Solar Backfeed Issue

[abcclub]

I am including a photo of a solar install that one of my inspectors sent me from one of his inspections today for your comments. I have never seen anything like this before. I thought maybe this picture could make a good showing on the worst installation list. A little background, both panels are rated at 100amps, an existing PV system was previously installed with a 20amp back-fed breaker, another PV system has just been installed at 20amps which caused the system to go way beyond the 120% rating of the bus-bar, hence the installation of the new 100amp panel and round-about way of running the service conductors. My direction for the contractor will be to either connect to the existing 100amp panel with a line side tap or replace the existing 100amp panel with a new 200amp panel. Your comments are welcome

 

[iwire]

My direction for the contractor will be to either connect to the existing 100amp panel with a line side tap or replace the existing 100amp panel with a new 200amp panel. Your comments are welcome

What is / are the code section(s) that you are gong to use to require this extra work?

 

[Pharon]

Sounds like 705.12(A) or (D).

 

[abcclub]

I was looking at 240.21, 250.142, which panel is considered the sub-panel? 300.3(B) for starters. Where I work we are combination inspectors and are not experts in any discipline. I rely heavily on this forum's knowledge. The installation seems very odd, again your comments are welcome.

 

[Pharon]

The 120% rule is in 705.12(D), and applies if you're on the load side of the main disconnect. 705.12(A) applies if you're on the line side of the main disconnect, and there is no such restriction. 705.12(D) applies whether it's the main panel or a sub-panel.

 

[ggunn]

I am including a photo of a solar install that one of my inspectors sent me from one of his inspections today for your comments. I have never seen anything like this before. I thought maybe this picture could make a good showing on the worst installation list. A little background, both panels are rated at 100amps, an existing PV system was previously installed with a 20amp back-fed breaker, another PV system has just been installed at 20amps which caused the system to go way beyond the 120% rating of the bus-bar, hence the installation of the new 100amp panel and round-about way of running the service conductors. My direction for the contractor will be to either connect to the existing 100amp panel with a line side tap or replace the existing 100amp panel with a new 200amp panel. Your comments are welcome

Beyond the violation of the 120% rule in the main panel, does the AHJ permit multiple interconnection points for PV? Most (all?) of the places I have worked would require that the two systems be combined onto one interconnection point.

 

[abcclub]

The main panel no longer has an issue with the 120% rule. The main service is now being fed by the 100 amp breaker located in the sub-panel. The sub-panel is being used as the combiner for the two inverter 20 amp breakers and is connected directly to the bottom of the meter base. The conductors that were factory installed between the meter base and the main disconnect in the service panel were removed, which in my opinion violates the listing of the panel. Another concern is what is the combined amperage at the conductors and bus-bar of the sub-panel being it is connected directly to the meter base of the main service?

 

[Pharon]

I don't see how there's no longer an issue with the 120% rule if your bus is rated for 100A and your total PV OCPD is 40A.

 

[abcclub]

The original 100 amp main service is now fed from the 100 amp sub-panel with a 100 amp breaker, no longer is there PV being back-fed at the original main service. The sub-panel has a 125 amp rated bus-bar. There is no issue with the 120% rule in the original main service. The sub-panel now becomes an issue without an main disconnect, concerning the 120% rule.

My concerns are:

1-voiding the listing of a listed assembly by removing the factory installed conductors between the meter socket and the main disconnect in the original main service ;
2-the grounded conductor is not installed with the un-grounded conductors to the sub-panel, which is now the service panel?
3-service raceway between the existing main service and the "new" main service is not service bonded.
4-neutral bus-bar in the "new" service is not bonded to the panel.
5-neutral bus-bar in the old main service which is now the (sub-panel) needs to be isolated from the ground bus-bar.
6-a 100 amp overcurrent device is required at the "new" main service to protect the bus from not more than 120% of the rating of that bus-bar which is 125 amps.
7-the "new" main service must be service rated.

 

[david]

The main panel no longer has an issue with the 120% rule. The main service is now being fed by the 100 amp breaker located in the sub-panel. The sub-panel is being used as the combiner for the two inverter 20 amp breakers and is connected directly to the bottom of the meter base. The conductors that were factory installed between the meter base and the main disconnect in the service panel were removed, which in my opinion violates the listing of the panel. Another concern is what is the combined amperage at the conductors and bus-bar of the sub-panel being it is connected directly to the meter base of the main service?

The main service is now being fed by the 100 amp breaker located in the sub-panel. …………………………….The conductors that were factory installed between the meter base and the main disconnect in the service panel were removed, ………………………………and bus-bar of the sub-panel being it is connected directly to the meter base of the main service?

If I am understanding you. You had a utility meter distribution factory wired combination.
The service entrance went from the line side (factory) to a main service panel.

Currently the factory service entrance (Jumpers) where removed, service entrance ungrounded conductors (THWN) now pass through the original panel and supply the main lugs of the new panel . The neutral from the meter combo is currently landed on the buss of the original panel ( it was not redirected). The 100 amp main lug panel has the neutral un- bonded.

You are calling this 100 amp main lug panel a combiner panel yet the only supply for the normal utility is landed to the main lug of the “combiner panel” from the main lug panel a 100 amp breaker feeds the original distribution of the meter/ main panel

Is all the above correct?

 

[abcclub]

If I am understanding you. You had a utility meter distribution factory wired combination.
The service entrance went from the line side (factory) to a main service panel.

Currently the factory service entrance (Jumpers) where removed, service entrance ungrounded conductors (THWN) now pass through the original panel and supply the main lugs of the new panel . The neutral from the meter combo is currently landed on the buss of the original panel ( it was not redirected). The 100 amp main lug panel has the neutral un- bonded.

You are calling this 100 amp main lug panel a combiner panel yet the only supply for the normal utility is landed to the main lug of the “combiner panel” from the main lug panel a 100 amp breaker feeds the original distribution of the meter/ main panel

Is all the above correct?

Pretty much, yes. I am not calling the main lug panel a combiner panel, though it is being used as such. In the picture the panel to the left is the service panel and the meter section above it is not shown. Could you comment on my concerns in the previous post?

 

[david]

Sounds like 705.12(A) or (D).

Pretty much, yes. I am not calling the main lug panel a combiner panel, though it is being used as such. In the picture the panel to the left is the service panel and the meter section above it is not shown. Could you comment on my concerns in the previous post?

Keep in mind I am on the 2008 National electric code
690.64 Point of Connection.
( A) Supply Side.
(B) Load Side.

I’m confused as to why the service entrance conductors where re-routed to what seems was intended to be a combiner (panel ) for the two photo voltaic sources.

I would think the service would have been left alone and 690.64 (B) would have been followed.
I am also unsure why the tie breaker (back feed into the service panel is not positioned in the furthest breaker position on the original service panel.

If the service panel was left supplied by the meter (utility) you still need to deal with the buss rating of the 100 amp buss being supplied by 40 amps (two 20 amp two pole) of solar

 

[electrofelon]

The original 100 amp main service is now fed from the 100 amp sub-panel with a 100 amp breaker, no longer is there PV being back-fed at the original main service. The sub-panel has a 125 amp rated bus-bar. There is no issue with the 120% rule in the original main service. The sub-panel now becomes an issue without an main disconnect, concerning the 120% rule.

My concerns are:

1-voiding the listing of a listed assembly by removing the factory installed conductors between the meter socket and the main disconnect in the original main service ;
2-the grounded conductor is not installed with the un-grounded conductors to the sub-panel, which is now the service panel?
3-service raceway between the existing main service and the "new" main service is not service bonded.
4-neutral bus-bar in the "new" service is not bonded to the panel.
5-neutral bus-bar in the old main service which is now the (sub-panel) needs to be isolated from the ground bus-bar.
6-a 100 amp overcurrent device is required at the "new" main service to protect the bus from not more than 120% of the rating of that bus-bar which is 125 amps.
7-the "new" main service must be service rated.

So If I am interpreting what is going on correctly, basically the service equipment now is the MLO panel with one service disconnect and two "line side taps."

1. Maybe.
2. I agree
3. I agree
4. I agree
5. I agree
6. I dont agree its a supply side connection.
7. If its not service rated than I agree

Also I see the service conductors routed with non service conductors (running through the sub) as a violation.

How are the service conductors connected in the meter compartment?

 

[ggunn]

Pretty much, yes. I am not calling the main lug panel a combiner panel, though it is being used as such. In the picture the panel to the left is the service panel and the meter section above it is not shown. Could you comment on my concerns in the previous post?

A picture is worth a thousand words. Could you sketch a clean drawing of what you are talking about and post it? The photo of the rat's nest of wires and the extended elocution are a bit hard to follow - for me, anyway. I have a lot of experience with solar but I don't have a clear idea of what you are asking about.

 

[abcclub]

So If I am interpreting what is going on correctly, basically the service equipment now is the MLO panel with one service disconnect and two "line side taps."

1. Maybe.
2. I agree
3. I agree
4. I agree
5. I agree
6. I dont agree its a supply side connection.
7. If its not service rated than I agree

Also I see the service conductors routed with non service conductors (running through the sub) as a violation.

How are the service conductors connected in the meter compartment?

First I am working out of the 2013 California Electrical Code

6. You are right, it is not a supply side connection. The PV system is interconnected at the panel on the right with the two 20 amp circuit breakers.
They are trying to use this panel as the service panel. The factory installed service jumpers between the meter and the main disconnect within the panel on the left which was the main service, have been removed and two new conductors installed from the meter base in the left panel to the bus lugs in the panel to the right. (service conductors routed with non service conductors) good catch, with all this mess I did not see that. thank you

 

[jaggedben]

The main panel no longer has an issue with the 120% rule. The main service is now being fed by the 100 amp breaker located in the sub-panel. The sub-panel is being used as the combiner for the two inverter 20 amp breakers and is connected directly to the bottom of the meter base.

What you are calling the subpanel is now actually the service panel, and vice versa. The service disconnecting means (there are three) are now located in the panel on the right side of the picture.

Another concern is what is the combined amperage at the conductors and bus-bar of the sub-panel being it is connected directly to the meter base of the main service?

This is not a concern in the current setup. The house cannot draw more than 100A load regardless of source. The solar cannot output more than 40A. These do not add together. The panel won't see more current than 100A.

The sub-panel now becomes an issue without an main disconnect, concerning the 120% rule.

I see now this has been discussed, but I'll expand on it anyway...

The panel on the right is the service panel now, and the solar is connected as supply side connections, and therefore not subject to the 120% rule. Read the 120% rule again carefully; it refers to the sum of solar and the breaker protecting the busbar. The 100A breaker is NOT protecting the busbar; it is protecting the feeder to the original panel and everything beyond that.

My concerns are:

1-voiding the listing of a listed assembly by removing the factory installed conductors between the meter socket and the main disconnect in the original main service ;
2-the grounded conductor is not installed with the un-grounded conductors to the sub-panel, which is now the service panel?
3-service raceway between the existing main service and the "new" main service is not service bonded.
4-neutral bus-bar in the "new" service is not bonded to the panel.
5-neutral bus-bar in the old main service which is now the (sub-panel) needs to be isolated from the ground bus-bar.
6-a 100 amp overcurrent device is required at the "new" main service to protect the bus from not more than 120% of the rating of that bus-bar which is 125 amps.
7-the "new" main service must be service rated.

Don't need to repeat everything that's been said, I agree with electrofelon, but a couple more comments.

1) This could depend on what the manufacturer or NRTL says.
2) This represents an actual inductive heating problem. Not good. Violation of 300.20(A).
5) Might be problematic from the listing point of view, too.

Not sure I agree that service conductors have been run with non-service conductors, but it's either that or the grounded service conductor has not been brought to the service disconnecting means as required by 250.24(C) (item 2). It depends on whether you regard that neutral brought to the new panel as the feeder neutral or the service neutral. Whichever it is, the other is missing.

 

[jaggedben]

Also I see the service conductors routed with non service conductors (running through the sub) as a violation.

I read this again and I see we are talking about the original panel on the left. Not sure if I agree that anything is sharing a raceway but I understand the point.

 

[abcclub]

A picture is worth a thousand words. Could you sketch a clean drawing of what you are talking about and post it? The photo of the rat's nest of wires and the extended elocution are a bit hard to follow - for me, anyway. I have a lot of experience with solar but I don't have a clear idea of what you are asking about.

The concern is not really about the PV, it's the round-about way they went about adding 40 amps of solar to a 100 amp service. I hope the drawing helps, I left out the grounds and neutrals so it would be less confusing.

 

[abcclub]

[I see now this has been discussed, but I'll expand on it anyway...
The panel on the right is the service panel now, and the solar is connected as supply side connections, and therefore not subject to the 120% rule. Read the 120% rule again carefully; it refers to the sum of solar and the breaker protecting the busbar. The 100A breaker is NOT protecting the busbar; it is protecting the feeder to the original panel and everything beyond that.]


new reply from abcclub
So basically what they are doing is connecting the PV source by using both 705.12(A)&(D), not (A),(B),(C)or(D). Key word OR. The PV power production source either ends at the dedicated overcurrent devices or at the connection on the supply side of the service disconnecting means. If the PV power production source ends at the connection on the supply side of the service disconnecting means, then is the 100 amp breaker supplying power to the sub-panel considered part of the PV power production source? and the two 20 amp breakers considered the disconnect means per 690.15?

 

[jaggedben]

]So basically what they are doing is connecting the PV source by using both 705.12(A)&(D), not (A),(B),(C)or(D).

They are only using 705.12(A).

I'll try to put it simply: 705.12(D) is for connections on the load side of the service disconnecting means. Since there is no service disconnecting means between the solar breakers and the service, 705.12(D) doesn't apply. None of it does.

If the PV power production source ends at the connection on the supply side of the service disconnecting means, then is the 100 amp breaker supplying power to the sub-panel considered part of the PV power production source?

No. It's a load breaker.

and the two 20 amp breakers considered the disconnect means per 690.15?

Yes.