On the high dry plains of Qinghai Province in northwestern China, one of the country’s fastest-growing solar-power facilities spreads amid desert sands. The hundreds of photovoltaic panels in the Golmud Solar Park track the sun’s location through the day to glean the most energy. An enormous expansion of panel arrays is underway in the region, with some estimates suggesting that, by 2030, the combined generation capacity when the sun is shining could be akin to that from five large coal or nuclear plants. At present, there is no way to store the energy for nighttime use. Golmud, Qinghai Province, China.