SOLAR-CELL COLLECTION EFFICIENCY AND ITS VARIATION WITH VOLTAGE

Internal collection efficiency of solar cells is calculated as a funct ion of depletion width, minority-carrier diffusion length, solar spect rum, and absorption coefficient. Particular attention is given to the variation of depletion width with voltage, which may reduce collection efficiency by a few percent at operating voltages and may be misinter preted as a shunting effect. Calculations of collection-efficiency mag nitude and voltage dependence, plus comparisons with experiment, are p resented for several types of solar cells. Primary emphasis is placed on polycrystalline thin-film cells with relatively short diffusion len gths and hence potentially more pronounced collection efficiency effec ts.