Conscious Choice: Photovoltaic Systems

October 1999 | Sensible Home

Photovoltaic Systems

by James Dulley

Dear Jim: Because of current and potential Y2K power outages, I am considering adding a PV (photovoltaic) system to my house. What do you think of this — and do you have any tips? — Russ A.

Dear Russ: PV systems use solar cells that convert the sun’s rays into electricity. Installing a PV electricity generating system is an effective method to provide electricity during power outages. In fact, the primary reasons to install a PV system are for backup electricity and out of concern for the environment and our children’s future. PV systems are silent, require very little maintenance (no moving parts) and create no pollution. Some small systems, like Evergreen, are sold as complete simple-to-install homeowner kits. There have been improvements in solar cell efficiency over the years, and costs have dropped.

Since a PV system generates electricity continuously during daylight hours, at times it will produce more electricity than you need. Some of the excess electricity will be used to keep several deep-draw backup batteries charged. In many states and municipalities, utility companies must offer net metering billing. For your home, this means that your electric meter slows down or runs in reverse when the PV system is generating electricity.

To plan a PV system, first determine the power usage of the appliances you need to keep running during an emergency. This often includes the refrigerator, a water or sump pump, lights, and a radio or TV. In considering potential Y2K problems in January, you may want to include your furnace blower. The total of the wattages of these necessary electrical appliances determines the size of the battery pack that is required. During a power outage at night, all the electricity comes from the batteries. During the day, the solar panels provide electricity and keep the batteries charged. Knowing the total wattage also determines the number of PV solar cell panels needed. This varies depending on the solar cell technology you choose, your budget, and the amount of sun energy available in your area of the country.

If your house needs a new roof, consider solar shingles. These solar shingles are attached with nails just like ordinary shingles. Solar cells are built into them. Otherwise, you can purchase solar cell panels. These are thin, lightweight, and easy to handle. They can be tilted up on the roof or laid flat against it so they are barely visible from the ground. The two basic types of PV solar cells are crystalline and thin film. Crystalline has proven reliability and some kits have a 20-year warranty. Thin film is newer and less expensive, but requires larger panels and more area.

For more details, write for (or instantly download) Update Bulletin No. 812, buyer’s guide of PV systems, kits, PV shingle manufacturers, selection/ sizing guide and prices. Please include $3.00 and a business-size SASE. James Dulley, Conscious Choice, 6906 Royalgreen Dr., Cincinnati, OH 45244

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