Small Wind Guidebook/How Do I Choose the Best Site for My Wind Turbine
How Do I Choose the Best Site for My Wind Turbine?
You can have varied wind resources within the same property. In addition to measuring or finding the annual wind speeds, you need to know about the prevailing directions of the wind at your site. If you live in complex terrain, take care in selecting the installation site. If you site your wind turbine on the top of or on the windy side of a hill, for example, you will have more access to prevailing winds than in a gully or on the leeward (sheltered) side of a hill on the same property. In addition to geologic formations, you need to consider existing obstacles such as trees, houses, and sheds, and you need to plan for future obstructions such as new buildings or trees that have not reached their full height. Your turbine needs to be sited upwind of buildings and trees, and it needs to be 25 to 35 feet above anything within a 300-foot horizontal radius. You also need enough room to raise and lower the tower for maintenance, and if your tower is guyed, you must allow room for the guy wires.
Whether the system is stand-alone or grid-connected, you also need to consider the length of the wire run between the turbine and the load (house, batteries, water pumps, etc.). A substantial amount of electricity can be lost as a result of the wire resistance—the longer the wire run, the more electricity is lost. Using more or larger wire will also increase your installation cost. Your wire run losses are greater when you have direct current (DC) instead of alternating current (AC). So, if you have a long wire run, it is advisable to invert DC to AC.
You may wish to consider hiring an experienced small wind site assessor who can determine where the turbine should be located on your property.
Wind Turbines Mounted on Buildings
The number of small wind turbines mounted on rooftops has increased in recent years. It should be noted that all wind turbines vibrate and transmit the vibration to the structure on which they are mounted. This can lead to noise problems within the building, and the wind resource on the rooftop is in an area of increased turbulence, which can shorten the life of the turbine and reduce energy production. Additional costs related to mitigating these concerns can lead to increased payback periods and total cost of the installation. For more information on the state of the rooftop wind turbine industry, see The Built-Environment Wind Turbine Roadmap.