As the world’s largest emitter of carbon, China has decided that one of the best ways to clean up its polluted air is through solar power. The country has led the world in solar installations for the last two years and will likely do so again in 2015. It’s on pace to reach 33 gigawatts of solar power capacity by the end of 2014, 42 times more than it had in 2010 and more than exists in Spain, Italy, and the U.K. combined, according to Bloomberg New Energy Finance. (The U.S. will have 20 gigawatts by the end of this year.) Most of China’s solar power comes from sprawling utility-scale solar farms in the country’s rural west. Now the idea is to distribute solar panels in urban areas, putting them on top of office buildings and factories and connecting them to the grid without building miles of costly transmission lines. In 2015, BNEF estimates that China will add as much as 15 gigawatts of solar capacity, enough to power roughly 16 million homes. More than half of that increase will come from cheap panels installed on commercial buildings. If the 2015 projection holds, China will have installed twice as much solar power in factories and office towers in one year than currently exists in all of Australia, one of the world’s sunniest countries.