The solar heating of buildings, the solar heating of water and solar thermal electricity generation are discussed. The importance of solar energy in determining the temperature of buildings is emphasized. The circuit representation of low-temperature heat transfer is used to estimate the heat loss and solar gain in buildings. The use of degree-days to predict the long-term performance of a building is illustrated and the behaviour of glass in capturing solar energy is described. The principles of solar water heating using a flat-plate or evacuated-tube solar collector is shown and the performance of a flat-plate solar collector is analysed. The use of selective absorber surfaces to improve the performance of a solar thermal system is discussed. High-temperature concentrated solar thermal systems are described with particular applications for electricity generation. Parabolic trough and Fresnel lens linear collectors are described as well as solar power tower schemes. The chapter is supported by 4 examples, 13 questions with answers and full solutions in the accompanying online material. Further reading and online resources are identified.