SOLAR TODAY - Fall/Winter 2009

NEXT STEPS working with an installer >>

naMaSte Solar

Patrick armentrout and Jason houston of namaste Solar install a 9.9-k W SunPower solar photovol-

taic system in Boulder, Colo.

How to Work
systems, they can also be used when looking
for a solar thermal installer.
With Your
Solar Installer
Solar is an investment for
the long term. Your solar
installer should be someone
you can rely on.
By Dan YeChout
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

solar Power is a Major investment that needs to be tailored to your house and your lifestyle. Designing the system is a complex process best tackled in detailed discussions with a knowledgeable installer. Moreover, it’s a long-term investment. Because the array may produce power for at least 30 years, you’ll want to establish a solid relationship with your installer. Follow these tips when searching for a system installer. Though these guidelines deal primarily with installers ofsolar electric

Designing Your System

Your installer can help you figure out the optimum size for your system. it will depend on the rate at which you use electricity, your budget, the size and shape of your roof and the incentives offered by your state and utility. For instance, in some areas, incentives won’t cover systems of more than 2 kilowatts.

Begin the design process with a review of the electricity usage history for the home. if past bills are not on file, get an account history from your utility company. Consider whether lifestyle changes will affect your utility bills in the future. are you adding a kid to the household or sending one off to college? setting up a home office? if you plan to add air conditioning, an electric car or more people to the household, estimate the additional future consumption.

You’ll need to understand the electric rate structure of your local utility. Your utility company may bill and pay for straight kilowatt-hour (kwh) rates, inverse-tiered rates or time-of-use rates.

where straight kwh net-meter rates are offered, the utility company typically buys all your solar-power generation at the same retail rate, up to 100 percent of your consumption.

in these cases, you can size your photovoltaic
(PV) system to cover up to 100 percent of your
expected energy use. Beyond 100 percent, the
utility company often buys the surplus at a
lower wholesale rate. Because PV systems tend
to be less expensive per watt as they grow larg-
er, the optimum investment in a straight-kwh
rate structure is often to generate just under
100 percent of your consumption. some utili-
ties may offer a feed-in tariff, where the solar
production is metered separately and the pur-
chase rate is not related to your consumption.
under an inverse-tier rate structure, the util-
ity company charges more for higher amounts
of usage, similar to a tax bracket structure. For
example, the utility may charge a base rate for
usage under 300 kwh per month, a higher rate
for the next 200 kwh, and so on. under an
inverse-tier structure, the PV system can help
you stay in lower-tier rates. Your best invest-
ment may be to size the PV system to get you
into the low-tier rates but not necessarily cover
100 percent of your usage.
in time-of-use structures, the utility com-
pany charges more for electricity during peak
consumption periods. Peak consumption typi-
cally occurs in the afternoon when people are
working and running air conditioners. under a
time-of-use structure, PV panels that face more
southwesterly will generate electricity when
electricity is most expensive.
Finally, estimate the remaining life of your
roof. Your PV system should be in place for at
least 20 years, so you want to make sure your
roof has that much life left as well. otherwise,
you will be facing an additional expense to
remove and reinstall the PV system when it is
time to reroof.

an experienced local installer will already have done the appropriate calculations for other customers and can walk you quickly through this exercise.