Non-linearity of solar cells in spectral response measurements

At the PV calibration laboratory of Fraunhofer ISE (ISE CalLab) the analysis and reduction of uncertainty components involved in solar cell and module measurements at Standard Testing Conditions (STC) in test laboratory as well as in industrial production control is a central topic. A major contribution to the uncertainty is the spectral mismatch which can be corrected. The spectral response of the test cell is usually measured with a differential spectral response (DSR) measurement setup. We have investigated different approaches for measuring the spectral response of non-linear solar cells. The aim is to simplify the differential spectral response method in order to determine the spectral response at STC with just one DSR measurement and estimate the uncertainty added by this simplification.