The under-performance tab can be used to create a performance loss by shifting the power curve to the right. The nice thing about this is that the performance loss is encountered below rated. The difficult part of this is that it is hard to specify a shift in m/s that will give a definite value of energy loss. For this reason, Openwind provides a rough tool to try to estimate the effects on energy production of a given reduction in wind speed. At present in Openwind the terms “sub-optimal performance” and “under-performance” are used interchangeably.
