European Solar Thermal Industry Federation


Estimating annual solar collector energy output at national level

31 March 2011 

The renewable heating and cooling (RHC) sector offers a huge potential that has been underestimated and even neglected, in part due to the lack of generally accepted methods for calculating and monitoring the decentralized production of renewable heat.

In the past, by developing a consensual conversion factor of 0,7kWth/m²., the solar thermal sector has contributed to facilitating the calculation of the installed solar thermal capacity in operation in terms of kWth..However, a new method was needed that would be reliable and simple to estimate the impressive amount of energy produced by solar thermal systems worldwide and compare it with other (renewable) energy sources.

Such a method has now been developed and agreed by the IEA-SHC and major solar trade associations.  

Webinar presentations now available to download:

  1. Solar Thermal at a Global Level and the need for estimating annual solar collector energy output

    Werner Weiss - IEA Solar Heating & Cooling Programme Chairman

  2. Calculating the contribution of solar thermal towards the world energy supply  - We should harmonize the methodology

    Lex Bosselaar- NL Agency, Netherlands

  3. Simple method for Converting Installed Solar Collector Area to
    Annual Collector Output

    Jan Erik Nielsen - ESTIF technical consultant

as well as the calculation method explanatory note in PDF format.


For furtrher information please contact:

Pedro Dias: pedro.dias(at)


15 March 2011 press release:

Common calculation method of the solar thermal energy produced worldwide now available 


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