How much electricity can a small wind turbine generate?

A well-sited 5 kW domestic wind turbine in a good location (mean wind speed 6+ m/s) can generate 8,000-15,000 kWh per year. In a poor location (urban, sheltered, mean speed below 4 m/s), the same turbine might generate only 1,000-3,000 kWh. Wind speed is the critical factor — energy increases with the cube of wind speed.

How does hub height affect generation?

Wind speed increases with height due to reduced surface friction. The relationship follows a power law: V(h) = V(10) x (h/10)^alpha, where alpha depends on terrain roughness. In urban areas (alpha 0.35), increasing from 10m to 20m hub height increases wind speed by about 27%, and energy by about 105%.

What is capacity factor?

Capacity factor is the actual energy produced as a percentage of the theoretical maximum (if running at rated power 24/7). Small UK wind turbines typically achieve 10-25% capacity factor. A 5 kW turbine at 20% CF generates 8,760 kWh/year. Capacity factor depends primarily on wind speed at the site.

Do I need planning permission for a wind turbine?

In England, permitted development rights may apply if: it is a single turbine, the hub height is below 15m, it is not in a conservation area, AONB, or World Heritage Site, and it meets noise limits. Otherwise, full planning permission is required. Scotland and Wales have different rules.

How do I find the wind speed at my location?

The NOABL wind speed database (available at RenewableUK) gives estimated mean wind speeds at 10m, 25m, and 45m heights for any UK location. More accurate data requires an anemometer installed at hub height for at least 12 months. Urban locations are typically much windier at height than ground level suggests.

TradeCalculator.co.uk

Wind Turbine Calculator

Estimate annual energy generation from a small wind turbine based on mean wind speed, hub height, and turbine power curve. Includes planning guidance.

Turbine SizeRated power output

Site TypeAffects estimated wind speed

Hub HeightHigher = more wind

Known Wind Speed (optional)

Override auto-estimate (at 10m)

How We Calculate This

This calculator estimates annual energy generation from a small wind turbine based on the mean wind speed at your location, adjusted for hub height and terrain.

Calculation method

Wind speed at hub: Base speed x (hub height / 10m)^alpha (wind shear)
Capacity factor: Estimated from mean wind speed / rated wind speed ratio
Annual kWh: Rated kW x capacity factor x 8,760 hours
Wind power: Energy in wind scales with the cube of velocity (P ~ v^3)

Site assessment

Mean wind speeds below 4 m/s at hub height make small wind turbines uneconomic. Sites with 5+ m/s are reasonable, and 6.5+ m/s are good. Coastal and hilltop sites are best.