Sorry to hear about your horse. Healthy horses heal remarkably well and with some TLC and time he should be fine. I understand about finances but the photos (though bad) show a pretty clean wound (esp the after pic) with no bone discolouration. (of course time can be evidence revealing). I have seen worse that healed pretty well (with close supervision and care) and no surgery needed. He will probably have a scar though which can be a bummer if he's a show prospect. Some horses like some ppl are just accident prone, no one can explain it. Perhaps he will out grow it. We can only hope.
Most of the electric fences I have been around usualy short out if they touch the ground. (grounded out) or diminish greatly in electricity depending on the voltage. Horses are sensitive to electricity. If he was getting royaly shocked he would have done by far more damage than just tearing up his leg. So I wouldnt worry to much in that respect.
"The question is not, can they reason? nor, can they talk? but, can they suffer?" Jeremy Bentham