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Solar Photovoltaic Power and BWP's Solar
Support Program
We appreciate your interest in solar photovoltaic (PV) power generation.
Following is an overview of photovoltaic power and the Burbank Water
and Power Solar Support Program. This should answer many, if not
most of your questions.
Photos of solar PV installations
in Burbank
· What is a Solar PV cell and how does
it work?
· How all the parts of a solar PV system work together
· Some problems solar PV faces and possible solutions
· There's only one drawback, the cost!
· The BWP Solar Support program
· How to Get Started
· Checking Contractors
· Determining the Correct Solar Photovoltaic
System Size for Your Needs
· Net-Metering - How does it work?
· Design for maximum financial benefit
· How a solar net-meter is read and billed
· Determining Solar Equipment Eligibility
· Minimum Warranty Requirements
· System Performance Meter
· Starting the Rebate Application Process
· Checklist for meeting BWP Solar Support Program
requirements
· Solar System Net Power Production Rating
· Issuing the Solar Support Rebate
· Payback Calculations
· Other recommended solar web links
What is a Solar PV cell and how does
it work?
You've probably seen calculators that have solar cells -- calculators
that never need batteries, and in some cases don't even have an
off button. As long as you have enough light, they seem to work
forever. You may have seen larger solar panels -- on emergency road
signs or call boxes, on buoys, even in parking lots to power lights.
Although these larger panels aren't as common as solar powered calculators,
they're out there, and not that hard to spot if you know where to
look. The first solar cell arrays were on satellites, where they
were used to power the electrical systems.
The solar cells that you see on calculators and satellites are photovoltaic
cells or modules (modules are simply a group of cells
electrically connected and packaged in one frame). Photovoltaics,
as the word implies (photo = light, voltaic = electricity), convert
sunlight directly into electricity. Once used almost exclusively
in space, photovoltaics are used more and more in less exotic ways.
They can even power your house!
How do these devices work? PV cells are made of special materials
called semiconductors such as silicon, which is currently
the most commonly used. Basically, when light strikes the cell,
a certain portion of it is absorbed within the semiconductor material.
This means that the energy of the absorbed light is transferred
to the semiconductor. The energy knocks electrons loose, allowing
them to flow freely. PV cells also all have one or more electric
fields that act to force electrons freed by light absorption to
flow in a certain direction. This flow of electrons is a direct
current, and by placing metal contacts on the top and bottom of
the PV cell, we can draw that current off to use externally. This
current, together with the cell's voltage (which is a result of
its built-in electric field or fields), defines the power (or wattage)
that the solar cell can produce.
How all the parts of a solar PV system
work together
Now that we have our PV module, how do you power your house with
solar energy? Although it's not as simple as just slapping some
modules on your roof, it's not extremely difficult to do.
First of all, not every roof has the correct orientation or angle
of inclination to take advantage of the sun's energy. Non-tracking
(most typical) PV systems in the Northern Hemisphere should point
toward true south (this is the orientation). They should be inclined
at an angle equal to the area's latitude to absorb the maximum amount
of energy year-round. In Burbank that's about 34 degrees. A different
orientation and/or inclination could be used if you want to maximize
energy production for the morning or afternoon, and/or the summer
or winter. Of course, for optimal operation, the modules should
never be shaded by nearby trees or buildings, no matter the time
of day or the time of year. In most PV modules, if just one of its
many cells is shaded, power production will be reduced by more than
half.
Several things go into the decision of what size system you need.
This is complicated by the fact that your electricity production
depends on the weather, which is never completely predictable, and
that your electricity demand will also vary. (See "Determining
the Correct Solar Photovoltaic System Size for Your Needs"
below.)
With that data, and knowing your average household usage (your BWP
utility bill conveniently lets you know how much energy you use
every month), there are simple methods your solar installer can
use to determine just how many PV modules you'll need. You should
design for slightly below your average needs since BWP does NOT
pay nor allow you to bank excess electric generation over the course
of an entire year. Your installer will also need to decide on
a system voltage, which will be determined by the type of inverter
used (see below) and this will determine how many modules to wire
in series.
Some problems solar PV faces and possible
solutions
You may have already guessed a couple of problems that you'll have
to solve. First, what do you do when the sun isn't shining? Certainly,
no one would accept only having electricity during the day, and
then only on clear days, if they have a choice. You need someplace
to store the extra energy you generate. In remote locations with
no electric utility service, this is done with batteries. Unfortunately,
batteries add a lot of cost and maintenance to the PV system. Currently,
however, it's a necessity if you want to be completely independent
from BWP.
Fortunately there is an alternative that solves this problem since
BWP allows you to connect your solar PV system to the utility grid.
You buy power from BWP when you need it and bank a credit by turning
the meter backward when you produce more than you need. This way,
BWP acts as a practically infinite storage system and the meter
becomes your "bank." This method of crediting you for
excess power is required by law in California and is known as "net
metering." (See "Net-Metering - How does it work?"
below.)
If you decide to use batteries, keep in mind that they will have
to be maintained, and then replaced after a certain number of years.
The PV modules should last 20 years or more, but batteries just
don't have that kind of useful life. Batteries in PV systems can
also be very dangerous because of the energy they store and the
acidic electrolytes they contain, so you'll need a well-ventilated,
non-metallic enclosure for them.
The other problem is that the electricity generated by your PV modules,
and extracted from your batteries if you choose to use them, is
direct current (DC), while the electricity supplied by your utility
(and the kind that every appliance in your house uses) is alternating
current (AC). So you will need an inverter, a device that converts
from DC to AC. Most of today's sophisticated inverters will also
automatically control how your system works.
The inverter needs to have special electronic circuitry to make
sure that the power you sell to BWP is synchronous with our generated
power -- that it shares the same sinusoidal waveform and frequency.
Safety is a big issue here. BWP also has to make sure that if there's
a power outage in your neighborhood, your PV system won't try to
feed electricity into lines that a lineman may think is dead. This
is called islanding. Inverters approved for use in Burbank will
not allow islanding to occur.
Throw in the mounting hardware, wiring, junction boxes, grounding
equipment, over current protection, DC and AC disconnects and other
accessories and you have yourself a system. Electrical codes must
be followed (there's a section in the National Electrical Code just
for PV), and it's highly recommended that the installation be done
by a licensed electrician who has experience with PV systems. Once
installed, a PV system requires little maintenance (especially if
no batteries are used), and should provide electricity cleanly and
quietly for 20 years or more.
There's only one drawback, the cost!
If photovoltaics are such a wonderful source of free energy, then
why doesn't the whole world run on solar power? Some people have
a flawed concept of solar energy. While it's true that sunlight
is free, the electricity generated by PV systems is not. As you
can see from our discussion of a household PV system, quite a bit
of hardware is needed. Currently, an installed PV system will cost
somewhere around $10 per Watt.
For example, A 2,000 Watt (2kW) PV system would be able to supply
the average Burbank house of 1,500-2,000 square feet with 20%-80%
of its annual power needs. This varies depending upon the actual
power consumption rate, if the home has a roof that's ideal for
solar (one that faces south, west or both) how much shading there
is, and so on. Installation prices also vary, but generally a 2
kW system costs approximately $20,000 before the rebate payment
and any available tax incentives. Please check with a tax professional
regarding the availability of tax incentives. Even after the rebate,
that system may take over twenty years to pay for itself at today's
electricity rates.
That's why PV is usually used in remote areas, far from a conventional
source of electricity. Right now, it simply can't compete with BWP's
electric rates. However, costs are coming down as research is being
done. Researchers are confident that PV will one day be cost effective
in urban areas as well as remote ones. Part of the problem is that
manufacturing needs to be done on a large scale to reduce costs
as much as possible. That kind of demand for PV, however, won't
exist until prices fall to competitive levels. So it's a Catch-22
situation. That's where Burbank's Solar Support Program comes
into the picture.
The BWP Solar Support program
On July 1, 2001, Burbank Water and Power instituted a Solar Support
program to help Burbank's residents and businesses support photovoltaic
energy. Any BWP residential or commercial electric customer is eligible
for this program. Through the Solar Support Program, BWP issues
a rebate, which is used to offset a portion of the purchase price
of solar photovoltaic (PV) systems. BWP does not recommend equipment
or contractors, nor do we design, evaluate, sell, install or remove
PV equipment. Solar thermal systems (that heat water) are not eligible
for the rebate program.
The Solar Rebate is $3 dollar per each Watt of the PV system up
to the limits listed below. Each time you install eligible PV equipment
you can apply for a rebate until you've reached the cumulative maximum
total.
The maximum solar rebate tops out at $10,000 (3.3 kW) for a residential
site, and $25,500 (8.5 kW) for a commercial site. A site's residential
or commercial status is determined by the existing electric rate
schedule in effect. A site is defined as an address. Multiple buildings
on a hospital or college campus, for example, would be considered
as one site.
With programs like Burbank's helping to support the solar industry,
demand and module efficiencies are constantly rising, prices are
falling, and the world is becoming increasingly aware of environmental
concerns associated with conventional power sources, photovoltaics
is becoming a technology with a bright future.
How to Get Started
You must hire your own contractor to evaluate your property and
design and install a PV system. Per the California State License
Board, three contractor classifications are eligible to install
Solar Photovoltaic Systems: Electrical (C10), Engineering (A), and
Solar Specialty (SC46). Alternatively, you can do the work yourself;
however, you must still meet all design and safety requirements
of BWP and the City of Burbank Community Development Department,
Building and Safety Division. In a do-it-yourself installation the
Solar Support Rebate will not exceed the actual cost of PV equipment,
so save your receipts for submittal.
Checking Contractors
The independent League of California Homeowners operates a contractor
approval system that is free to the public. Contractors apply and
provide proof of licenses and insurance, which the League verifies
monthly. They also investigate for previous complaints, etc. The
League can be contacted at (800) 692-HOME or at their web site www.homeowners.org
(click on "approved contractors"). There are listings
under the categories of "electrical" and "solar."
The California Energy Commission also provides a list of retailers
and vendors of solar photovoltaic equipment at: www.consumerenergycenter.org/erprebate/database
Determining the Correct Solar Photovoltaic
System Size for Your Needs
Your BWP utility bill conveniently shows you how much energy you
use every month. To determine your average power usage, locate the
total kilowatt-hours (kWh). Each bill should be for approximately
one month, so the kWhs shown is typically monthly kWh consumption.
Check the period to make sure. You should average a year of kWh
data to be sure you don't oversize your system because BWP will
NOT pay you for excess (net) electricity generated, nor let you
store a kWh credit in your meter for more than a year. Divide
the calculated monthly average kWh by 165 (there are about 165 solar
hours-or hours of full sunlight- on average per month in Burbank).
The sum will indicate how many net solar kilowatts (kW) are needed
for full (100%) power on average over the course of the year. If
you don't have a copy of your bills for each month of the year,
you may contact our Customer Service section at 818 238-3700 and
ask for a year of electrical consumption history.
Your available roof or installation space with the proper orientation
and inclination will determine what percentage of this power could
be produced with a solar PV system. Each square foot of installation
space averages to about 10 Watts of power generation. 1,000 Watts
equals 1 kilo-watt (kW). You may need racks mounted to the roof
to incline the panels at the ideal angle. You can also use ground
based mounting racks if you have enough sunny space and the right
orientation.
The Energy Technology Development Division of the California Energy
Commission has created a very useful document named: A GUIDE TO
PHOTOVOLTAIC (PV) SYSTEM DESIGN AND INSTALLATION. This document
can be accessed at the following address and requires the free Adobe
Reader be installed: www.energy.ca.gov/reports/2001-09-04_500-01-020.PDF.
Minimum & Maximum Sizes and Cost Approximation
The minimum size PV system that is allowed in the rebate program
is 300 Watts. The maximum is one designed to produce 100% of your
expected annual power needs, but can't be greater than 1 megawatt
in size.
Net-Metering - How does it work?
California law requires that PV systems in the state be allowed
"net-metering" by their utility. Net metering means that
when the PV system is supplying all of the power that the residence
or business needs, the electricity meter stops spinning. If there
is more generation than current needs, the meter will turn backwards
and the kWh read decreases.
When the PV system isn't operating, such as at night, the BWP utility
grid provides power for your electric needs, the meter spins forward,
and the read increases again. In effect, the meter becomes a kWh
"bank" for your excess generation. It's likely that during
most of the daylight hours, both the PV system and BWP will be providing
power and the meter will spin forward more slowly than usual (at
the rate of actual consumption from the utility grid). If you do
generate excess power from your PV system, it is fed into the BWP
grid and offsets utility generation that would have otherwise been
required to serve your neighbors.
In other parts of the country the utility might only buy excess
power from you at a much lower price than their own selling price.
California has been leading the way by requiring net metering for
solar PV for several years.
Design for maximum financial benefit
Since solar PV customer/generators will receive a kWh credit rather
than a dollar credit for any excess power, they are guaranteed the
same rate for excess solar generation as that which they are billed.
The credit in kWh may be carried forward for up to one year as long
as a Utility Interconnection Agreement is in place. There will never
be a credit shown on the bill nor any payment from BWP. However,
you can read your meter and, by comparing it to your last bill,
you can tell if you currently have a credit or debit in kWhs. Since
BWP does not allow a customer to carry a kWh credit in their meter
for more than a year, it is to your benefit to not over-size your
solar PV system.
How a solar net-meter is read and billed
When a new solar installation is approved for interconnection BWP
will install a special meter capable of accurately measuring power
flowing in both directions. When we read the solar net meter and
it registers a negative number, it means that the solar system produced
more electricity than what was consumed during the billing period.
BWP will then enter the previous month's meter read into our billing
system and this will generate a zero usage of kilowatt-hours for
the current billing period and no kWh charge will be reflected for
energy consumption. The meter itself will, of course, reflect the
true usage, and in this case, hold your kWh credit.
If the following month yields a positive consumption meter read,
measured against the highest read previously recorded, it indicates
that you consumed your banked kilowatt-hour credit at your home
or business facility. The additional usage will reflect on your
bill. Please keep in mind that while your kWh energy costs will
be zero in periods of negative usage (i.e., the PV system produces
more energy than you use), your monthly invoice will always reflect
the Customer Service Charge and the Demand Charge if you are a commercial
customer. Of course other municipal service fees such as water and
sewer will be unaffected.
Determining Solar Equipment Eligibility
Since new PV equipment is being introduced continually, BWP has
opted to use the California Energy Commission's (CEC) list of eligible
equipment to determine eligibility for the Solar Support Program.
For PV Modules (Panels) and PV inverters see: www.consumerenergycenter.org/erprebate/equipment.html
Minimum Warranty Requirements
All systems must have a minimum five-year warranty to protect the
purchaser against system or component breakdown. The written warranty
must cover and provide for no-cost repair or replacement of the
system or any defective components, including any associated labor
for five years. The warranty must also cover the photovoltaic modules
and inverter against breakdown or degradation in electrical output
of more than ten percent from their originally rated electrical
output during the five year period.
Click here to
download a sample warranty form.
Self-installed systems must have a minimum five-year manufacturer's
warranty on all parts to protect the purchaser. The written warranty
need not cover the labor costs associated with removing or replacing
defective components since the repairs would be likely done by the
customer.
System Performance Meter
All systems installed after March 31, 2003 must be equipped with
a performance meter so that the customer can determine the amount
of energy produced by the system. The meter must measure the total
energy produced by the system in kilowatt hours (or watt hours)
and have a manufacturer's uncertainty specification of plus or minus
five percent. The meter must retain the kilowatt-hour production
data in the event of a power outage and must provide a display of
system output that the customer can easily understand. A system
need not include a separate meter if the system inverter contains
internal metering and display equipment that meets the meter requirements
above.
Starting the Rebate Application
Process
It's recommended that you first hire a solar designer, consultant
or contractor. After you and your contractor have selected the PV
system and know the brand, model and number of panels you plan to
install, you should call BWP's Marketing Department at (818) 238-3653
for an update on the Solar Support Program's funding status. All
rebates will be paid on a first come first served basis until funding
is exhausted. BWP does not reserve funds for proposed PV projects.
In addition you must submit plans and sign a BWP Electrical Interconnection
and Net Metering Agreement, and submit to an inspection by the utility
BEFORE you connect the PV system to the utility grid.
Click here to
download the BWP Electrical Interconnection and Net Metering Agreement.
You or your contractor must also submit plans and secure both a
building permit and an electrical permit from the City of Burbank
Community Development Department, Building and Safety Division.
You can reach them at (818) 238-5220.
Checklist for meeting BWP Solar Support
Program requirements:
1. A fully executed Electrical Interconnection and Net Metering
Agreement with BWP
2. Written approval from Burbank's Building and Safety Division
(copy of final signed-off building and electrical permit)
3. The system is completely installed and operational
4. Full 5 year warranty information must be on file with BWP and
provided by the installer to the customer
5. Panels and inverter must be listed as approved on the CEC web
site (listed above)
6. Written approval by the BWP Electrical Distribution Superintendent
as to safe operation of the system to protect our field personnel
7. We encourage you to call BWP before you sign a contract to
get up-to-date rebate availability information
Solar System Net Power Production Rating
The solar organization PV USA issues PTC Ratings (PV USA Test Conditions)
that determine how many Watts various solar modules actually
produce. A factory may label a panel as 100 Watts, but the panel
may actually produce only 89 Watts. In addition, the inverter has
a certain measured amount of energy loss, expressed as a percentage.
To determine the amount of the rebate, BWP multiplies the total
panel array PTC rating times the efficiency percentage to determine
the total number of Watts eligible in calculation of the Solar Rebate.
The CEC web site www.consumerenergycenter.org/erprebate/equipment.html
lists the PTC ratings of each model module and the inverter list
includes the efficiency percentage.
In this example, a system contains twenty, factory-labeled 100-Watt
panels with a PTC rating of 89 Watts each. The DC to AC inverter
carries a rating of 96% efficient. The rebate would be calculated
as:
20 panels @ 89 Watts each = 1,780 Watts,
1,780 Watts times the inverter efficiency of 96% = 1,709 Watts
(1.709 kW)
1,709 Watts x $3/Watt Rebate = $ 5,127 total Rebate payment
Issuing the Solar Support Rebate
The payment can be made to the PV system manufacturer, consultant,
installer or property owner. The customer of record will designate
the receiving party via a written request to BWP. If the check is
sent to a customer/generator, they will receive a 1099 statement
from BWP for the amount of the rebate, which may be considered taxable
income (check with a tax professional).
Payback Calculations
To determine how long it will take for your system to pay for itself
and compare financing options, please visit the Clean Power Estimator
on the California Energy Commission Renewable Energy web site: www.consumerenergycenter.org/renewables/estimator
and follow the directions you find there.
More Solar Information
You can receive updated information on BWP's solar rebates and program
requirements by calling John Joyce at (818) 238-3653 or email him
at jjoyce@ci.burbank.ca.us
Other recommended solar web links:
Tax Incentives Assistance Project
www.energytaxincentives.org
California Solar Center
www.californiasolarcenter.org
U.S. Dept. of Energy - Energy Efficiency and Renewable Energy
www.eere.energy.gov/solar
National Center for Photovoltaics
www.nrel.gov/ncpv
National Renewable Energy Laboratory
www.nrel.gov/solar
Solar Electric Power Association
www.solarelectricpower.org
Thank you for your interest in Solar Power!
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