It's not market demand. The government is ordering the construction of solar and wind farms without regard to the market demand or to the citizens residing in the locations where the solar farms and wind farms are to be built.
That's the exact opposite of democracy and capitalism.
It's a rational way to deal with their energy needs, reduce pollution and their impact on the climate.
They have small gas and oil reserves if I remember. Unfortunately, if they were sitting on Venezuela or Russian style reserves or oil/gas the story might be different. But unlike Europe, the Chinese can see that being beholden to foreign states to keep the lights on is asking for trouble.
They seem to have avoided the ideology the big fossil fuel companies push in the west to make fossil vs green a political/class discussion, not a rational one. Rationally it makes most sense for a nation to generate their energy needs in a way they control with wind/solar/nuclear.