Mr. Farber said that mass production and improved manufacturing techniques had pushed prices down, and estimated that photovoltaic technology now costs one and a half to four times as much as conventional power sources when costs are spread over time. But the cost can be lower than that of electricity from conventional sources in areas with high power bills and government subsidies for the use of alternative energy.

Glenn Hamer, executive director of the Solar Energy Industries Association, said that the leaky water heaters that tainted the industry had been driven from the market.

A slow but steady resurgence of solar technology has taken place in the last two decades. In 1982, the year the government's Energy Information Administration started tracking shipments of PV modules, about 7,000 peak kilowatts (the measure used by photovoltaic companies) were shipped to purchasers in the United States. In 2001, about five times that many -- 36,000 -- were shipped.

Across the country, and particularly in California, where energy costs have spiked, more solar roofs are being installed each year. Some are generating a surplus of electricity that can be sold to the electric companies.

''It's starting to get very exciting,'' said Steven J. Strong, the solar designer who guided the White House project and whose company, Solar Design Associates, has been advocating the technology since the 1970's. ''We're busier than ever.''

At the same time, solar thermal systems for heating water have become almost commonplace for new pools, said Maureen McIntyre, editor of Solar Today, a monthly magazine. ''We now have solar hot water systems that are mature and affordably priced and make sense,'' she said.

Still, solar power makes up only 1 percent of the total energy generated in the United States, according to Mr. Hamer of the industries association.