PRACTICAL PHOTOVOLTAICS

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If you shop prudently, you can probably find imperfect collectors for as little as $5.00 per watt. And, if you are able and qualified to inspect them before you lay your money down (or know someone else who is), seconds may prove to be the best way to start a home photovoltaic setup. But be forewarned . . . the increased interest in solar electricity is rapidly drying up the surplus-and-seconds market. Therefore, bargains are getting harder and harder to come by . . . and you'll have to do your homework.

There is, however, still one more way to save on the cost of solar cells: quantity buying. Because manufacturing expense drops dramatically with increased production, companies are usually willing to give a significant discount on large orders. As a matter of fact, as much as 50% can be lopped off the sticker price when groups of homeowners buy cooperatively.

But, you may want to know, why would someone opt to use solar electricity in the first place? Even at $10 per watt, a photovoltaic system can hardly compete with readily available utility power. (Of course, folks who are facing steep installation charges for long service entrance wires may find that solar cells are already a bargain.) But consider for a moment: Oil prices have been rising and will certainly continue to do so . . . and over two-thirds of the electrical generation capacity in the United States is petroleum fueled. Photovoltaic cells, on the other hand—while subject to short-term price fluctuations—are generally becoming less expensive. Many experts think that the costs associated with the two systems will be equal before the turn of the century . .. some even believe that the prices will balance out within five years.

My point is that today is a good time to begin building the groundwork for your home photovoltaic system . .. by setting up a small powerplant that can be expanded as panels become less expensive.

PRACTICAL PHOTOVOLTAICS

A basic solar-electric system consists of nothing more than a photovoltaic collector and a load. Such arrangements are commonly employed to pump water in remote areas. By referring to Fig. 1, you'll notice that the wires from the solar panel connect directly to the motor. When sunlight strikes the collector, it generates electricity . . . which in turn powers the pump. Now to get acceptable performance and reliability out of such a setup, it's important to be sure that the pump motor is compatible with the panel's output. The voltage must be the same, and the collector must be capable of supplying enough current to match the pump's rated capacity. However, in order to make such comparisons, you'll have to know just how the demand and the output are related.

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