While we are waiting to figure out the bonding problem, here is some feedback on your drawing.
* on that inverter there is no neutral-in. It only takes the two hots.
* On that inverter there is a single ground connection where the AC-in and AC-Out is connected. There should be a ground wire from that connection back to the main panel. There should not be another connection to ground or earth ground.
* In your main panel, you almost certainly have a neutral-ground bond and a connection to earth ground.
* The sub-panel should have exactly one ground wire between its grounding bus and the main panel grounding bus.
* The heater Equipment Grounding Conductor should be tied to the Grounding conductor of the Romex going back to the sub-panel...
or it can be tied to the ground bar of the main panel. If you tie it to the main panel ground bar, do not use the grounding conductor in the Romex going back to the sub-panel.
* The frames of the solar panels should be tied to the main panel grounding bus bar.
View attachment 94079
Wow, you're awesome, FilterGuy!
I'll take your points one by one here:
1. On that inverter there is no neutral-in. It only takes the two hots.
-- Yes it's my mistake that I drew a neutral line between the main breaker panel & the inverter. It should've just been the 2 hot lines and a ground. I'll make that change to the drawing.
2. On that inverter there is a single ground connection where the AC-in and AC-Out is connected. There should be a ground wire from that connection back to the main panel. There should not be another connection to ground or earth ground.
-- Points D & E weren't meant to represent an actual earth grounding at those locations, just that there are grounding terminals on those devices. I guess I should've been more clear in my drawing. Sorry about that!
3. In your main panel, you almost certainly have a neutral-ground bond and a connection to earth ground.
-- Yes, there is a neutral/ground bond in my main panel with a connection to earth. I'll add that to my drawing as well.
4. & 5. The sub-panel should have exactly one ground wire between its grounding bus and the main panel grounding bus.
The heater Equipment Grounding Conductor should be tied to the Grounding conductor of the Romex going back to the sub-panel... or it can be tied to the ground bar of the main panel. If you tie it to the main panel ground bar, do not use the grounding conductor in the Romex going back to the sub-panel.
-- Hmm OK. I was thinking I could leave the ground wire for all of my critical load circuits connected to the grounding bus on the main panel, and then also connect the grounds on both ends of the 14/2 Romex to their respective grounding busses as well. That would save me from having to remove them all from the main panel's bus & join them to their respective feeder/extension wires to the sub panel. (i.e. connect points A & B to C. But this would provide multiple paths back to the main panel's grounding bus via all of the other circuits in the panel connected this way, which aren't shown in the diagram). So I agree with you. One properly sized grounding cable connecting the 2 grounding busses is a better solution.
6. The frames of the solar panels should be tied to the main panel grounding bus bar.
-- OK perfect.
I'll make changes to my drawing & upload it here shortly.
Thanks again, FilterGuy. You've been a huge help!
-Daniel