Your system manufacturer or dealer can also help you with finding the best location for your wind system. Some general considerations include:
Wind Resource Considerations -- 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. You can have varied wind resources within the same property. In addition to measuring or finding out about the annual wind speeds, you need to know about the prevailing directions of the wind at your site. In addition to geological formations, you need to consider existing obstacles, such as trees, houses, and sheds. You also 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 any buildings and trees, and it needs to be 30 feet above anything within 300 feet.
System Considerations -- Be sure to leave enough room to raise and lower the tower for maintenance. If your tower is guyed, you must allow room for the guy wires. Whether the system is stand-alone or grid-connected, you also will need to take the length of the wire run between the turbine and the load (house, batteries, water pumps, etc.) into consideration. 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). If you have a long wire run, it is advisable to invert DC to AC.
Small wind turbines used in residential applications typically range in size from 400 watts to 20 kilowatts, depending on the amount of electricity you want to generate.
A typical home uses approximately 10,932 kilowatt-hours of electricity per year (about 911 kilowatt-hours per month). Depending on the average wind speed in the area, a wind turbine rated in the range of 5–15 kilowatts would be required to make a significant contribution to this demand. A 1.5-kilowatt wind turbine will meet the needs of a home requiring 300 kilowatt-hours per month in a location with a 14 mile-per-hour (6.26 meters-per-second) annual average wind speed.
To help you determine what size turbine you'll need, first establish an energy budget. Because energy efficiency is usually less expensive than energy production, reducing your home's electricity use will probably be more cost effective and will reduce the size of the wind turbine you need.
The height of a wind turbine's tower also affects how much electricity the turbine will generate. A manufacturer should help you determine the tower height you will need.
An estimate of the annual energy output from a wind turbine (in kilowatt-hours per year) is the best way to determine whether it and the tower will produce enough electricity to meet your needs.
A wind turbine manufacturer can help you estimate the energy production you can expect. The manufacturer will use a calculation based on these factors:
Particular wind turbine power curve
Average annual wind speed at your site
Height of the tower that you plan to use
Frequency distribution of the wind -- an estimate of the number of hours that the wind will blow at each speed during an average year.