Frequently Asked Questions

What is a capacity factor?

Capacity factor is a measure of how often an electric generator runs for a specific period of time. It indicates how much electricity a generator actually produces relative to the maximum it could produce at continuous full power operation during the same period.

For example, if a one megawatt generator produced 5,000 megawatthours the entire year, its capacity factor would be 0.57 or 57% (5,000 megawatthours / 8,760 megawatthours at full capacity for the entire year) of the total amount of electricity the generator could have produced if it operated at full capacity the entire year.

Generators with relatively low fuel costs are usually operated to supply base load power and typically have average annual capacity factors of 0.70 or more. Conversely, generators with lower capacity factors might indicate average operation during peak demand periods and/or high fuel costs, or operation based on the availability of a variable energy source, such as hydro, solar, and wind energy.

Learn more:

 Monthly generator capacity factor data now available by fuel and technology.

Table 6.7.A. Capacity Factors for Utility Scale Generators Primarily Using Fossil Fuels, January 2008-October 2013.

Table 6.7.B. Capacity Factors for Utility Scale Generators Not Primarily Using Fossil Fuels, January 2008-October 2013.

Last updated: May 13, 2014


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