The bits of China where most of its people live are pretty mediocre for solar power. Like, Southern France at best, not Australia, not even California.

China is huge, and it does have huge solar farms, but the trouble is now you need a huge power transport infrastructure. Australia can move enough power from a desert where nobody lives to a small city 100 kilometres away on a few ordinary hundred kV pylons and be happy. China has huge cities, 2-3 thousand kilometres from those solar farms so it is building long chains of 1MV pylons which is the same idea but at this incredible scale.