The thought just occurred to me... forget roadways, those are peanuts in the solar scope and possible land coverage... I am thinking even more grandiose. Solar Freaking Oceans!
I mean think about it, the earth is 2/3rd covered by water... all that water space just sitting there going to waste. I mean... even if we just use 1/3 of that space to cover the oceans (leaving the rest open for oceanic traveling) that would be an enormous amount of coverage enough to supply more power than we could possibly consume even going far into the future.
But power generation isn't everything... As you know, there is a global crisis, and one of the causes is melting polar ice caps (which reflect the suns energy) vs water growth (which absorbs the suns energy) is causing a dramatic heat increase on the planets surface. We might not be able to immediately stop the major increase in carbon in our atmosphere, but we can instead start to deflect that absorption of the heat into the ocean.
Don't you see? This is what we should invest our money in!
(note, this post is satire, please do not think I was actually serious about this)