It surely is interesting, but of all energy moved/spent on an airport most goes into the fuel for the planes. The rest is probably a few percent for lighting and maybe air condition, climate control, antenna systems.
It would be like outsourcing the fueling to a different company and saying : see, our company does not emit carbon.
But i agree, the airports usually need a flat area, without forest and that area can be used for solar panels. Might even help them with avoiding bird strike for offering less nesting area.