R&D program SOLARIS propose a new solar thermal collectors since 2016 (Vitosol 200 FM Thermprotect) in order to strongly reduce the technical problems associated to high stagnation temperature.
This new product is based on an intelligent absorber layer protects the collectors from overheating. Viessmann/IJL's patented ThermProtect technology switches the solar collectors off when they reach a specific temperature. Temperatures of 68°C and above cause changes in the crystalline structure of the absorber layer, increasing the rate of heat radiation and reducing the collector output. ThermProtect significantly lowers the max temperature inside the collector and prevents steam formation in the solar circuit. When the collector temperature is lowered, the crystalline structure reverts to its original state. More than 95 percent of the incoming solar energy will then be absorbed and converted into heat. Only the remaining five percent is reflected. There is no limit to the number of times the crystalline structure can reverse, making this function available at all times.
This new selective layer operates on a vanadium/aluminum system which improves the thermal regulation (patent WO 2014140499 A1). This success convinced Viessmann to transfer all its production means from the standard selective layer to the new thermochromic layer that was developed as part of SOLARIS. However, a heterogeneity in the chemical composition of the layer is currently observed requiring an adaptation of the manufacturing process. Furthermore, it is necessary to find a solution to increase the temperature of the thermochromic effect, a new generation of thermochromic solar layers is actually developed by SOLARIS.
Monsieur Fabien CAPON (Institut Jean Lamour)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
IJL Institut Jean Lamour
Help of the ANR 62,500 euros
Beginning and duration of the scientific project: March 2018 - 18 Months