The behaviour of the whole thermal solar system or its subsystems, respectively, was observed during different operating conditions (e. g. stagnation). In order to assess the durability and reliability, the quality and the suitability of the materials used as well as the way how they were processed was considered. Additionally the period of warranty for the most important components (collector, store and controller) was assessed.

2.2 Environmental aspects

The energy payback time was determined and the used materials as well as the packaging was assessed.

2.3 Safety aspects

The most important components as well as the whole system was investigated with respect to electrical safety and the risk of injury due to sharp edges, burning and scald. The documentation was checked with regard to notes dealing with safety aspects during the installation of the system. For systems with an integrated gas burner safety aspects related to gas and fire were considered additionally.

2.4 Handling

The way how the system has to be mounted, maintained and operated was assessed. Criteria of this assessment were e. g. the time required for the system installation as well as ergonomic aspects. Additionally it was examined if the corresponding work steps were described understandably, detailed and correctly in the documentation supplied with the system.