I don't know what 'snail tape' is. Is it 4 seperate conductors, +, -, +, -?
That is the only way it would make sense to me, related to snails.
If all 4 conductors are 'hot' the snail has to reach the tape and ground at the same time. Or one tape to the next.
A blade of grass touching the 'hot' tape will use a lot of power. Damp wood will too.
I would look for a 12V battery powered fencer. Not a solar powered fencer.
They use very little power. A 5W 12V PV would keep up, if the weeds are not shorting it out. Some factory made solar fencers only have 2W PVs.
It is cheaper to get a 12V fencer, small battery, and small solar panel, than it is to get a Solar Powered Fencer.
Plus some of the solar fencers use strange and very expensive batteries (ie: 4V SLA).
A 120V / 220V AC fencer will need an inverter. The inverter will waste more power than the fencer uses.
G-