Development and Testing of the PVSPEC Model of Photovoltaic Spectral Mismatch Factor

The PVSPEC model of spectral mismatch factor (SMM) for photovoltaic modules was developed using spectral irradiance and other meteorological data from eight locations. PVSPEC depends on clear sky index and absolute air mass. Cross-validation was used to evaluate model performance: the model was trained on data from seven locations and tested on data from the remaining location, going through all permutations. Root mean square errors on SMM were 3.2% on average, while absolute errors on long-term spectral effects were 0.8% on average. PVSPEC outperformed existing models developed by First Solar and by the European Commission's Joint Research Center.