A critical consideration in Long's decision, Reznick adds, has been the dramatic decline in the cost of manufacturing photovoltaic cells since their first application as power sources for satellites in the space program in the '50s. At that time the cost was as high as $2,000 per peak watt--the term used to describe the electrical output of a cell. As commercial applications began increasing demand in the '60s the price dropped to about $200 and then to about $15 per peak watt in the '70s.
"Now," Reznick continues, "it's down to about half that--about $7.50 per peak watt--and how much farther, and when, it will go lower depends almost entirely on demand. It may have leveled off for awhile."
Essentially, he adds, the photovoltaic module converts light directly into electricity by virtue of the fact that when a photon (a unit of electromagnetic energy) strikes a solar cell (consisting principally of a silicon diode "very similar to a computer chip") it sets an electron in motion along a circuit and the light is directly converted to energy.
"Early in the '70s," according to Long, who built his first Phoenix home in 1947 and, in the interim, has constructed more than 30,000 others, "we started concentrating on photovoltaic panels with an eye to the heating of water with which to generate steam, and then using the steam to turn a turbine. But it was just too expensive for single-family homes. The answer lay in \o7 directly \f7 converting sunlight to directcurrent (DC) and then converting it to alternating current (AC), which is not only compatible with both the utility and household appliances, but which is also a lot \o7 cleaner \f7 than energy produced by the utility." ("Cleaner," because, according to Reznick, a direct creation of energy bypasses the utility's normal water-cooling process and the waste created in this phase of the conversion.)
Under the guarantee given Long by Arco Solar, the 132,000 photovoltaic cells in Solar 1's Energy Center will generate 350,000 kilowatt hours of electricity a year (the cost of any shortfall will be guaranteed by Arco for 10 years at peak rates) and each of the 24 homes in the development will be individually metered as to output and input and, therefore, entitled to one-twenty-fourth of the energy generated, or 14,583 kilowatt hours a year.
(In the Los Angeles area, according to a spokesman for the Department of Water and Power, the average home with air conditioning and a heated pool is estimated to consume 10,000 kilowatt hours a year. In Phoenix's torrid summers, however, when air conditioning becomes a 24-hour matter of survival, kilowatt usage soars, Long says, and an annual consumption of 18,000 to 20,000 kilowatt hours isn't unusual for a conventional home \o7 without \f7 the passive energy features in his solar homes. \o7 With \f7 them, however, annual consumption is on a par with comparable homes in Los Angeles).
"The whole idea of Solar 1," Long adds, "is that, without changing his life style, the home owner should strike a balance--generating more than his own needs during the peak hours and drawing on that surplus during the off-hours--so that he will never have an electric bill to pay.
"Now if, through his own conservation efforts, he should use less than his monthly allocation, then he'll get a small--maybe $10 or $15 check--back from the Salt River Project. If he's wasteful, he might end up having to pay a little. We're not really encouraging anyone to buy one of these homes if he isn't already concerned about energy, but, again, we're not talking about changing life styles."
Admittedly, Long adds, Solar 1's feasibility without the Internal Revenue Service's solar tax credit would have been doubtful. And, unless Congress intervenes, these tax credits are slated to run out at the end of this year.
"I'd estimate," Long continues, "that, without the tax credit, the active and passive energy devices used--and which, incidentally, the home buyer doesn't pay for, we pick up the entire cost of them--would add about $50,000 to $60,000 to the price of the house. And, even if you amortize that over 30 years--which is the estimated life of the photovoltaic panels--you'd be hard-pressed to justify the cost effectiveness. But, of course, if the price of photovoltaic equipment continues to come down as it has in the past, well, that could put the whole thing in a different light."
(The Federal solar tax credits, a spokeswoman for the IRS here said, allow a write-off of 40% of the cost of active and passive solar equipment up to a maximum of $10,000--or, in Long's case, 24x$10,000--plus the other tax and depreciation considerations already in place).