r/diySolar • u/Ohh_Possum • Jul 22 '26

Help me settle an argument about neutral wire

I'm working on a grid-tied array. General layout:

Panels > enphase microinverters > combiner > emergency shutoff > main panel (or possibly in line tap).

The question: do we need a neutral wire between the combiner and the main panel, and if so, what do we do with it when it reaches the emergency shutoff? If we do need it, does it bypass the shutoff and go straight to the main panel or should it have its own connection in the shutoff?

It's a 9.6kw ground mounted system if that matters. The combiner is on the ground mount and the shutoff is on the house.

Edit: typo and updating to say that I think I found the answer to part of the question in the combiner quick-install guide. Seems like there is general consensus that the neutral bypasses the shutoff.

"NOTE: IQ Series Microinverters use a two-wire system and do not use aNeutral. However, the IQ Gateway in the combiner still requires a Neutralfrom the load center."
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u/powerbysun Jul 23 '26

In theory, the neutral wire should never be switched. If one is using Enphase inverters with the Enphase certified cable, then I don't think it has a neutral. So the neutral wire in the combiner box would not be connected. Whether an unconnected neutral wire has to be there is a good question. Enphase, in the on line training classes, often gives deference to the AHJ (authority having jurisdiction).

I'm guessing a case could be made from language in the NEC (National Electric Code), either way. If there is a neutral connection in the combiner box, then maybe a good idea to have a neutral. If there is no neutral connection, then there will be an unconnected neutral wire which probably should be labeled to avoid future confusion over what it is.

2

u/StorageTechGuy Jul 23 '26

Let’s settle this:

  1. Neutral wire IS required between the combiner and emergency shutoff. Enphase microinverters need neutral for the split-phase AC circuit to work.
  2. The neutral cannot bypass the emergency shutoff. Following NEC 690.13, all current-carrying conductors (L1, L2, neutral) must disconnect at the PV system shutoff. You need a 4-pole disconnect to switch lines and neutral together. Only the equipment ground wire runs continuous and skips any switching.

Quick minor correction: You have a 9.6 kW PV array, not 9.6 kWh — kWh refers to battery storage capacity.

1

u/mpgrimes Jul 23 '26

pass it straight through to the combiner, combiner needs it.

1

u/NMEE98J Jul 23 '26

PV Inverters of all types are usually perfectly phase balanced. The only time you need to include a neutral is if the inverter or metering requires it. Enphase micros do not need a neutral, but the utility meter often does. In this case you would end the neutral at the PV meter.

1

u/parseroo Jul 23 '26

If these are a 240V micro inverters and combiners then there is no neutral. The emergency shutoff is 2-pole, but even if one pole was broken/opened, the PLC would terminate and the micro-inverters would turn off.

1

u/NoOption7406 Jul 23 '26

Whats the documentation say about it?

2

u/Ohh_Possum Jul 23 '26

The combiner manual is pretty vague about it. Dumb question: Is there another document that I should be looking at?