How? By taking advantage of the free market while being closed off themselves. Not having those annoying environmental concerns when mining and processing rare earths probably helped a great deal too. And let’s not forget slave-like labour conditions. China dominates solar by being clever and ruthless, not by being smart or efficient. They can’t offset the burst of their housing market bubble by dumping more cheap electric cars and solar panels on western harbors and they know it. That being said western governments are foolish to first happily sign trade agreements with China just to moan about how unfair state capitalism is to compete with now. You knew what you signed up for and lied through your teeth when you said more trade would surely democratise the mainland.