Only five solar-power vendors remain in a space built for 170 at a sprawling complex of offices stacked three stories high outside Xinyu city in China’s southeast. Locked doors and empty offices are what’s left of the government’s audacious plan to dominate the global solar industry. What happened in Xinyu is being replicated across China, which used subsidies and $47.5 billion of credit to wrest supremacy from Germany, Japan and the U.S., saddling an industry with losses for at least two years.