My system is similar, I used 150 amp dc breaker off the battery and use it as a disconnect switch also. 4awg is a bit small for battery to inverter, I tried the original 4awg wires that came with the inverter, they were about 18" long attached to BB that was fed with 2/0 cable. The 4awg got pretty warm after about a half hour running 1600 watt load so I swapped the 4awg to 2/0