We use polyposts and a Rutland ESB202 energiser running of a 12v Leisure battery, it has worked well through the winter and rest of the year. We linked old polytape and polywire in 6 strands with alternate live and earth wires, you need extra earth wires to catch any animal that tries to jump through the fencing, We will probably got for wooden post and wire once the current set up wears out.
As an aside, our chooks are locked up at night so we set the energiser onto its night/day setting which turns the power on automatically at dawn an off at night, gives the battery more time between charges.