Combiner Boxes Explained

A combiner box is a simple electrical component for combining and housing the wiring coming from your solar panels. Combiner boxes are small rectangle boxes made of sheet metal or fiberglass rated to NEMA 3R or NEMA 4X for outdoor use. If you are going to use one then it will usually be mounted near the solar panels, either on the roof or just below where the wiring exits from the panels. For residential grid-tied systems, combiner boxes are rarely used. Off-grid systems will benefit from a combiner box as it provides a place to make multiple parallel connections without splicing the panels. Combiner boxes are very inexpensive, compared to the total system price and are effective in promoting a "clean" install.