Take a look at the wind turbine power curve below; you will notice that there are two axes, the X-axis and the Y-axis. The X-axis represents the hub wind speed in meters per second (m/s) and the Y-axis represents the expected power output in kilo Watts (kW) of the wind turbine.
|Wind Turbine Power Curve|
If you have taken wind speed data at the location you intend to install your wind turbine, then you can predict the average power output from your wind turbine generator from the power curve. Just make sure that the wind speed data recorded is taken at the same height as the hub height, otherwise your wind speed data would be incorrect.
For example, if you are planning to install a 10kW wind turbine at your location and the average wind speed recorded over a week period during summer time was 5 m/s at ground level, then your site location may be ideal for installation of a wind turbine. You might not believe this if you were to look at the wind turbine power curve above since at 5 m/s the wind turbine would produce about ~2kW.
Actually, you may not have noted that you have taken your wind speed data at ground level. Usually the hub height is at least 10 meters above ground level and wind speed tend to approximately double every ~12 meters provided obstacles such as buildings and trees are not in close vicinity to your wind turbine.
However, 5 m/s at ground level during summer time (winter time wind speed is higher) is a good indication for a suitable location for wind turbine installation and you should take measurements at higher heights to be certain. It is highly recommended that you take several readings around the same location as wind paths can be a few meters away from where you are.
For homeowners who intend to install small permanent magnet generators (alternators) it is extremely important to get the power curve from the manufacturer since this power curve is different from one manufacturer to another. Furthermore, a wind turbine power curve is usually corrected if your site location is more than 300m above sea level or ambient temperature is far above 20 degrees C.