![weisser pixel weisser pixel](https://www.elvwis.com/media/7c/98/c5/1696225050/weisser_pixel.jpg?ts=1716102351)
Performance values of wind power plants - too good to be
true !?
Before you buy a wind power plant, you will ask yourself if you can rely on the
manufacturer's data and if these correspond to the reality. You might also want
to know, which performance you can expect.
The maximum achievable power of the wind energy is 59% according to Betz.
Depending on the degree of efficiency, each wind turbine can convert only a
certain proportion into a mechanical and a coupled generator thereof into
electrical energy. Any performance data that is stated above this theoretically
achievable maximum requires extreme caution. Therefore we would like to give you
the opportunity to check the performance data of our and of course also other
small wind turbines and to simulate different constellations.
The basis for calculating the output power of a wind turbine is always the area
swept by the rotor (projection area from the perspective of the wind direction,
e.g. circular area for horizontal or rectangular area for vertical wind
turbines) and, in addition to the air density, primarily the wind speed. These
factors define the volume of air flowing through the rotor and thus the
available energy in the wind. Then, the efficiency shows the relationship
between the energy contained in the wind and the power that the wind turbine
can obtain from it.
The power (P) in Watt is calculated with: P=(ρ*A*v³*cp)/2
Air density (ρ) here 1,22 kg/m³; rotor area (A) m²; wind speed (v) m/s;
efficiency (cp) e.g. 0,2 for 20%
Example: (1,22 * 0,304 * 12³ * 0,16) / 2 = 51,3 Watt (ElvWiS® III rotor)
Here we also provide you with a calculator that you can use to quickly simulate various constellations of rotor area, wind speed and efficiency:
For our vertical turbines, enter the height and width of the swept rotor surface in the calculator, using the following dimensions for the different rotor sizes:
ElvWiS® 125S (Savonius): 45 x 30 cm
ElvWiS® 25S (Savonius): 22 x 30 cm
ElvWiS® I (Savonius): 40 x 30 cm
ElvWiS® II (Savonius): 80 x 30 cm
ElvWiS® III (Savonius): 80 x 38 cm
The power calculation for our wind turbines refers to average rotor efficiency
values of 16 % for Savonius turbines, which were
determined by us in the wind tunnel, as well as a nominal power at 12 m/s and a
maximum power at 20 m/s.
For in the
article descriptions and the power calculator stated values, the air density is
based on 1.22 kg/m³.
![Efficiencies Savonius Efficiencies Savonius](https://www.elvwis.com/media/fd/54/ec/1695148268/Wirkungsgrade_Savonius_EN_02082019.jpg?ts=1712308085)