Power is the rate of producing energy. Power is measured in kiloWatts (kW) or MegaWatts (MW). Energy is what is used to do work and is measured in kilowatt-hours (kWh) or Megawatt-hours (MWh).
The power output from a wind turbine at any moment is determined by the speed of the wind at that moment, though there will be a maximum power output based on the wind turbine generator rating which is closely related to the swept area of the blades. For example, a wind turbine with a rotor diameter of 52 metres would normally have a maximum power output of 800 kW, and a turbine with a rotor diameter of 82 metres would have a maximum power output of 2.5 to 3 MW.
For onshore wind turbines the largest ones are normally around 3 MW, though the largest available is the Enercon E126 (126 metre diameter rotor!) with a maximum power output of 7.5 MW. The table below shows the commonly available medium and large wind turbines along with the rotor diameter, tower height and maximum wind turbine power output.
|Rotor Diameter||Maximum Power Output||Typical Hub Heights||Example Turbines|
|24 metres||100 kW||24.5 to 36.0 metres||Norvento nED 100|
|47 to 54 metres||1 MW||35 to 76 metres||EWT DW52, 54, 61, Enercon E53 & E48|
|70 to 101 metres||2 to 3 MW||57 to 138 metres||Enercon E70, E82, E92, E101|
|101 metres+||2.4 to 7.5 MW||91 to 140 metres||Nordex N117, Enercon E126|
- There are often a range of turbines with different rotor diameters available for a given maximum power output. This is because of the wind class of the turbine where it is acceptable to use larger rotors on sites with lower annual average wind speeds.
There are many things to consider when working out how large a wind turbine(s) should be at a site including planning consent considerations (proximity to neighbours, visual impact, ecological sensitivities, aviation constraints etc.), site accessibility for delivering and assembling the turbine, the strength of the local electricity distribution network and the site owner’s project budget. All of these things would be considered in detail when determining the wind turbine power output during the wind feasibility study stage.
Remember how much energy you generate is more important that the headline power output and this is dependent on how windy your site is.
Want to install a wind turbine?
If you are in the UK then take our Wind Site Self-Assessment - The first step to provide information we need to complete a Windpower Feasibility Study. It takes about 20 minutes to work through the basic checks, including:
- Estimating wind speed
- Checking proximity of nearby properties
- Checking site access and approach roads
- Investigating connection with the grid