Duke Energy = No Line Side tap and im over current on bus bar. Options?

[jarred125]

So here is my dilemma.

Due to my noobness (I knew this would come, so I am not surprised, just a hurdle) I went into this thinking my system would be a good fit for my home. It's an 8.9kW system (for now) with room for a little more gain from the bifacial panels. This means that I will need more than 40A in order to back feed (and going larger would require more than that), so I am over the 120% rule on my bus bar (200A) service panel.

Duke Energy says no to line (supply) side taps, which would have solved this for me.

So currently I am weighing my options of the Sol Ark 15K as it has a 200A main with pass through to feed my other sub panels. What I love about this is now I have battery options out the wazoo (which I DID plan to do and would require replacing my Growatt inverter anyways), what I do not like is the cost increase.

So what other options do I have? I have looked into "solar ready" service panels, but a) they are nowhere in stock and b) are 1K or more when they do come in stock (vs the normal price they should be).

If you were in my shoes, what would your direction be?

 

[ncsolarelectric]

You can replace the main breaker on the panel with a 175A, then you can use a 60A PV breaker.
I've done jobs for Duke Energy in NC. Supply side taps are allowed. Just not in the main panel. You need to tap at the meter box with dual lugs, not wire peircing taps.

 

[jarred125]

You can replace the main breaker on the panel with a 175A, then you can use a 60A PV breaker.
I've done jobs for Duke Energy in NC. Supply side taps are allowed. Just not in the main panel. You need to tap at the meter box with dual lugs, not wire peircing taps.

They told me today specifically they don’t allow line side taps, which is why I mentioned that here. They didn’t give any options, just not allowed.

I’ve thought about the derating breaker. I’ll check into this more. Thank you!

 

[ncsolarelectric]

I would ask them to please show me where that rule is in their interconnection requirements. I've never seen it in writing.

 

[Supervstech]

Check your panel, many "200A" panels have busbars rated over 250.
It should say the max load on the door lable.

 

[ncsolarelectric]

updated: They do allow but it's not a tap. It's in their procedures. See Fig 72A for NET metering, it shows a line side connection, but it says it has to be done with dual lugs. That's their way of doing it. Show them this, 72A and request they install the PV interconnection as shown. Call them out on their BS. They allow up to a 20kW PV system, you can only connect a system that size on the supply side. The only reason they could deny it is if the transformer supplying your home isn't big enough to handle more than 32A.

 

[jarred125]

Thank you both!!!

 

[Solar Guppy]

NEC 120% rule allows up to 40 amp breaker for 200 amp panel. so no issues there.

As for Duke, above 10kw gets into a whole can of worms, and what you get for the payback rates and insurance requirements. Just have your inverter(s) that is limited to 10kw maximum and your good to go.

Also, with Duke, they won't approve systems that can generate more than your annual usage ( also more than your net-meter tier allowed peak kw), so having more solar doesn't do anything but get you wholesale rates if your generation exceeds consumption on a annual basis and they can/will come after you to the point of pulling your approval if you do this on an ongoing basis.

FYI I'm with Duke Florida net-metered, get to pay 30 dollars a month for minimum usage charge, I track my systems performance closely and adjust the inverter limits to keep within the rules as needed.

 

[jarred125]

updated: They do allow but it's not a tap. It's in their procedures. See Fig 72A for NET metering, it shows a line side connection, but it says it has to be done with dual lugs. That's their way of doing it. Show them this, 72A and request they install the PV interconnection as shown. Call them out on their BS. They allow up to a 20kW PV system, you can only connect a system that size on the supply side. The only reason they could deny it is if the transformer supplying your home isn't big enough to handle more than 32A.

Found this as well. I will push back on them tomorrow. Thank you! I’m far below 20kW so we’re safe.

 

[jarred125]

NEC 120% rule allows up to 40 amp breaker for 200 amp panel. so no issues there.

I realized my wording was not exactly great, the inverter I have has an output of 42A which pushes me over that 240 limit.

Check your panel, many "200A" panels have busbars rated over 250.
It should say the max load on the door lable.

I checked my service panel and couldn't find max load specifically, but there are designations which state "Ampere Max", I have attached the door tag. The model # for this one is

HOM816M200PFTRB​

 

[Supervstech]

I realized my wording was not exactly great, the inverter I have has an output of 42A which pushes me over that 240 limit.


I checked my service panel and couldn't find max load specifically, but there are designations which state "Ampere Max", I have attached the door tag. The model # for this one is

HOM816M200PFTRB​

Is that the only label on the panel? THats a generic scope sheet… nothing specific to your panel?

 

[Maitake]

Check your bus bar ampacity, there's a chance its 225. Should be labeled on there somewhere.
I'm replacing my 200A main breaker with a 175A to deal with this.

 

[jarred125]

Is that the only label on the panel? THats a generic scope sheet… nothing specific to your panel?

Found it inside, bus bar is 225A

 

[dr.diesel]

Also, with Duke, they won't approve systems that can generate more than your annual usage ( also more than your net-meter tier allowed peak kw), so having more solar doesn't do anything but get you wholesale rates if your generation exceeds consumption on a annual basis and they can/will come after you to the point of pulling your approval if you do this on an ongoing basis.

Interesting. I've been generating more than I use for about 5 years now, so far no issues, but I'm in Indiana.

 

[Hedges]

Have service entrance come in through meter, then 200A breaker or disconnect and 200A fuse.
After that, branch to two 225A panels, each with its own main breaker. 225A x 120% = 270A. Put a 150A main breaker in one, and 100A backfeed is allowed. Or, just feed 200A straight into SolArk, and also branch 200A to your other panel

By having a 200A fuse/breaker after the meter and then splitting off, it isn't a "line side tap".

Found it inside, bus bar is 225A

Mine is 225A. With 200A main breaker, 70A backfeed allowed. With 150A main breaker, 120A would be allowed (don't know if you can get away with 125A, but 100A would work.)

I started that way, later moved inverter tap to between this panel and the meter which has its own 200A breaker.

 

[Solar Guppy]

I realized my wording was not exactly great, the inverter I have has an output of 42A which pushes me over that 240 limit.

What state are you looking to connect in? every State with Duke has different rules / requirements

Duke looks at the solar panel STC ratings in your application and most listed inverters can be programmed to reduced output.

As for permitting, they just look at the panel breaker and your PE stamped drawings, they don't get into inverter specs

On the Bus-bars, yes homeline is 225A but don't count on your local inspectors believing that has any input to the 120% rule, they go by the main breaker and the current the panel ( not bus bars ) are rated at.

 

[jarred125]

What state are you looking to connect in? every State with Duke has different rules / requirements

Duke looks at the solar panel STC ratings in your application and most listed inverters can be programmed to reduced output.

As for permitting, they just look at the panel breaker and your PE stamped drawings, they don't get into inverter specs

On the Bus-bars, yes homeline is 225A but don't count on your local inspectors believing that has any input to the 120% rule, they go by the main breaker and the current the panel ( not bus bars ) are rated at.

Im in Ohio. I will have to check to see how this inverter works and if it can reduce output. The physical interface is very limited, but the app seems to give a lot of function so I am sure it is in there.

 

[Maitake]

On the Bus-bars, yes homeline is 225A but don't count on your local inspectors believing that has any input to the 120% rule, they go by the main breaker and the current the panel ( not bus bars ) are rated at.

This is contrary to the rules:

“When two sources, one a primary power source and the other another power source, are located at opposite ends of a busbar that contains loads, the sum of 125 percent of the power source(s) output circuit current and the rating of the overcurrent device protecting the busbar, shall not exceed 120 percent of the ampacity of the busbar.”

Nothing about main breakers in there.
I am not an electrician.

 

[Solar Guppy]

I would just use the 40 amp and when you create your permit package which has to be signed off / stamped by a PE just have as a 40 amp breaker in the line diagram.

Dukes interconnection portal process just asks about the panels and inverter and your approved permit ( this is after the system is completed )

I suspect your panels will be far lower output than the inverters rated maximum output and its a non issue.

 

[Solar Guppy]

This is contrary to the rules:

“When two sources, one a primary power source and the other another power source, are located at opposite ends of a busbar that contains loads, the sum of 125 percent of the power source(s) output circuit current and the rating of the overcurrent device protecting the busbar, shall not exceed 120 percent of the ampacity of the busbar.”

Nothing about main breakers in there.
I am not an electrician.

Yup, and even my PE stamped documents called out the 225 amp rating of the Homeline panel, specifically said solar breaker could be in any location of the panel due to this overhead. Inspector said move the breaker or no permit on final.

So he watched me move the breaker, had to add wire and wire-nuts in the panel and signed off the final.

In the end, codes and PE stamped documents are just suggestions for the inspectors, they know one way and its that way or the highway