The Technical Guidelines Part 2 – Determination of Power Curves and Standardized Energy Yields – was prepared with the aim of specifying the measurement procedure by which reliable and comparable data on the power curve of a wind turbine (WTG) can be determined according to the state of the art. The performance curves are the determining plant parameter for the calculation of the annual energy yield, which is often the basis for purchase decisions and financing commitments. This results in the special need for accurate and reliable measurement. In particular, measuring institutes, manufacturers of wind turbines and other engineering offices participated in the development of the guideline within the framework of the responsible working group.