Book excerpt: The use of solar collectors for domestic hot water over the past 20 years has demonstrated that solar heating systems are now founded on a reliable and mature technology. However, the development of similar, but more complex, systems to provide both domestic hot water and space heating (solar combisystems) resulted in a diverse range of different designs that were not carefully optimized to reflect local climate and practice. Application of energy-efficient building strategies such as improved thermal insulation and use of low temperature heat supply systems is becoming increasingly common. This trend, combined with growing environmental awareness and the subsidies available in certain countries, favours an increase in market share for solar combisystems. The need for guidelines in selecting the appropriate system and designing this system according to the specific needs of the building and the local environment is therefore now increasingly pressing. This book fills that need.