a solar fencer generally has a built in battery for reserve power. Without sun, you still get a few days of "zapping" power. The "low impedience" deals with how the jolt is regulated I believe. The fencer does'nt actually "burn" the grass away(never heard of one starting a fire), but with low impedience, the grass that does happen to touch it won't "short" out the fencer. Mann Lake carries a couple models I believe, but you'll save some good money buy purchasing from your local farm supply. Another option you may look into(if your bee area isn't to big) is to take lumber(I like 1x4's) and punch them full of 2" nails. Lay these around your hive area say 3 or 4 boards wide as a bear deterent. I use these around mine, and also around our food caches when I guided in Alaska. You may get a bear to step on them once, but not twice. It's alot cheaper than buying a fencer,posts,fence and time. Steve