This book aims to provide a friendly and comprehensive tool in the study of the key issues of Renewable Energy Systems, in order to gain a deeper insight in this broad field through thematic investigations, and, finally, to become able to design competitive innovations and intelligent applications of Renewable Energy Systems in the domestic, agricultural and industrial sectors. This work is a collaborative attempt to elaborate useful technical information from many countries around the world concerning the efficient and effective use and management of Renewable Energy Systems, either autonomous or hybrids, and to deliver theoretical and experimental analysis in Renewable Energy Systems issues, with numerous exercises, extended problems and case studies, simulation models and algorithms, which radically contribute to comprehensive learning, innovative design and engineering applications.