The sun, an inexhaustible powerhouse, has long been recognized as humanity's most abundant energy resource. In an era increasingly defined by urgent climate concerns, diminishing fossil fuel reserves, and a burgeoning global energy demand, the harnessing of solar energy stands at the forefront of sustainable development. The landscape of solar energy is evolving at an unprecedented pace. While conventional silicon photovoltaics and established solar thermal systems have paved the way for widespread adoption, groundbreaking research and technological innovations are continuously pushing the boundaries of efficiency, cost-effectiveness, and versatility. This book aims to bridge the gap between foundational principles and these cutting-edge developments, offering a holistic view suitable for students pursuing a Bachelor of Technology degree in relevant disciplines such as Electrical, Electronics, Mechanical, Energy, and Materials Engineering.