Adapted for Washington
By Mike Nelson
Are you thinking about buying a solar electric system for your
home or business?
If so, this booklet will provide basic information that you need to know are showing increased interest in solar electric systems
for their homes and businesses. These solar electric systems are reliable, pollution free, and use a renewable source of
energy—the sun. They are becoming more affordable all the time. And remember: The more energy-efficient your house, the
greater the impact of a solar electric system. Measures such as increased insulation and energy-efficient lighting, appliances, and
windows will drastically reduce your home’s use of electricity.
Washington utilities offer net metering to make solar
electric systems more economical. Net metering means
that when your solar electric system generates more power
than you need, the meter runs backwards resulting in an
even swap for the grid power that you use at other times.
In essence, you receive full retail value for all the power
that your solar electric system generates.
This booklet is designed to guide you through the process
of buying a solar electric system. A word of caution: This
is not a technical guide for designing or installing your
system—for that information, we recommend that you
contact your utility or consult an experienced solar electric
system designer or system supplier (“solar electric
provider”) who will have detailed technical specifications
and other necessary information. A solar electric system
can be a substantial investment, and as with any
investment, careful planning will help ensure that you
make the right decisions.
What is a solar electric system?
Solar electric technology converts sunlight directly into electricity. It works any time the sun is shining, but more electricity will be
produced when the light is more intense (a sunny day) and is striking the solar electric modules directly (when the rays of sunlight
are perpendicular to the solar electric modules). Unlike solar systems for heating water, which you might be more familiar with,
solar electric technology does not use the sun's heat to make electricity. Instead, solar electric produces electricity directly from the
electrons freed by the interaction of sunlight with semiconductor materials in the solar electric cells.
The basic building block of solar electric technology is the solar “cell.” solar electric cells are wired together to produce a solar
electric “module,” the smallest solar electric component sold commercially, and these modules range in power output from about
10 watts to 300 watts. A solar electric system tied to the utility grid consists of one or more solar electric modules connected to an
inverter. The inverter changes the system's direct-current (DC) electricity to alternating current (AC), which is compatible with the
utility grid and able to power devices such as lights, appliances, computers, and televisions. You may include batteries in the
system to provide back-up power in case your utility experiences a power outage.
Before you decide to buy a solar electric system, you should understand the current
You don't need to understand
status of the technology:
the detailed physics of how solar
electric works to understand its
First, it produces power intermittently because it works only when the sun is shining.
appeal: investing in solar electric
This is not a problem for solar electric systems connected to the utility grid, because
allows you to produce your own
additional electricity you need is automatically delivered to you by your utility.
electricity with no noise, no air
Second, if you live near existing electrical service, Solar electricity is usually more
pollution, and no moving parts
expensive than conventional utility-supplied electricity. Improved manufacturing has
while using a clean, renewable
reduced the cost to less than one percent of what it was in the 1970s, but the cost
resource. A solar electric system
(amortized over the life of the system) is still about 25 cents per kilowatt-hour. This
will never run out of fuel, and it
is about two to five times the retail price that residents now pay for electricity from
won't increase our oil imports
their utilities. A solar rebate program and net metering can help make solar electric
from overseas. In fact, it may
more affordable, but it can't match today's price for electricity from your utility,
unless of course your building site is more than a quarter mile from the power grid.
not even contribute to the trade
deficit, because many solar
Finally, unlike electricity purchased month by month from a utility, solar electric
electric system components are
power comes with a high initial investment and no monthly charge thereafter. This
manufactured in the United
means that buying a solar electric system is like paying years of electric bills up
States. Due to these unique
front. You'll probably appreciate the reduction in your monthly electric bills, but the
characteristics, solar electric
initial expense may be significant. By financing your solar electric system, you can
spread the cost over many years, and rebates or utility discounts can also lighten your
technology has been called “the
ultimate energy source for the
A typical solar electric system and components (From Astropower)
Are incentives available to help reduce the cost?
Net Metering—Customers who own solar electric systems can benefit from laws and regulations that require “net” electric
meter reading. The customer is billed for the “net” electricity purchased from the utility over the entire billing period—that is, the
difference between the electricity coming from the power grid and the electricity generated by the solar electric system. Hence, the
monthly reading indicates net customer usage. Through net metering, the customer obtains the full retail electricity rate—rather
than the much lower wholesale rate-for kilowatt-hours of-produced electricity sent back to the utility power grid. The consumer
benefits of net metering are especially significant in areas such as Hawaii and New York, which have high retail rates. Utilities also
benefit because the solar-generated energy often coincides with their peak demand.
Federal Taxes — The U.S. government also provides financial support for solar electric technology through a tax credit for
commercial uses of solar energy. This energy investment credit provides businesses (but not individuals or utilities) with a 10%
tax credit and 5-year accelerated depreciation for the cost of equipment used to generate electricity by solar technologies.
State Taxes – As of July 1, 2001 there is a sales tax exemption for solar electric systems, of 200 watts or larger.
Local Utilities – Some progressive Washington Utilities are bginning to offer incentives to their scustomers – check with your
local PUD, Co-op, Municipal, or Private Power Company.
Investing in a solar electric system
Why should I buy a solar electric system?
People decide to buy solar electric systems for a variety of reasons. Some want to help preserve the earth's finite fossil-fuel
resources and reduce air pollution. Others would rather spend their money on an energy-producing improvement to their property
than to send their money to a utility. Some people like the security of reducing the amount of electricity they buy from their utility,
because it makes them less vulnerable to future increases in the price of electricity. Finally, some people just don't like paying
utility bills and appreciate the independence that a solar electric system provides.
If you plan to build away from established utility service, you should consider the cost of installing a utility line needed to provide
power. Often, the cost of extending conventional power to your residence is more expensive than the solar option.
Whatever your reason, solar energy is widely thought to be the energy source of choice for the future.
Is my home or business a good
place for a solar system?
Is your site free from shading by trees,
nearby buildings, or other obstructions?
To make the best use of your solar electric
system, the solar electric modules must have a
clear “view” of the sun for most or all of the
day—unobstructed by trees, roof gables,
chimneys, buildings, and other features of
your home and the surrounding landscape.
Note that even though the area where a system
is mounted may be unshaded during one part
of the day, it may be shaded during another. If
this is the case, then this shading may
substantially reduce the amount of electricity
that your system will produce. To be eligible
for some rebates, your system must be
unshaded between certain hours during
certain times of the year. Some states have
laws that establish your right to protect your
solar access through the creation of a “solar
To conduct a solar site survey:
You will need:
A. Angle Gauge
3. Solar site survey chart
1. The goal of this exercise is to plot the southern skyline at your site.
2. Use the compass to find true south. Make certain that you compensate for magnetic deviation. (Deviation is about 22° E. in
most of Washington.)
3. After locating true south, use the angle gauge to site on the top of the highest object or horizon, mark it on a copy of the
4. Repeat the process with each tree, building or other obstruction. If any objects fall in the white zone of the chart, you have
problems with your site and should consult a professional before purchasing solar equipment.
A well-designed solar electric system needs clear and unobstructed access to the sun's rays for most or all of the day, throughout
the year. You can make an initial assessment yourself, and if the location looks promising, your solar electric provider has the tools
to trace the sun's path at your location and determine whether your home or business can make use of a solar electric solar system.
The orientation of your solar electric system (the compass direction that your system faces) will affect performance. In the United
States, the sun is always in the southern half of the sky and is higher in the summer and lower in the winter. Usually, the best
location for a solar electric system is a south-facing roof, but roofs that face east or west may also be acceptable. Flat roofs also
work well for solar systems because the solar electric modules can be mounted flat on the roof facing the sky or mounted on
frames tilted toward the south at the optimal angle.
If a rooftop can't be used, your solar modules can also be placed on the ground, either on a fixed mount or a “tracking” mount
that follows the sun to orient the solar electric modules for maximum performance. Other options (used most often in multifamily
or commercial applications) include mounting structures that create covered parking or provide shade as window awnings.
Do you have enough area on your roof or property?
The amount of space needed by a solar electric system is based on the physical size of the system you purchase. Most residential
systems require as little as 50 square feet (for a small “starter” system) up to as much as 1,000 square feet. Commercial systems
are typically even larger. If your location limits the physical size of your system, you may want to install a system that uses more-
efficient solar electric modules. Greater efficiency means that the module uses less surface area to convert sunlight into a given
amount of electric power. Solar electric modules are available today in a range of types, and some offer more efficiency per square
foot than do others. The cost per kilowatt of higher-efficiency modules is about the same as low-efficiency modules, so this may
not add to your system's price. System sizing is discussed later in this booklet and should also be discussed with your solar
What kind of roof do you have, and what is its condition?
Some roof types are simpler and cheaper to work with, but a solar electric system can be installed on any type. Typically,
composition shingles are easiest to work with, and slate is the most difficult. In any case, an experienced solar installer will know
how to work on all roof types and can use roofing techniques that eliminate any possibility of leaks. Ask your solar electric
provider how the solar electric system affects your roof warranty.
If your roof is older and needs to be replaced in the very near future, you may want to replace it at the time the solar electric system
is installed to avoid the cost of removing and reinstalling your solar electric system. Panels often can be integrated into the roof
itself, and some modules are actually designed as three-tab shingles or raised-seam metal roof sections. One benefit of these
systems is their ability to offset the cost of roof materials.
How big should my solar electric system be, and what features should it have?
As a starting point, you might consider how much of your present electricity needs you would like to meet with your solar electric
system. For example, suppose that you would like to meet 50 percent of your electricity needs with your solar electric system. You
could work with your solar electric provider to examine past electric bills and determine the size of the solar electric system needed
to achieve that goal.
You can contact your utility and request the total electricity usage, measured in kilowatt-hours, for your household or business
over the last 12 months (or consult your electric bills if you save them). Ask your solar electric provider how much your new solar
electric system will produce on an annual basis (also measured in kilowatt-hours) and compare that number to your annual
electricity demand to get an idea of how much you will save.
To qualify for “net metering”, your solar electric system must have a peak generating capacity of not more than typically 25
kilowatts (25,000 watts) This would be a very big system for a household
One optional feature you might consider is a battery system to provide back-up power in case of a utility power outage. Batteries
add value to your system, but at an increased price.
As you size your system, you should consider the “economies of scale” that can decrease the cost per kilowatt-hour as you
increase the size of the system. For example, many inverters are sized for systems up to 2.5 kilowatts, and if your solar electric
array is smaller (say 1 kilowatt), you may still end up buying the same inverter. Labor costs for a small system may be nearly as
much as those for a large system. Therefore, it's worth remembering that your solar electric provider is likely to offer you a better
price to install a 2-kilowatt system all at once, than to install a 1-kilowatt this year and another similar system next year-because
multiple orders and multiple site visits are more expensive.
How much will my solar electric system save me?
The value of your solar electric system's electricity will depend on how much you pay your utility for electricity and how much
your utility will pay you for any excess that you generate. If your utility offers net metering (and so pays the full retail price for
your excess electricity), your calculation may be fairly easy because you and your utility will each pay the same price for each
other's electricity. You can use the calculation box to roughly approximate how much electricity your solar electric system will
produce and how much that electricity will be worth. Keep in mind that actual energy production from your solar electric system
will vary by up to 20 percent from these figures, depending on your geographic location, the angle and orientation of your system,
the quality of the components of your system, and the quality of the installation. Also keep in mind that you may not get full retail
value for excess electricity produced by your system on an annual basis, even if your utility does offer net metering. Be sure to
discuss these issues with your solar electric provider. Consider asking for a written estimate of the average annual energy
production from the solar electric system. However, you should realize that even if an estimate is accurate for an average year,
actual electricity production will fluctuate from year to year due to natural variations in weather and climate.