WIND GENERATORS for HOME USE

HOME MADE WIND GENERATOR

If you are going to build a homemade system, consider the following. The commercially available wind turbines for home use are generally designed to generate maximum output at air speeds around 24-36 mph (10.5-16 m/s). In reality, in many areas you rarely get such speeds. At the lower air velocity you obviously get less power. So, don't count much on the advertised ratings.
A horizontal axis turbine have to be mounted on a toll tower to harvest more energy. It is generally recommended to place it at least 10 feet (3 meters) plus the blade length above the top of any obstruction, such as a tree or a building within 300 feet (100 meters). That is why home wind generators are used primarily in rural areas. You need to check your local zoning rules which may impose certain height restrictions on any structures. Many zoning ordinances in US have a height limit of 35 feet or so. Also be sure to check local noise restrictions, which could be 10dB above a background noise. The horisontal wind power systems for homes are usually built with guyed towers, which consist of lattice sections, a pipe, and supporting guy wires. The wires are anchored to the ground to hold the tower erect. Such design lets you raise and lower the tower easily, but it occupies more land area.
Vertical axis (VAWT) systems are less efficient. However you don't have to deal with the tower. There is a lesser-know type of VAWT called Savonius, which is probably the easiest one to build at home. I would stay away from the blades made of metal to avoid an interference with TV and other sensitive electronics. Use materials that are transparent to electromagnetic waves, such as fiberglass or wood.

Since any inverter can operate only within a specific input voltage range, and the turbine's output varies all the time, you need a voltage regulator. In the above diagram it is a boost converter. If you feed a rectified DC voltage into a battery, it will act as a regulator. However, this is the least efficient approach, which requires carefully designed overcharge protection. It is always preferred to use PWM regulators- see schematics of various configurations. Note that if the battery is fully charged, and your electric loads consume less than what's generated by the turbine, the excess of the energy has to go somewhere. This is normally accomplished by diverting electric current from the alternator into a so-called "dump load" (NEC® calls it "diversion load").

Turbine manufacturers data sheets usually should provide power curves and specify cut-in and cut-out speeds. Cut-in speed is the minimum air speed needed to turn a wind turbine and produce electricity. Generally, for small installations an average air speed of at least 9 mph (4 m/s) is required. Cut-out speed is the maximum speed a turbine can handle. It should stops spinning at the air streams greater than the cut-out to prevent its damage. There are atlases that provide data on annual average wind speed for various geographical areas. A power curve however will not tell you how much kilowatt-hours you will produce at a certain average air speed. It all depends on how that average came about, i.e. if winds vary a lot, or if they blow relatively steady. For more information see wind power system's calculation.

Wind generators remain relatively expensive. A small turbine alone runs for $1,500-2,000 per kilowatt capacity. At this, as I mentioned above, the capacity is usually specified at unrealistically high winds. A complete professionally installed residential system typically costs $4,000-$6,000 per rated kW before credits and rebates. Generally, the higher capacity the lower price per kW. Depending on the rated output, the typical installation cost for a small home may be anywhere from $15,000 to $40,000 before incentives. This is somewhat lower than an average cost of a solar system, which is $6,000/kW in 2014, but it's still not cheap. You just need to remember that a wind system will rarely provide its rated wattage. Nevertheless, in a remote location without easy access to the grid, it may help you stay off-grid and avoid the high costs of extending utility power lines to your place. Of course, the cost will be lower if you build your system by yourself, but then you may not get a warranty (except for the warranty on individual parts) or rebates.

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