When the Rev. George Buchanan and his wife, Harlene, put $19,000 worth of solar electric panels on their roof here two years ago, they did it as a matter of principle, not to save money. Someday the earth will run out of fuel to burn, or ruin the atmosphere trying, the Buchanans said, and someone has to take the plunge and try something better.
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Thousands of people have been drawn by the same logic, and by the idea that the sun works every day, even if the electric system fails as it did during the big Northeast blackout one year ago this week.
"It's the right thing to do," said Mr. Buchanan, 82, a retired professor of New Testament theology at the Wesley Theological Seminary in Washington.
In the 1980's, solar energy was pitched as a path to energy independence. More recently, the rationales have shifted toward the pleasure of ownership, coupled with the attraction of a fallback source of power.
Few solar advocates expect the investment to pay off quickly, even when softened by tax rebates and other subsidies. And few install enough panels or batteries for total independence. The Buchanans, for example, generate only about a third of their power during a given 24 hours, saving about a dollar in the process.
With out-of-pocket costs at about $13,000, their system will pay for itself by 2037, assuming electricity costs stay the same — and their equipment lasts that long.
What they appreciate right now is the step toward self sufficiency. Every evening Mrs. Buchanan, 74, takes a spiral notebook out to the garage to jot down the number of kilowatt-hours generated, just as she used to record the eggs in the henhouse every morning on the family farm in Kansas during the Depression. On sunny days, the couple sell surplus power back to the Potomac Electric Power Company at 7.4 cents a kilowatt-hour.
When the sun sets or disappears behind a cloud, the meter runs the other way.
"It isn't financially sound," Mr. Buchanan acknowledged as he stood on his roof, which he visits four times a year to adjust the angle of the panels.
Clean, quiet and homegrown, solar power appeals to early adopters, including many businesses, electric companies and homeowners. Sales of solar cells in the United States increased sevenfold between 1993 and 2002, according to the Energy Information Administration. (Information on home solar systems is at www.nrel.gov/solar, the National Renewable Energy Laboratory's Web site.)
Prices for solar panels have come down about 40 percent in the last decade, but economies remain elusive. When the equipment is amortized, solar ends up costing about 25 cents a kilowatt-hour, about four times the cost of conventional electricity.
Mr. Buchanan says he likes to take the long view. "Sooner or later, they will have to get better," he said of emerging solar technologies. And dropping $19,000 on a solar system is no less rational than spending as much on a swimming pool or a new kitchen, proponents point out.
The Buchanans' photovoltaic panels generate direct current. An inverter in the garage converts this to alternating current, the kind that comes out of an electric outlet.
Having a system that works when the utility company does not requires a bank of batteries, a step the Buchanans have not taken. In such a system, the panels charge the batteries continuously. To work during a blackout, the house's electric service has to be rewired in order to draw power from the batteries.
A system can also be set up with no inverter to generate direct current, which can be used for laptops and some lights and refrigerators. A less expensive solar system can also be set up without an inverter, for people who can use direct current. This system is often the choice for vacation cabins deep in the woods.
Then there are solar thermal systems — rooftop panels that collect heat in a mixture of water and antifreeze. The fluid is pumped to the basement, where it heats water for tap use or to warm the house. Where electricity is especially expensive, experts say, these systems can be cheaper in the long run than conventional water heaters.
In all cases, upfront costs are high. Photovoltaic cells and their trappings cost about $10 for every watt of capacity at maximum output, when the sun is directly overhead. A typical refrigerator draws about 300 watts, a hair dryer about 1,500 watts. (Electrical consumption over time is measured in kilowatt-hours, or the number of watts, in thousands, times the number of hours.)
But even a big system like the Buchanans', which covers a fair chunk of their roof, generates only a portion of the kilowatt-hours a household consumes. Mrs. Buchanan said that on her best day, the system provided 17 kilowatt-hours. On her worst, it was less than 1.
Solar water-heating systems also run into the thousands of dollars, the cost depending on capacity. By comparison, investments in energy efficiency are a bargain. And some renewable energy advocates say that it makes more sense to buy wind power from one of the independent turbine-generators that have sprung up than to go solar.
But solar energy enthusiasts are not dissuaded. Molly Hauck, a psychologist in Rockville, Md., has a photovoltaic system on her roof similar to the one at the Buchanans'.
"I know the sun is coming in, even on gray days," she said. "The sun is creating power, and it makes me happy."