timselectric
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Yes
They continue to be available. But now for this purpose, instead of saving money on the main breaker costs.
Split Bus Panelboard for a hybrid inverter with NEC compliance?
- Thread starter poldim
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They continue to be available. But now for this purpose, instead of saving money on the main breaker costs.
timselectric
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No, it's not.
It must already be a split bus panel.
timselectric
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Do not do that.
It leaves the sub bus feeders unprotected.
And the modification breaks the UL listing.
timselectric
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You don't want to remove the N/G bond.
This is still the enclosure with the first means of disconnect.
Secondary sources should be unbonded, up to this point.
A typical common neutral setup.
timselectric
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Actually, most interlocks are between the main and a backfeed breaker.
Do you mean NQ or from other manufacturers?
QO should be available split-bus, NQ for sure. Equivalents with other manufacturers as well. Homeline is pared back AFAIK.
zanydroid
Solar Wizard
Oh ok. All my panels at home have backfed mains.
Either way the power source is INTO the panel. Whether main or backfed.
In the original document the top position of interlock has OUT direction and IN direction at bottom position
zanydroid
Solar Wizard
I was presuming use in the most likely situation for me.
Which is NOT replace of first means of disconnect.
Rather to get two buses in one subpanel
Which requires convertibility
zanydroid
Solar Wizard
It’s not clear that the first one was unmodified either. You would need to specifically find a split bus that skips two positions on the jumper to the second bus. Look at the home line split bus listed above, it doesn’t skip. Now assuming that split bus has a breaker feeding second bus, and there is a left to right interlock, then the inverter backfeed can be put to the left. With no modification
The modification seems to be in an ambiguous area since the connection between buses is done with standard components from factory anyway / whether the individual buses inside are listed appropriately.
timselectric
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Not sure what you mean by skip.
It is a split-phase bus, being fed by a 2 pole breaker.
timselectric
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Not left to right.
Up and down.
timselectric
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There shouldn't be any modifications done.
Just add the backfeed breaker and interlock.
zanydroid
Solar Wizard
The Homeline picture has
Factory breaker (2 pole) (a)
Factory breaker (2 pole) (b)
A and b are connected
The OP post has
Breaker (2 pole) (a)
User installed breaker (2 pole) (to inverter)
Lug (2 pole) (b)
A and B are connected
IOW it would require modification to the home line panel pasted above
zanydroid
Solar Wizard
In the OP it is up to down interlock
That will not work with the homeline panel as OP drew it.
It is probably possible to do either left right or top bottom interlock but not how OP drew it. Because OP inserts a inverter backfeed in between the jumper between top and bottom buses
It’s way clearer if I draw it but I will only put the time into drawing if someone makes a strong case the time I put in is worth it to them.
I don’t think trying to reach consensus via text is efficient but I also don’t know that anyone really cares or benefits. (I’m satisfied with my learning and understanding of the situation)
timselectric
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The homeline panel posted above would also be up and down interlock.
The backfeed breaker would be installed below the lower section existing feeding breaker.
zanydroid
Solar Wizard
Yes this is what I had in mind.
I think it works with left and right too, the flexibility is good in case only one type is available.
Hedges
I See Electromagnetic Fields!
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I actually got as far a disassembling a QO panel and marking the busbar where I would cut it.
I also thought about 3-phase panel, with one branch for backed up loads.
I'm using multiple breaker panels for heavy loads on grid, critical loads + AC coupled PV, important backed up loads. And I use a main breaker only panel for load-side tap (no 120% rule.
You can get PV ready panels with line side tap and second main breaker.
I also thought about 3-phase panel, with one branch for backed up loads.
I'm using multiple breaker panels for heavy loads on grid, critical loads + AC coupled PV, important backed up loads. And I use a main breaker only panel for load-side tap (no 120% rule.
You can get PV ready panels with line side tap and second main breaker.
zanydroid
Solar Wizard
How does the 3 phase panel work? 120V critical loads panel? Does it end up being confusing or space inefficient to work around the stab arrangement?
Hedges
I See Electromagnetic Fields!
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3-phase panel would be confusing, and putting a 2-pole breaker between wrong two poles could couple backup to grid side.
I never did it. But I was thinking about it with single Sunny Island (120V). I think it could work if you had 120V Sunny Boy, but mine were 240V. I did buy and install a 3-phase panel initially, just used two busbars.
A tall panel with upper and lower busbars for grid & island would be the way to go.
I never did it. But I was thinking about it with single Sunny Island (120V). I think it could work if you had 120V Sunny Boy, but mine were 240V. I did buy and install a 3-phase panel initially, just used two busbars.
A tall panel with upper and lower busbars for grid & island would be the way to go.
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