The book "Modelling of Solar Thermal Energy System" by Manuel Cusseiala offers a comprehensive analysis and modeling of solar thermal energy systems used for generating hot water through the utilization of solar energy. In recent years, the use of solar collectors for water heating has significantly increased, as they can both reduce energy costs and minimize environmental impacts. The book discusses the necessity of a detailed model with hourly resolution to optimize the efficiency and functionality of solar thermal systems. It explains how solar collectors convert sunlight into heat and the role they play in the hydraulic circuit of the system. The absorption of sunlight by special materials is a central topic addressed in this technical book.