Wind generators, or small wind electric systems, can be compared according to how much energy the system generates, the cost of the system in relation to the cost of conventional electricity, the size of the wind turbine and the height of the tower. Other factors include the level of noise the turbine makes and the materials with which the system is made.
To power residences, wind turbines range from 400 watts to 100 kilowatts. Smaller turbines can be used for such jobs as pumping water and charging batteries. Costs are generally based on the amount of kilowatts generated. Some systems are hooked up to the utility grid, so that when the wind generator does not meet electricity requirements, the conventional utility can make up the difference. Other systems, called hybrids, go completely off-grid. These can provide power for homes and farms that are far from utility lines. The wind generator provides the primary power, but when wind is low, either batteries or an engine generator run on a fuel such as diesel, supplies the power.
Taller towers usually generate more power, as wind speeds increase with height. Towers can be either free-standing or guyed, with guyed towers needing more space. Tilt-down towers, though more expensive, offer the option of lowering the tower for maintenance or during dangerous weather. The U.S. Department of Energy suggests not purchasing aluminum towers, which tend to crack.