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SEEN: Archives
Article 3: The
Back Door to Renewables*
Spring 2004 Editorial, by Drs. Robert & Sonia Vogl
Part
2: What We Did
We
came to renewable energy via our long standing interest in ecology. When we realized
that widespread changes in native ecosystems were probably being caused by the use of
fossil fuels, we investigated renewables.
Photovoltaics especially interested us. In the late 1980s, we developed a solar
electric education kit and used it to explain how pv works and what factors affect its
output and use.
When we became officers of the newly formed Illinois Renewable Energy Association, we
decided that we should model the behavior we encouraged.
Before we installed our pv system, we made changes in our energy use. We replaced
nearly all of our light bulbs with compact fluorescents. We also hang all of
our laundry out to dry in summer and most of it on an indoor rack in winter. We
use cold water for laundry and allow our dishes to air dry.
In April, 2001, we installed the first half of a 1.5 kilowatt photovoltaic
system. The next fall, we installed the second half. The system
provides us with about one third of our electrical needs. If we add more panels
in the future, we could eventually produce all of the electricity we use.
We selected amorphous panels by UniSolar which produce electricity even on cloudy
days. (Thin film panels are mass produced and are likely to become cost
competitive with fossil fuels as markets grow. They convert 8% of the sunlight
falling on them to electricity.) Our system consists of 24 panels, each
producing 64 watts. We selected a Trace inverter with enough capacity to handle
a system three times the size of our current one. The system also contains a
solar boost which changes excess voltage (needed to charge batteries) to amperage,
providing the equivalent of another three or four panels.
We wanted a degree of autonomy, so have battery backup. Several times since our
system was installed, grid electricity has been interrupted. The transition to
photovoltaic power has been seamless. Since our pv system produces only a part
of the electricity we need, we wired essential circuits to it. Non-essential
uses are cut when grid electricity is down.
We are grid connected as part of ComEd’s pricing experiment. When we need
grid power, we purchase it; when we produce excess electricity, we sell it to ComEd at the
same price they charge us. We also received a 60 percent rebate on the entire
system except the batteries through the Illinois Department of Commerce and Community
Affairs’ renewable energy support program.
Siting the system is an important decision. Our house is densely
shaded. While trees provide cooling in summer, they prevent a site’s use
for solar panels.
Our farm’s old outbuildings still look much the same as when they were
built. Since aesthetics and historic preservation are both important to us, we
wanted the pv installation to blend with the overall appearance of the site. We
decided to place the panels flush on the south facing roof of an old corn crib which is
fairly close to the house. They blend so well that most visitors don’t
know they’re there.
A year later, we added another 3.2 kW of Sharp polycrystalline panels to another
outbuilding. The new system is tied into the original system. Both
provide nearly two thirds of our electrical needs.
The only upkeep necessary has been checking water levels in the batteries and slightly
overcharging them twice a year to remove accumulated sulfur from the battery
plates. These tasks take less than an hour. We also change the tilt
on the lower set of panels at the spring and autumn equinoxes.
The installation has served us well and is expected to do so for up to 30 years.
*
This article was previously published in The
Rock River Times newspaper.
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