Spectrum Splitting-Based Performance of Combined Photovoltaic Thermoelectric Generator System

This article demonstrates the effect of spectrum splitting of the solar spectrum on the output performance of the combined system for low concentration levels. The full spectrum has been split into two parts, the postbandgap spectrum (PBS) with a range of 1100–4000 nm is transferred to the thermoelectric device, and the within-bandgap spectrum with a range of 350–1100 nm is further split into two smaller partitions and divided between the solar cell and thermoelectric generator (TEG). The calculations were performed for 15 configurations, where the splitting wavelength was increased in steps of 50 nm. The results showed that splitting the spectrum decreases the thermal load of the solar cell reducing its temperature, while the TEG device can compensate for the decrease of the solar cell power caused by the reduction of the spectral range transferred to the solar cell. At higher solar concentration levels, the optimal splitting wavelength increases, meaning that the optimal spectral distribution between TEG and photovoltaic (PV) is shifted toward the TEG device as light concentration levels and power densities increase. It was also verified that with increasing light concentration the spectrum-splitting combined system shows a growing efficiency advantage compared with standalone PV cells. This is explained on one hand by the temperature reduction of the PV cells, and on the other by the higher power contribution of the TEG device.