Bus Backfeed options - 120% rule

[inetdog]

Even so with a sub panel arrangement it is possible to limit the OCPD to lower than the 120% rule. The issue is his 1 kw system puts a little over 4A but has a 15A circuit breaker.
In this case a 6 or 8 circuit solar combiner/sub panel to combine all the arrays will allow him to connect all of them to 1 2 pole 40A breaker and feed the 200A panel no problem.

Which is exactly what I said......

[rsilvers]

So... I have 400 amp service at my house that is split into three main panels. Two of the panels are 200 amp bus bars with 150 amp breakers. A third is a 100 amp panel that is not part of this question. From what I can tell by reading here, I can have 90 amp back-fed solar breakers in each of the two larger panels.

I have learned so much from this, and answered my own questions. A few days ago I asked my town inspector some of this and he said "I would rather be talking to a licensed electrician as he would know what you need."

[solarix]

A 200 panel can be backfed with up to 7.7kW of inverters. You just need an AC combiner (for your three 15A breakers) to bring your three inverters together then run that into a 40A breaker in the main panel. Make it a dedicated panel with no other loads - needs to be labeled "Dedicated Combiner - Do Not Add Loads to the Panel". The imbalance from the one 120Vac inverter is not a problem.

[solarix]

"So... I have 400 amp service at my house that is split into three main panels. Two of the panels are 200 amp bus bars with 150 amp breakers. A third is a 100 amp panel that is not part of this question. From what I can tell by reading here, I can have 90 amp back-fed solar breakers in the two larger panels."

A 400 service can still be a backfeed problem as the busbars are only 200A limiting you to no more than 40A backfeed each - or 32A inverter max - or 7.7kW. Most utilities want you to have a single disconnect for all your solar backfeed so you can't split it up between several panels. Solution is to have less than 200 of absolute max potential load on one of the 200 busbars - then you can backfeed up to 200A no problem. You just need to label it so that additional loads can't be added.

[rsilvers]

"A 400 service can still be a backfeed problem as the busbars are only 200A limiting you to no more than 40A backfeed each - or 32A inverter max

I have 150 amp main breakers in each. So that is 90 each that can be back fed.