wind speed of 8 mph, the Bergey Excel-S can increase its power output to 550 kWh from 330 kWh by placing it 120 feet up instead of 60 feet. The power output increases by two thirds when the tower height doubles.

But before you rush to purchase a 700-foot super-tower (213m), consider all the costs involved: the tower itself, wiring expenses and foundation work are just some. A 60-80ft tower is good enough for small turbines of below 1,000W. Larger turbines are good for up to 120 feet but consider your budget carefully.