Design Concepts for a Spectral Splitting CPVT Receiver
Abstract
The technology of combined photovoltaic and solar thermal energy conversion (PVT) can have certain advantages compared to separate solar systems, if the corresponding PVT collectors are utilized in proper applications. However, if the considered heat sink requires temperatures beyond 100°C, the conventional PVT collector would not be suitable anymore, as thermal absorber and PV cells are thermally coupled in typical PVT systems. This would lead to an undesired temperature level in the PV part that makes the electrical energy conversion highly inefficient. This discrepancy between the optimum operating temperatures of the thermal and the electrical part becomes even more significant for concentrating PVT (CPVT) collectors. The approach of Spectral Splitting can provide a possible solution for this challenge. The basic principle is to split the solar spectrum into several wavelength ranges and impinge the PV cells only with the specific spectral range of highest conversion efficiency. The remaining parts of the spectrum are absorbed in the thermal receiver part and directly transformed into heat. Thermal decoupling between electrical and thermal receiver parts supports both the thermal and the electrical conversion efficiency. This presented paper describes the development of novel design concepts for the implementation of Spectral Splitting in a CPVT receiver for a linear Fresnel collector. A quantitative assessment revealed two favorable designs with different PV technologies that will be used for further investigations.