generator:
How many kWh are produced when a 5 kW PV system
operates at full power for 6 hours? 30 kWh
In a load:
How many kWh are used when a 200 W bulb shines for
10 hours? 2000 Wh or 2 kWh
Voltage and Current
Watts
Amps
Volts
Volts
Volts x Amps = Watts
Watts
Amps
Area of rectangle = total power (watts)
Same area = same power, just in different form.
Voltage and Current
2 amps
20 amps
The larger the current, the larger the wire needed to
make it flow efficiently (more “pipe”).
Copper wire is expensive.
Using higher voltage allows the same amount of power
to be transmitted with lower current, saving money.
Types of Electrical Current
Voltage x Time
+V
1/60 of a second
*PV panels produce DC
*Batteries only store DC
0V
-V
DC = Direct current
AC = Alternating current
60 Hertz in U.S.
(60 cycles / second)
*Utility Power
AC power can be stepped up and down in voltage much
easier than DC power, therefore most power is AC.
The Electric Grid
Source: PG&E
The Electric Grid
Electricity can be transported at the speed of light,
therefore any point can be said to be connected to
all others.
This network is called the GRID and is nation-wide.
Source: NPR
http://w w w .npr.org/templates/story/story.php?storyId=110997398
Source: NREL
The Electric Grid
There are three main components of the grid:
Generation: Creating electricity.
Transmission: Moving it in bulk from
generators to distribution centers.
Distribution: Bringing it from centers
(sub-stations) to individual homes and
businesses.
Source: NREL
The Electric Grid
Above 50,000 V (69 kV up to 765 kV)
Step
up
Sub-station
Transmission
10,000 V (10 kV)
Step
down
Distribution
120V – 240V
Generation
480V
Home
12,000 V (12 kV)
Step
down
Business
Source: NREL
Grid Terms
Supply side
Generation
Demand side
Usage (load)
Source: NREL
Grid Terms
Baseload: Minimum amount of power that is
always needed
Seasonal load: Increase in demand in
specific times of the year.
Peak load: Maximum amount needed.
Capacity: Total power that the system can
provide.
Grid Terms
Baseload
PG&E 2006 Annual Usage
Grid Terms
Seasonal load
PG&E 2006 Annual Usage
Grid Terms
Peak load
PG&E 2006 Annual Usage
Grid Terms
Highest demand occurs on only a few hours in the year
The top “50 Hours”
represent 0.6% of the
total hours in a year
20000
18000
16000
14000
M Ws
12000
10000
8000
6000
Load
Loa
d Du
Duration Cu
Curve
4000
2000
0
1
501
1001
1501
2001
2501
3001
3501
4001
4501
Tim e
5001
5501
6001
6501
7001
7501
8001
8501
Grid Terms
Capacity
PG&E 2006 Annual Usage
Grid Terms
Unused Capacity
PG&E 2006 Annual Usage
Grid Terms
Spread out the demand and you
can lower the capacity need.
PG&E 2006 Annual Usage
Grid Terms
Demand Management or
Demand-side Management
Load-shifting
“How do you get people to use less power
during peak times and more during off-peak?”
Demand Management Strategies
1. Reduce overall load.
— Energy efficiency, conservation
2. Inform people so they can cooperate
voluntarily.
— Publicity, “Flex Your Power” alerts
3. Create the ability to remotely turn off
certain appliances.
— Smart AC, smart meters, etc.
4. Charge more for peak usage.
— Time-of-Use rates, Peak-Time pricing
… and others.
PV Technology
Different types of “Solar”
Light energy
Photovoltaic (PV)
Electricity produced directly from light
Heat energy
Concentrated Solar Power (CSP)
Electricity produced by steam
Water Heating
Solar Pool Heating
Hot water for pools
Solar Water Heating (SWH or
Solar Thermal)
Hot water for domestic use (DHW)
All courtesy of DOE/NREL
Solar Electricity
• Photovoltaic Effect
– photo = light;
voltaic = produces voltage
– Photovoltaic (PV) systems convert light directly
into electricity (using semiconductors)
Electron Orbits
Free electron
How a PV Cell Works
Sunlight
Metallic Contact Finger
(electron pickup)
Antireflective coating
Electron flow
-
N-Layer (Phosphorus)
P-N Junction
P-Layer (Boron)
Metallic back contact
+
Solar Cells & the PV Effect
• Usually produced with semiconductor grade
silicon
• Dopants create positive and negative regions
• P/N junction results in .5 volts per cell
• Sunlight knocks available electrons loose for
potential electrical current
• Wire grid provides path for current
PV Terminology
Cell
Module
Array
Courtesy of DOE/NREL
PV System Sizing
200 HP engine: means that 200
horsepower is the MAXIMUM it will
produce.
4 kW PV system: means that 4,000
watts (4 kW) is the MAXIMUM it will
produce in full sunlight.
Crystalline Silicon (Mono)
Source: DOE National Renew able Energy Laboratory
Crystalline Silicon (Poly)
Source: Darren Bouton
Crystalline Silicon PV Products
• Firm, like crystals
• Longest track record, over 50 years
• Most common, over 85% of the market
• Highest efficiencies: avg. 15%, up to 22%
• Requires about 100 sf. per kilowatt
Source: DOE National Renewable Energy Laboratory
64
Thin-Film PV Products
Source: DOE National Renew able Energy Laboratory
Thin-Film PV Products
Source: DOE National Renewable Energy Laboratory
• Can be applied on many different materials
• Longevity still to be proven
• Production growing at high rate
• Lower efficiencies: avg. 7%, up to 15%
• Has potential for big cost reduction
Pacific Energy
Center
•
Requires
about 200 sf. per kilowatt
San Francisco
66
PV “General Rules”
• Crystalline PV Products
– Efficiencies (rated) range from 12-22%
– Space required: 90-150 s.f. per kW
• Thin-Film PV Products
– Efficiencies (rated) range from 5-10%
– Space required: 170-300 s.f. per kW
Crystalline vs. Thin-Film
1.2 kW
Crystalline
Silicon
Thin-film needs about twice as much
space for the same-size system, but
the total cost is about the same.
1.2 kW
Thin-Film
Source: DOE National Renew able Energy Laboratory
Efficiency vs. Capacity
1.2 kW (1,200w)
75 square feet
16w per sq.ft.
Capacity = total
power
Efficiency =
power per sq.ft.
1.2 kW (1,200w)
150 square feet
8w per sq.ft.
Courtesy of DOE/NREL
Heat effect
Air temperature
70° F
Roof surface
100° F
Under modules
120° F
Courtesy: Schott Solar
Crystalline vs. Thin-Film: Heat response
• Heat increases electrical resistance, which
lowers power output.
• Output begins dropping at 20°C (68°F).
• Percentage of drop is called Temperature
Coefficient of Power.
• It is measured in % per degree Centigrade,
i.e. -0.35%/°C
• Thin film degrades less than crystalline.
Crystalline vs. Thin-Film: Heat response
Sample data from spec sheets
Crystalline -0.478%
Thin film -0.19%
Crystalline vs. Thin-Film: Heat response
100
% of Power
95
90
85
80
75
70
65
60
20
(68)
25
30
(86)
35
40
45
(113)
50
55
Degrees Centigrade
(Fahrenheit)
Thin Film
Crystalline
60
(140)
65
70
PV Panel Technology Summary
Module
Efficiency
(Commercial)
Cell
Efficiency
(Laboratory)
Sample Companies
Employing
Technologies
Technology
Description
Crystalline Silicon
T he orignal approach; grow silicon crystal structures in a variety of ways. Represents almost 90%
of total market. Appearance dark blue to black but other colors possible with changes to antireflective coatings.
Single Crystal
Grown in Cylinders and wire- or
laser-sliced into circular wafers as
thin as 200 microns. Cells are
circular and modules are inherently
flat black or charcoal.
14 - 15%
25%
BP Solar
GE/AstroPower
Sanyo
Sharp
SunWorld
Multi-Crystalline
Cast in blocks or drawn through a
die to create a "ribbon" and wiresliced or cut into rectangular
wafers. Cells are typically vibrant
blue.
12 - 14%
19%
BP Solar
Evergreen Solar
Kyocera Solar
Schott Solar
Sharp
SunWorld
Thin-Film Materials
Near single-atom vapor or electro-deposition on low-cost materials (glass, stainless steel, or
plastic). Modules can be flexible. Appearance dark charcoal to near black; can also be semitransparent.
Amorphous Silicon
(a-Si)
Cell and module production part of
same process. Widely used in
consumer products and on flexible
substrates.
5 - 7%
13%
BP Solar
Kaneka Solar
T erraSolar
United Solar Ovonic
Copper Indium Diselenide
(CIS)
Alternative semiconductor material
under commercialization.
8 - 10%
19%
Global Solar
Shell Solar
Cadmium Telluride
(CdTe)
Alternative semiconductor material
under commercialization.
7 - 9%
17%
BP Solar
First Solar
Growth Forecast?
Source: Renew able Energy World.com
Inverters
Inverter
DC
AC
Changes Direct Current (DC) to
Alternating Current (AC)
Pacific Energy Center
San Francisco
76
Inverters
• Range in size from 1 Kw to 500+ Kw
• Can easily be connected together,
even different models
• Best to locate in cooler area
Source: Darren Bouton
Pacific Energy Center
San Francisco
77
Inverters
Typical system layout
Panel &
meter
Inverter
“Strings” of modules
Strings must be of specific length and number,
of equal size, and on the same plane.
Power production is very sensitive to shading.
Pacific Energy Center
San Francisco
78
System Inverters: Online string sizing tool
Limited configurations, cannot deviate.
Pacific Energy Center
San Francisco
79
Inverters
Micro-inverter
One per module
Inverts DC to AC right there
System layout
Panel &
Combiner box &
meter Energy Center
communicator
Pacific
San Francisco
80
Reliability
Source: NASA
Pacific Energy Center
San Francisco
81
Reliability
• Mature technology—over 50 years old
• Essential to the space program
• Millions in use
• Products tested and approved by CEC
• Long warranties backed by large,
stable companies
— 20 to 25 years on panels
— 10 to 25 years on inverters
— 10 year labor warranty
Pacific Energy Center
San Francisco
82
It works during the day, but what about at night?
Previously, there was
only one solution:
Courtesy of DOE/NREL
Store the excess in
batteries during the day,
then draw off the
batteries at night, or
when it’s cloudy.
But now?
83
Net Metering
The utility grid is a twoway street!
Electricity can be “sent
back” to the grid by the
customer.
Source Andy Black © 2006 All rights reserved.
Source: Andy Black
• Eliminates the need for batteries.
• Reduces cost and maintenance.
X
• Ensures a constant supply of electricity.
Source: DOE NREL
Typical System Components
Array
Inverter
Meter
Panel
Balance of System
(BOS)
Source: Darren Bouton
Loads
Typical System Components
1. Solar array
2. Inverter
3. House electrical
panel
Source: PG&E
86
Monitoring
•
•
•
•
Extra hardware sends inverter data to internet
Inverter company or 3rd party hosts website
Customer can view system from home or remotely
Current and historical data can be displayed
Can cost extra but some
companies are offering it as
standard package.
Courtesy SMA http://www.sma.de/en/products/monitoring-systems/sunny-beam-with-bluetoothr.html
Monitoring
Total system history.
Real-time, per panel.
Courtesy Enphase http://enlighten.enphaseenergy.com/public/systems/LWtm4844
Feasibility
89
Solar Geometry
90
Solar Geometry
Plane of the Ecliptic
91
92
Solar Geometry
ACTUAL:
The sun radiates in all
directions.
EXPERIENTIAL:
On Earth all radiation from the
sun is parallel to one another.
93
Horizon
in winter
Horizon in
summer
94
Source: Wikipedia
This ray strikes parallel to the surface.
This ray strikes +45 degree angle to the surface.
This ray strikes perpendicular to the surface.
95
Latitude and Longitude
96
Sun Path
Spring/Fall Noon:
90o – Latitude
52.5o in SF
Summer Noon:
90o – Latitude +23.5
76o in SF
Winter Noon:
90o – Latitude – 23.5
29o in SF
W
S
Winter: Rises 30o south of
E
N
E
Summer: Rises 30o north of
E
Source: PG&E
97
Sun Path Overhead Projection
98
Sun Path Overhead Projection
99
Summer sun
Winter sun
Source: NASA
100
Sun Path Horizon Projection
Edward Mazria. Passive Solar Energy Book, Expanded
101
Professional Edition
Rodale Press, 1979, Pg. 311
Sun Chart: San Francisco
Source: University of Oregon, Solar Radiation Monitoring Laboratory
http://solardat.uoregon.edu/SunChartProgram.html
Does the site have
an appropriate southern exposure?
Use a compass to identify north (and thus south),
a first step in assessing solar access at a site.
103
104
105
106
107
108
San Francisco: declination = 14º
True south reads as 166º
true
In west:
True azimuth = Compass azimuth + Declination
109
true
In east:
True azimuth = Compass azimuth - Declination
110
Magnetic South vs. True South
Magnetic South = Compass South
• A compass aligns with the earth’s magnetic field, which is not
exactly aligned with the earth’s rotational axis.
• Magnetic Declination = the number of degrees that true south is
east or west from magnetic south.
• True south ~ 15° east of magnetic south
(SF, SJ, Stockton)
True South = Solar South
NOTE: go to National Geophysical Data Center (NGDC) at
http://www.ngdc.noaa.gov/seg/geomag/jsp/Declination.jsp
to determine your site’s magnetic declination
111
Describing Location of the Sun
First understand where it is!
• Azimuth - horizontal
angle of sun east or west
of due south
• Altitude - angle of sun
above the horizon
• Azimuth and altitude
describe the location of
the sun in the sky at a
given time.
90
180
45
0
270
Illustration from Environmental Control Systems by
Fuller Moore, McGraw-Hill, Inc., 1993, p. 76.
PV Siting Issues to Consider
1. Sun energy potential (insolation)
2. Space
3. Shading
4. Orientation (N – S)
5. Tilt angle
6. Aesthetics
113
Peak Sun Hours Equivalent
1000
w/m²
“Digital” sunlight
114
Peak Sun Hours Equivalent
3500
Kwh Produced
3000
2500
2000
1500
1000
500
0
1
3
5
7
9
11
13
15
17
19
21
23
Hours of the Day
Typical daily pattern
115
Peak Sun Hours Equivalent
3500
Kwh Produced
3000
2500
2000
1500
1000
500
0
1
3
5
7
9
11
13
15
17
19
21
23
Hours of the Day
Equal areas
116
What is the solar resource potential?
Peak Sun-hours Measured in kWh/m2/day
Source: DOE National Renewable Energy Laboratory (NREL) Resource Assessment Program
http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/serve.cgi
117
What is the solar resource potential?
Peak Sun-hours Measured in kWh/m2/day
118
Monthly Percentages
Source: morehead.unc.edu
Percentage of yearly insolation per month
City
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
San Francisco
4.0%
5.7%
7.5% 10.1% 11.5% 12.16.% 12.~~ 11.1%
Los Angeles
4.8%
1
6.1{)%
1.9"%
Portland
3.0%
5.1%
Sep
Oct
Nov
Dec
g.8%
fi.1%
4 _5,3
'3.5%
11.3·% 11.8% 11.5% 10.4% g_43
7.16°.16 1J0.0% ll.1!Ji% 13.3% 14.5% 12.16% 10.5%
b.8%
5.3%
4.1%
6..1%
3.1%
2.4%
1JO.~~
Ratio of sunniest six months to least sunny (“summer to winter”)
<
'
'
City
Sunniest
San Francisco
Los Angeles
Least sunny
Ratio
08.1%
31.!Jr%
2.14to 1
64..5%
35.5%
1.82to 1
1 ~
Portland
-
12.1%
'
273%
119
2.fi7to 1
'
Weather/Sun Potential Summary
• California climate ideal for solar
• Panels produce in all light
• Fog has cooling effect, which raises
efficiency
• Microclimates likely less than 15%
loss from normal
120
Space Requirements
Roof / Ground Area:
• Crystalline Silicon
90-150 square feet per kW
• Thin-Film
170-250 square feet per kW
For a 4 kW residential system:
Crystalline: 360 to 600 sf.
Thin film: 650 to 1000 sf.
Note: Consideration should also be given for access
to the system (can add up to 20% of needed area)
121
Space Requirements: Overhead Photos
47 x 13 = 611 sf.
122
PV Orientation
For tilted roof:
North
Not
good
West
East
Good
Very
good
OK
South
123
PV Orientation
N
W
E
S
Overhead
maps: true N-S
124
Tilt
Tilt = Angle at which the collectors are
mounted relative to 0º (flat horizontal surface)
Ex. 30º
tilt angleº
125
Tilt
12 ft.
4 ft.
18 deg.
Typical roof in this area is 4:12.
For every 12 feet horizontal, it drops 4 feet.
This equals 18 degrees up from horizontal.
Normal roof pitch is a very good mounting angle.
126
Orientation / Degrees from South
Tilt Angle vs. Building Orientation
0°°
23°°
45°
68°
90°°
(South)
(SSE, SSW)
(SE, SW)
(ESE, WSW)
(E, W)
0°
Flat
0.89
0.89
0.89
0.89
0.89
18° 30°
4:12 7:12
0.97 1.00
0.97 0.99
0.95 0.96
0.92 0.91
0.88 0.84
45°
12:12
0.97
0.96
0.93
0.87
0.78
60°
21:12
0.89
0.88
0.85
0.79
0.70
90°
Vertical
0.58
0.59
0.60
0.57
0.52
Source: “A Guide to Photov oltaic (PV) System Design and Installation” -- CEC, June 2001
Bottom line: Tilt is a factor, but not a major one.
127
Tracking
Courtesy of DOE/NREL
For most home systems, the extra expense and maintenance of
tracking motors is not worth the efficiency gain. Better to buy a few
extra panels.
For large commercial systems it may be worth it.
128
Will the PV system be free from shade?
Source: DOE National Renew able Energy Laboratory
129
72-cell PV module
+
Copyright Solmetric 2010
72-cell PV module with bypass diodes
+
Copyright Solmetric 2010
Module I-V curve with shaded cell strings
Cell
I
Cell string
Copyright Solmetric 2010
V
Shade one cell of one cell string
One bypass diode turns on
I
V
Copyright Solmetric 2010
Shade one cell in each of two cell strings
Two bypass diodes turn on
I
V
Copyright Solmetric 2010
Monocrystalline Shading Effect
Partial Module Shading Effect
3
Unshaded Module
The Extreme Effects of Shading
2.5
1 cell 25%
shaded
Amps
2
% of One Cell Shaded
0%
0%
25 %
25 %
1 cell 75%
shaded
50 %
50 %
75 %
66 %
1 cell 100%
shaded
l00 %
75 %
w ith 3 cells shaded
93 %
1 cell 50%
shaded
1.5
1
0.5
% Loss of Module Power
0
0
5
10
15
20
25
Volts
Courtesy: Solar Energy International
135
Per-Module Devices
Solar Magic
National Semiconductor
Enphase Microinverter
Enphase Energy
Module Maximizer
Tigo Energy
Direct Grid Microinverter
Direct Grid Technologies
PV AC Module
EXELTECH
SunMizer
Xandex
PowerBox
Solar Edge
Parallux vBoost
eIQ Energy
Per-Module Devices: Two Basic Types
Enphase Microinverter
Enphase Energy
Module Maximizer
Tigo Energy
Microinverter
Changes DC to AC
Needs no other inverter
Maximizer
Adjusts DC voltage: DC to DC
Needs system inverter
Solar Access
PV Requirements
• Solar Window = 9 am - 3 pm (ideal)
8 am - 4 pm (possible)
• Need minimum of 4 hours during solar
window with no shade (prefer 5 hours)
• Summer more important than winter
138
Shading
Sunset
Sunrise
Solar Window
“Shade-free from 9 to 3”
Good chance for PV
139
Shading
Bad chance for PV
140
Planning for Shade
Source: PEC Staff
141
Planning for Shade
S
2 to 1 ratio
recommended
1 ft.
2 ft.
No good
Source: PEC Staff
142
Solar Pathfinder
Used to gain a quick and approximate understanding
of solar access and objects on the horizon that shade a
given location.
• Latitude specific sun path diagram is
placed in the pathfinder.
• The transparent, convex plastic dome
reflects objects on the horizon, enabling
the user to see the relationship between
these objects and the path of the sun.
• Obstructions can be traced onto sunpath
diagram.
143
Courtesy of Andy Black
144
Solmetric SunEyeTM
110
210
145
Courtesy: Solmetric, Corp.
Sunpath View
• Visually
demonstrates
seasonal sun
path and
shading effects
of obstructions
• Summary
tabular data
Courtesy: Solmetric, Corp.
146
Detailed View
• Chart shows
proportion of total
solar energy
available at this
site each month
Courtesy: Solmetric, Corp.
147
Where to Go for Tools
• Pacific Energy Center: Tool Lending Library
Phone: 415-973-9945
Email: [email protected]
• Pacific Energy Center Web Site:
www.pge.com/pec/tll
148
How will PV affect site aesthetics?
Source: Darren Bouton
149
How will PV affect site aesthetics?
Source: Darren Bouton
150
Roof Issues
Don’t put a new PV system on an old roof!
• Minimum roof life should be 5 – 7 years.
• Good idea to do PV and roof at same time
• Estimate for panel removal/replacement is $1,000 per
Kw of system size.
Courtesy London Flat Roofing, Ltd
http://www.londonflatroofing.co.uk/flat-roof-repairs/asphalt-flat-roofs/
Online Production Calculator
www.csi-epbb.com
• Official program for CSI rebate, everyone must
use.
• Buyers don’t have to “trust the salesperson”.
• Takes all relevant factors as input and gives
estimated annual production and rebate
amount.
Online Production Calculator
Online Production Calculator
Online Production Calculator
Online Production Calculator: Shading
Online Production Calculator: Shading
No shade
With shade
Finances
158
Net Metering
Sell Power to the
Utility by Day
Source Andy Black © 2006 All rights reserved.
Buy Power at Night
and Winter
.
• Exchange at Retail
• Annual Cycle
Source Andy Black © 2006 All rights reserved.
159
Net Metering – No Blackout Protection
Unsafe to send live
power into grid while
workers repairing
downed lines
X
Source Andy Black © 2006 All rights reserved.
No “voltage reservoir”
means house current
could fluctuate and
damage appliances
X
Source Andy Black © 2006 All rights reserved.
160
Reduce Your Energy Bills!
Spin Your Meter Slower
• Use the electricity you generate
first to reduce electricity you
would normally buy from the
utility or electric service provider
Spin Your Meter Backwards
• Excess electricity generated
goes through your meter and
into the grid
• Spins your meter backwards!
Source: Darren Bouton
• Get credit for “stored” electricity
on the grid
Net Metering
Meter
Customer side
Utility side
Net Metering
Generation: 3 kWh
Surplus: 2 kWh
Meter
Load: 1 kWh
Customer side
Cash credit: $ .60
2 kWh @ $(going rate)
Utility side
Net Metering
Generation: 1 kWh
Surplus: 0 kWh
Meter
Load: 1 kWh
Customer side
Cash credit: $ .00
Utility side
Net Metering
Generation: 0 kWh
Need: 1 kWh
Meter
Load: 1 kWh
Customer side
Cash debit: $ .09
1 kWh @ $(going rate)
Utility side
Net Metering
What do you get paid if your system over-produces?
Cost of power at $.16/Kwh
Wholesale cost: $.10/kwh
Markup to cover grid
maintenance: $.06/kwh
• CPUC rule—PG&E must comply
• The “full retail” rate that PV owners get paid for their
power includes a subsidy (markup) that comes from
all rate payers.
• The CPUC determined that this full subsidy would
only be allowed to cover your usage, not for you to go
into the power-generation business.
• For over-production, compensation will be at a lower
rate, to be determined.
166
Net Metering
Average monthly usage
PV system production
kWh/mo
Roll over
750
500
250
May
“SUMMER”
October
“WINTER”
April
167
Net Metering
Average monthly usage
PV system production
kWh/mo
The surplus covers the shortfall,
and your yearly bill is minimal.
750
500
250
May
“SUMMER”
October
“WINTER”
April
168
Net Metering
Average monthly usage
PV system production
kWh/mo
PV system produces less than
your yearly usage.
750
500
You pay this amount
250
May
“SUMMER”
October
“WINTER”
April
169
Net Metering
Average monthly usage
PV system production
kWh/mo
PV system produces more
than your yearly usage.
750
You are paid a different rate for this amount – around 4¢ per kWh.
500
250
May
“SUMMER”
October
“WINTER”
April
170
Methods of Payment
Two fundamentally different concepts:
Net Metering
Serves the onsite load FIRST, then
interacts with the utility grid.
One meter
Feed-in Tariff
Does not serve the onsite load and
ONLY interacts with the utility grid.
Two meters
171
Feed-in Tariff
Generation track
Feed-in (credit)
Meter
Usage (debit)
Meter
Usage track
172
Net Metering vs. Feed-in Tariff
Net Metering:
For PV systems from 1 kW to 1 mW
Feed-in Tariff:
For PV systems from 1 mW to 20 mW.
See www.pge.com/feedintariffs
173
PG&E Renewable Energy Programs
California Solar Initiative
Solar Water Heating (CSI Thermal)
Available PG&E Programs
Self Generation Incentive Program
Net Energy Metering
Feed‐in Tariff Programs*
Renewable Auction Renewable
Auction Mechanism*
Renewables RFO
PV RFO*
Utility Owned Renewables*
System Size
1 kW
100 kW
Customer‐scale
* New or revised program
1 MW
3 MW
20 MW
100 MW ++
Utility‐scale
174
Rate Schedules (Tariffs)
Two main types of residential rates:
TIERED (E-1)
The more you use, the more you pay.
Baseline amounts plus tier charges based on
percentage of baseline.
Time-of-Use (TOU)
Additional factor depending on when you
use the power.
175
PG&E Baseline
Territory Map
Baseline=guaranteed minimum
amount of low cost electricity
for everyone--all income levels.
Baseline allocation determined by
geographic territory averages.
176
PG&E Baseline Territory Allocations
177
Tiered Rate (E-1)
PG&E monthly electric bill for a large home user:
…
178
Tiered Rate (E-1)
PG&E monthly electric bill for a large home user:
Baseline = 9.8 x 33 = 323.4 kWh
5 rate tiers
978.00
= $ 38.41
= $ 13.10
= $ 65.79
= $ 129.46
= $ 3.12
$ 249.88
1
2
3
4
5
Used 978 Kwh costing $ 249.88
179
Tiered Rate (E-1)
Breakdown of charges:
The net charges shown above include the following component(s)
Please see definitions on Page 2 of the bill.
Generation
Transmission
Distribution
Public Purpose Programs
Nuclear Decommissioning
DWR Bond Charge
Ongoing CTC
Energy Cost Recovery Amount
Taxes and Other
Energy Commission Tax
TOTAL CHARGES
$1 19.27
10.62
95.07
11.97
0.28
5.04
5.42
2.21
$0.22
$250.1 0
180
E-1 / PG&E Standard Rate Schedule (Residential)
of 1/1/12 Rate 6/1/10
PG&E E-1 As
Residential
45.0
40.0
Cents per kWh
35.0
40.0
33.5
40.0
33.5
201% 300%
Over 300%
29.1
29.5
30.0
25.0
20.0
15.0
12.8
11.9
13.5
14.6
Less than
100%
101% 130%
10.0
5.0
0.0
131% 200%
Perce ntage of base line allocation
181
Rate Tiers
The less you use, the more you eliminate the
expensive upper tiers:
5 rate tiers
978.00
= $ 38.41
= $ 13.10
= $ 65.79
= $ 129.46
= $ 3.12
$ 249.88
1
2
3
4
5
182
Rate Tiers
The less you use, the more you eliminate the
expensive upper tiers:
5 rate tiers
421.42
= $ 38.41
= $ 13.10
= $ 65.79
= $ 129.46
= $ 3.12
$ 51.52
1
2
3
4
5
Used 421 kWh costing $ 51.52
From 978 Kwh to 421 Kwh -- from $250 to $50.
Lowering the usage 57% lowers the bill 80%.
183
E-1 / PG&E Standard Rate Schedule (Residential)
PG&E E-1 As
Residential
of 1/1/12 Rate 6/1/10
45.0
40.0
Cents per kWh
35.0
40.0
33.5
40.0
33.5
201% 300%
Over 300%
29.1
29.5
30.0
25.0
20.0
15.0
11.9
12.8
13.5
14.6
Less than
100%
101% 130%
10.0
5.0
0.0
131% 200%
Perce ntage of base line allocation
184
E-1 / PG&E Standard Rate Schedule (Residential)
of 1/1/12 Rate 6/1/10
PG&E E-1 As
Residential
45.0
40.0
33.5
40.0
Cents per kWh
35.0
29.1
29.5
30.0
25.0
20.0
15.0
10.0
5.0
40.0
33.5
13.5
14.6
12.8
11.9
Solar reverses the
rate tier effect
Lower ROI
Higher ROI
0.0
Less than
100%
101% 130%
131% 200%
201% 300%
Over 300%
Perce ntage of base line allocation
185
Demand Management Strategies
1. Reduce overall load.
— Energy efficiency, conservation
2. Inform people so they can cooperate
voluntarily.
— Publicity, “Flex Your Power” alerts
3. Create the ability to remotely turn off
certain appliances.
— Smart AC, smart meters, etc.
4. Charge more for peak usage.
— Time-of-Use rates, Peak-Time pricing
… and others.
186
Time of Use Rates
PG&E 2006 Annual Usage
21,000
19,000
PG&E Peak Load
July 25 @ 1700 hours
20,883 MWs
17,000
15,000
13,000
11,000
9,000
7,000
5,000
Jan
Fe b
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
187
Time of Use Rates
188
Time of Use Rates
Residential "E6" Time-of-Use Pricing Periods
Midnight - 6am
6am - 10am
Sunday Monday TuesdayWednesdayThursday Friday Saturday
Off-Peak Off-Peak Off-Peak Off-Peak Off-Peak Off-Peak Off-Peak
Off-Peak Off-Peak Off-Peak Off-Peak Off-Peak Off-Peak Off-Peak
10am - 1pm
1pm - 7pm
Off-Peak Part-Peak Part-Peak Part-Peak Part-Peak Part-Peak Off-Peak
Off-Peak
Peak
Peak
Peak
Peak
Peak
Off-Peak
7pm - 9pm
Part-Peak Part-Peak Part-Peak Part-Peak Part-Peak Part-Peak Part-Peak
9pm - Midnight Off-Peak Off-Peak Off-Peak Off-Peak Off-Peak Off-Peak Off-Peak
• Peak rates in Summer Afternoons 29¢/kWh + tier surcharges
• Part-Peak rates: 14¢/kWh + tiers
• Off-Peak rates (Nights & Weekends) 8.5-10¢/kWh + tiers
189
Time of Use Rates
35
30
Cents per Kwh
25
20
15
10
5
0
1
2 3 4 5 6
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hours of the Day
E-6 summer rates (May – October)
190
Time of Use Rates
3500
Kwh Produced
3000
2500
2000
1500
1000
500
0
1
3
5
7
9
11
13
15
17
19
21
23
Hours of the Day
Typical summer production
191
Time of Use Rates
35
30
Cents per Kwh
25
20
15
10
5
0
1
2 3 4 5 6
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hours of the Day
Summer pattern (May – October)
192
Time of Use Rates
35
Sell
30
Cents per Kwh
25
Buy
Buy
20
15
10
5
0
1
2 3 4 5 6
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hours of the Day
Buying low and selling high adds value.
193
Should I go on a TOU rate with my PV system?
High
On-peak
usage
No
Med
Low
Yes
0
25%
50%
75%
100%
Percentage of yearly usage covered by solar
194
With PV: Change in Utility Billing
• Two bills, gas & electric
• Yearly billing cycle for electricity
• Fixed minimum electric charge reflected on
gas (blue) bill
195
Change in Utility Billing
Minimum
electric
hookup
charge
196
Change in Utility Billing
Minimum
electric
charge
Current monthly
charge
Cumulative
charge
197
Change in Utility Billing
PV electric bill: meter readings
CURRENT .MONTH METER INllORMATION:
METBR
TOU
PRIOR CURRBNT
READ
BADGE ID SEASON PEIUOD RBAD
48,842
48,759
50M544
Winter
l'eak
SOMS44
14.575
14,800
Winter
Off
63,4 17
63,559
TOTALS
DIFFERENCE
-83
225
MET BR
CONSTANT
I
I
BNERGY
-83
225
142
CUIUmNT MONTH METER INFORMATION:
PRIOR CURRENT
METER
RBAD
BADGE ID SEASON READ
\\.'inter
63,417
63,559
50MS44
63,559
TOTALS
63,417
v ... ..Yeat(: tS no an ac1u:u meter read. Your meterCisplays the peak read an<! the 10<al 1ead.
Tite off-peal< •read" provided on your bill is calculate<! as follows: Off·Peak Read = Total Read · On-Peak Read.
If this is a seasonal Cl"O$S-over monlh (May or November), this calculation will be completed for boU1seasons by prorating the data from your meter.
CURRENT MONTII BASELINE QUANTITY 1Nl'ORMATION1
RATE
EFFECTIVE
DATE
RATE DAYS UNITS
DESCRIPTION SEASON
B Units
\\'inter
03/01/08
32
l
TOTAL
.,.sc11ne 1.1uant1()' , Kale v ays 1 lieason-Uays xllmts xlloufRatc
DAILY
BASELINE
QUANTITY
MONTHLY
BASEl...IN!l
OUANTITY
9.80
313 .600
313.600
198
Change in Utility Billing
PV electric bill: usage history
SUMMER
ON
SUMM BR
OFF
WINT ER
\VINTllR
OPI'
BILI.ING
MONTH
BILL 1'0
MAY2008
04/29/08
·83
APR 2008
MAR2008
FEB2008
03/28/08
02/28/08
01/29/08
- 19
399
JAN 2008
12/31/07
SI
434
~
NOV 2007
11/29/07
10/29/07
10/01/07
OATB
DEC 2007
OCT2007
225
285
.33
49
0
23
-53
249
-77
····~-----------·· ..-
6
335
2n
•
TOTALS
..E,,.,rgy Chargu11.rcd11s (·)include all energy
400
ON
~!area
TOTAL
ENERGY
ENERGY
CHARGE!S
/CREDITS
142
$8.46
252
380
$ 17.93
416
364
196
195
2,428
$34.S8
$29.24
483
$50.79
$28.27
$2.98
S-2.0S
Sl70.20
a mounts and 1axes.
·~ ..... ~................,~......,.....-.....~............... _,..._ _ _ _ __ _ __...,.....................-..·................
~
..~.~--,,,..,....-..- - ...·"'
300 .......................................................
~~
~
-~
_,_,_ ~:-:.. ..................._, ~- - ············..···--· -~ .............................. 1.. -·-·····-···· . · ·. . . ·-·-·-···-·"•"•'"''. . . . . .
:.·
-
-~·
200 ... ... -·-······--··-.. f.<.,
- - - -· -
~ - - - -+-If-· .........- -.
.:. - - ---..- -: ·- ·-
····-·--
·-
.·
!
;
'}·
'
~
~
.,,
, ----t1l~---•wt--~~--.... ~i----;~··i----~[*I---~
1 00 f-l-t-----~,l----+.,~
i1
.
(}1 "
ffi
~nt:,~,~·'~·.____,~'.!r....,~\....__ __ u:~-~.~~·~---~M.~....·~!.___lll "
t
fit
'.!
d
i
"'i......__"'
·100iil'
-------------~
'+--~~----~--------------,..._ _ .,,
'°'r
',.,_---u""c
""""---~N'ov
ec
o"'
N_ _ _"'
---::i'A""
MAY
2008
IWR
2008
MAR
2008
FEB
2008
2008
2007
2007
2007
199
Change in Utility Billing
Yearly “trueup” example
• Yearly usage total $170.20
• Already paid the fixed amount of $6.71 per
month for 12 months, total of $80.52
• Amount owed is 170.20 – 80.52 = $89.68
200
Relatively Low Maintenance
Source: DOE National Renew able Energy Laboratory
Soiling Factors
• Three basic categories for rainy / dry season areas
– Washed as often as necessary
– Washed once in July
– Never washed
~ 1.0
~ 0.96
~ 0.93
• Factors affecting number
–
–
–
–
–
Rainy / dry seasons
Dirt roads
Near agricultural activity
Close to road surface of busy street
In airport flight path
Cleaning Costs
Residential systems
• Around $5 per panel
• High because of fixed costs (travel, insurance, etc.)
Commercial systems
•
•
•
•
•
•
In PPA, contracted out to separate company
Cleaning and inspections typically done together
Frequency usually twice per year
Full service cost about 2¢/watt per year
One time cleaning-only cost around 1/2¢/watt or $1/panel
Must be careful with power washers, psi not too high
500 kW system = 2,500 panels:
Yearly cleaning & maintenance = $10,000.
Environmental “Footprint”
• Best overall estimates from 1 to 2.5 years
• Depends on site and power production--in
California is about 1.1 years.
• Shrinking as costs drop and production gets
“greener”
• Pays back 10 to 30 times or more its
environmental cost
Most PV manufacturing
plants will have their own
PV system on the roof.
Courtesy of DOE/NREL
Source: January 2008 Environmental Science & Technology
http://sustenergy.blogactiv.eu/2008/05/29/emissions-from-photovoltaic-manufacturing/
California Solar Initiative (CSI)
SB 1
CPUC (California Public Utilities
Commission)
Existing Residential
Existing Commercial
Commercial New Construction
CSI
(California Solar Initiative)
Program Administrators
PG&E
SCE
CCSE
(SDREO)
CEC
(California Energy Commission)
Residential New Construction
NSHP
(New Solar Homes Partnership)
Program Administrators
PG&E
SCE
SDG&E
The CSI makes PV …
• Economical:
Gives financial incentives to lower the cost
• Secure
Screens and tests equipment
Requires long warranties
Helps screen and check installers
Standardizes production estimates
• Easy
Helps installers handle everything
CSI Financial Incentives—two types
EPBB
(Expected Performance-Based Buydown)
• One-time, up-front payment (rebate)
• Based on expected production
• Only for smaller systems (< 50 kW)
PBI
(Performance-based Incentive)
• Ongoing monthly payment for 5 years
• Based on actual production
• Possible for all systems, but required for
large ones (> 50 kW)
CSI Financial Incentives—numbers
EPBB
PBI
Overall outline:
Incentives step down according to amount of PV
installed (MW)
CSI Financial Incentives—numbers
Data as of 2/7/12
MW remaining – MW under review = best estimate of how much left.
For PG&E residential: 26.48 – 1.08 = 25.4 MW.
Trigger Tracker. Helps determine when incentives drop.
http://www.csi-trigger.com/
CSI Rebate Adjustments
Base system size in AC kilowatts (CEC) may be
adjusted downwards depending on design
and geography.
Determined by EPBB calculator: www.csi-epbb.com
according to the following inputs:
1. Zip code
2. Orientation (azimuth)
3. Tilt (from horizontal)
4. Shading (detailed shading table)
– Design rewards summer energy, not annual
– No design penalty for any orientation from South to West
– Geography factor capped at 1.0 relative to Orange, CA
Sample Current Situation
Case study
Electric bill: $100/month = $1200/year
After 10 years you will have paid $12,000
… if rates do not rise.
Is this a reasonable assumption?
Pacific Energy Center
San Francisco
211
Sample Current Situation
Case study
Electric bill: $100/month = $1200/year
With inflation, after 10 years you likely will have paid
$14,000 to $17,000 …
With nothing to show for it except higher electric bills
($150+/mo).
• No equity
• Nothing “paid off”
So the real question is
Can solar be less expensive than this?
Pacific Energy Center
San Francisco
212
PV Statistics & Performance for
the “Average” Family of Four
(monthly electrical bill $100-$200)
4.0 Kw AC System
COST (before rebate = $6,500 / kW)
REBATE (est. $230 / kW)
TAX CREDIT
$26,000
$920
$7524
NET COST
Maintenance (25 – 40 yrs.)
Total lifecycle cost
$17,556
$5,000
kWh Production
~ 6,500 kWh / year
Space requirements
Avg. cost of power now ($150/mo)
25-yr. cost of power (est.)
40-yr. cost of power (est.)
Pacific Energy Center
$22,556
San Francisco
~ 350 - 500 s.f.
$.18/Kwh
$.14/Kwh
$.09/Kwh
213
Three Ways to Buy
1. Full purchase (cash or borrowing)
You
PV Vendor
Owner of system
Borrow money or pay cash
Full payment up front
$$$
Maintain and monitor
system
Design and install
Sell
Honor warranties
(equipment & labor)
Economics:
Cash / total savings
Loan pmt. / monthly savings
Pacific Energy Center
San Francisco
214
Three Ways to Buy
2. Solar Lease
You
Low or no money down
Fixed lease payment
Possible buyout in the
future
Economics:
Lease pmt. / monthly
savings
Pacific Energy Center
San Francisco
PV Vendor
$
$
Owner of system
Design and install
Lease
Maintain and monitor
system
Honor warranties
(equipment & labor)
Remove system at end if
needed
215
Three Ways to Buy
3. Power Purchase Agreement (PPA)
You
Low or no money down
Monthly power payment
Possible buyout in the
future
Economics:
Monthly pmt. / monthly
savings
Pacific Energy Center
San Francisco
PV Vendor
$
$
Owner of system
Design and install
Sell power
Maintain and monitor
system
Honor warranties
(equipment & labor)
Remove system at end if
needed
216
Solar lease
Lease
Pacific Energy Center
San Francisco
217
Solar lease
Pacific Energy Center
San Francisco
218
PV System Costs by Component
• Retail costs of system under 30 kW
– PV Panels
– Inverter
– Balance of System
– Installation / Labor
~ $2 per Watt
~ $.50 per Watt
~ $1 per Watt
~ $3 per Watt
Total cost ~ $6.50 per watt installed
THE BIG QUESTION:
What’s the
payback?
Return on Investment
Different ways to measure
“Payback”: Time period when savings = investment cost
IRR (internal rate of return): Percentage of annual return
which looks at full life cycle
NPV (net present value): Cash flow projection which takes
in financing costs
Monthly Cash Flow: Change in your monthly payment
221
Return on Investment
Monthly Cash Flow:
• Financed by a home-secured loan
• Loan interest is tax-deductible
• Assuming historical rate escalation continues
Monthly cash flow can be immediately positive for
many people with higher electric bills.
They can start making money from day one and
continue for over 30 years!
Lower bill amounts will typically start out slightly
negative and improve over time.
222
Grid Parity
When the price per kWh of electricity from a
renewable source is equal to the current average
grid price.
PV example:
System net cost: $20,000, lifetime maintenance $4,000.
Expected to generate average of 5,000 kWh per year for 30
years, total of 150,000 kWh.
$24,000 / 150,000 = $ .16 per kWh
Current utility average price = $ .16 per kWh
= Grid Parity
223
Increase in Home Value
Appraisal Value
• Will likely go up
• Less utility cost means more money available for mortgage
payment
• Data so far is supportive, new report just released
• Much more to come as solar houses turn over
Solar Rights Act
•
•
•
•
California law that supports solar
Keeps HOAs and other CC&Rs from prohibiting solar systems
Forbids increased property taxes on owner’s system
Restriction ends when home is sold, and assessment can go up
to reflect system
224
“We find compelling evidence that solar PV systems in California have boosted home sales prices.”
http://eetd.lbl.gov/ea/emp/reports/lbnl‐4476e.pdf Renewable Energy Credits
• Called RECs or “green tags”
• The “green attribute” of the power
• Connected to carbon offset accounting
Central feature of a system to move money
from polluters to non-polluters.
226
Bad guys
Renewable Energy Certificates
Good guys
Cap and Trade
Trade
Polluters must buy RECs
according to penalty.
Penalty
Permitted
Cap
Pollution preventers
Polluters
Source: W ikipedia free license
Pollution removers
227
Carbon Offsets
• Making activity “carbon neutral”
• Funding projects that remove as much
carbon as you generate
• Additional social & business image value
228
Strategies for Cost Reduction
Strategies for Cost Reduction
• Installation efficiencies/roofing
• Multiple benefits from one strategy
• Design integration
• Package with energy efficiency
• The PV Bulk-Buy?
Installation Efficiencies
Courtesy of DOE/NREL
PV Roof Tiles
BIPV Building Integrated Photovoltaics
Installation Efficiencies
Tiles interlock quickly
with NO roof penetrations
Source: DOE National Renew able Energy Laboratory
Installation Efficiencies
PV Integrated Roofing Membrane
Courtesy: Solar Integrated
Installation Efficiencies
PV Skylights
Source: DOE National Renew able Energy Laboratory
Multiple Benefits
•
Mitigate unwanted
solar heat gain
•
Control glare
•
Displace existing
materials cost
•
Produce electricity
Source: Darren Bouton
Package with Energy Efficiency
• Conservation gives best payback
• Many EE rebates available
• Will be required for rebate
• Can handle entire package for client
Source: DOE National Renew able Energy Laboratory
PV Bulk Buy
• Community targets for total Kw
• Can lead to 10% or more discounts
• Many companies offering it
Source: Pete Shoemaker
Sales and Installation
Process
Case Studies
Residential Case Study
Phone screening information:
• “John Doe” in Gilroy, CA
• $200/month PG&E electric bill
• Usage projected to stay the same
• Composition shingle roof
• Thinks there are no shade issues
• Overhead photos not clear
Site Visit Data:
Roof Layout
25’
N
W
E
S
Back of
house
4:12 pitch
65’
Front of
house
W
N
E
S
Source: Pete Shoemaker
Site Visit First Pass
• No shading issues
• Roof in good shape
• About 200 sf. south-facing
• Lots of room west-facing
• Good site for inverter(s)
• Electrical service and panel OK
• Substantial electric bill
What Size System?
Usage History
Jul-06
946
Aug-06
1127
Sep-06
1349
Oct-06
970
Nov-06
1093
Dec-06
1077
Jan-07
1349
Feb-07
867
Mar-07
886
Apr-07
768
May-07
815
Jun-07
836
Total
12083
Avg.
1007
• Usage pattern normal
• Monthly average is good
starting point
• Propose maximum size
system and then work to
customer’s budget
• Check for competitive
bids, ask to see them
5. PG&E Bill Analysis
Sy s t em Size:
4.56 Kw DC
3.81 Kw AC
Before solar:
Avg. baseline aUo\v ance per day :
Avg. billing days fo r m onth:
Avg. baseline per month:
Avg. us age per month:!
Rate Tiers
12 .2
30
366.00 K\\'h
1007!K\vh
Char efKw h
Tier Usa e Kwh
Oto i 00% of Sasel.ine
101to 130% of Baseline
131 ~o 200% of Baseline
201 to 300% of 8 ;,;seline
Over 300% of Baseline
Total
366.00
1-09.80
256.20
275.00
0 .00
1007
S0.11430
A n1ount
$41 .83
S0.12Q89
$ 14.26
$0.22722
S0.3 1719
S0.36434
$58.21
$87.23
SO.QC
$20 1.54
-· - -
After solar:
Solar produces on a vg .:~------'4"'9"->
7 K\vh
Net usage with s o lar:.!_ _ _ _ _ _~5~1-"'
0!K\\lh
Rate Tiers
Tier Usane tKwhl
Oto 100% cf Sasefine
101 to 130% of Baseline
131 to 200% of Baseline
201 ~o 300% of Baseline
Over 300% of Baseline
Total
Estin1ated increa se in v alue
with Time of -U se rate {E7>: 8%
4
366.00
109.80
34 .20
0 .00
0 .00
510
CharnefKwh
S0.11430
S0.12989
S0.22722
$0.31719
S0.36434
Est. bill wit h E7 rate:
Amo unt
$41 .83
$ 14.26
57.77
S0.00
SO.QC
863.8 7
$52.85
...... -· -· -· ...
Acme Solar final bid
3. Financial Summary
John Doe-4.56 DC system
Gilroy, CA 95020
System size:
3.81 KwAC (CEC)
24 190-w att modules
Tw o 2000-w att inv erters
You r system is expected to produce an average of 5967 Kilowatt hours per yea r.
It is expected to save you $1784 the first year. with this amount in creasing stead ily
for the next 30 years or more.
Pricing:
Full system price
$34 ,900
Includes everything except permff fees
CSI rebate
Out of Pocl<et cost
Federal tax credit
Net system cost
($7 ,992 )
I S26.907
($2,000
I S24.907
Price per AC watt (CEC)
$9 16
Old monthly electric bill
Estimated new bill with solar
Percentage of bill to offset
$202
$53
74%
Savings in first month
Savings in first year
Net savings over 30 years
$149
$1,784
$89 ,561
Assuming an annual utility rate increase of 6%.
Commercial Case Study
Car dealership in Gilroy
Commercial Case Study
•
•
•
•
Check usable space
Estimate maximum size of system
Determine average usage from bill
Give ballpark financial numbers
80
90
90
30 x 40
140
Total space is about 16,000 square feet, but how much
is usable? Need site visit to determine.
Visual estimate about
60+% usable space.
about 10,000 sf. total =
100 KW system
maximum.
Electric bill yearly average: 31,000 Kwh/month
11
Rate Schedule
A·1
Basic general service rate. Generally
. optimal rate for customers with low electric use
and low load factors, with most usage during
PG&E's peak and partial peak TOU periods.
Season
Summer
Total Energy Charge
(per kWh)
"Average"
Total Rate21
(per kWh)
$0.18264
$0'.1659'4
Winter
$0.12941
Average blended rate per Kwh = $ .16594
Average monthly bill = 31,000 x $ .16594 = $5,144
or about $5,000 per month.
From website: www.csi-epbb.com
Page 1
Page 2
Name:
Car Dealership
System Size:
100 Kw AC (CEC)
Date:
FULL SYSTEM PRICE (out-of-pocket cost) -----------------------------This image cannot currently be display ed.
FEDERAL TAX CREDIT (30%)
51812008
$825,000
($247,500)
Note: This could revert to 10% after 11112009 if currellt Jaw is not extended
NET COST AFTER TAX CREDIT
TOTAL FED. TAX DEPRECIATION
% of full cost
$577,500
(over 5 years at 30% tax bracket)
TOTAL STATE TAX DEPRECIATION
(over 5 years at 7% tax bracket)
NET COST AFTER DEPRECIATION
CSI PBI PAYMENTS
($210,375)
($49,088)
$318,038
(estimated total over 5 years @$.22/Kwh)
Note: These paymellts are taxable
($179,311)
CSI PBI PAYMENTS
($112,966)
(tax adj usted)
NET COST AFTER 5 YEARS (all financial incentives deducted)
70%
$205,0721
AVERAGE YEARLY PRODUCTION (Kwh) ----------------------------163,000
AVERAGE UTILITY COST PER Kwh
$0.165
YEARLY SAVINGS, FIRST YEAR - - - - - - - - - - - - - - - - - - - _ _$_2~6,8_9_5
YEARLY SAVINGS (tax adjusted)
$16,944
-------------------------- ---~YEARS TO PAYBACK, NO RATE INCREASES
-----------------------12.1
YEARS TO PAYBACK, 6% ANNUAL RATE INCREASES
--------------9.5
39%
25%
PV Sales-Installation Process
• STEP 1: Complete an Energy Survey
• STEP 2: Contact and Choose an Installer
INSTALLER HANDLES THE REST
• STEP 3: Complete and Submit Applications for CSI
• STEP 4: Obtain Building Permits
• STEP 5: Install System
• STEP 6: Schedule Final Building Inspection
• STEP 7: Schedule Final Utility Inspection
• STEP 8: Claim Incentives
Find Installers
• Personal references
• CSI website
http://gosolarcalifornia.org
• CalSEIA Members
http://calseia.org/, “Find an Expert” link
• Internet
• Advertising
• Better Business Bureau
• Diamond Certified
Comparing Bids: DC vs. AC watts
• DC watts are “name only”
• DC rating is determined under
Standard Test Conditions (STC), not
real-world
• DC must be changed to AC before
use
DC system size: 20 Sharp 200-watt
modules
= 20 x 200 = 4000 watts = 4.0 kW DC
Comparing Bids: DC vs. AC watts
Lookup CEC ratings for panels.
http://www.gosolarcalifornia.org/equipment/
Comparing Bids: DC vs. AC watts
Lookup CEC ratings for inverters.
http://www.gosolarcalifornia.org/equipment/
Comparing Bids: DC vs. AC watts
• AC watts are “real power”
• AC rating is determined under Practical
Test Conditions (PTC), real-world
• AC takes efficiency losses into account
AC system size: 20 Sharp 200-watt modules
PTC rating 176 watts, inverter efficiency 96%
= 20 x 176 = 3520 watts x .96 = 3379 watts
= 3.38 kW AC
Comparing Bids: DC vs. AC watts
System size: 20 Sharp 200-watt modules
1 SMA SB 4000US inverter
4.0 kW DC
3.38 kW AC
(CEC rating)
DC is about 18% more, but misleading.
AC is the important number, and if installer
only gives DC numbers ask for CEC AC size.
Comparing Bids: Per-watt price
1. Full price, before incentives. This includes all
“adders” (such as extra roof charges), and extras
(such as monitoring), an estimate for permit fees
(around $300), and taxes.
2. The system size in similar units: CEC AC watts is the
preferred measurement.
3. The per-watt price. This is determined by dividing the
full price by the system size. This is the “unit price”
that allows you to compare “apples to apples”. It will
typically be around $6.50/watt.
262
Comparing Bids: Per-watt price
Base price: $20,000
Roof adder: $2,000
Permit fee:
$500
Total:
$22,500
System Size:
4.0 Kw DC
3.38 Kw AC (CEC)
(3,380 watts)
Per-watt price:
$22,500 / 3,380 = $6.65/watt
263
Comparing Bids: Group discount
Three options:
1. 20 Sharp 185 panels, 3.19 Kw AC,
$6.05/watt
2. 20 Evergreen 180 panels, 3.12 Kw AC,
$6.45/watt
3. 20 Kyocera 190 panels, 3.28 Kw AC,
$6.90/watt
If group target of 100 kW is met, price
will drop to $6.00/watt
264
Review of Learning Objectives
Class Quiz
Jobs Overview
and
Future Trends
Solar Incentive Data: National and State
http://www.dsireusa.org/
Courtesy DOE
Solar Installation Data: National and State
http://openpv.nrel.gov/visualization/index.php
Courtesy NREL
Solar Installation Data: State
Detailed statistics
http://www.gosolarcalifornia.org/
Courtesy CSI
Solar Installation Data: State
Complete data file
Courtesy CSI
http://www.gosolarcalifornia.org/
Information Available from Analysis of Full Data File
# Installers by # of Systems
1/07 to 4/10 CSI Data
600
500
480
502
400
300
191
200
100
0
1 system
2-10 systems
11-50 systems
39
32
26
51-99 systems
100-200 systems
200+ systems
Compiled by Verve Solar Consulting from data CaliforniaSolarStatistics.ca.gov
Courtesy Verve Solar Consulting
Top 30 Residential Installers
by total # installs
CSI Residential Projects # installed systems 1/07 to 4/10
SolarCity
REC Solar, Inc.
Akeena Solar, Inc.
Borrego Solar Systems, Inc.
REgrid Power, Inc. DBA Real Goods Solar
Sungate Energy Solutions, Inc.
Self-Install (Same as Host Customer)
SPG Solar, Inc.
Stout & Burg Electric, Inc.
Mohr Power Solar, Inc.
NextEnergy Corp.
Marin Solar Inc. DBA Real Goods Solar
HelioPower, Inc.
Advanced Solar Electric, Inc
Sun Light and Power
Independent Energy Systems, Inc. dba Real Goods Solar
Premier Power Renewable Energy, Inc.
SolarCraft Services, Inc.
Solar Technologies
Acro Energy Technologies, Inc.
Cobalt Power Systems, Inc.
Sullivan Solar Power
Sierra Pacific Home & Comfort Inc.
Horizon Energy Systems
Luminalt Energy Corporation
Sungevity, Inc.
The Solar Company
SunWize Technologies
Potero Corp.
Occidental Power
Compiled by Verv e Solar Consulting from data CaliforniaSolarStatistics.ca.gov
0
500
1000
1500
2000
2500
3000
Courtesy Verve Solar Consulting
Top 30 Lg Commercial CSI Installers
kWp installed
through CSI
1/07 to
4/7/2010
SunPower Corporation, Systems
Sun Edison LLC
Team-Solar, Inc.
REC Solar, Inc.
SPG Solar, Inc.
BP Solar International, Inc.
Conergy Projects, Inc.
SolarCity
Pacific Power Management, LLC
Permacity Construction Corp.
Erickson Construction Co.
Stellar Energy GP, Inc.
Bleyco Inc
Chico Electric
Solar Integrated Technologies, Inc.
Unlimited Energy, Inc.
SPG Solar, Inc. - Novato
EI Solutions
Premier Power Renewable Energy, Inc.
Permacity Construction
Akeena Solar, Inc.
SunPower Corporation
Borrego Solar Systems, Inc.
Sunlight Electric LLC
EI Solutions, Inc.
Granite Bay Energy (Formerly GBEG dba Granite Bay Solar)
Solar Power, Inc.
BAP Power Corporation
INTERIOR ELECTRIC INCORPORATED
Sunview Vineyards of California, Inc.
34,013
17,211
11,413
10,110
8,199
6,347
5,265
4,913
4,419
4,191
2,889
2,862
2,852
2,181
2,105
2,089
1,963
1,920
1,797
1,761
1,667
1,649
1,539
1,459
1,364
1,197
1,176
1,120
1,109
1,030
0
5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000
Compiled by Verv e Solar Consulting from data CaliforniaSolarStatistics.ca.gov
Courtesy Verve Solar Consulting
Solar job trends
Courtesy Verve Solar Consulting
http://library.constantcontact.com/download/get/file/110558592629873/SWIC_EmployerSurvey_SummaryReport_1.23.2011.pdf
SWI C Weekly Jobs Report Summa ry
Q4 20 11
Solar - Total Unique Q4 2011 Postings: 590
Sources of Data: Ernployer Websites, Craigslist, SimplyHired, Linkedin
Regional Scope: San Francisco Bay Area (includes North Bay, East Bay, San Francisco, Peninsula, and
South Bay)
The total number of job postings in Q4 2011 was 2,116. However, after the list was deduplicated, the
total number of unique job postings V\ras 590.
Solar Postings Per Source
Solar Job Postings Per Source
Q4 2011
• Employer sites: 328
• SimplyHired: 124
• Craigslist: 109
• tmplo.,.r Site
• SlmplyHlred
• Linkedln: 29
• Cr>lgsllst
• unkedln
http://library.constantcontact.com/download/get/file/110558592629874/2011Q4_SWIC_JobsReport_Summary_1+23+2012.pdf
PV Job Categories
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Lead Generator (canvasser, outside sales)
Sales 1 (inside sales, lead qualifier)
Sales 2 (field rep, closer)
Project Developer (creating and selling large, longer-term projects)
Designer 1 (pre-sale, estimation)
Designer 2 (typical designer category, creates plans and drawings)
Designer 3 (large-scale, commercial)
Project Manager (post-sale, operations)
Application Processor (paperwork, rebates, etc.)
Permit Processor (w/ building officials, inspections)
PV Installer 1 (laborer, apprentice, entry level)
PV Installer 2 (typical crew member)
Installer Crew Lead
Monitoring / Maintenance
Technician / Troubleshooter
Safety Manager
Financial Operations (work with banks, etc.)
HR / Hiring
Marketing
Smart Grid
Adding information technology to the electric grid infrastructure
http://www.smartgridnews.com/artman/publish/Technologies_Communications_Resources/CSR2009-Environment-The-Smart-Grid-Vision-1563.html
Smart Grid
Source: NIST
Adding information technology to the
electric grid infrastructure
rJ" A Smart Grid
Overlay with intelligence and automation
Sense
Power
Plants
Communicate
Transmission
Networks
Substations
Compute
Distribution
Networks
Control
Consumers
Courtesy PG&E
Smart Meter
Gas Meter with SmartMeter™ Module
Gas Meter Module
 Attaches to existing gas meters
 Measures 5.5 x 6.5 inches
 Transmits wireless signals to the
Data Collector Unit
 20 year life span
 A.k.a. Meter Transmission Unit
(MTU)
9/7/2012
©2010 Pacific Gas and Electric Company. All rights reserved
282
Electric Network Components
Meters
Relays
Access
Points
3G Cellular
Network
Head
End
Utility IQ
9/7/2012
©2009 Pacific Gas and Electric Company. All rights reserved
283
A Platform for Innovation
Customer Energy Management
From meter to the home
 Near-time electric usage
information
 Timely price signals
 Appliance / energy
management control signals
From meter to utility
Internet
 Customer electric use
 Customer energy generation
(e.g. solar)
PG&E
Premise
 Appliance response to energy
management control signals
CEM network communication
SmartMeter™ communication
Don’t forget the bottom line
Paper
Wealth
Contact Information
Pete Shoemaker
Pacific Energy Center
851 Howard St.
San Francisco, CA 94103
(415) 973-8850
[email protected]
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