In the past, residential applications for PV have been largely limited to powering off-the-grid homes and rural vacation cabins. That's because installing a PV system often costs much less than running utility lines, making remote, inexpensive land buildable. But now PV is making inroads in suburbia as well. National and regional homebuilders such as US Homes, Shea and Pardee are beginning to offer solar electric systems on the houses they sell. The Home Depot also has joined in with pilot programs in California, New Jersey, Delaware and Long Island, New York, through which it finances, sells and installs systems on existing homes.
Two big reasons for this growth are the electric-utility deregulation of the late 1990s and recently enacted state-government incentives. Deregulation has enabled homeowners in most states to connect their PV systems to the power grid and sell their excess production to a utility. This sale is reflected as a credit on their electric bills, a process called net-metering. In addition, many states offer tax incentives and/or rebates to homeowners who install PV systems (see Making photovoltaics cost-effective).
So why doesn't everyone have solar panels sprouting from their roofs? Because the sun doesn't shine equally in all areas of the country; because the technology isn't widely recognized yet; because financial support from state and federal governments is uneven; and because it's expensive -- in effect, a PV system can be like buying 20 years of electricity in one fell swoop. Still, many of the major international oil and electronics companies are convinced that PV is a big potential market, and they're investing considerable resources toward its development. So are major industrial countries such as Germany and Japan. For anyone who wants to live off-grid or who just likes the idea of making cleaner energy, photovoltaics are becoming a truly viable alternative.