Impact of Atmospheric Aerosols on Solar Photovoltaic Electricity Generation in China

Solar photovoltaic (PV) electricity generation has been expanding rapidly in China. Total capacity quintupled from 8 to 43 GW between 2012 and 2015. The Chinese government aims to increase total capacity to 400 GW, fulfilling about 10% of total electricity demand, by 2030. However, severe aerosol pollution in China reduces solar radiation reaching the surface by scattering and absorbing sunlight. We estimate the aerosol impact on solar PV electricity generation in China by examining the 12-year (2003-2014) average reduction in surface solar irradiance due to aerosols in the atmosphere. We apply the PVLIB-Python model, a PV performance tool, to calculate point-of-array irradiance (POAI), radiation incident on a PV panel of 220W and 1.7 m2, and the capacity factor (CF) every 3 hours from 2003-2014 at spatial resolution of 1° latitude x 1° longitude. For model input, we use (1) satellite-derived surface irradiance data from the NASA Clouds and the Earth's Radiant Energy System (CERES) -SYN1deg for POAI, and (2) observation-constrained reanalysis weather data (temperature and wind speed at 2 meters) from the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA2) for system operating temperature that affects power output. We use the CERES irradiance data for multiple aerosol and cloud conditions to evaluate the impact of aerosols versus clouds on power output. Our results show that removing aerosols over Northern and Eastern China, the most polluted regions, increases annual average POAI on a fixed panel by up to 1.5 kWh/m2/day relative to current aerosol levels. This corresponds to an increase up to 35%. Over Northern China, aerosols, which influence POAI by up to 20%, are as important as clouds, and annually reduce POAI by about 25%. We evaluate the seasonal and diurnal variability of the impact and find that aerosols outperform clouds in reducing surface radiation in early morning and late afternoon during winter over both Northern and Eastern China. In winter, the monthly average decrease of POAI due to aerosols over these two regions reaches up to 50%. Furthermore, we find aerosols decrease electricity output of tracking PV systems more than of those with fixed arrays in terms of changes in both absolute value and percentages.