Capacity factor

Capacity factor is the ratio of the electrical energy a generating unit actually produced over a period of time to the energy it could have produced if it had run at full capacity for that entire period. A plant with a 50% capacity factor produced only half of what it theoretically could have. Capacity factor varies a lot by source: solar and wind have inherently lower capacity factors than a plant that can run continuously, since they only generate when the sun shines or the wind blows.