Performance analysis of a novel solar radiation cascade conversion system for combined heat and power generation based on spectrum splitting and reshaping

In this paper, a novel cascading solar photovoltaic system with concentrating spectrum splitting and reshaping for combined heat and power generation is proposed for the first time to break through the limitations of photovoltaic efficiency. Two spectral splitters divide the solar spectrum into three parts, and each part of the spectrum is used by photovoltaics, thermophotovoltaics, and heat exchange fluids according to the photon grade. In addition, the heat exchange fluid also recovers the waste heat of concentrating photovoltaic and thermophotovoltaic cells. Therefore, the system achieves solar energy cascade utilization and has high electrical and thermal efficiency simultaneously. The effect of the fluid flow rate, solar irradiance, and cutoff wavelength of the spectral splitter on the hybrid system is discussed. The results show that under the conditions of 1000 sunlight and outlet fluid temperature of 60 °C, the solar energy conversion rate and exergy efficiency of the hybrid system are 90.17% and 39.84%, which are 63.97 percentage points and 11.62 percentage points higher than those of the single photovoltaic system, respectively.