Europe: Solar Keymark Scheme Rules for concentrating solar collectors
 Europe: Solar Keymark Scheme Rules for concentrating solar collectors

Europe: Solar Keymark Scheme Rules for concentrating solar collectors

 Solar Keymark Network Meeting During the meeting in Paris in October 2011, the Solar Keymark Network has accepted an extension of the Solar Keymark Scheme Rules. In the future, Solar Keymark will be available for both solar water heater stores and concentrating solar collectors. At the same meeting, the Solar Keymark Network has approved the new Annual Collector Energy Output Calculation Tool as a standard measuring tool for all Solar Keymark certified collectors. The energy output calculated with it can from now on be found on all Solar Keymark data sheets.
Photo: Henry Rosik

Between 5 and 6 October 2011, around 40 members of the Solar Keymark Network followed an invitation of French certification authority CERTITA to the autumn meeting of the Solar Keymark Network in Paris. One of the main topics of the meeting was how to integrate solar water heater stores and concentrating collectors into the Solar Keymark Scheme Rules.

In the view of Dr. Harald Drück, Chairman of the Solar Keymark Network, the main criterion for solar water heater stores would be thermal losses. So far, only solar water heater stores pursuant to EN 12977-3 have been able to get a Solar Keymark certification. The rules of the European Committee for Standardization (CEN) state that Keymarks can only be assigned based on valid European norms. Combi storage tanks are subject to CEN/TS 12977-4, which is only a pre-norm at the moment, but is expected to be established as a “proper” norm next year. Before the first solar water heater stores can be certified for Solar Keymark, the CEN Management Centre has to accept the changes to the Solar Keymark scheme rules, which will probably happen before the end of this year. An updated version of the Solar Keymark Scheme Rules will soon be available on the website (

Moreover, the responsible committee has extended norm EN 12975-2 by an amendment which makes the standard also applicable for concentrating collectors. The term concentrating collector refers to any kind of solar collector which uses lenses or reflectors to redirect the sunlight, including vacuum tube collectors using CPC mirrors, Fresnel or parabolic trough collectors.

A second topic discussed at the autumn meeting was how to implement one common European calculation method for the energy output of solar collectors. Many national incentive programmes require energy output calculations. For example, applying for the German Marktanreizprogramm (Market Rebate Programme for Renewable Energies) requires an energy yield of 525 kWh/m2 and year, pursuant to the so-called BMWi frame conditions. Because the European countries did not use one standard calculation method for their incentive programmes, every national incentive scheme had its own method to calculate the output. Now, the Swedish testing authority SP developed in its QAiST (Quality Assurance in Solar Heating and Cooling Technology) project an Excel-based tool to calculate the energy output for solar collectors under arbitrary climate conditions. The Solar Keymark Network has approved the Excel programme as a valid tool and has agreed to include its calculation results on the Solar Keymark data sheets of any certified collector. Until now, however, this has not changed the differing requirements of the national incentive schemes. “We have provided a basis,” Drück says. The next step will be to convince the decision makers of the incentive schemes to accept the results determined by the new calculation method as a common basis for their incentive schemes.

The members of the network have also expressed the need for a common worldwide certification process. A working group was set up to deal with this issue. A second working group will develop testing criteria for the freeze resistance of heat pipes in vacuum tube collectors.

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Chris Laughton

Chris Laughton is Founder and Managing Director of the Solar Design Company in Great Britain.