I was speaking to a Kuwaiti princeling a few years ago about solar and he just couldn’t get his head around zero marginal cost, the efficiency of assembly of the panels, and the economics that would drive the growth. We spoke for about half an hour and he kept bringing up that powerbrokers don’t care about the environment and I had to repeatedly point out that I hadn’t mentioned the environment once.
The biggest thing is truly that solar has now reached a price tag where it just makes sense to replace other sources. You don't need to think about the environment any more to prefer it.