Spectral Mismatch Correction for Multi-coloured BIPV Cells with Spot-area Spectral Responsivity Measurements

Spectral mismatch correction (between the standard reference spectrum and the spectral irradiance of the light source in use for testing, and between the spectral responsivities of the device to be tested and of the reference device use to measure the test irradiance) is important for accurate power and energy rating of photovoltaic modules in the laboratory practice. The spectral mismatch factor (MMF) is not negligible in coloured PV modules for their unconventional spectral responsivity (SR), which is usually significantly different from any reference device's SR: these modules are nowadays gaining interest for building applications. Direct SR measurement and MMF evaluation for multi-coloured PV modules may be challenging as full-area monochromatic irradiation is required, which can be achieved with solar simulator and bandpass filters. Such an equipment is costly and hence with limited availability to research and testing laboratories. In this study, we address the limitation and demonstrate that the evaluation of MMF for multi-coloured PV cells is also achievable using spot-area SR measurement. We first measure the localized SR of each individual coloured sector in the device under test. Following, we define the "global SR" and show how to calculate it from the localized SRs. Finally, we apply the MMF correction based on the "global SR" to the short-circuit current of coloured 1-cell minimodules, according to the standard procedure, and proof the validity of our proposed approach. When compared to direct measurement of the global SR on a filtered solar simulator, a good validation with deviations of <0.5% is found.