Lester, We had a Xantrex 2512 inverter (2500 watts) so that is similar to the 2812. Our wiring from the battery bank is 3/0 wire in parallel (2 neg, 2 pos) to a junction box near the inverter. From the J box, its 4/0 for the 3 or 4 feet remaining to the inverter. That's pretty big wire and maybe unique with the parallel cable run. 2500 watts A/C will pull over 200 amps (dc) from your batteries so you want as little voltage drop as possible. Check your wire size to see if it will handle the amps. You might not need all 2500 (or whatever size inverter you use) watts, but you want to make sure the wiring can handle the current.