I use a 1.6Joule ESB200 (battery powered) for my sheep (& chickens) as that was recommended for the well-insulated sheep. It's powerfull enough to kill grass, nettles etc when they grow into it, although it's still worth regular trims during the spring as the sheer quantity of growing stuff can exceed it's ability to kill 'em off.
Snow doesn't seem to affect it badly - I think it zaps the snowflakes in contact with the netting 'til they melt - but we haven't had bad snow here this year - yet.
I got my netting from mole valley (posted to me - I'm in Suffolk) as even with postage it was still cheaper than my local suppliers.
Biggest problem with the netting is that it has flexible posts with 6" spikes that don't provide much support in soft soil. I tie it to substantial stakes driven into the ground at the ends of straight runs to keep it under tension and to avoid the bottom string drooping to the ground.
PS. you can get a 4 foot earth rod from screwfix for £2.65 (order code 13335-12) - the cheapest I've found.