Capacity factor compares the electricity generated over a period with the amount that would have been generated at continuous rated power. If an imaginary 1-megawatt machine produced 8 megawatt-hours over 24 hours, its capacity factor for that day would be one third. This is an arithmetic example, not a typical value for any particular technology.
Keep the period visible
A windy week can look very different from a calm month. Annual figures smooth some short-term variation, but still reflect that year's weather and operating conditions. When comparing projects, use compatible periods and definitions. A figure without a timeframe is missing an essential part of its meaning.
Do not confuse it with efficiency
Capacity factor does not measure how much of the available wind energy a turbine converts to electricity. It reflects production relative to nameplate capacity, including resource availability, downtime and curtailment. A generator deliberately held in reserve can have a low capacity factor while still performing an important system role. Different technologies use capacity for different purposes.
Add the questions the ratio cannot answer
When was the electricity delivered? How predictable was it? What did the project cost to build and operate? What network infrastructure was needed? Those questions matter alongside annual production. For wind, a well-sited project can have a strong production record, yet its output still varies with weather. Capacity factor is helpful for understanding that record. It becomes misleading when treated as a universal ranking of reliability, affordability or environmental value. Use it as one window into performance, with the surrounding context left in view.
