Case History
Financing It
1.7-kilowatt photovoltaic system,
Chicago
■ Eight 208-watt Sharp PV modules
■ SMA 1800 Sunny Boy inverter
Total system costs before incentives $12,276
Illinois state rebate ($3,683)
Federal tax credit ($2,000)
Total after incentives $6,593
(Left) Sarah and Kiril used their wedding registry blog to educate friends and family
about solar energy. (Right) The couple’s vision for a solar life together was on display
at their wedding reception in Chicago. Photos from their wedding two months prior
in Bulgaria mixed with PV system images to decorate the gifts table.
of emergencies or repairs. That means we needed to find a place for
the inverter and the DC disconnect inside our unit.
After gaining permission from the condominium board to install
our PV system on the roof, the next hurdle was determining the
layout of the remaining solar components. Placement is rarely a
problem in houses, because the electric panel — into which the system must feed — is typically in an unfinished portion of the basement.
In our unit, however, the electric panel is located in the kitchen. We
didn’t want the kitchen to look like a spider web of conduit with
visible solar equipment mounted on the walls.
Luckily our kitchen is along an outside wall, although the electric
panel is not. We installed additional cabinets to house the components
and ran conduit to the outside wall along the top of the cabinets, out
of sight. We decided to locate the inverter inside a cabinet with openings at the top and bottom for air circulation. It’s important that the
inverter does not overheat to avoid reduced performance or system
shutdown. Although our kitchen now houses solar components,
they’re invisible when the cabinets are closed. We were also concerned
about noise from the inverter, but when the cabinets are closed, the
sound is barely audible.
Minimizing Electricity Needs
In planning our PV system design and financing, we were able
to minimize the system’s size by reducing the amount of electricity we consume. Conservation is the best way to reduce the upfront
cost of going solar, and it allowed us to install a system that
generates 100 percent of our electricity. Even with three adults
living in the 800-square-foot (74-square-meter) home, our average
electricity use is 120 kilowatt-hours during noncooling months
and just under 200 k Wh during the summer. By comparison, the
average U.S. household used 920 k Wh per month in 2006, according to the U.S. Department of Energy.
To achieve this efficiency, we invested in an energy-efficient refrigerator, washer and dryer and installed compact fluorescent and LED light
bulbs. The dryer is rarely used because we line-dry our clothes. That also
reduces the need to run a humidifier during the winter because the
clothes naturally humidify the air as they dry. We use air conditioners
modestly, only cooling the rooms in use and only as necessary.
We conducted a home energy audit using a device that monitors
how much electricity a given appliance consumes. The device showed
that our television, VCR, DVD player and stereo all constantly drain
electricity, even when turned off. We now use power strips for these
items, disconnecting them from the power supply when not in use.
To determine the size of the solar system, we used electric bills to
calculate our energy usage during the prior year. PV Watts, a free web
tool from the National Renewable Energy Laboratory, estimates the
output of the solar system, taking climate, efficiency of system components and available daylight into account. We then matched the
estimated output of the solar system with our electricity consumption
for the past year. (See “Getting Started” sidebar for more resources.)
Crunching the Numbers
Illinois has a state rebate program that pays 30 percent of the cost
of the solar system. The paperwork for the program is relatively simple, and we received our rebate check within a couple months of completing the installation. We were also eligible for a federal tax credit
of $2,000 (this credit is set to expire Dec. 31). The two incentives
reduced the solar system cost of about $12,300 nearly 50 percent —
to just under $6,600.
Illinois also recently passed net-metering legislation, making it
one of the 40 states whose large utilities must purchase surplus electricity generated from solar systems and credit the generator’s utility bill. Our system will produce an estimated 2,000 k Wh each year.
We typically generate surplus electricity during the day and need more
electricity from the grid at night. Our solar system does not have batteries, so electricity that we don’t consume flows to the power grid.
Some of my neighbors like knowing that a portion of their daytime
electricity may have been generated by the solar system. And the credits we receive on our electric bills for our surplus generation will
reduce our low electric bills even further.
Chicago has relatively low-cost electricity, at about 8 cents per kilowatt-hour. The rates in Illinois were frozen for the last 10 years, with
the freeze ending in January 2007. Some parts of the state saw spikes
in electric rates, but our bills saw only a small increase because we use
so little electricity. The utilities plan to raise rates again soon, thus
shortening the payback period of our solar system.
Chicago has moderate sunshine, with blue skies about 55 percent
of the time. A combination of modest electric rates and sunshine
make the payback period of our system longer than if the same system were located in an area with higher rates, good sun and favorable
