Solar Installation WITHOUT Main Breaker?

[titan1021]

I am working on a Solar installation where the 200a main service has no disconnect. I am working with 28 panels at 325w each for total of 9,100watts, the company that the system was purchased from says I only need to install a 60a breaker for the inverter disconnect. They are telling me that I don't have to worry about derating or downsizing the main breaker because there isn't one in this particular Square D Homeline panel.

My plan was to install a small sub-panel to route some of the existing circuits in the main to free up space in the main for the Solar inverter disconnect breaker.

However, the inspector is insisting that this main service is illegal and I do have to provide a 175a main breaker.

I know the panel is legal as it contains no more than six handles, even though someone snuck the two single poles in there.

Just hoping for a little input.

Thank you

 

[electrofelon]

View attachment 14989 View attachment 14990

I am working on a Solar installation where the 200a main service has no disconnect. I am working with 28 panels at 325w each for total of 9,100watts, the company that the system was purchased from says I only need to install a 60a breaker for the inverter disconnect. They are telling me that I don't have to worry about derating or downsizing the main breaker because there isn't one in this particular Square D Homeline panel.

My plan was to install a small sub-panel to route some of the existing circuits in the main to free up space in the main for the Solar inverter disconnect breaker.

However, the inspector is insisting that this main service is illegal and I do have to provide a 175a main breaker.

I know the panel is legal as it contains no more than six handles, even though someone snuck the two single poles in there.

Just hoping for a little input.

Thank you

Generally a PV breaker in a MLO panel is considered a legitimate supply side connection, however, IMO, the literal wording in the code isnt quite there so is is plausible that an AHJ could have a different interpretation. The potential issue is 230.40 Exception #5 and that you are not adding another set of service entrance conductors to supply the PV disconnect.

 

[jaggedben]

I've designed half a dozen PV systems connecting to this particular Square-D panel in the past year or so. I haven't had a problem with any inspector telling me the panel is illegal; that's ridiculous. Tell the inspector to read 230.71. Services are allowed to have up to six disconnects. And yes, it's a supply side connection so no derating or downsizing is necessary. 705.12(A).

Your plan to install a sub and relocate some circuits to get the number down to six is exactly the correct idea. I've had to call for this on a couple myself. It's true that those two single pole breakers violate the six disconnect rule, as well as the listing of the panel. (Look at the panel label carefully, if the label is still there. It says not to install more than six circuit breakers. The busbars will not accept tandems or quads either.) Because the manufacturer of the panel has limited the panel to six breakers, any debate about whether the PV counts towards the six service disconnects is moot in this case.

You could also find an inverter for a 9.1kW system that only requires a 40A breaker. Replacing an inverter would probably be cheaper than replacing that panel, especially if you haven't installed the inverter yet. :lol: That might help if this inspector can't be convinced to follow what the code says.

 

[titan1021]

I've designed half a dozen PV systems connecting to this particular Square-D panel in the past year or so. I haven't had a problem with any inspector telling me the panel is illegal; that's ridiculous. Tell the inspector to read 230.71. Services are allowed to have up to six disconnects. And yes, it's a supply side connection so no derating or downsizing is necessary. 705.12(A).

Your plan to install a sub and relocate some circuits to get the number down to six is exactly the correct idea. I've had to call for this on a couple myself. It's true that those two single pole breakers violate the six disconnect rule, as well as the listing of the panel. (Look at the panel label carefully, if the label is still there. It says not to install more than six circuit breakers. The busbars will not accept tandems or quads either.) Because the manufacturer of the panel has limited the panel to six breakers, any debate about whether the PV counts towards the six service disconnects is moot in this case.

You could also find an inverter for a 9.1kW system that only requires a 40A breaker. Replacing an inverter would probably be cheaper than replacing that panel, especially if you haven't installed the inverter yet. :lol: That might help if this inspector can't be convinced to follow what the code says.

Thanks!

 

[ggunn]

It really depends on your AHJ. I do a lot of work in Austin and San Antonio. In Austin we must install a fused disco and tap onto the MLO bus or use IPC's to tap the service conductors, i.e., we cannot land on a breaker in the MLO MDP.

In San Antonio we cannot land on a breaker in a MLO panel no matter where it is, even if it is protected by upstream OCPD. Since they consider a line side connection to be a service entrance, if the MDP is MLO we have to install a tap box (no IPC's), bond neutral to ground in the disco and drive a new rod at the disco and not carry the EGC back to the service, and we have to move the service GEC from the MDP to the tap box. Either all that or we install a main breaker in the MDP so it's a load side interconnection.

AHJ's can be picky about line side interconnections.

 

[jaggedben]

Yeah, yeah yeah ggunn. But we've never heard of any of that Texas stuff in northern California.

 

[ggunn]

Yeah, yeah yeah ggunn. But we've never heard of any of that Texas stuff in northern California.

Yeah, well, if I couldn't live in Austin northern CA would be my next choice.

 

[electrofelon]

.....Since they consider a line side connection to be a service entrance, if the MDP is MLO we have to install a tap box (no IPC's), bond neutral to ground in the disco and drive a new rod at the disco and not carry the EGC back to the service, and we have to move the service GEC from the MDP to the tap box. Either all that or we install a main breaker in the MDP so it's a load side interconnection.

Probably preaching to the choir here, but how does "Since they consider a line side connection to be a service entrance...." logically lead to those requirements?

 

[ggunn]

Probably preaching to the choir here, but how does "Since they consider a line side connection to be a service entrance...." logically lead to those requirements?

CPS (San Antonio) requires a neutral to ground bond in the AC disco and the rest follows from that. Austin disagrees.

 

[electrofelon]

CPS (San Antonio) requires a neutral to ground bond in the AC disco and the rest follows

Fair enough but I guess what I am saying is I don't see where they get the no mlo supply side breaket requirement...

 

[jaggedben]

I think it only makes sense if it you read it as "Since they think a supply-side connection requires it's own set of service conductors...". As if somehow the code requires that. How many years will it take for the CMP to figure out that 705.12(A) needs clarification?

I still don't understand how they come up with those grounding requirements though. (One rod has to be at the disco but the other has to be at the tap?)

 

[ggunn]

Fair enough but I guess what I am saying is I don't see where they get the no mlo supply side breaket requirement...

Sorry; I guess I scrambled things a bit. CPS (San Antonio) says no backfed breakers in a MLO panel, period, not that that specifically follows from their opinion that line side interconnections are service entrances.