Recent progress in thermal energy recovery from the decoupled photovoltaic/thermal system equipped with spectral splitters

Thermal decoupling of the photovoltaic (PV) and photothermal (PT) modules has been successfully implemented by employing the spectral separation technique, which is conducive to the thermal damage prevention of the PV cells caused by the absorption of unavailable photons. Moreover, the thermally decoupled spectral splitter-assembled PV/T (SPV/T) system has also achieved high-grade output heat while utilizing the full spectrum of solar energy. It has been widely reported that recovering the output thermal energy from the SPV/T system is an effective approach to improving the overall solar energy utilization efficiency. However, due to the limitations of optical performances of spectral splitter and heat transfer coefficients of the heat sink, the up-to-date solar energy utilization efficiency is still lower than the theoretical expectation. Herein, the recent progress in thermal energy recovery from thermally decoupled SPV/T systems was reviewed. The authors simply classified these recovery patterns as heating, power generation, and solar fuel production processes. Meanwhile, various optical designs and engineering strategies to improve the efficiency of the SPV/T system were introduced from principles to applications. Finally, the present challenges and future research opportunities were discussed. The purposes of this review are: (1) to provide ideas for improving the utilization efficiency of the solar energy system which combines the SPV/T and thermal recovery processes; (2) to stimulate inspiration to promote the stability and schedulability of the SPV/T system in practical applications; (3) to boost the application of thermal energy recovery from thermally decoupled SPV/T system. • The development of thermal recovery from decoupled PV/T systems was highlighted. • The methods of spectral separation techniques were discussed. • Harvesting thermal for heating, power generation, and fuel production was summarized. • The improvement of the efficiency of the splitter-assembled PV/T system was introduced. • The current challenges and future research opportunities were emphasized.