An Analysis of the Influence of Solar Radiation Variation on the Optimum Dip Angle of Photovoltaic Power Plant

The 1961—2016 data of total solar radiation, horizontal direct radiation and diffuse radiation were co-llected at six primary radiation stations in China's typical resource areas (Beijing Railway Station, Ejinaqi Station, Golmud Station, Lhasa Station, Kashi Station, Zhengzhou Station). The climate tendency estimation method was used to analyze the trend of solar radiation, and the Klein-Hay model was applied to calculate the optimal dip angle. Then the influence of solar radiation variation on the optimal dip angle of the photovoltaic power station was ana-lyzed. The results were as follows. Firstly, the overall trend of solar radiation variation in the six first-stage radiation stations in the past 56 years is a decline; the direct radiation in the four regions except Golmud and Zhengzhou has shown a downward trend; in Beijing, the diffuse irradiation ratio has been greater than the direct irradiation ratio since 2003; in 1976, the diffuse irradiation ratio of Zhengzhou was larger than its direct irradiation ratio; the direct irradiation ratio of Golmud, Kashi and Lhasa in the past 56 years has been higher than their diffuse irradiation ratio; the change in the direct irradiation ratio and the diffuse irradiation ratio of Ejina has not been obvious. Secondly, at the six primary radiation stations in China's typical resource areas, the optimum inclination of the radiation station has been declining with the decrease of solar radiation; the decline of the optimum dip angle in Beijing, Kashi and Lhasa has been influenced by the total radiation and the direct irradiation ratio; the decline of the optimum dip angle in Golmud and Zhengzhou has been influenced by the total radiation and the direct diffuse ratio.