Wind Turbine Calculator

Horizontal-axis wind turbines (HAWT) rotate around a horizontal axis and are the most common type, typically seen on wind farms. Vertical-axis wind turbines (VAWT) rotate around a vertical axis and include designs like the H-Rotor, Darrieus, and Savonius. HAWTs are generally more efficient, while VAWTs can capture wind from any direction and are better suited to turbulent urban environments.

Wind turbine power is calculated using P = ½ × ρ × A × v³ × ξ, where ρ is air density (kg/m³), A is the swept rotor area (m²), v is wind speed (m/s), and ξ is the turbine efficiency. The cubic relationship with wind speed means a 20% increase in wind velocity results in roughly a 73% increase in power output.

The Betz limit is the theoretical maximum efficiency a wind turbine can achieve, equal to 59.3% (16/27). No turbine can extract more than 59.3% of the kinetic energy from the wind, as some air must continue flowing through the rotor. Most modern turbines operate at 35–45% efficiency, which represents 60–75% of the Betz limit.

A typical household in the US uses about 10,500 kWh per year. At an average wind speed of 6–7 m/s and a capacity factor of ~30%, a turbine with 5–15 kW rated power (rotor diameter roughly 4–7 meters) can meet most household needs. Actual requirements depend heavily on your local average wind speed and household consumption.

This depends on the turbine's rated power and local wind conditions. A 1 kW turbine with a 30% capacity factor produces about 7.2 kWh per day. A large 2 MW utility-scale turbine at 35% capacity factor generates roughly 16,800 kWh per day. Use the annual energy figure and divide by 365 for a daily estimate.

Air density (ρ) directly proportional to power output — denser air carries more kinetic energy. Standard sea-level density is 1.225 kg/m³, but it decreases with altitude and higher temperatures. A turbine at high altitude or in hot conditions will produce less power than the same turbine at sea level in cooler air.

Torque is the rotational force exerted by the turbine rotor. It is calculated as T = P / ω, where P is the actual power output in watts and ω is the angular velocity in radians per second (ω = 2π × RPM / 60). Higher torque at lower RPM is typical for wind turbines, which is why most connect to generators via gearboxes.

A 500W rated turbine operating at a 25% capacity factor produces approximately 1,095 kWh per year (500W × 0.25 × 8,760 hours). This can power some household appliances but typically won't cover all energy needs for an average home. Wind speed at your site is the biggest factor determining actual output.