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Uncertainty of PV Module Energy Rating Caused by Spectral Effects
W. Herrmann, I. Nixdorf, J. Bonilla Castro
Energy Rating, Energy Performance, PV Module
Photovoltaic Modules and BoS Components
Subtopic: PV Module Design, Manufacture, Performance and Reliability
Event: 37th European Photovoltaic Solar Energy Conference and Exhibition
Session: 4BO.13.3
816 - 821
ISBN: 3-936338-73-6
Paper DOI: 10.4229/EUPVSEC20202020-4BO.13.3
0,00 EUR
Document(s): paper, presentation


The aim of this work was to re-evaluate the methodology for Climate Specific Energy Rating (CSER), as defined in the IEC 61853 standard series “Photovoltaic (PV) module performance testing and energy rating”, in view of spectral related uncertainties. Our research covered two aspects: (a) IEC 61853 assumes a fixed spectral response curve of the PV device and does not consider its temperature dependence. (b) CSER calculation uses tabulated lowresolution spectral irradiance data (29 data points) for spectral mismatch calculation whereas real solar spectra result from high-resolution measurement. To quantify uncertainties for CSER caused by these effects, we used historical data from our PV energy yield test sites in Cologne (Germany) and Tempe (Arizona, USA) that include both a highresolution spectral irradiance measurement and temperature measurements of various PV module technologies. PV module spectral response curves at variable temperatures resulted from laboratory measurements. We introduced the annual irradiance-weighted spectral mismatch as an indicator for spectral impacts on CSER and compared the current IEC 61853 methodology (baseline) with a methodology that considers the above mentioned temperature and spectral irradiance aspects. Our results show that the current CSER methodology is insensitive to temperature effects (uncertainty < ±0.05%). However, the transition from high-resolution spectra to low-resolution Kato-band spectra can cause systematic errors in CSER. While there are only small impacts for CdTe (-0.1%) and CIGS (-0.3%) the transition to low-resolution Kato-bands leads to systematic CSER errors up to -0.9% for c-Si PV technologies. These systematic CSER errors are significantly reduced by adjustment of the wavelength intervals of low-resolution spectra. We propose these “PV-bands” to introduce in the CSER methodology.