Analysis on the hourly spatiotemporal complementarities between China's solar and wind energy resources spreading in a wide area

China is rich in solar and wind energy resources, of which the proportion of China's power sources has been rapidly increasing. Such fluctuating and intermittent energy sources will bring significant challenges to the safe and stable operation power system. However, making use of the spatiotemporal complementarities between different renewable energy resources is a feasible way to level fluctuating power especially when they have a widely geographical dispersion. Based on the data provided by China Meteorological Administration (CMA), this research explores the spatiotemporal complementarities between wind and solar energy resources. This paper nondimensionalizes hourly wind speed and global solar radiation data and employs several indexes to compare the smoothing effect with various combining scenarios. The results show that combining wind and solar powers within a certain area can cause a fall of zero-power or very-full power hours. Besides, combining different resources improves 'smoothness' in power output when compared with that from each individual resource. However, under hourly time scale, when the dispersion of sites is large enough, the smoothing effect of combining the dispersed wind power is very close to the combination of those two different resources. Nevertheless, this complementary effect is much better than that of just combining solar energy resources.