A grid-interactive PV system with battery backup is being installed with a ground-mounted PV array located
200 ft, from the inverter and batteries. The dc PV output circuit has overcuit has overcurrent protection rated from 30A. To reduce voltage drop between the array and batteries, the output circuit wire size was determined to be 6 AWG. The fused dc disconnect between the inverted and batteries is rated for 300A. What is the required size of the equipment grounding conductor between the metal battery case and the inverter?