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Wind Turbine Output Calculator

Get a realistic estimate of a wind turbine's annual energy output from its rated power and your site's capacity factor — a quick planning estimate, not a substitute for a real site-specific wind assessment.

Estimated annual output10950 kWh/year

How to measure your inputs

  • Rated power: from the turbine's spec sheet, its nameplate/maximum output.
  • Site quality: use Swales' Wind Potential dashboard for a specific site's real capacity factor rather than guessing from the presets here.

Methodology

Standard wind-energy estimate: annual output (kWh) = rated power (kW) × capacity factor × 8,760 (hours in a year) — the same capacity-factor concept used for real site-specific turbine sizing elsewhere on Swales, simplified here to a manual preset.

Why "rated power" massively overstates real wind output

Rated power is a best-case number

A turbine’s rated (nameplate) power is its output at one specific, often quite high, wind speed — real wind doesn’t blow at that speed continuously. Capacity factor is the standard way to translate that best-case number into a realistic annual average, expressing actual output as a fraction of what the turbine would produce running at rated power nonstop for a full year.

Why capacity factor varies so much by site

A turbine on an exposed ridge with strong, steady wind can see a capacity factor of 35-45%; the same turbine in a sheltered, turbulent, or generally calm location might see 15% or less. This is exactly why turbine output claims from a spec sheet alone are misleading without knowing the specific site’s wind resource.

Where a real capacity factor number comes from

The most reliable source is a real site-specific wind assessment — Swales’ Wind Potential dashboard computes this from actual wind data for a pinned location, which is far more trustworthy than picking a preset here. Use the presets in this calculator as a rough planning estimate before you’ve analyzed a specific site, not as a replacement for real data once you have it.

Frequently asked questions

What is capacity factor in simple terms?

The percentage of a turbine’s theoretical maximum output (running at rated power 24/7 all year) that it actually produces on average, accounting for real wind variability. A 25% capacity factor means the turbine averages a quarter of its rated output over a year.

Why is my turbine’s real output so much lower than its rated power?

Because rated power is measured at one specific wind speed the site rarely sustains continuously — wind speed varies constantly, and output drops sharply below the rated wind speed (roughly with the cube of wind speed), so real average output is always well below the nameplate figure.

How do I find my site’s real capacity factor?

A proper wind resource assessment for your specific location is the reliable way — Swales’ free Wind Potential dashboard computes this from real wind data for any pinned site, rather than relying on a generic preset.

Does turbine height affect capacity factor?

Yes — wind speed generally increases with height above ground (less friction/turbulence from terrain and obstacles), so a taller mast on the same site typically sees a higher capacity factor, up to a point.