Class 4 site, 6 m rotor, 6 m/s avg
~12,000 kWh/year. Enough to offset a typical US home if shading and battery aren't issues.
Wind turbine calculator
How much energy will a small wind turbine produce?
Estimate annual kWh from rotor swept area, average wind speed, air density, capacity factor and turbine efficiency. Uses the Weibull-corrected power equation.
Wind Turbine
Wind turbine annual energy estimator
Estimated annual energy4,007 kWh
Daily average11 kWh
Mean power0.48 kW
Swept area7.1 m²
Capacity factor22.7%
Results are first-pass estimates. Verify with installers, manufacturers, and utility tariffs before purchase.
How it works
How it works
- Swept area A = π × (rotor diameter ÷ 2)². Double the diameter = 4× the energy.
- Average power = 0.5 × ρ × A × v̄³ × Cp × EPF. ρ ≈ 1.225 kg/m³; Cp max 0.59 (Betz); modern small turbines 0.30–0.40.
- EPF (Energy Pattern Factor) = 1.91 for typical inland Weibull shape — corrects for variability so v̄³ matches real wind distribution.
Worked examples
Worked examples
Class 2 site (5 m/s)
Same rotor: ~7,000 kWh. Note v³ scaling — 1 m/s less wind cuts output 30%+.
10 m rotor at 7 m/s
~52,000 kWh — small commercial scale.
Wind turbine FAQ
Wind turbine FAQ
Where can I find my average wind speed?
NREL Wind Prospector or 50 m wind maps. At hub height (10–30 m for residential) it's usually 10–25% higher than the surface number.
Why is small wind often disappointing?
Sites with <5 m/s average produce poorly. The cube law punishes low wind: a 4 m/s site yields 1/3 of a 6 m/s site.
How tall should the tower be?
Minimum 30 ft above any obstruction within 500 ft. AWEA recommends 80 ft+ for residential.
Are residential turbines worth it?
Rarely in suburbs. Best ROI is rural Class 3+ sites paired with solar (winter wind, summer solar diversification).
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