Comparison between spectrum-split conversion and thermophotovoltaic for solar energy utilization: Thermodynamic limitation and parametric analysis

Abstract

The mismatch between solar radiation spectrum and photovoltaic cells is the main obstacle on photovoltaic efficiency. Solar spectrum-split conversion (SSSC) and solar thermophotovoltaic (STPV) are two important technologies to solve this problem. In this study, the basic characteristics of the two technologies are considered and compared from the perspectives of thermodynamic evaluation and parameter analysis. Based on the radiative thermodynamics, a theoretical model is established to analyze the thermodynamic limitation of the solar spectrum-split photo-thermal cascade conversion, which is in the range of 84.96%–93.10% and higher than that of STPV (84.96%). Furthermore, a parameter model is established for the three-band solar spectrum-split photovoltaic-heat engine combined system. Parameter optimization analysis indicates that the theoretical efficiency of the three-band SSSC system can reach 64%, which is higher than the two-band spectrum-split by 5–20 percent points and is also higher than the theoretical maximum efficiency of STPV by approximately 25 percent points. The study points out that the high-temperature emission loss of STPV absorber for concentrating solar energy is as high as 70%, which is the loss of high-quality energy and directly reduces the working capability of solar energy. Future development of STPV should pay more attention to the selective absorbers. The study provides guidance for the integrated utilization of solar energy.