Performance analysis and selective emitter design for an efficient concentrated solar thermophotovoltaic system based on cavity-structured absorber and high-bandgap cell

Abstract

In order to break through the limitation of solar photovoltaic (PV) cell efficiency, this study proposes a concentrated solar thermophotovoltaic (STPV) system based on cavity-structured absorber, which can reshape the solar spectrum to match PV cell. An energy-balance model of the system is established for performance analysis, indicating that the theoretical power generation efficiency of system can reach 52.25% when using ideal selective emitter to match Si cell with high bandgap. The efficiency of STPV system using Si cell is 12–13 percentage points higher than that using low-bandgap cells such as GaSb. Furthermore, a metamaterial selective emitter is designed based on Ta and Al2O3 to match the high-bandgap Si cell for the first time, the simulation method is also verified by comparison with previous studies. The concentrated STPV system which based on Si cell achieves an efficiency of 37.18% with the designed selective emitter. The available proportion of spectrum for Si cell increases from 16.52% to 72.69% through reshaping blackbody radiation by designed selective emitter. The results of this study point out that using cavity-structured absorber and metamaterial selective emitter with high-bandgap PV cell is an effective STPV conversion path with the advantages of simple structure and high theoretical efficiency. It provides reference and inspiration for the application of STPV system.