Resumo/Summary:

The STRAWBERRIES project was designed to develop a transformative and unique solution to address the problem of limited land-availability and high land use requirements for conventional large-scale solar thermal systems. We use an innovative design approach to develop bifacial solar thermal flat-plate collectors

At the University of Minho we address the issue of the coating design and process: on component level, the absorber has to feature a bifacial coating and therefore a bifacial coating process must be developed within the project. Due to the second thermally active absorber side, overheating may become a threat for reliable collector operation and this might shorten a typical technology-lifetime up to 25 years. This is why the collector needs a so-called thermochromic coating which prevents overheating but still provides the required thermal efficiency for the energy conversion process of the collector.

The bifacial ST collector and system design represents the core technological innovation in the project. At design level, this comprises the development of highly selective coatings for bifacial operation, adding a thermochromic functionality. This coating, when it reaches a temperature close to the stagnation temperature should change its optical selectivity in order to reduce the stagnation temperature. This process must be reversible, returning to its original optical selectivity when the temperature is below the transition temperature.