Like the roofs of the charging stations are the only roofs in town? I imagine Musk is already working out deals with warehouses and utilities to use those roofs to provide electricity to his charging stations.
I've been employed for most of the past year installing solar power systems on rooftops of stores and warehouses and such. They don't provide enough power to completely meet the needs of the buildings on which they are installed. They are grid-tie systems, wherein the building still gets power from the utility as well as from their own solar power systems, with the net result being that they buy a lot less power from the utilities. In theory, if they generated more power than they needed, they could sell the excess to the utility, but it is my understanding that that is not expected to happen.
So how's it that you expect that a warehouse or other business is going to have a solar power system installed on its roof, just to give that power to something else, while it continues to pay full price to the utility for all the power to meet its own needs?