KAIHUA INDUSTRIAL PARK, China — By many measures, this industrial park built to cater to solar businesses in eastern China's Kaihua County appears to be dead. Roads are unimpeded by traffic. Most buildings stand vacant. Walking past dozens of factories here, no workers pass by. No machinery whirs. Much the same thing is happening across China. While Beijing continues aiming for leadership in the global clean tech sector, one of its landmark green industries is stumbling. Overcapacity and trade disputes have been driving the Chinese solar industry to a breaking point, and the government is mounting efforts to save it.