What is a Solar Combiner Box?
A PV combiner box is an electrical distribution box where DC breakers are housed. Its main purpose is to combine multiple DC inputs from the panels in the system into a single DC output. This output is then connected to a charge controller or inverter, depending on the type of system. They also allow you to transition to larger wires between the array and the batteries or inverter to minimize transmission voltage drop.
- The number of strings determine the number of breakers that can be placed in the PV combiner box
- Ex: MNPV3 = 3 strings, 3 breakers
- Ex: SMA 12 = 12 strings, 12 breakers
- Overcurrent protection for each string
- Must meet UL 1741
- Busbar to hold the fuses
- Metal, Fiberglass, or Plastic NEMA (usually 3R or 4) rated Enclosure Box
- Plastic housing for fuses/breakers
Can you have AC and DC Breakers in the Same Box?
Yes and no. A solar combiner box is meant to combine many inputs to make it into one output to reduce wiring. If you use DC and AC breakers in the same box, you would not be combining the inputs, since DC and AC cannot be combined in this way, so essentially the box would be a junction box strictly for breaker housing and not combining. Also, if you put both DC and AC combiners in a PV combiner box, it would not pass code.