Personally, no. A few locations like Ft. Tejon, Rocklin Service Center, Barstow, Hawthorne (maybe Inyokern) have solar panels atop the canopy that covers the charging station. It is likely that these installations do not furnish all the electricity needed to charge our cars, especially during heavy usage. (There have been a couple of other threads devoted to this.) I understand that Tesla eventually wants to have battery storage at the Supercharger sites to be able to store any self-generated electricity and also to be able to download electricity during off-peak hours when juice is cheaper and perhaps also to level out the demand spike charges. At one time it was Tesla's goal to have renewables generate all the electricity utilized by the Supercharger network, if I recall correctly.
As far as being able to select how the electricity is generated that goes into charging our cars, I do not know for sure. Probably a way to find out would be to find a SC under construction and ask one of the crew members or the public utility that covers the area when the utility comes around to do their thing.
Good question!