I definitely think that the vacant land is a good location to put solar panels. Another is to locate the panels on canopies that cover spaces in parking lots.
One problem we had was vandals. There are electric gates along the bike trail and gates are run by a solar panel. The panels were on posts about 10 feet tall. Vandals threw stones and damaged the solar panels. So they installed taller street light poles and put the solar panels on them so now they are too high for the vandals to break with stones.
The solar panels need to have a fence and some distance to keep vandals from throwing things at them. Security and video cameras would be a great help.
Why putting solar panels beside highways is a no-brainer