Spectral Measurements Using Component Cells: Examinations on Measurement Precision

In outdoor measurements, frequently one solar cell (or a set of component cells) is used to evaluate the effect of spectral changes on a PV module. For concentrator photovoltaic (CPV) power plants with multi-junction solar cells, a common method is to use component cells to study the influence of the spectral conditions on the output current of the module performance. However, quite often the spectral response of the component cells is different from the one in the subcell of the multi-junction solar cell. In such situations, the current generation in the component cell is not directly related to that of the III-V multi-junction solar cell. In this paper, we use a large set of simulated spectra based on climate data from eight different locations to evaluate the error which is induced by the difference in the spectral response between two solar cells. We also introduce an empirical mismatch function (EMF), which allows to significantly reduce the transformation errors.