The imminent exhaustion of fossil energy resources and the increasing demand for energy were the motives to put into practice an energy policy based on rational use of energy, and on exploitation of new and renewable energy sources. Since the supply of conventional energy has not been able to follow the tremendous increase of the production demand in rural areas of the world, a renewed interest for the application of solar and wind energy has shown in many places. Therefore, researchers and engineers began to pay more attention to wind and solar energy utilisation in rural areas. This book presents the background and ideas of the developments being made in the use of solar and wind resources.