The Influence of Air Quality on Solar irradiances in most air polluted months in China

Solar energy, as a kind of clean and sustainable energy, is widely used in most countries, and the number of PV generators is increasing year by year in China. The solar energy generation directly depends on the amount of solar irradiance, which is easily affected by atmosphere situation. With the rapid development of urbanization and industrialization, the atmosphere situation in China become worse and worse, and the air is always heavily polluted in recent years, which will reduce the irradiance getting to the ground. In order to analyze the effect of air quality on the solar irradiance, we analyze three kinds of solar irradiance Direct Normal Irradiance (DNI), Global Horizontal Irradiance (GHI), and Diffuse Irradiance (DIF). The influence of the Air Quality Index (AQI) on DNI, GHI, DIF are analyzed from November to February in the most air polluted months in recent four years for Beijing, Harbin, Shanghai and Guangzhou. The date when the AQI was the local maximum(minimum), DNI and GHI were the local minimum(maximum), and DIF was also the local maximum(minimum) are selected. The results shows that DNI and GHI decrease, and DIF increases with the increase of AQI,. The six-order polynomial is used to fit the difference of the three irradiance and the difference of AQI. The average fitting coefficient R² for GHI is 0.8855, DNI is 0.8529 and DIF is 0.8466, and the highest R² for GHI is 0.9748, DNI is 0.9794 and DIF is 0.9820.