Solar Shingles Home Technology Plumbing, HVAC & Electrical This Old House

Solar Shingles Home Technology Plumbing, HVAC & Electrical This Old House

A seamless appearanceand generous tax breaksmake rooftop power plants more attractive than ever

After a long eclipse, solar energy is shining again. Its comeback is being fueled by an enticing combination of federal and state tax incentives, the desire of fed-up homeowners to lower their utility bills, and increasing concern over dwindling natural resources (not to mention presidential warnings to start 12-stepping our national addiction to oil).

But one of the biggest reasons for solar’s renewed popularity has to do with aesthetics. In the 1970s, going solar meant mounting panels the size of ping-pong tables in cumbersome racks on your roof. But in the past five years, the industry has become more architecturally savvy, offering up solar-powered shingles that blend almost seamlessly with traditional roofing materials.

These systemscalled "building-integrated photovoltaics," or BIPVscombine solar cells with slate, metal, fiber-cement, even ­asphalt roofing. Electricity is generated when the sun strikes a semiconductor layer, typically crystalline silicon, laminated to the shingle’s surface. One shingle by itself doesn’t produce a whole lot of powerbetween 50 and 200 watts, enough to run a window fanbut harness hundreds of square feet of them together, and you can generate enough electricity to power a whole house. The shingles get installed over new or existing roof sheathing, then an electrician (or trained roofer) has to wire the units together and tie them in to your home’s electrical system.

Going solar doesn’t mean cutting ties to your local supply grid. Most BIPV systems work in concert with existing power lines, which kick back into service after sundown and on rainy days, when the shingles don’t produce much juice. And if you generate more power when the sun is shining than you actually need (not uncommon in places like California and Arizona), at least 39 states let you sell unused watts back to the local utility for a credit, thus making your electric meter do something really remarkable: spin backward. That’s what Sheri Gage discovered when she and her husband bought their Live Oak, California, home earlier this year. They opted for an energy-efficiency package, offered by the builder, that included a 2-kilowatt BIPV system integrated into the cement-tile roof (general guidelines call for 1 kilowatt, or 1,000 watts, per 1,000 square feet of house area). The system cost $15,000, which they rolled into their mortgage, adding about $100 to the monthly bill. Come tax time, they’ll receive a generous federal tax break thanks to the Energy ­Policy Act of 2005, which gives homeowners a credit of 30 ­percent, or up to $2,000, toward the cost of a system. Gage has no worries about the new roof paying for itself: Her last electrical bill was a paltry $3.85. "I am now a firm believer in the power of the sun," she says.

Solar Shingles Home Technology Plumbing, HVAC & Electrical This Old House

Even before new federal and state tax incentives, "the cost of generating solar electricity has fallen 95 percent since the 1970s," says Noah Kaye, of the Washington, D.C. based Solar Energy Industries Association. But that doesn’t mean it’s cheap: Factoring in equipment and installation costs, the price of a kilowatt-hour of solar energy (the amount required to power ten 100-watt lightbulbs for an hour) is about 25 cents, versus around 10 cents for a kilowatt-hour of natural gas- or coal-generated electricity from the grid.

The economics of whether or not to install a system depend heavily on where you live. While houses in sunnier states can collect more solar power than those in northern climes, solar payback is strongly affected by local electric rates. "If you have a 2-kilowatt PV system in Albuquerque, New Mexico, it produces 25 percent more electricity than the same system in Boston," says Kaye. "But the savings are greater in Boston, since electricity there costs so much more."

Still, if the high cost is what’s keeping you from going solar, you won’t have long to wait before increased demand and advances in PV efficiency make these systems more affordable. "As electric rates continue to rise, solar prices will come down," Kaye predicts. "We think it’s possible to make solar cost-competitive with retail prices, without subsidies, within the next decade." Manufacturers are already working on products that are even better-looking and simpler to install. For example, Atlantis Energy Systems has figured out how to sandwich PV cells inside semitransparent glass panels, a technology that could someday show up on the residential market as super-powered skylights. Just a glimpse of what’s to come as the solar industry heats up again.

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