The influence of high light inclination angles on the performance of GaInP2/GaAs/Ge triple junction solar cells

We report on the angular dependence (0° to 86°) of the current and voltage behavior of GaInP₂/GaAs/Ge triple-junction cells and corresponding GaInP₂ and GaAs component cells. Thereby, additional parameters such as temperature, cover glassing, degradation due to particle irradiation and subsequent annealing have been varied and their impact on the angular dependence has been assessed. The current limiting subcell of the triple-junction cell has been identified in each case and special focus has been put to the question whether a change of the current limitation from the GaInP₂ top cell to the GaAs middle cell can happen in some cases simply because of the light entering the cell at a higher inclination angle. The validity of the one diode model when measuring the solar cell under various angles has been verified analyzing respective open circuit voltage-short circuit current pairs.