Adding solar electric panels to an old house

Scott Gibson

We love the idea of putting solar panels on the roof and making our own electricity, but we have an older farmhouse and wonder how it would look. How do we prevent this "green" addition from ruining the appearance of a charming old house? And is it worth the expense?

There's much to be said for installing solar panels and letting the sun take the sting our of your power bills, but you have a good point. Roofs festooned with photovoltaic (PV) panels won't win many prizes for colonial authenticity. And, no, solar electricity is still far from cheap.But it's getting cheaper, thanks in part to federal tax credits that pick up 30% of the tab. Many states have their own incentives on top of that, making a solar system even less expensive.

You also have more options when it comes to choosing the type of PV panel you want. A number of companies make "building integrated" products, which means the panels are incorporated into the structure of the house. You don't have to be stuck with homely aluminum racks on your roof.

One such option are tiles that look sort of like roofing shingles but are actually PV panels in disguise. Atlantis Energy Systems makes one version called Sunslates. They're put on a section of roof in place of conventional shingles, and from a distance the house looks more or less like every other house on the block.Because the panels are in the same plane with the rest of the roof, and are not supported by big aluminum racks, they blend in nicely.

Or you could opt for thin-film PV, which is a peel-and-stick membrane that can be applied directly to metal roofing.

One consideration is the pitch of the roof and the direction it faces. A south-facing roof is best, with an angle that approximates your latitude. If you're at 45 degrees north latitude, for example, the system is most efficient when the roof angle is also 45 degrees. (A roofer or carpenter would call this a 12-in-12 roof, or one that rises 12 inches for every 12 inches of run.)If the roof pitch is off or the roof faces away from south, there is some dropoff in efficiency. But there's some wiggle room here. It doesn't have to be exact.

There's still the issue of cost. Even with government subsidies, power produced from PV systems is generally more expensive than what you're buying from the utility. PV is priced by the watt, and it's currently running between $8 and $12 "per installed watt." That means a system capable of producing 3,000 watts of electricity (or 3 kilowatts) is going to cost you $24,000 to $36,000 before rebates and credits. Building integrated panels like Sunslates cost more.That's a big expense. But in areas where utility rates are high, your savings may outweigh the cost of the loan.

Most systems installed these days are grid tied, meaning you are still hooked up to the grid. When you produce excess power, it's sold to the utility. When the panels can't keep up with demand, you import power.On a blazing July afternoon, you could turn the tables on your local power company as the panels produce power and your meter runs backwards. That would be a good feeling, even if your roof does look a little funny.

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