Injection-level Dependent Series Resistance: Comparison of CELLO and Photoluminescence-based Measurements

We have investigated the spatially resolved series resistance Rser of multicrystalline silicon solar cells in dependence on the injection level. For the global series resistance, a variation with the injection level is known from literature. Using CELLO and photoluminescence-based Rser measurements we find a qualitative change in the series resistance distribution: For low injection levels, highly recombination-active areas lead to locally increased ohmic losses; with increasing injection level, these areas become less pronounced in the Rser images. This can be understood in terms of lateral currents whose strength varies with the injection level due to varying current fractions passing through the grid or being shorted by the p –n junction. A linear response-based series resistance description, comprising the variation of the series resistance with the injection level, is used to explain these findings.