Analysis of a novel photovoltaic/thermal system using InGaN/GaN MQWs cells in high temperature applications

Abstract The solar cells commonly adopted in the photovoltaic/thermal (PV/T) have negative temperature coefficients, leading to a significant decrement in electrical efficiency as cell’s temperature exceeds 80 °C, and thus the PV/T systems are mainly used at low-temperature applications. A new type of InGaN/GaN multiple quantum wells (InGaN/GaN MQWs) cells have attracted increasing interest in past few years. The cells have positive or near-zero temperature coefficients and are a promising option in medium-high temperature applications. It is the first time that InGaN/GaN MQWs cells are proposed in a PV/T system, and evacuated flat plate PV/T (EFP-PV/T) collectors are employed. A mathematical model is established to investigate the performance of EFP-PV/T collectors using two kinds of InGaN/GaN MQWs cells at high temperatures. Performance comparison with PV/T systems using conventional solar cells is also conducted. As the operating temperature increases to 150 °C, the efficiency of traditional cell-based PV/T collector decreases to 5.21%, while the efficiency of Type-1 InGaN/GaN MQWs has a minor drop from 4.34% to 4.16% and it increases to 2.07% for Type-2 InGaN/GaN MQWs. The characteristics of large absorption coefficient, radiation-hard, and superior thermal stability, and positive or near-zero temperature coefficients make InGaN/GaN MQWs cells suitable for use in high-temperature PV/T systems.