What is the capacity factor of a wind turbine?
A ‘capacity factor’ of conventional and renewable generation alike indicates what proportion of the maximum theoretical electricity generation has been (or is likely to be) achieved in reality. So a generator with a high capacity factor is being utilised at close to its maximum theoretical output. The capacity factor of a wind farm is not a measure of efficiency. There are many reasons why generating plant operates at less than 100% capacity factor. For conventional plant this could include requirements for maintenance periods, faults or generation not being required from the plant due to variations in consumer demand. For wind turbines specifically, the capacity factor provides a measure of the amount of electricity generated compared with what could be generated under ideal wind conditions. Capacity factor is not a measure of the amount of time a generator is running, though it is often quoted incorrectly as being so. The Environmental Change Institute report states that ‘In the UK,
