hi andy,
our host has an easy to use calculator that does a nice job at wire run sizing.
http://howto.altenergystore.com/How-to-Size-Wiring-and-Cabling-for-Your-System/a62/ when we plug in our info it looks like an acceptable 3.5% voltage drop using that awg#2 cu wire you have. 2% is what to shoot for but up 5% would be a go. (depending on the pv module)
the same #2 wire from controller to battery bank is good.
as far as the cable from battery to inverter goes, that would depend on the inverter size but we really want to go for the overkill with this connection. nice big lugs,oversize wire size and short run. ie.#00 cable minimun and five feet max. (my opinion only)
andy. i would rethink my charge controller options. even with the biggest 60amp pwm controllers we are right on the max or even over with the derate. think about going with one of the open format mppt units. you will be able to come down at much higher voltages at reduced current with a very reasonable wire size and have better pv production with the muiti(sometimes called maximum) power point tracking.
also, maybe it's just me but i don't like any aluminum wire in any part of a dc power system. it's great for ac subpanel service runs tho. (opinion only)
best regards,
