I'm jealous of the lightening bugs. They don't live anywhere near me and didn't see one until I traveled all the way to India. What a treat of an evening to enjoy!
Have you tested the actual fence voltage with this hack? This may not produce enough voltage for a long run. The fence charger is connected to the 12v side of the solar charge controller. A small solar charge controller usually only allows 30amps x 12v = 365watts. I don't know if thats enough for the fence charger. If not, It might be best to hook the fence charger directly to the battery along with the charge controller. It all depends on how many watts your fence charger needs. Good job, though. 👍