Solar Array Combiner Boxes

A combiner box is a fairly simple, outdoor-rated circuit breaker enclosure that is designed to take multiple circuits from the typical solar array and combine them into a single output circuit that connects to a charge controller (off-grid systems) or inverter (grid-tie systems). The wire from the combiner to the charge controller is often called the "transmission line", and it must be sized appropriately for the array size and transmission distance.

National Electric Code specifies that a disconnecting means must exist at the solar array, so using the proper circuit breakers allows each string of panels to be disconnected from the system individually. This facilitates troubleshooting, while providing over-current protection for the solar array wiring. Nearly as important, it makes installation easier and safer. Please consider a combiner box to be a necessary component of your solar power system.

A combiner box is also a perfect junction point for solar array grounding, which is also required by NEC. This same ground terminal also can be used for installation of a lightning arrestor (also called a SPD, or surge protection device). Although nothing offers complete protection against lightning damage, a properly installed lightning arrestor can save your expensive electronics from the most common high-voltage surges. SPDs are commonly installed in the power center, but an additional well-grounded lightning arrestor installed at the combiner box is highly recommended. Delta lightning arrestors have long been the standard of the industry, but the new Midnite Solar SPD has several times the effectiveness and can clamp up to a 115,000 amp surge!

Combiner boxes are available in several sizes and styles. As always, contact us if you have questions about finding the right combiner box for your needs.