For determination of the thermal performance of small custom-built systems according to ENV 12977-2, the CTSS (Component Testing – System Simulation) method has to be used. The CTSS method is based on separate tests of the most important components (see Figure 10.3). The test for the collector is carried out according to EN 12975—2. The store is tested according to ENV 12977—3. The controller is checked according to ENV 12977-2, Annex B. Based on the parameters determined for the different components, the thermal performance of the complete system is predicted by using a component-based system simulation program such as TRNSYS.
The application range of the CTSS method is very flexible because of its component-oriented approach. Flence, it is possible to apply the CTSS method on nearly every system configuration, including solar combisystems.