What is the availability factor of wind turbines

Turbit Systems GmbH, Tejas Bodke

Availability in wind turbines is an important factor considered in economic  operations, energy estimates, revenue projections, performance evaluation and warranties.


High availability of wind turbines is essential for the economic operations of a wind farm. Generally, the availability is more than 90%, and modern wind turbine manufacturers claim to have more than 95 % availability for their turbines.

The wind turbines are considered available if they produce electricity or if they are technically capable of producing electricity. Down-times due to lack of wind is also considered as available. Power failures, storm, downtime for maintenance or other external influences are not deducted from the availability since these problems are not caused by the wind turbines. Availability for a wind turbine can be measured with the help of an hourly meter. The total availability of a wind turbine is the available hours divided by the total hours:


Availability (Turbine) =  [T (Available) / T (Total) ] x 100%


Availability (Turbine): Availability of a wind turbine

T (Available): Period for which the turbine produces electricity, or  is deemed to be available according to contract and general laws

T (Total): Total time period

Note: Automatic payment system for the electricity from wind turbines might not be precise. Therefore,  manual checking might be required.


Past observations show that the operational time of wind turbines can be divided into the following segments:

  • A turbine unit produces electricity about 80% of the time, out of which 2.5% it runs on the nominal power

  • A turbine unit is stopped about 20% of the total time due to lack of wind

  • A turbine unit is stopped for about 2.5% of the time although there is sufficient wind ( either failure or manual stop)

However, these values have a wide range, depending upon wind conditions, wind turbine model, and wind farm.



Find and analyse the exact availability of your turbines with our  Turbit Web Report