In today's world, the issue of dwindling raw material reserves and increasing energy consumption is a significant aspect. For this reason, special attention and action must be given to the development, research, and improvement of alternative energy sources. The content of this book deals with the verification of energy yield calculations in complex terrain. It focuses on the utilization of wind energy through large wind farm installations, not only in coastal areas but also in complex landscapes such as mountainous regions. The expected energy yield from wind turbines is one of the most important foundations for assessing the economic viability of wind farms. Various measurement and evaluation methods in the form of software programs are available, which are compared in this work. This book aims to provide insights for all.