I use a single strand of the wire about 20 cm off the ground (not poly wire which has much higher resistance) around the fence line. This stops them digging under and protects the fence. The pen is divided by two strands of 4cm wide white tape. This uses more electric due to higher resistance but I prefer it to be visible to the pigs, not least of all so when you take it down they are reassured they can move to the next part of the pen. Mine is wired back to a mains unit. Battery is fine (Leisure battery for caravans work well), solar good too. A good fence tester is very helpful and earthing is essential. That is, make sure fence is not compromised by vegetation and make sure whichever system you use you have a good earth stake or two or three even.
If your weaners are not electric fence trained set up,the white tape infront of a solid barrier first so they don't panic and run straight through it. I make a small corale from hurdles and put the White tape 30cm inside the corale. Once they have touched it a couple of times remove the hurdles and make the corale bigger.