The events leading up to the publication of this book started effectively in 1976 with the exchange of information between those modelling teams in Europe which were involved in the R&D-programme on Solar Energy of the Commission. When it became clear that the availability of experimental datafor model validation wm next to nothing, the Commission took the initiative to support in the frame of the Solar Energy R&D-programme the construction of Solar Pilot Test Facilities on eight sites in Europe. Each experimental facility consisted of two real solar heating systems with collectors, storage,...