Need feedback whether this wiring scheme will work for Growatt or MPP All-In-One to sub-panel hookup

[Gaze]

Please see attached diagram.
Main house panel is about 150ft to solar shed where Growatt or MPP single-phase all-in-one (off-grid) inverter will be housed below PV array.

Would prefer to run one 3-conductor (red/blk/wht plus bare copper ground) cable from main house panel to shed instead of two separate 2-conductor cables. Existing underground conduit has limited space.

At inverter: 'AC Input' lugs will receive Line (blk), Neutral (wht), and Ground (grn) feed from Main panel as normal, from new circuit breaker.

A new loads sub-panel will be installed right next to existing main panel. Sub-panel will be grounded to main panel ground and neutral busbar will connect to main panel neutral bus as shown. Sub-panel neutral bus will be unbonded from ground at the sub-panel. Main panel neutral is bonded to ground.

At inverter: 'AC Output' Line (red) will connect back to new sub-panel to power new loads breakers.
Ground (grn) will be jumpered from Ground at 'AC Input' lug as shown.
Neutral (wht) will be jumpered from Neutral at 'AC Input' lug as shown.

Question is...will this work or will my equipment get fried? Trying to avoid having to re-trench the long distance.

 

[Samsonite801]

Theoretically, this should work, so long as the neutral wire gauge is sized properly for maximum combined current to handle the return of max inverter input and max potential inverter output loads simultaneously. Now code is another thing, you might want to run this by your county inspector and see if he has a problem with this topology (I am not a certified electrician, nor an expert on NEC).

There may also be some requirements for how those neutral and ground wires are bridged. I know on certain breakers for example, you cannot place 2 wires into the same screw lug.

Exception:
"The only time two wires can be installed under a single screw or lug is when the terminal is identified for this purpose. Circuit breakers rated not more than 30 amperes are often identified for the termination of two conductors. This can be verified by reviewing the circuit breaker manufacture's catalog."

Not sure what kind of screw lugs the MPP or Growatt inverters use on them (whether designed to accept 2 wires). You might need a combiner box of sorts, again check code requirements if necessary...


Also, is your remote solar shed grounded? If not it should be where ground is also bridged there to a grounding electrode outside of structure:

NEC 2014 - 250.32(A)
Grounding Electrode. Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with Part III of Article 250. The grounding electrode conductor(s) shall be connected in accordance with 250.32(B) or (C). Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed.

 

[Gaze]

Thanks for the reply. Now I'm thinking this approach may be feasible and the most efficient way to do it.

 

[Gaze]

Theoretically, this should work, so long as the neutral wire gauge is sized properly for maximum combined current to handle the return of max inverter input and max potential inverter output loads simultaneously.

This is a good point I need to ponder further...

 

[Jim in NH]

How did this work out for you?

 

[Gaze]

How did this work out for you?

The diagram I posted works perfectly.

 

[gnoeld]

The diagram I posted works perfectly.

What size wiring did you use for N?