Textbook in PDF format This book presents a comprehensive exploration of solar energy sources, with a particular emphasis on comparing them to fossil fuels regarding their impact on global warming. It covers various aspects of solar energy power generation in practice, including details about the sun, such as the solar constant, different types of solar radiation, solar time, and the direction of beam radiation. Additionally, the book delves into the thermal performance of different types of solar concentrating collectors, focusing specifically on the fundamental principles of parabolic solar trough collectors. Drawing upon historical contexts, it examines the detailed evolution of these collectors in terms of thermal and optical performance, and it addresses techniques developed to tackle challenges such as non-uniform heat flux distribution on the receiver tube's outermost surface