“A properly sited small wind turbine can be very cost-competitive with solar at a windy site,” says Tom Gray, a spokesman for the American Wind Energy Association. Here’s what to know before you start.

Reality check

An average American home uses roughly 10,000 kilowatt hours per year, depending on the size of the house and its location. You’d need a 10-kilowatt turbine to meet this kind of demand. Picture a windmill on a 100-foot tower, with blades 25 feet in diameter, and you start to appreciate that a little spinner strapped to the chimney won’t help keep the lights on.

So-called horizontal-axis turbines like this will cost between $25,000 and $30,000—a figure that doesn’t include the tower, which is another $10,000 or so, plus labor, engineering, and the “balance of service” components such as cables and equipment that will safely tie you into your home’s service panel. All in all, you can easily drop $40,000 or more before you throw the big switch and start lowering your power bills by 50% to 90%.

If energy independence is your goal, as Gray says, that price is much cheaper than the array of photovoltaic solar panels you’d need to do the same job. But since wind’s payback is similarly measured in decades, you’ll want to do your homework before making such a significant up-front investment.

According to the American Wind Energy Association, wind will only make economic sense if you pay at least 10 cents per kilowatt hour for your electricity (check your last utility bill), and if you have at least 10 mile-per-hour average wind speeds. Zoom in on the U.S. Department of Energy Wind Resource Maps to find out if you’re in a suitable zone.

Fortunately, incentives make the price a little easier to bear. Chief among these is the federal renewable energy tax credit, which knocks 30% off the total installed cost of your system—slashing that $40,000 setup down to about $28,000. Beyond this, the Database of State Incentives for Renewables & Efficiency will unlock additional local and regional-government rebates and deals.

How to buy

There’s no central database of wind-turbine installers, but reputable firms can be found through dealers across the country. Like anything else involving the home, get an agreement in writing, check references, and ask to speak with others who have had similar systems installed.

Wind contractors will often offer an all-in-one price that includes a suitable turbine, tower, and other components. But comparison shopping can be challenging, because companies each select a different wind speed to rate the power output of their various models. “There is no way to easily compare turbines,” explains Larry Sherwood, a renewable-energy consultant and veteran of the U.S. solar industries.

Fortunately, that’s about to change. Sherwood is leading the Small Wind Certification Council, a fledgling organization that will soon be rating residential-scale windmills with standardized criteria for energy output, power, and noise. By mid-2010, Sherwood expects the labels will be on most small wind turbines sold in the United States, providing consumers with the same comparison information as a miles-per-gallon sticker does on a new vehicle. If you are planning an installation, you may wish to hold off until then.

The scoop on property value

No empirical evidence exists that wind towers or wind farms depress nearby property values. In fact, an extensive 2003 survey of wind installations conducted by the Renewable Energy Policy Project concluded precisely the opposite: “For the great majority of projects, the property values actually rose more quickly in the viewshed than they did in the comparable community,” the report notes. The study also found that values increased faster in the viewshed—all the land within sight of the tower—after the projects came online than they did before.

Meanwhile, an earlier California Energy Commission survey found that most people are interested in—or willing to pay more—for homes equipped with solar panels or wind turbines.

Typical concerns center around visible impacts of towers, but also noise. Turbines are far from silent, but depending on size, wind speed, and distance from nearby homes, the sound can be quite modest—like that of a washing machine humming on the spin cycle in your basement.

Share your concerns with your dealer, share your plans with your neighbors, and check with your local-government office about relevant permit requirements, as well as any existing land use-bylaws that may restrict the height of structures in your area. If the numbers add up for you, before long you can start spinning your way toward green, clean, and—eventually—dirt-cheap electricity.