On the optimal mix of wind and solar generation in the future Chinese power system

China is one of the largest and fastest growing economies in the world. Until now, the corresponding growth of electricity consumption has been mainly provided by coal. However, as national reserves are limited and since burning coal leads to severe environmental problems, the employment of alternative sources of energy supply has become an important part of the Chinese energy policy. Recent studies show that wind energy alone could meet all of China's electricity demand. While our results validate these findings with regard to annual production, we look at the hour-by-hour resolution and uncover a major limitation: wind generation will not match the demand at every given point in time. This results in significant periods with over- and undersupply. Our study shows that combining wind and solar generation in the power system reduces overproduction significantly and increases the capacity credit of the combined VRE (variable renewable energy sources). The article demonstrates that up to 70% of VRE comprising 20–30% solar generation in the form of photovoltaics (PV) can be integrated into China's electricity system with moderate storage requirements. We encourage planners to consider those findings in their long-term planning in order to set up a sustainable power system for China at low costs.