> Ultimately this is the problem I have with solar: It puts an effective cap on our energy use. Solar will never be more than 100% efficient, and there is only so much land that it is reasonable to use, so if we say, wanted to expand our worldwide energy usage 10x, it's not really feasible.

Isn't this exactly why we should be installing solar on rooftops. It might be more exensive, but it's a bettet use of space. Plus most of the extra cost is labour, and aren't we constantly worrying about how their aren't enough jobs. Seems like a win-win to me.