Which Home Solar Power Systems Are Best For You?

Are you thinking about buying home solar power systems for your home or business?

If so, this post provides some basic information that can help you. Solar electric systems, which are also called photovoltaic or PV systems,
are reliable and pollution-free. They make use of a renewable source of energy—the sun. And PV systems for homes and businesses are becoming more affordable all the time. PV works best in an energy-efficient building. So, adding insulation and energy-efficient lighting, appliances, and windows is a good idea, to reduce your home’s overall electricity use before you install a PV system.

To make PV systems even more affordable, several states offer financial incentives through solar rebates and other programs. Some utilities have net metering programs, which further enhance the economics of PV. Net metering means that when your PV system generates more power than you need, the excess goes to the utility grid and the meter runs backward. This allows you to receive full retail value for the power that your PV system generates.

This post can guide you through the process of buying a solar electric system.

It is not a technical guide to designing or installing a system—for that information, we recommend
consulting an experienced PV system designeror supplier. A PV system can be a substantial
investment. As with any investment, careful planning will help you make the right decisions for your
home or business.

What is a solar electric or photovoltaic system?

Photovoltaic (PV) systems convert sunlight directly to electricity. They work any time the sun is
shining, but more electricity is producedwhen the sunlight is more intense and strikes the PV modules
directly (as when rays of sunlight are perpendicular to the PV modules). Unlike solar thermal systems
for heating water, PV does not use the sun’s heat to make electricity. Instead, electrons freed by
the interaction of sunlight with semiconductor materials in PV cells are captured in an electric current.

PV allows you to produce electricity—without noise or air pollution—from a clean, renewable resource.
A PV system never runs out of fuel, and it won’t increase U.S. oil imports. Many PV system components
are manufactured right here in the United States. These characteristics could make PV technology the
U.S. energy source of choice for the 21st century.

The basic building block of PV technology is the solar “cell.” Multiple PV cells are connected to form a
PV “module,” the smallest PV component sold commercially. Modules range in power output from about
10 watts to 300 watts. A PV system connected or “tied” to the utility grid has these components:

• One or more PV modules, which are connected to an inverter
• The inverter, which converts the system’s direct-current (DC) electricity to alternating current (AC)
• Batteries (optional) to provide energy storage or backup power in case of a power interruption or
outage on the grid.

AC electricity is compatible with the utility grid. It powers our lights, appliances, computers, and
televisions.

Special appliances that run directly on DC power are available, but they can be expensive. Before
you decide to buy a PV system, there are some things to consider:

First, PV produces power intermittently because it works only when the sun is shining. This is not
a problem for PV systems connected to the utility grid, because any additional electricity required
is automatically delivered to you by your utility. In the case of non-grid, or stand-alone,
PV systems, batteries can be purchased to store energy for later use.

Second, if you live near existing power lines, PV-generated electricity is usually more expensive
than conventional utility-supplied electricity.

Although PV now costs less than 1% of what it did in the 1970s, the amortized price over the
life of the system is still about 25 cents per kilowatt-hour. This is double to quadruple what
most people pay for electricity from their utilities. A solar rebate program and net metering can
help make PV more affordable, but they can’t match today’s price for utility electricity in most
cases.

Finally, unlike the electricity you purchase monthly from a utility, PV power requires a high initial
investment. This means that buying a PVsystem is like paying years of electric bills up front. Your
monthly electric bills will go down, but the initial expense of PV may be significant. By financing
your PV system, you can spread the cost over many years,  and rebates can also lighten your
financial load.

Are incentives available to help reduce the cost?

Yes, many states offer incentives. For specific information, call one of the contacts listed under
“Getting Help” at the end of this post. Another excellent source is the National Database of State
Incentives for Renewable Energy (DSIRE). Prepared by the North Carolina Solar Center, this
database contains information on financial and regulatory incentives that promote renewable
energy technologies.

Net Metering

In more than 35 states, customers who own PV 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 PV system. Through net metering,
the customer obtains the full retail electricity rate—rather than the much lower wholesale rate—for
kilowatt-hours of PV-produced electricity sent to the utility power grid. The benefits of net metering
to consumers are especially significant in areas such as Hawaii and New York, which have high
retail electric rates. Utilities also benefit because the solar-generated energy often coincides with
their periods of “peak” demand for electricity.

Property and Sales Tax

Tax incentives may include a sales tax exemption on the PV system purchase, a property tax
exemption, or state personal income-tax credits,

all of which provide an economic benefit to consumers by lowering high capital costs. The U.S.
government also provides financial support for PV 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
solar electricity.

Buy-Down

Rebates and buydowns, typically based on the rated power of the system, help to defray high capital
costs and to create competitive, sustainable market growth. In the United States, the U.S. Department
of Energy has been involved in a program known as TEAM-UP, or Technology Experience to Accelerate
Markets in Utility Photovoltaics. Through this program, some 80 utilities in 40 states have installed more
than 7 megawatts of grid-connected PV; supplier buydowns and consumer rebates range between $2
and $4 per watt.

Residential Energy Rate

This is the average retail residential rate for energy from utilities, in cents per kilowatt-hour. Check your utility
bill for your actual rate.

Investing In A Photovoltaic System

Why should you buy a PV system?

People decide to buy PV systems for a variety of reasons. Some people want to help preserve
the Earth’s finite fossil-fuel resources and reduce air pollution. Others want to invest in an
energy-producing improvement to their property. Some people like the security of reducing the
amount of electricity they buy from their utility because it makes them less vulnerable to future
price increases. And some people just appreciate the independence that a PV system provides.

If you plan to build a home away from an established utility service, inquire about the cost of
installing a utility line. Often, the cost of extending conventional power to your residence is
higher than the cost of a solar option.

Whatever your reason, solar energy is widely thought to be the energy source of choice for
the future, and you may be able to take advantage of a state-sponsored program to help
make it your energy choice for today and tomorrow.

Is your home or business a good place for a PV system?
Can you locate your system so it works well?

A well-designed PV 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. If the
location looks promising, your PV provider can determine whether your home or business can
effectively use a PV system.

The orientation of your PV system (the compass direction that your system faces) affects its
performance. In the United States, the sun is always in the southern half of the sky but is higher
in the summer and lower in the winter. Usually, the best location for a PV system is a south-facing
roof, but roofs that face east or west may also be acceptable. Flat roofs also work well for solar
electric systems, because PV modules can be mounted flat on the roof facing the sky or bolted
on frames tilted toward the south at an optimal angle. They can also be attached directly to the
roof as “PV shingles.”

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 PV modules. Other options (often
used in multifamily or commercial applications) include mounting structures that create covered
parking, or that provide shade as window awnings.

Is your site free from shading by trees, nearby buildings, or other obstructions?

To make the best use of your PV system, the PV 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. Some potential sites for your
PV system may be bright and sunny during certain times of the day, but shaded during other
times. Such 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 easement.” Your PV provider
can help you determine whether your site is suitable for a solar electric system.

Does your roof or property contain a large enough area for the PV system?

The amount of space that a PV system needs depends on the size of the system you purchase.
Some residential systems require as little as 50 square feet (for a small “starter” system), but
others could need as much as 1,000 square feet.

Commercial systems are typically even larger. If your location limits the size of your system,
you may want to install one that uses more efficient PV modules. Greater efficiency means
that the module needs less surface area to convert sunlight into a given amount of electric
power. PV modules are available in a range of types, and some offer more efficiency per square
foot than others do (see table on the next page).

Although the efficiency (percent of sunlight converted to electricity) varies with the different
types of PV modules available today, higher efficiency modules typically cost more. System
sizing, discussed later in this booklet, should also be discussed with your PV provider.

What kind of roof do you have, and what is its condition?

Some types of roofs are simpler and cheaper to work with, but a PV system can be installed
on any type. Typically, roofs with composition shingles are the easiest to work with, and
those with slate are the most difficult. In any case, an experienced solar installer will know
how to work on all types and can use roofing techniques that eliminate any possibility of leaks.
Ask your PV provider how the PV system affects your roof warranty.

If your roof is older and needs to be replaced in the near future, you may want to replace it
at the time the PV system is installed to avoid the cost of removing and reinstalling your PV
system. PV 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 your PV system be, and what features should it have?

To begin, consider what portion of your current electricity needs you would like your PV
system to meet.

For example, suppose that you would like to meet 50% of your electricity needs with your
PV system. You could work with your PV provider to examine past electric bills and determine
the size of the PV 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 past 12 months (or consult
your electric bills if you save them). Ask your PV provider how much your new PV system
will produce per year (also measured in kilowatt-hours) and compare that number to your
annual electricity usage (called demand) to get an idea of how much you will
save. In the next section, we’ll provide more information on estimating how
much you will save.

Some solar rebate programs are capped at a certain dollar amount. Therefore, a solar
electric system that matches this cap maximizes the benefit of the solar rebate. To qualify
for net metering in some service territories, your PV system must have a peak generating
capacity that is typically not more 10 kilowatts (10,000 watts), although this peak may
differ from state to state.

Also, utilities have different provisions for buying excess electricity produced by your
system on an annual basis (see the section on net metering). Finally, customers eligible
for net metering vary from utility to utility; for example, net metering could be allowed
for residential customers only, commercial customers only, or both.

One optional feature to consider is a battery system to provide energy storage (for
stand-alone systems) or backup power in case of a utility power outage (for grid-connected
systems). Batteries add value to your system, but at an increased price.

As a rule, the cost per kilowatt-hour goes down as you increase the size of the system.
For example, many inverters are sized for systems up to 5 kilowatts, so even if your PV
array is smaller (say, 3 kilowatts), you may have to buy the same size of inverter.

Labor costs for a small system may be nearly as much as those for a large system, so
you are likely to get a better price for installing a 2-kilowatt system all at once, rather
than installing 1 kilowatt each year for two years.

All information and images in this Home Solar Power Systems post came from the US
Department of Energy publication A Consumer’s Guide – Get Your Power
from The Sun

Originally posted 2010-01-10 08:36:26. Republished by Blog Post Promoter

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