Higher conversion efficiency for combined systems with triple-junction GaAs photovoltaic cell and thermoelectric device

Photovoltaic (PV) and thermoelectric (TE) hybrid systems have the potential to increase solar energy utilization and possess broad development prospects. However, it is critical to select a suitable PV cell to couple with TE device and improve the efficiency of the photovoltaic–thermoelectric (PV-TE) hybrid system. This study used thermal interface materials (TIMs) with different thermal conductivities in triple-junction InGaP/GaAs/GeInG (tj-GaAs) PV-TE hybrid systems to reduce thermal contact resistance (TCR). The performance was investigated using a solar simulator with adjustable irradiation intensity and a liquid cooling device with controllable temperature. A comparative study has also been conducted with mono-crystalline (mc-Si) PV-TE system of the similar structure. The results indicated that the total output power of the direct contact PV-TE hybrid device and the optimized hybrid device using a thermal grease with a conductivity of 5.8 W m−1 K−1 could increase by 5.50% and 16.24%, respectively, compared with that of the pure PV. Moreover, lower cooling water temperatures have improved the performance of both PV cell and TE device. Results also indicated that the output power produced by the PV cell and TE device in the tj-GaAs PV-TE system are 537 mW and 0.76 mW higher than that produced by the PV cell and TE device in mc-Si silicon PV-TE system at 3.5 suns and 20 °C cooling water temperature, respectively. Compared to mc-Si PV cells, GaAs PV cells are more suitable for PV-TE hybrid systems and more adaptable under concentrated light conditions.