Wind and solar installed capacity in China has been expanding rapidly since 2010. Meanwhile, there have been consistent curtailment issues for the wind and solar farms in the inland provinces. In the early years, curtailment was mainly due to an inability to connect to transmission lines; but it has become much more complex – even for wind and solar farms that have good connection to transmission lines, they still are frequently curtailed, especially in the winter and spring. China’s electricity demand and supply are spatially imbalanced with major load centers in the East and South, fossil, wind and solar energy resources in the North, Northwest and Northeast, and hydro resources in the Southwest. Despite slow transmission system development, inefficient planning and slow demand growth, there is a continued high rate of thermal capacity development. All these factors have led to serious curtailment concerns in in Northeast, Northwest and Northern China (Three North). Figure 1 summarizes wind and solar curtailment rates in 2013-2016. Both wind and solar curtailment rates have generally increased over the years. Curtailment varies considerably across provinces, as well as among projects; some states, such as Gansu and Xinjiang, have experienced curtailment rates above 40 percent. Wind curtailment is also more widespread than solar, mainly because wind does not coincide with high load times on a diurnal and annual basis to the same degree that solar does.
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