Performance Evaluation of Solar Irradiance Models at 11 Sites in South America

Abstract This study provides the first continental-scale, multi-model validation of solar irradiance products in South America, comparing satellite-based datasets (CAMS, LSA-SAF) and reanalysis products (ERA-5, MERRA-2) against high-quality ground measurements from eleven stations spanning tropical, subtropical, and high-altitude environments. Using 15- and 60-minute data, we quantify accuracy through relative MBE, MAE, and RMSE. Results show that CAMS and LSA-SAF consistently outperform reanalysis products, with CAMS achieving up to 18% lower rRMSE than ERA-5 in lowland tropical regions and LSA-SAF reducing rRMSE by 30–40% relative to MERRA-2 at high-altitude Andean sites. ERA-5 exhibits moderate errors (20–30%) at mid-altitude locations but larger discrepancies in complex terrain, while MERRA-2 systematically overestimates GHI with rMBE exceeding +40% at several stations. All models show pronounced degradation at large solar zenith angles (> 60°). These results fill a major gap in regional literature by establishing a unified benchmark for model performance across diverse climatic regimes in South America, providing guidance for solar resource assessment and photovoltaic project planning.