It’s not specifically solar power, but as there have been several mentions of wind turbines…
I wish that I could find the paper again, but I read several years ago about a proposal to mount wind turbines along interstate highway medians in the US. Small, enclosed turbines (so the reasoning went) would be far less vulnerable to high atmospheric winds, less dangerous to wildlife, and the fronts and wakes caused by passing traffic would keep them spinning for a minimum of 20 hours a day.
So far as I know, nobody has built so much as a test line, which I find disappointing. The American obsession with the automobile isn’t going away any time soon. Why not make it, if not a virtue, at least somewhat less of a vice?