How about the first layout where you delete the J Box and the Wiring Trough (at least logically, not necessarily physically)? So all conductors go through the PV disconnect and through the Hybrid Inverter. Then in any state, the current path for the hot and the neutral of a 120V load follow the same physical path.
That might work, but the whole idea of having bypass, etc is to make it easy to keep the critical loads operating if there were a major inverter failure. Having all wiring go thru the inverter would make it difficult for maintenance or replacement of the inverter. Plus, there is not a ton of wiring space in that compartment.
The utility requires "a disconnect switch meeting the requirements of the NEC between the Company meter and the DER PoC. The switch shall be clearly marked, "Generator Disconnect Switch”, with permanent 3/8 inch or larger letters. The preferred location of the switch is outside the building in the immediate vicinity of the electric meter to facilitate access by Company personnel."
Usually the above means putting a disconnect outside between inverter and PoC. I am putting the E-Stop button outside anyway because of 706.15, so I will add labels to it to serve both functions and not put the disconnect out there.
But it still seems a good idea to have a disconnect to remove power from the Inverter Grid input if isolation is necessary. So was thinking about rearranging per below, with the PV Disconnect inside, between the Inverter and the Critical Loadcenter, with all conductors passing thru it.
With the below arrangement and paths, it seems like there are no conduits that would have nonzero sum currents, so no magnetic heating, and there are no current loops.
The neutral return path does not follow the line path when the Interlock is in Inv pos and the grid is supplying the power, but conduits all still sum zero current.
This install is half done, so I really need to finalize this. I appreciate the feedback if Wayne or anyone else has any so I can finish it up.
