Combiner Box

A combiner box is an electrical enclosure that merges the output of multiple strings of solar panels into a single feed before it reaches the inverter. Each string of panels connects to the combiner box through its own circuit, protected by individual fuses or breakers.

In larger residential and commercial solar systems with a string inverter, panels are wired into multiple strings. The combiner box consolidates these strings, simplifying the wiring between the array and the inverter. It also provides overcurrent protection for each string, making it easier to isolate and troubleshoot individual strings if an issue arises. Combiner boxes are weatherproof enclosures typically mounted near the solar array on the roof or on a wall below. Smaller residential systems with only one or two strings may not require a separate combiner box, as the connections can be made directly at the inverter. Systems using microinverters generally do not use combiner boxes since each panel converts to AC independently.