This book can be used as a textbook for students and as a reference book for engineers. It aims to provide students and beginners in the field of solar technology with knowledge from thermodynamics, heat transfer, and fluid mechanics in a compact form, which forms the basis for understanding the processes in the components of solar systems. Photovoltaic systems are briefly covered as a supplement. The book describes the current state of development in thermal solar technology, modern collectors, heat storage, and other facilities. Further information can be found in the literature listed in the current bibliography referenced in the text. The book outlines the application of recognized methods for the calculation and planning of active and passive solar systems, as well as methods for economic analysis and optimization of solar systems.