Thermotropic overheating protection for façade-integrated solar thermal collectors

•Application demonstration of thermotropic overheating protection glazing in solar thermal collectors.•Development of thermotropic formulations exhibiting high long-term stability and weather-ability.•Six months of in-situ testing in solar thermal collector integrated in south façade of an office building.•Prove of application relevant overheating protection efficiency.•Corroboration of theoretical modeling.

The capability of thermotropic glazing to reduce stagnation temperatures in solar thermal collectors is evaluated in in-situ testing (south-façade of an office building). Therefore, a thermotropic formulation which is curable by sunlight and which exhibits both, excellent light-shielding characteristics (transmittance reduction by ~20%) and long-term stability is specifically designed. Application relevant overheating protection efficiency is given: absorber temperatures are reduced by up to 29 K in collector stagnation. Performance characteristics are not changed during the six month period of in-situ testing. The application demonstration emphasizes the high innovative capacity of thermotropic materials.