After slowing down their solar investment last year, it looks like China is going to reverse the policy and provide subsidies for 30GW of solar projects this year.
https://cleantechnica.com/2019/04/17/chinas-447-million-solar-subsidy-could-yield-30-gigawatts-in-2019/
For the past few years, the additions to Chinese solar capacity have been (IRENA figures);
2014: 10GW;
2015: 15GW;
2016: 34GW;
2017: 53GW;
2018: 44GW. So 30-50GW (hi-lo forecasts) would be about the same to less than 2018.
If I take the mid of the forecasts for 2019, then the percentage yearly increase in installed capacity would be
2014: 60.7%;
2015: 53.9%;
2016: 79.3%;
2017: 68.7%;
2018: 34%;
2019: 22.9%. The kind of slowdown that would be expected as the installed capacity gets bigger, and therefore more absolute capacity has to be added to maintain the % growth rate.
In 2017 solar provided 1.84% of Chinese electricity generation. If they can keep going at 22% growth the solar capacity (and assuming generation grows in line with capacity) and solar electricity generation would double every 3.3 years. They would be needing to install 80GW/yr 3.3 years from now and 160GW 6.6 years from now, which should be doable. That would mean approx. 8% of Chinese electricity generation would be from solar in 2025, 16% in 2028ish and 32% in 2031ish (probably a bit lower due to the fast growth in overall electricity generation). Would be a great achievement but faster growth would be needed to reduce electricity-related GHGs given the high growth in electricity demand.
Wind was 4% of Chinese electricity generation in 2016, but that is growing at only 10% per year (doubling every 7 years). So maybe solar + wind growth could start offsetting the growth in electricity in the mid 2020s with a little help from nuclear and hydro.
Given the role of EV's in slowing oil consumption growth, and perhaps stopping that growth in the mid 2020's, then China's emissions could start falling from the mid 2020s. That would be a huge achievement for an economy growing at 6% a year, and massively expanding the use of coal until quite recently.