Evaluation of temperature characteristics of high-efficiency InGaP/InGaAs/Ge triple-junction solar cells under concentration

Temperature characteristics of the open-circuit voltage (V_oc) were investigated in the temperature range from 30°C to 240°C for the InGaP/InGaAs/Ge triple-junction cells. Also, single-junction cells that had the similar structure to the subcells in the triple-junction cells were studied. In the high-temperature range (from 170°C to 240°C), the temperature coefficients of V_oc of the InGaP/InGaAs/Ge triple-junction solar cell (dV_oc/dT) were different from those in the low-temperature range (from 30°C to 100°C). This is because photo-voltage from the Ge subcell becomes almost 0 V in the high-temperature range. It was found that the open-circuit voltage of a Ge single-junction cell reduced to almost 0 V temperatures over 120°C under 1 sun condition.