| Abstract: | Solar energy is clean and renewable energy that plays an important role in mitigating impacts of environmental problems and climate change. Solar radiation received on the earth's surface determines the efficiency of power generation and the location and layout of photovoltaic arrays. In this paper, the average daily solar radiation of 77 stations in China from 1957 to 2016 was analyzed in terms of spatial and temporal characteristics. The results indicate that Xinjiang, the Qinghai-Tibet Plateau, North, Central and East China show a decreasing trend with an average of 2.54×10?3 MJ/(m2?10a), while Northwest and Northeast China are basically stabilized, and Southwest China shows a clear increasing trend with an average increase of 1.79×10?3 MJ/(m2?10a). The average daily solar radiation in summer and winter in China from 1957 to 2016 was 18.74 MJ/m2 and 9.09 MJ/m2, respectively. Except for spring in Northwest, East and South China, and summer in northeast China, the average daily solar radiation in all other regions show a downward trend. A critical point for the change is 1983 in the average daily solar radiation. Meanwhile, large-scale (25?30 years) oscillation changes are more obvious, while small-scale (5?10 years) changes are stable and have a global scope. The average daily solar radiation shows an increasing-decreasing gradient from west to east, which can be divided into three areas west of 80°E, 80°E?100°E and east of 100°E. The average daily solar radiation was 2.07 MJ/m2 in the 1980s, and that in 1990s lower than that in the 1960s and the 1970s. The average daily solar radiation has rebounded in the 21st century, but overall it is still lower than the average daily solar radiation from 1957 to 2016 (13.87 MJ/m2). |
