Workers inspect a photovoltaic power plant built on barren mountains at Xishacheng Village of Huai'an County in Zhangjiakou City, north China's Hebei Province, May 13, 2019. In recent years, Zhangjiakou city has vigorously developed and utilized new energy, with installed new-energy capacity surpassing 12 million kilowatts. (Xinhua/Yang Shiyao)