Earlier quoted context omitted.
The thing I don't understand is why it's assumed that somehow the Paris Treaty is somehow enforced, or binding, or that it will even actually improve conditions more-so than independent initiative. I personally think that the USA can achieve its goal without the Paris Treaty through personal responsibility of the states, and independent initiatives through counties, and cities. That type of independent resolution is…
Treaties like this have a big signaling component, just like macroeconomics. Improvements are perfectly possible without them, but even a toothless treaty affects all kinds of decisions downstream. We also take into account that energy production is about large capital investments that aren't looking at tomorrow, but a decade or two ahead at the minimum. Building a new coal plant today isn't a bad idea because it'll…
That's really the tipping point for solar - if it can provide a better return then coal plants. It's getting close, but the significant thing is that solar scales so much better then coal because you can build it anywhere - minimal environmental impact statements, no real supply lines other then grid access, minimal staffing and maintenance. If a straight up solar farm can provide a reliable return on investment over coal power, then no one is going to bother building coal plants any longer unless tax-breaks rain from the heavens (which they might).
And the kicker is very much that scalability aspect - solar doesn't even need to provide much of a better return then coal plants to beat them, it just needs to be deployable in such volume that the obvious investment strategy becomes "build solar".
And we're getting there - fast.