This depends on the motor, of course. If your average wind speed is low, then you'll want a lower powered motor - a high powered motor will not produce enough of a voltage in low winds to start charging your batteries, and as such will not operate efficiently. We recommend that you work out the power you need on a daily or hourly basis, and the power any given motor will need based on the RPMs your area's wind speed will generate, and the RPM-Wattage ratio of the motor. Ensure that given your area's wind speed, the RPM-Wattage ratio of the motor will still be enough to cover your desired hourly/daily wattage output.