Learn how to wire a DC Combiner Box correctly for your solar PV system. This quick guide shows the proper DC input, output, grounding, and protection device l. A PV combiner box or DC combiner box acts as a central hub, combining the direct current (DC) from multiple strings into a single, organized output safely fed to your inverter. Without it, wiring becomes tangled, voltage drops occur, maintenance costs rise, and safety risks increase. These safety devices protect the solar panels from overcurrent and short circuits. The wiring diagram will indicate. This allows for the easy connection of multiple solar panels to a single inverter, which converts the DC power from the solar panels into AC power that can be used by appliances and devices. VIOX. Wiring a Pass-Through Box If you're only passing through one or two strings from your solar array, here's what you do: Mount the pass-through box securely: Your box should be rated for outdoor conditions—NEMA 3 or NEMA 4 if it's outside. Run your solar PV wire into the box: Use appropriately sized.