Toward the Development of an Empirical Model of Air Pollution Impact on Solar PV Output for Industry Use

The absence of practical models for estimating the impact of air pollution on solar output presents a challenge for forecasting of solar electricity production and creates more uncertainty for financing and insuring solar plants. While the physics of irradiance attenuation due to aerosols are well understood, complex atmospheric conditions and lack of detailed atmospheric measurement make them impractical for industry or small-scale solar users to calculate its impact on PV power generation. Simple, empirical models to quantify the overall effect from real-world observations are scarce. In this study, we make use of both the experimental approach as well as large-scale real-world observational data from more than 15 sites to empirically evaluate the impact of air pollution on PV production using only common weather parameters. We show that the impact of PM2.5 on irradiance and, hence, PV output is approximately linear at low and moderate levels of PM2.5, with a 100 μg/m
³
increase corresponding to a reduction of around 15 ± 5% relative under clear sky conditions, which is broadly consistent with previous preliminary results reported from literature. This effect saturates at higher PM2.5 concentrations beyond 300 μg/m
³
and is reduced at high cloud coverage. The methodology developed in this study represents a viable path towards establishing a common ground for standards. The results obtained are the most comprehensive so far in terms of breadth and depth among similar empirical studies using ground-based observations. They provide a basis for establishing a functional model for industry practitioners in the PV community.