The book *Principles of Solar Engineering, Fourth Edition* by D. Yogi Goswami addresses the need for solar resource assessment and highlights advancements in photovoltaics, solar thermal technologies, grid power, and energy storage. Each chapter has been updated to cover new technologies such as organic, dye-sensitized, and perovskite solar cells, and the design of solar systems and power plants. The book also features battery energy storage for distributed and bulk storage and electrical integration with main solar systems. Additionally, it includes the latest advancements in concentrating solar power plants, such as the supercritical CO₂ cycle. Readers will benefit from discussions on the economics of solar energy systems, which apply to all systems covered in the subsequent chapters. The book is intended for senior undergraduate and graduate engineering students taking courses in Energy Engineering and Solar Energy.The book *Principles of Solar Engineering, Fourth Edition* by D. Yogi Goswami addresses the need for solar resource assessment and highlights advancements in photovoltaics, solar thermal technologies, grid power, and energy storage. Each chapter has been updated to cover new technologies such as organic, dye-sensitized, and perovskite solar cells, and the design of solar systems and power plants. The book also features battery energy storage for distributed and bulk storage and electrical integration with main solar systems. Additionally, it includes the latest advancements in concentrating solar power plants, such as the supercritical CO₂ cycle. Readers will benefit from discussions on the economics of solar energy systems, which apply to all systems covered in the subsequent chapters. The book is intended for senior undergraduate and graduate engineering students taking courses in Energy Engineering and Solar Energy.