The first step to designing your system is determining if you have enough wind to justify the expense of the system and the time and expense of operating and maintaining your equipment. Remember: a small turbine without enough wind is like a solar panel in the shade: it won't produce energy!
Generally, a site with an annual average wind speed of 12 miles per hour or greater does not need a detailed wind resource study to be performed. A site with an average wind resource of 10 miles per hour or less usually does not have enough wind to justify installing a turbine. A site that has an average wind speed between 10 and 12 miles per hour should have a wind resource assessment performed to determine if there is adequate wind to support a small wind turbine.
In general a good place to begin determining your wind resource is National Renewable Energy Laboratory's (NREL) wind resource maps. Download the map for your state and find the general area where your property is located. This will give you a fairly good sense of the average wind speed in your area at no expense.
If you are in Minnesota, the state Department of Commerce, Energy Division, provides an excellent interactive tool that provides an estimate of the average wind speed 100 feet up for any point in the state.
Airports also take regular meteorological data. If there is an airport in your area, contact them and ask them for wind data. State-specific consumer guides can also be found at the Department of Energy's Energy Efficiency and Renewable Energy website. For further information from Windustry on wind resource assessment, visit our Know Your Wind page.