Indeed so! But I suppose there may be enough slanted surfaces facing approximately south. If solar were cheap enough to depoy, it could help. But possibly it may be not, due to labor costs.

I still see some (tall, multifamily / office) houses in Brooklyn and even on Manhattan adorning their roofs with solar panels. I know only one house that incorporated them right from the start though, it's on Coney Island, facing the ocean.

I think when someone comes up with translucent solar panels which can work as window shades on a skyscraper while looking good from the outside and not requiring a fortune to deploy, that will change the face of metropolises around the globe.