Wind power can be a very cost effective source of renewable energy if you happen to have an appropriate wind site. A Whisper wind generator can produce between 900-3200 watts at peak output. This power can either be fed into the grid using an inverter, or can be used to keep a battery bank charged. Since a wind speed of 7 mph must be reached before the wind generator produces electricity, it is important to know how much wind is available at your site.