“Capacity factor” is how much electricity a generating unit actually produces in a given year, divided by how much it would produce if it ran full-time at its full rated capacity. Capacity factors differ by technology, location, and year.

Typical global-average capacity factors in recent years are:

• Cogeneration: ~83%
• Nuclear ~80% (cumulative ~77%)
• All micropower ~66%
• Geothermal + small hydro + biomass/waste combustion ~60%
• All renewables other than big hydro dams ~40%
• Windpower 26%
• Photovoltaics ~17%

Recent U.S. averages are:

• Nuclear 91–92% (79% cumulative)
• Wind 35–37%, with many over 40% and the best over 50%
• Photovoltaics ~30% with 1-axis tracking, typically the cheapest solution