Analysis of thermoelectric coupling under parallel mismatch in triple-junction GaAs solar cells for satellites

Triple-junction gallium arsenide (GaAs) solar cells used in satellites can experience decreased reliability due to parallel mismatch during operation. This study presents a thermoelectric coupling model to calculate the temperature changes induced by parallel mismatch. The model's accuracy is verified using solar cell temperature data from space thermal environments and positive bias experimental conditions. The results indicate that when reverse current flows non-uniformly into the cell due to parallel mismatch, the temperature is higher compared to uniform current flow. The maximum relative error between the theoretically calculated temperature and the experimental result is 4.8 %. In space conditions, the on-orbit temperature data of the satellite solar cells during normal operation show a relative error of 5.69 %. When operating in space under 300 km orbital conditions, the cell temperature reaches 279 degrees C at a forward bias of 3.5 V with uniformly distributed reverse current, and 551 degrees C with non-uniformly distributed reverse current. With reasonable assumptions about local heat sources, the cell temperature can exceed 1000 degrees C under a current of 1.5 A, potentially causing permanent damage to the solar cell.