The sun offers us its beautiful rays of light every day: let's make the most of them!This book aims to explore the four forms of solar energy, including photovoltaic, thermal, thermodynamic and passive solar energy which is a solution not to be overlooked! It presents the basic principles, their operation, their applications, and their potential for integration in various environments. Through case studies, this book guides the reader in understanding the challenges related to optimizing the capture and use of solar energy. It also emphasizes the importance of energy efficiency, sustainability, and innovation in the development of solar systems, in order to contribute to a cleaner and more responsible energy future. And at the end of this manuscript, there are ten exercises with solutions and Annex (Solar potential in Algeria) .