China is the world's biggest emitter of greenhouse gases, but it's also leading the world in clean energy investment and deployment. The growth in China's solar power sector, in particular, has been swift.

According to Bloomberg New Energy Finance, China added 53 gigawatts of solar photovoltaic (PV) capacity in 2017 alone, up from 30 gigawatts the year before. Part of the reason for this large increase? The Chinese government paid subsidies to developers of solar projects so as not to build more of the coal-fired power plants fouling the air in the country.

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At the same time, solar energy costs have fallen in China and around the world to the point where, in some areas, solar power is comparable to — if not less expensive than — non-renewable energy sources like coal and natural gas.

These time-lapse videos from the NASA/USGS Landsat 8 and ESA Sentinel-2 satellites show the expansion of solar energy facilities in China — the above at Longyangxia and the below at Jinchang — during the five-year period between April 2013 and 2018.The images were processed by Descartes Labs, a technology company creating a "data refinery for satellite imagery analysis" that includes information from environmental satellites.

For a time, the installation at Longyangxia was ranked as the largest solar installation in the world, with solar panels covering 10 square miles of Qinghai province.

Overall, Chinese investment in clean energy technologies in 2017 was about $133 billion, which was well ahead of the next biggest investor, the U.S., which devoted $57 billion. Solar power attracted 48 percent of the total global investment in clean energy last year.