Wind power has been the fastest growing source of new electric power, according to the U.S. Energy Information Administration. But if you're considering a wind turbine to supplement your home's power, consider our experience with one product, the Honeywell WT6500 Wind Turbine, a cautionary tale.
Among the few wind turbines that can be mounted on a roof, the WT6500 is similar to traditional wind turbines: Any unused energy it generates can be sent or sold to a utility for credit off your power bill. But it's quieter than traditional turbines, and according to the manufacturer WindTronics, starts generating power at lower wind speeds. The company claims the unit starts spinning from winds of a mere 0.5 mph—with electricity generated from only 3 mph. Traditional gearbox wind turbines, said the company, require at least 7.5-mph winds to start generating power.
A tool on Windtronics' website had calculated we'd get 1,155 kWh per year at the 12-mph average it predicted for our area of Yonkers, New York. And the authorized installer, during his initial visit, didn't say the roof of our headquarters might generate any less, but that rating is at a height of 164 feet, not the 33 feet WindTronics requires for rooftop installations.
In the 15 months since the turbine was installed, though, it has delivered less than 4 kWh—enough only to power a 12,000 btu window air conditioner for one afternoon. A company representative in charge of installations worldwide recently visited our offices and confirmed that our test model was correctly installed. What's more, he told us that while the WT6500 should start generating power at about 3 mph, the initial juice goes just to power the system's inverter, which must be running before it supplies any AC power elsewhere. The true wind speed needed to start producing AC while the inverter is on is 6 mph, not far from the 7.5 mph needed by a traditional gearbox wind turbine.
The Honeywell costs $11,000 installed, comes with a five-year warranty and has a 20-year expected product life. But having a thorough site analysis by a manufacturer-authorized installer, backed by your own research on websites such as the National Renewable Energy Laboratory, is vital.
At the rate the WT6500 is delivering power at our test site, it would take several millennia for the product to pay for itself in savings—not the 56 years it would take even with the 1,155 kWh quote we received.