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

Temperature characteristics of InGaP/InGaAs/Ge triple-junction solar cells under concentration were evaluated. In the high-temperature range, the temperature coefficients of conversion efficiency and Voc were different from those in the low-temperature range. It was found that the temperature at which the temperature coefficient changed shifted up to the higher temperature with increasing concentration ratio. Because Voc of the Ge single-junction solar cell increased with increasing concentration ratio, the temperature at which Voc became almost 0V rose. A contribution of the induced voltage from the Ge junction to Voc of the triple-junction cell can be maintained at higher temperature by concentration operation. Even low concentration ratio of 14sun was found to be effective for increase in Voc of the triple-junction cell under high temperature operation.