how much energy will your small wind turbine produce?
kWh per year = [rotor area in sq. ft] * [annual average wind speed mph]^3 * 0.085 * OTE
The 0.085 number in the equation represents air density and the acronym OTE stands for overall turbine efficiency. The OTE will vary depending on the make and model of the wind turbine, the number can range anywhere between 15% and 25%.
I hope this equation will help you make effective decisions when purchasing a small scale wind turbine.