How to properly connect a 120v inverter to 240v service panel(only using 120v)?

[HighDesertOffgrid]

lol. No. For some reason I didn’t see the picture posted show up in my feed. Weird.

Ok, all is well!

You two have me counting neutral returns in a picture. Congratulations!

 

[Hedges]

5kW inverter is 40A at 120V. One MWBC with two 20A circuits sharing a single 12 awg neutral could be seriously overloaded. 2x current, 4x power dissipation in wire, 240 degrees C rise. Guaranteed to melt the insulation.
Do check for them. if found, you can wire both red and black to a single 120V 20A breaker.

Oh, one saving grace is 20A circuit, 12 awg, actually has 30A ampacity. So 40A is 1.33x current, 1.77x power and temperature rise, 30C + 1.77x 60C = 136 degrees C. And that's at 20A continuous per circuit. If inverter was bigger, might be 30A per for 15 minutes, but you are limited by inverter.

Looking at his panel I do not see any MWBC, do you?

Good point. All black except or feed in.

But the education, including how to identify, is important for others who find this thread.
And notes for future expansion.

I've always done MWBC. Because that's what I saw the first house I reverse-engineered.
Is it now proper to do MWBC with neutral spliced in nuts not daisychained, and with 2-pole ganged handle breaker?
I plan to retrofit AFCI breakers in My Old House.

 

[Mattb4]

lol. No. For some reason I didn’t see the picture posted show up in my feed. Weird.

Ok, all is well!

Your point was good. (about MWBC, I sometimes forget to type out my thinking)

 

[ChrisG]

Your point was good. (about MWBC, I sometimes forget to type out my thinking)

I have a real world example with my first 4kw 120v inverter, similar to what I typed above. MWBC in kitchen. One hot went left of sink counter outlets, one went right with a toaster on one and coffee pot on the other. Wife said she smelled plastic burning. Turned everything off with no smell from either device. Turned both on again and plastic burn smell came back. Kinda got lucky and the neutral was spliced in crawlspace under kitchen and cooked. Had to rerun romex to panel from splice location. It was even melted in the panel.