What does the IEC Class of a site mean?
The IEC defines 3 classes of wind turbines for different wind regimes. Roughly speaking, Class 1 turbines are for sites with average speeds of more than 8.5 m/s, Class 3 turbines are for winds less than 7.5 m/s and Class 2 turbines are in the middle. All turbines in the plant are the same type (1, 2 or 3) determined from the average wind speed (with an adjustment for site altitude). Composite power curves for IEC 1 and 2 are based on a composite of 3 machines (GE, Vestas, Gamesa), while the IEC 3 curve is based on the GE 1.5xle and the Gamesa G90.
