Wind Turbine Capacity Factor Calculator

Gauge expected wind turbine output compared to its nameplate rating. Provide average wind speed, rated speed, availability, and estimated losses to calculate the net capacity factor.

Long-term mean wind speed at hub height.
Wind speed at which the turbine reaches rated power.
Percent of the year the turbine is operational.
Combined performance losses outside of availability.

Uses a simplified cubic model; actual turbine curves vary by manufacturer.

Examples

  • 7.5 m/s average, 12 m/s rated, 95% availability, 12% losses ⇒ 32.36 %
  • 9 m/s average, 11 m/s rated, 92% availability, 15% losses ⇒ 48.95 %

FAQ

Why cap the raw factor at 100%?

Once the turbine hits its rated speed it cannot exceed nameplate power, so the factor is limited to 1.

Can I include curtailment?

Yes. Add curtailment percentage to the losses input so the factor reflects reduced generation.

How do I convert the result to annual energy?

Multiply the capacity factor (in decimal form) by rated power and 8,760 hours to estimate yearly MWh.

Additional Information

  • Capacity factor is actual energy output divided by the theoretical maximum over 8,760 hours.
  • The cubic relationship between wind speed and power means small wind increases deliver large output gains until rated speed.
  • Losses include wake interaction, blade soiling, icing, and electrical inefficiencies beyond downtime.

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