18kpv setup right?? can you feeder tap meter/main panel ?

[Treepin]

I currently have 200amp meter/main combo panel. I thought we could do the whole home backup install method for the 18kpv using feeder taps, but my electrician is saying to use a 200amp sub panel as a critical loads panel. Is that because the meter/main combo? He said install should be meter / main panel (with EV charger and hot tub loads only) then feeder tap to 200 amp breaker outside. Then inside garage, a 200 amp sub panel with interlock setup instead of manual transfer switch. I’m not sure why the sub panel? He’s using a feeder tap either way, why create a separate panel when only the EV charger and hot tub pump are removed?

 

[Hedges]

Sub-panel ought to have load 18kpv is capable of powering, so if the grid goes down, inverter is not overloaded.

I would also put interlock on main panel so I could choose to manually enable EV charger or hot tub when grid is down.

If utility drop can supply main panel (up to 200A) and simultaneously supply loads via feeder tap (does 18kpv have 200A pass-through?), I would think utility would be concerned about 400A draw.

I did:

meter --> 200A breaker --> load-side feeder taps to several panels and safety switch.

My sister has 200A meter-main so I may do "Hawaiian tie-in", remove all breakers and install a 200A breaker (or tap) on busbar to supply feeder taps. Also known as 100% rule, 100% of all breakers other than main breaker do not exceed busbar rating.

 

[Treepin]

And if the EV charger and hot tub aren’t in the 18kpv loads, doesn’t that mean that no matter how much solar produced or batteries installed, those 2 loads will always pull from the grid only? I’m not sure I like that.

18kpv does have 200amp pass through, but I was not thinking about a 400a draw

 

[Hedges]

If set up for net metering, all surplus PV will backfeed from inverter to grid and/or EV an hot tub.

If set up for zero export or peak shaving, CT installed on grid wires near meter let inverter detect load of EV/hot tub pulling from grid, and it can backfeed from PV and battery seeking to eliminate draw from grid.

Line side tap seemed good for GT PV. House can draw up to 200A from grid, and GT PV can backfeed 40A or 60A. Utility drop never overloaded.

Line side tap used for a hybrid means hybrid and its loads can draw from grid, and main panel can too. I don't know if utility objects to that.

I prefer a "Meter Main" which lets me cut power an install feeder taps to multiple boxes without talking to utility and having them cut power. I was lucky my first place for PV install had meter main. I initially landed GT PV on main panel, then did battery backup same way, then moved the wires to load side tap. New place, I replaced 100A CSED with 200A meter-main.

 

[Treepin]

Ok, thanks. I see I should be good the for ev/hot tub not always using grid. I’m still confused on why he can’t use a feeder tap between the meter and main breaker in order to just use my current main panel as the load center.

Some of the diagrams also talk about a 70a backfeed breaker. But I was under the impression that I didn’t need that with my install setup. My electrician didn’t mention it either, but with his install method, we are only doing a partial backup. I have a nem agreement. I have a feeling I’m blending terms and misunderstanding something.

 

[Hedges]

Depending on your CSED construction, may be possible to tap between meter and main breaker. May be possible to tap between main breaker and busbars (but in that case, backfeed from inverter + main breaker would exceed busbar rating so not allowed; for that reason my setup has another main breaker before busbar.)

SolArk has internal 200A main breaker for output, none for input so OCP required between meter and SolArk.
Not sure about your 18kpv.

If you don't already have the inverter, consider also Midnight The One.
They note that inverter can't pick up 200A load so don't provide that much pass-through.
They do have multiple relay controlled outputs with breakers, allowing load shedding.

 

[zanydroid]

If you have NEM why do you care about self consumption? You probably have some TOU or low compensation rate.

A CSED generally cannot be used as the CLP for several reasons of "optimized design" for the application (non-comprehensive, just going off memory):
1 A CLP must be a subpanel which means N-G separate. Usually these are not separable in a CSED
2 You will need to be able to splice into the meter -> busbar connection. Usually they use as little wire as possible. I'd like to see how you're visualizing tapping into a busbar or conductor with no slack :laugh:

With enough grokking of these, you'll accept that feeding out of a CSED is a lot easier than other ways

NGL, subpanels are cheap except for the space and labor. Worst case you end up with 2 new subpanels, one for loads you want to offset but not be backed up, one for loads that are backed up.

2 also affects the difficulty of offsetting loads that sit on your CSED and not your CLP. Often with busbars or very short wires between meter and bus, you can't get standard CTs (the round transformer sensors) into there. Then you have to hope that the inverter support rope-style or other lower profile ones. Which... can cost more than another subpanel. And on some CSED, you might not be able to squeeze it in.

(As well, if you are DIYing and not hiring out. Modifying the CSED requires either working on hot components if you don't pull the meter, or coordinating meter pull with POCO. If you're in an area where that has red tape, it is annoying. While, if you do things after the CSED, you have much more agency to de-energize components

An electrician knows what they can do quickly/get away with. While a DIYer will rarely be able to scope that)

 

[Treepin]

If you have NEM why do you care about self consumption? You probably have some TOU or low compensation rate.

A CSED generally cannot be used as the CLP for several reasons of "optimized design" for the application (non-comprehensive, just going off memory):
1 A CLP must be a subpanel which means N-G separate. Usually these are not separable in a CSED
2 You will need to be able to splice into the meter -> busbar connection. Usually they use as little wire as possible. I'd like to see how you're visualizing tapping into a busbar or conductor with no slack :laugh:

With enough grokking of these, you'll accept that feeding out of a CSED is a lot easier than other ways

NGL, subpanels are cheap except for the space and labor. Worst case you end up with 2 new subpanels, one for loads you want to offset but not be backed up, one for loads that are backed up.

2 also affects the difficulty of offsetting loads that sit on your CSED and not your CLP. Often with busbars or very short wires between meter and bus, you can't get standard CTs (the round transformer sensors) into there. Then you have to hope that the inverter support rope-style or other lower profile ones. Which... can cost more than another subpanel. And on some CSED, you might not be able to squeeze it in.

(As well, if you are DIYing and not hiring out. Modifying the CSED requires either working on hot components if you don't pull the meter, or coordinating meter pull with POCO. If you're in an area where that has red tape, it is annoying. While, if you do things after the CSED, you have much more agency to de-energize components

An electrician knows what they can do quickly/get away with. While a DIYer will rarely be able to scope that)

Ok. So he’s not installing via the feeder tap diagram since I have a CSED. Where would the CTs go in this case?

 

[Hedges]

Often with busbars or very short wires between meter and bus, you can't get standard CTs (the round transformer sensors) into there.

if overhead service, I would just clip CT around the wires outside the mast head. Maybe wrap in something for UV protection.

No reason to feed more amps through inverter than it can source. I might put a breaker in the load center suitable for the inverter (e.g. 70A), then put a 125A breaker in the load center to feed a sub panel. 70A + 125A = 195A, < 200A for 100% rule. Then put move all loads to sub panels.

Main breakers and backfed interlocked breakers on all sub panels, and you can chose what to backfeed.


Alternatively, one 200A breaker on tap on existing panel and hang multiple sub-panels and safety switches off that.

 

[Treepin]

if overhead service, I would just clip CT around the wires outside the mast head. Maybe wrap in something for UV protection.

No reason to feed more amps through inverter than it can source. I might put a breaker in the load center suitable for the inverter (e.g. 70A), then put a 125A breaker in the load center to feed a sub panel. 70A + 125A = 195A, < 200A for 100% rule. Then put move all loads to sub panels.

Main breakers and backfed interlocked breakers on all sub panels, and you can chose what to backfeed.


Alternatively, one 200A breaker on tap on existing panel and hang multiple sub-panels and safety switches off that.

I have underground service.

I see what you’re saying. It sounds like my electrician is using your second option and just using 1 200 amp sub-panel. Is one option better than the other? I only need one load panel, not multiple sub panels.

 

[Hedges]

The 18kpv can put out 50A, 6kW per phase, 12kW at 240V

https://eg4electronics.com/wp-content/uploads/2024/04/EG4-18KPV-12LV-Spec-Sheet.pdf

If you would ever have more load than that, you need multiple panels.
One sub-panel downstream of 18kpv should never have more than 50A active at any one time.
Another panel, main or sub, can have additional loads up to 160A continuous.

If power goes out the big loads panel shuts off, but all loads downstream of 18kpv remain on so long as battery has enough charge.

It is still useful to control loads. You may be able to power A/C while sun is on PV, but not so long after the sun drops. Same goes for charging EV.

My SMA equipment is able to control two load-shed relays based on SoC.
Probably EG4 and SolArk inverters offer similar.
Midnight does, built in to the box.

 

[zanydroid]

Ok. So he’s not installing via the feeder tap diagram since I have a CSED. Where would the CTs go in this case?

The CTs would go between CSED main breaker and the meter. Or around the service conductors before the meter. The second one raises potential of getting in trouble with POCO for doing stuff before the meter. But so does clipping them on the service drop.

Do you have a picture with the deadfront open? That would help determine how easy/hard it would be.

No reason to feed more amps through inverter than it can source. I might put a breaker in the load center suitable for the inverter (e.g. 70A), then put a 125A breaker in the load center to feed a sub panel. 70A + 125A = 195A, < 200A for 100% rule. Then put move all loads to sub panels.

Depends on if OP plans to use bypass capacity greater than the inverter's output, so that the CLP can draw more than what the inverter can provide during normal operation. Which requires manual load shed during grid down operation.

The 70A backfeed breaker I think is a way to simplify compliance with 120%/100%/sum of breaker rule. Since using a bigger breaker, like 125A or 200A will cause big problems with sum of breakers unless you empty out that busbar of load breakers.

If you don't already have the inverter, consider also Midnight The One.

NGL based on goldserve's experience with The One I'm switching to 12kpv.

 

[zanydroid]

[Hedges] Alternatively, one 200A breaker on tap on existing panel and hang multiple sub-panels and safety switches off that.

I see what you’re saying. It sounds like my electrician is using your second option and just using 1 200 amp sub-panel. Is one option better than the other? I only need one load panel, not multiple sub panels.

Might have been mentioned already but I'll try to summarize. The advantage of single 200A breaker or feed-thru on CSED are:

• Do not need to turn off service to home to make this change (DIYer preference). Any kind of line side tap or new disconnect will require a service off dance
• Allows you to scale to arbitrary amount of solar. Otherwise, you have to follow the 120% rule. 200A busbar yields. (200 * 1.2 - 200)*.8 * 240 = 7.68kW ; 225A busbar yields 13.4kW
  • A single 18kpv or 12kpv will exceed backfeed of a 200A busbar. You will need to hire an electrician to swap the hot main unless you're really slick at doing this. OR you need to confirm with EG4 that the PCS to limit export power is good enough to use for 120% rule calculation. And, if you actually do need to export this amount of power to POCO or your major loads in CSED you are kind of in a pickle
  • If you stack a second inverter you get a lot of value out of it.
• By contrast if you only have one 200A load breaker in CSED, you are eligible for Sum of Breakers rule, which allows you to put 160*240 = 38.4kW of inverter

Two load panels helps with organizing critical loads and non-critical loads away from each other. I thought you said you wanted that.

 

[Treepin]

The 18kpv can put out 50A, 6kW per phase, 12kW at 240V

https://eg4electronics.com/wp-content/uploads/2024/04/EG4-18KPV-12LV-Spec-Sheet.pdf

If you would ever have more load than that, you need multiple panels.
One sub-panel downstream of 18kpv should never have more than 50A active at any one time.
Another panel, main or sub, can have additional loads up to 160A continuous.

If power goes out the big loads panel shuts off, but all loads downstream of 18kpv remain on so long as battery has enough charge.

It is still useful to control loads. You may be able to power A/C while sun is on PV, but not so long after the sun drops. Same goes for charging EV.

My SMA equipment is able to control two load-shed relays based on SoC.
Probably EG4 and SolArk inverters offer similar.
Midnight does, built in to the box.

Ok, I see. And by more panels, you mean another 18kpv as well. There is a small chance I exceed 50a active. I looked back over 12 months and saw that I exceeded it twice briefly. I was planning on adding a future 18kpv down the road if necessary, but in the meantime, monitor it closely. I’ve already purchased one 18kpv.

Between the CLP downstream of the 18kpv and the main panel with only EV and hot tub, I should never exceed 160a continuous.

 

[Treepin]

Might have been mentioned already but I'll try to summarize. The advantage of single 200A breaker or feed-thru on CSED are:

• Do not need to turn off service to home to make this change (DIYer preference). Any kind of line side tap or new disconnect will require a service off dance
• Allows you to scale to arbitrary amount of solar. Otherwise, you have to follow the 120% rule. 200A busbar yields. (200 * 1.2 - 200)*.8 * 240 = 7.68kW ; 225A busbar yields 13.4kW
  • A single 18kpv or 12kpv will exceed backfeed of a 200A busbar. You will need to hire an electrician to swap the hot main unless you're really slick at doing this. OR you need to confirm with EG4 that the PCS to limit export power is good enough to use for 120% rule calculation. And, if you actually do need to export this amount of power to POCO or your major loads in CSED you are kind of in a pickle
  • If you stack a second inverter you get a lot of value out of it.
• By contrast if you only have one 200A load breaker in CSED, you are eligible for Sum of Breakers rule, which allows you to put 160*240 = 38.4kW of inverter

Two load panels helps with organizing critical loads and non-critical loads away from each other. I thought you said you wanted that.

Ok. With a single 200a CSED, where would the tap be? He said he’s going from main CSED (which will house EV and hot tub only) to another 200a standalone breaker. Then to the subpanel which will have two 200a breakers used with an interlock. And I believe both main CSED and sub panel have 225 bus rating.

 

[Hedges]

What make and model CSED?
For Square D QO and Homeline, I think there are 200A breakers available, also plug-on taps.
Not cheap, maybe as much as a panel itself, but simplifies the job. Just plug on and downstream you can connect anything you want.
I uses Polaris multi-tap connector.
Feeder tap rules: < 10' wire length, in metal conduit, OCP at far end.

If you have 225A busbar and 200A main breaker in your CSED, then you can just install a 70A branch breaker feeding 18kpv and leave any circuits you want on CSED.
Install a subpanel downstream of 18kpv and put protected loads there. Interlocked breaker to bypass 18kpv if it fails.
Interlocked breaker in CSED, and you can manually disconnect from grid and backfeed any loads you want. But you have to look at neighbor's houses to figure out when power goes back on.

225A x 120% = 270A. 270A - 200A main = 70A PV breaker allowed.
70A x 80% = 56A continuous, sufficient or 18kpv backfeed.

 

[zanydroid]

Ok. With a single 200a CSED, where would the tap be? He said he’s going from main CSED (which will house EV and hot tub only) to another 200a standalone breaker. Then to the subpanel which will have two 200a breakers used with an interlock. And I believe both main CSED and sub panel have 225 bus rating.

You can sometimes wedge a tap between the Meter and Main breaker on the designs where the two are connected with wires.

Otherwise, you can use plug-on feed through lugs. It looks like the following picture - lugs in plug-on breaker form factor, that goes on the bus. These spark joy for me as DIYer. Yes, they are expensive and cost a significant % of a new CSED or panel, but they save a lot of time and trouble.

(EDIT: also 200A breakers as hedges said, those are I believe less common than 200A feed through lugs in most panel accessory lineups)

Plug-on Feed Through Lug Accessory, LFTLA

The Feed Through Lug accessory facilitates the installation of sub-panels in combination with Leviton Load Centers that do not have sub-feed lugs already installed. This product has a short circuit rating of 22kA for Main Breaker panel applications, and 10kA for Main Lug panel applications -...

store.leviton.com

With a 225A bus on the CSED my calculations above indicate that the plug-on lug is OK for a single 18kpv

What does the interlock on the subpanel do? Does it select between the CSED directly (IE bypass 18kpv), and the 18kpv, as the input?

(TBH I feel like we're slightly going in circles here/more slowly than I would expect; I think most of the info & options have already been dumped here, and you seem to be quite familiar with this equipment)

 

[Offgrid Jungle]

How about two 12000XP inverters and forget feeding back to grid?

 

[Treepin]

You can sometimes wedge a tap between the Meter and Main breaker on the designs where the two are connected with wires.

Otherwise, you can use plug-on feed through lugs. It looks like the following picture - lugs in plug-on breaker form factor, that goes on the bus. These spark joy for me as DIYer. Yes, they are expensive and cost a significant % of a new CSED or panel, but they save a lot of time and trouble.

(EDIT: also 200A breakers as hedges said, those are I believe less common than 200A feed through lugs in most panel accessory lineups)

Plug-on Feed Through Lug Accessory, LFTLA

The Feed Through Lug accessory facilitates the installation of sub-panels in combination with Leviton Load Centers that do not have sub-feed lugs already installed. This product has a short circuit rating of 22kA for Main Breaker panel applications, and 10kA for Main Lug panel applications -...

store.leviton.com

With a 225A bus on the CSED my calculations above indicate that the plug-on lug is OK for a single 18kpv

What does the interlock on the subpanel do? Does it select between the CSED directly (IE bypass 18kpv), and the 18kpv, as the input?

(TBH I feel like we're slightly going in circles here/more slowly than I would expect; I think most of the info & options have already been dumped here, and you seem to be quite familiar with this equipment)

Sorry, It definitely feels like going in circles. Just when I think I understand this stuff, I get lost. Let me approach from a different angle. Below are the parts for the install:

CSED - SC2040M200C - All in one, Homeline, CSED, ringed socket, 200A, surface mount, 20 spaces, 40 circuits, 10kA SCCR, no bypass | Schneider Electric USA

Sub Panel - https://www.homedepot.com/p/Square-...ver-HOM3060M200PCVP-HOM3060M200PCVP/204836369

200a stand alone breaker - https://www.amazon.com/Square-Schneider-Electric-QOM2E2200NRB-Enclosure/dp/B00002N7N5

Tap - https://www.amazon.com/OHLECTRIC-Bl...36e-44f7-8426-c78689629fd0&pd_rd_i=B09SGHZ614

And yes, the interlock inside the sub panel is there to select between the CSED directly (bypass 18kpv), and the 18kpv, as the input. It was to avoid a manual transfer switch.

Those are the parts my electrician is using. I am out of town and haven’t had a chance to speak to him and he said he might try and do the work while I’m gone. I’m trying to see if it all makes sense to the forum gurus because he hasn’t heard of the 18kpv. None of the wiring diagrams seem to line up with this install method which is why it’s harder for me to see it in my mind (like where the tap is). And there was no mention of using a 70a breaker for the inverter.

 

[Treepin]

It also seems like his install method has the tap happening after the main panel that has EV and hot tub loads. I didn’t think you can tap after loads

 

[Hedges]

I used the same 200A stand-alone breaker.

Post in thread 'Cost for utility transformer installation?'

Apr 5, 2024

New service panel energized, "Cut and Swing" complete.



New backed up loads panel, 125A bus, 100A main breaker now fed by load-side tap from 200A service disconnect (same for PV disconnect switch and future 200A panel to replace old panel and meter.)

For now this panel has 40A breaker for oven, and 40A breaker backfeeding old 100A panel (which has no heavy loads actually used.)

The interlocked breaker top right had been receiving backfeed from old panel. Next it will go to a 30A 120/240V inlet plug for generator, later to be 100A from inverters.

...

• Hedges

• 

Seen here before I replaced original 100A panel with new 200A panel.

I use QO, not Homeline like you've listed. More expensive, "Quick Open" faster breakers, I think. Copper bus. Used for commercial installations as well.

Is electrician putting in a new CSED, replacing your existing service equipment?

 

[Treepin]

I used the same 200A stand-alone breaker.

Post in thread 'Cost for utility transformer installation?'

Apr 5, 2024

New service panel energized, "Cut and Swing" complete.



New backed up loads panel, 125A bus, 100A main breaker now fed by load-side tap from 200A service disconnect (same for PV disconnect switch and future 200A panel to replace old panel and meter.)

For now this panel has 40A breaker for oven, and 40A breaker backfeeding old 100A panel (which has no heavy loads actually used.)

The interlocked breaker top right had been receiving backfeed from old panel. Next it will go to a 30A 120/240V inlet plug for generator, later to be 100A from inverters.

...

• Hedges

• 

Seen here before I replaced original 100A panel with new 200A panel.

I use QO, not Homeline like you've listed. More expensive, "Quick Open" faster breakers, I think. Copper bus. Used for commercial installations as well.

Is electrician putting in a new CSED, replacing your existing service equipment?

yes, electrician is installing the one linked above. I had originally bought a larger CSED with more breaker space with the intent of having one panel, but once he saw everything, he suggested to go the route I’ve mentioned above. He’s actually installing now while I’m out of town. He mentioned that he was just going to put ALL the breakers in the 200a sub panel. So I’ll have a 200a CSED outside with no other circuits, going to a 200a standalone breaker (which doesn’t make sense to me now that I think about it..) which feeds a 200a sub panel in the garage. No inverter 70a circuit either. Does that sound right?

 

[Hedges]

A one-line diagram would help to understand.

I installed separate Square-D meter socket and Square-D 200A main breaker only.
I would suggest Siemens 200A Meter-Main instead. Then Polaris, then feeder taps to multiple panels.

But your guy is already doing the work, so it is whatever he designed.

 

[Treepin]

A one-line diagram would help to understand.

I installed separate Square-D meter socket and Square-D 200A main breaker only.
I would suggest Siemens 200A Meter-Main instead. Then Polaris, then feeder taps to multiple panels.

But your guy is already doing the work, so it is whatever he designed.

I think we have to have a CSED for local area code, but not sure on that one. This is a licensed pro doing it off books, but he’s not super familiar with the 18kpv.

 

[zanydroid]

I'm afraid I'm going to have to dip out of this thread until more concrete / easy to analyze data is supplied.

<Parts list>

That CSED is 200A bus bar. It's in the specs that you linked, contrary to what you had said. This means that you cannot have any breakers on the CSED other than 200A to the next device, or a feed-through lug to the next device.



The subpanel is 225A bus bar.



The standalone 200A may not be needed, but I'm not going to draw this out & reason it carefully, since it could be wasted work without knowing how close it is to how it's installed.

<Reply to Hedges>

I agree a schematic (one line would be better than the vague English thus far) would be helpful to share; it would also disambiguate what you're getting when you communicate with the electrician.

What does doing it "off the books" mean? Is he working for you under a permit that you pull?

A “tap” (which has a specific NEC meaning, that is different from English) can come at several places. If you take off the service conductors from the meter, that creates a new main panel.

yes, electrician is installing the one linked above. I had originally bought a larger CSED with more breaker space with the intent of having one panel, but once he saw everything, he suggested to go the route I’ve mentioned above. He’s actually installing now while I’m out of town. He mentioned that he was just going to put ALL the breakers in the 200a sub panel. So I’ll have a 200a CSED outside with no other circuits, going to a 200a standalone breaker (which doesn’t make sense to me now that I think about it..) which feeds a 200a sub panel in the garage. No inverter 70a circuit either. Does that sound right?

That English can line up (vaguely) with one of the variants described above, and there are no red flags.

I guess the next step is for you to send us pictures of the installation & draw your own post-facto SLD. Backwards way to work IMO vs having it up-front. 18kpv is typically used with an interconnection agreement, and in California you used to need to provide an single line diagram (not sure if this changed with the recent simplifications).