Wind Conditions

Not to state the obvious, but in order to generate electricity from a wind turbine you need to have wind. But, what may not be obvious is that wind turbines can only operate in a range of winds. If the wind speed is too low (below the “cut-in” speed) or too high (above the “cut-out” speed), the turbine will not produce any energy. This is illustrated in the following diagram:

Power Profile Graph

The amount of time that a turbine can generate electricity is dependent on the distribution of wind speeds. That is, how often does the wind blow at a given speed at the location where the turbines are located. This distribution is typically what is called a Weibull Distribution and must be determined by actual wind measurements at the proposed installation site for at least a year. A typical graph of wind speeds at a location is shown below:

Example Weibull Distribution for Wind Speed

A website that has a lot more detail and useful information about wind speeds, turbine efficiency, etc., is

The following FAQ from the National Wind Watch is very helpful in explaining the various terms and aspects of wind turbine output: National Wind Watch Output From Industrial Wind Power

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