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Small wind turbine annual energy calculator.
The U.S. Department of Energy's preliminary estimate of yearly kWh from rotor diameter and average wind speed.
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How many kWh does a small wind turbine produce per year?
The U.S. DOE's Small Wind Guidebook gives a preliminary estimate: AEO = 0.01328 x D² x V³, where AEO is annual energy output in kWh, D is rotor diameter in feet and V is the annual average wind speed in mph. DOE does not explain the coefficient, so treat it as a first screening figure, and ask for the turbine's tested power curve or a site assessment before buying. The guidebook also says wind speeds may be 15% to 25% greater at hub height than at airport anemometer height, and recommends at least 9 mph (4 m/s) average for an off-grid hybrid system.
Worked example. A 10 ft rotor at 12 mph: 0.01328 x 100 x 1,728 = 2,295 kWh per year, about 191 kWh per month. DOE's own sizing example is a 1.5 kW turbine for a home using 300 kWh per month at 14 mph average wind.
Frequently asked questions
How much electricity does a small wind turbine generate?
DOE's preliminary formula is 0.01328 x rotor diameter in feet squared x average wind speed in mph cubed. A 10 ft rotor at 12 mph is about 2,295 kWh per year.
Is the DOE formula accurate?
It is a preliminary estimate. Use the manufacturer's tested power curve and a site wind assessment for a real decision, and use hub-height wind speed, not ground-level.
What average wind speed do I need?
DOE lists at least 10 mph (4.5 m/s) for grid-connected systems and at least 9 mph (4 m/s) for off-grid hybrid systems.
Why do small wind speed changes matter so much?
Energy scales with the cube of wind speed. A site averaging 12 mph instead of 10 mph yields about 73% more energy.
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The formula and the 9 and 10 mph minimums are from the DOE Small Wind Guidebook. The tool does not model turbulence, tower height or the turbine's own power curve. Runs entirely in your browser. Nothing you type is sent or stored.
Scope
Preliminary estimate only. Get the turbine's tested power curve and a professional site assessment before spending money, and check local zoning and tower height rules.