How much you can reduce your energy costs with a small wind energy system depends on your location and the details of the system you install. Before you start, you have to make sure your budget covers all the essential components. The amount of energy you can produce varies with your location and the amount of wind you normally get. Once you have evaluated these factors, you can decide whether a home wind energy system makes sense for you.
The wind turbine is made up of a rotor with blades, a generator and a tail that keeps the turbine pointing into the wind. Turbines are equipped with devices that turn them off when the wind is blowing too hard, in order to protect them from damage. A typical residence will require a wind turbine rated between 5 and 15 kilowatts to make a significant contribution to electricity needs. The amount of power the turbine generates per year depends on the amount of wind you get in your area and what percentage of the time the wind turbine is running. You can use the wind maps from the Wind Powering America program of the U.S. Department of Energy to find the average wind speed for your location. The turbine specifications tell you how much power the turbine produces for a particular wind speed, and you can then estimate how much power the turbine will generate per year at that speed. Be sure to factor in how much of the time the turbine will operate between times the wind is too weak or too strong.
The wind turbine tower raises the wind turbine to a height where the wind is stronger and less turbulent. The U.S. Department of Energy wind maps are for towers about 100 feet high, and reducing the height to 60 feet reduces wind energy by about 10 percent. Wind eddies reduce the efficiency of the turbine for lower towers. Guyed towers are less expensive but need a lot of room for attaching the guys, while self-supporting towers are more compact, but costlier. Towers that can be lowered are more convenient because wind turbines need occasional maintenance and repair. Tilt-down towers can also be lowered during bad weather to protect the equipment.
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Most residential wind turbines generate direct current electric power in varying quantities, depending on the wind. A controller keeps the voltage at the correct level for charging batteries or for powering an inverter that changes the direct current to alternating current for use in your home. You will probably need a licensed electrician to connect these components to your home electrical system so that they work automatically to supply the power you need.
If your system is intended to provide all your power and keep you off the grid, batteries will need to be used to supply power when there is no wind. The direct current power from the controller charges the batteries, which power the inverter to supply your home when there is no other source of electricity. Batteries should be located away from living areas because they may leak corrosive chemicals or explosive vapors.
In some jurisdictions, you can sell excess power back to the utility through a grid connection. Your local utility will provide the details on how you have to configure it. Such a connection may help you pay for your installation in cases where the utility credits you for power at the same rate you pay. If the rate the utility pays is lower, such as its wholesale rate of only a few cents a kilowatt hour, the contribution may be quite small.
Types of Wind Turbines
While horizontal-axis wind turbines are the most common, homeowners and farm operators can install vertical axis wind turbines without a tower, and in turbulent wind conditions. These types of turbines are less efficient than horizontal-axis turbines, but the rugged and basic units with simple designs are suitable for DIY installation. Such turbines are especially effective for remote duty, such as running electric pumps to draw water out of wells into tanks, or for irrigation.