The back door to renewables: Part 2: What we did
By Drs. Robert and Sonia Vogl, President and Vice President Illinois Renewable Energy Association
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 percent 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 ComEds 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 sites use for solar panels.
Our farms 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 dont know theyre there.
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.