Intelligent Energy Europe

Service tools

  • Current languageen

Navigation path

Solar Combi systems promotion and standardisation (COMBISOL)

Download PDFDownload PDF
Solar combisystems (SCS) are solar heating installations providing both space heating and domestic hot water in buildings. The main objective of Combisol project was to encourage an accelerated market deployment of SCS and to promote an improved quality of the systems installed. In particular, Combisol project wanted to: (i) promote best practices for SCS in new and existing buildings, (ii) promote standardized systems and cost-effective solutions (iii) propose recommendations to manufacturers with regard to SCS design,(iv) provide useful material for installers training, (v) develop specific dimensioning tools in order to facilitate the recommendation for SCS based on the EPBD methodology, (vi) increase consumers confidence, providing information on energy efficiency of SCS, based on in-situ monitoring and test labs. To achieve this main objective, qualitative and quantitative evaluations of SCS were conducted thereby providing valuable information on the thermal performances of systems and clear and precise recommendations for optimum efficiency.


  • Within CombiSol project, a unique set of tools and documents have been produced and used for qualitative and quantitative evaluation of solar combisystems. This set constitutes the common basis of evaluation for all participants, and some of the documents are the fundamental basis for a valuable intercomparison between the different partners. Some of them can also be of valuable interest for technical inspection of systems (for example in the Qualisol procedure in France)
  • 70 solar combisystems have been qualitatively evaluated thanks to a questionnaire focusing on 113 points, divided in the eight main groups General Data, Collector, Solar Loop, Heat Store, Domestic Hot Water Preparation, Space Heating, Auxiliary Heating and Controller. As a result of the qualitative evaluations major recommendations have been elaborated for manufacturers, system suppliers, installers and planers for improvements
  • 41. Monitoring is finished (one year measurements) for 15 of them and valuable results could be obtained with an extrapolation procedure for 16 other systems. Monitoring will continue in 2011 in some countries (France, Germany, Austria). Results have proved that thermal efficiency of systems could be high provided that systems design and installation quality are good
  • To improve quality, a set of tools/training material have been elaborated. A simplified calculation tool based on the standard has been prepared and is available from the website. Training material based on the outcomes of the qualitative and quantitative evaluation has been elaborated
  • Dissemination activities, mainly towards installers and manufacturers, have been organized. These dissemination activities have focused on the required quality of systems to achieve high efficiency, based on the results of the evaluation

Lessons learned

  • The qualitative evaluation of 70 combisystems in 4 countries has provided an overview of materials and installation quality. It has been observed that a high degree of quality can be achieved when systems are well designed and installers’ skills are good. But the qualitative evaluation has also proved than there is still some place for progress, especially regarding insulation of storage and piping.
  • Results of in-situ monitoring are much lower than expected, but this conclusion must be temperate. Some systems are performing well, and it has been demonstrated that compact prefabricated systems performs better than the others: this important lesson has been reported to manufacturers in order they can improve their systems. A second point should also be mentioned: thanks to both qualitative and quantitative evaluation, clear explanations about the lower thermal efficiency have been provided.
  • Valuable outputs have been obtained with the lab-testing. One should mention the comparison made between two different test methods, which have proved that CTSS method and global method provide comparable results provided that CTSS is adapted to take into account for real heat losses. The second major outcome is that global approach provides similar results than well installed and performing systems.

Partners and coordinator

List Map


Commissariat à l'Energie Atomique
Contact point: 
Philippe Papillon


Key documents

More documents

In brief

01/12/2007 to 30/11/2010
Contract number: 

Related projects

More projects