I read the same type of question here:

Here is a link that might be useful: Solar fence discussion

I have several small pastures and a few of the Parmak 6 volt solar chargers. They work real good for me and I use the electric tape. I guess for the bear, you would be using bare wire, which would be much better. Just make sure you sure you ground it real well. The little 12 inch long stakes that usually come with them are OK if the ground is wet and the area is small. Otherwise, ground it good and deep. For your case, I'd run a second wire close to (but seperate from) the hot wire and hook it to the ground post also. Pretty much foolproof then and will give Smokey the best appreciation of the fencer's ability. We don't have bear here, but plenty of wild boar and the solar chargers work OK for them.

Good Luck,

Dave