Highly efficient spectrum-splitting solar energy utilization based on near- and far-field thermophotovoltaics

Improving the efficiency of solar energy utilization systems is of great importance in solar energy utilization. Near-field thermophotovoltaic cells can achieve a high power density and, therefore, efficiently utilize radiative heat transfer. An efficient spectrum-splitting solar energy utilization system based on near- and far-field thermophotovoltaics was proposed. The input solar energy was divided by the splitter, and the two parts of the energy were utilized differently. The concentration ratio can determine the energy input of the system, which can affect the photoelectric conversion efficiency of the system. Further, the vacuum distance can modulate the near-field radiative heat transfer, thus significantly impacting system performance. Based on the fluctuation dissipation theorem and Maxwell's equations, a system model was constructed and calculated using the optimal design method, and the effects of these parameters were investigated. Moreover, the optimal efficiency was obtained under different operating conditions. The optimal cascade system efficiency reached 39.93 % at a concentration ratio of 3000, which was 15.59 % higher than that of a single photovoltaic system. Thus, this study proposes a method for the efficient utilization of solar energy. In addition, it provides guidance for the subsequent design and construction of spectrum-splitting cascade systems based on near- and far-field thermophotovoltaics.