Rudi Kaiser’, Vojtech Svoboda, Fraunhofer-Institute for Solar Energy Systems, Germany; Heinz Wenzl*, Beratung fur Batterien und Energietechnik, Germany; Ian Baring-Gould, National Renewable Energy Laboratory, USA; Nigel Wilmot, Murdoch University, Australia; Florence Mattera, Commissariat a l’Energie Atomique — Groupement Energetique de Cadarache, France; Stathis Tselepis, Centre for Renewable Energy Systems, Greece; Frans Nieuwenhout, The Netherlands Energy Research Foundation, Netherlands; Carlos Rodrigues, National Institute for Engineering and Industrial Technology, Portugal; Adolfo Perujo, Joint Research Center- Institute for Environment and Sustainability — Renewable Energies Unit (ISPRA), Italy; Alan Ruddell, Energy Research Unit (ERU) at Rutherford Appleton Laboratory, UK; Per Lundsager, Risoe National Laboratory, Denmark; Andreas Jossen, Centre for Solar Energy and Hydrogen Research, Germany.

Renewable energy systems (RES) are unique among energy supply systems because their performance and design depends entirely on the location and climatic conditions. As a result of design options, user requirements and local climatic conditions, there are enormous variations between RES. This paper describes a method how to evaluate the data on monitored renewable energy systems (RES) in such a way that the operating conditions and performance of individual components and the system as a whole can be analysed and compared. It shows how categories of similar use can be defined and recommendations for each category can be made to assist in the selection of the most suitable products.