Service conductor size

[PsychicViking]

I am working on a solar installation for a house with the following:

60amp 240/120V Service (#4 AL)
60amp main breaker panel.(60amp bus)

The inverter has an output of 34A requiring a 45A breaker.

Do the service conductors have to be upgraded whether I do a load side or supply side point of connection? I know the panel has to be upgraded to a 100A bus if doing a load side connection with a 60A main and 45A inverter breaker. 690.64 (B)(2) is confusing me with "busbar or conductor". Do they mean the conductor feeding the panel (#4 AL service conductor.)

 

[Smart $]

... 690.64 (B)(2) is confusing me with "busbar or conductor". Do they mean the conductor feeding the panel (#4 AL service conductor.)

If the service disconnecting means is a main breaker in the panel, 690.64(B)(2) would not apply when the point of connection is on its supply side. That would fall under 690.64(A).

PS: IIRC, "tapping" the service conductors requires your PV ocpd equipment rating to be not less than the service disconnecting means, or something like that. The ocpd rating itself can be less.

 

[BillK-AZ]

busbar or conductor

busbar or conductor

If you have separate meter enclosure and panel, and the connection between them was made by the installer, you can do a line side connection (tap) on the cable between the meter enclosure and panel with an OCPD rated up to the stated service or the ampacity of the cable between the meter enclosure and panel. You need not upgrade the 60-amp panel. This is 690.64(A).

If you have a one piece enclosure and panel (factory assembled) then you are limited to a 12-amp OCPD and need to place it opposite the 60A main.

If you replace the 60A panel with a 100A panel that has a 60A main, then you can have a PV breaker up to 60A (60 + 60 <or= 100 x 1.2). All modern breakers are listed for back feed, but the old 60A main breaker may not be listed or suitable for back feed. Look carefully at it to see if the terminals are marked line and load, if so marked, it should not be back fed.

I have seen one home that had a 200A meter (no switch or main) and a long trough with 3/0 cable. There were several safety switches tapped off the 3/0 for panels or heavy loads. No busbar. In this case the city would allow the PV to connect as an additional tap on this cable so long as the six-switch rule was observed. The PV OCPD could be up to 200A (lower if ambient temperature reduced the ampacity of the 3/0).