Wiring EG4 18KPV to Combo Breaker/Meter Box (Grid Tied, Full Home Backup)

[SurferJon]

Hi, I'm installing solar later this year in SoCal. I signed up for NEM 2.0 last year under Edison, which allows for 1:1 net metering. My system will be wired with whole home battery backup in the event of an outage. I will have 14kW panels and the EG4 18KPV inverter.

I currently have a 100 amp combo breaker/meter box. The meter sits at the top and the load panel is right below. My electrician is planning to replace the whole box with this Square D 200 amp combo meter/breaker box.

However, all the wiring diagrams and discussions I see online for the 18KPV show the meter and the main panel as separate boxes. In SoCal I don't really see homes with separate meters and main panels. The wiring diagram also show different boxes in-between the meter and main panel, like the Feeder Tap Breaker and the Manual Transfer Switch.

Is replacing my old breaker box with a new 200 amp combo box the best / cleanest way to approach this?

View attachment 241858

 

[BentleyJ]

Per the attachment 241858, read the notes on the Right side of the document regarding combination panels that have an integrated main breaker. There is a suggestion on how to do the Line Side Tap using KUP-L-Taps or Polaris connectors.

 

[SurferJon]

Right, I understand wiring in the feeder taps. I'm more asking if using a combo meter/load panel, wouldn't that mean we would have to have wires going out and then back in for the Manual Transfer Switch and the 200 Amp Feeder Tap Breaker? Isn't that messy versus having everything separate?

 

[Backtrack8189]

I did a combo box when i replaced mine. I now regret it as i tied all my subpanels into this combo panel. I have nowhere to put the CT's before the meter. I have to rig some crap up with polaris connectors. I suggest to put in a meter box and conduit over to a transfer switch and then conduit over to a main panel.

 

[BentleyJ]

Wouldn't that mean we would have to have wires going out and then back in for the Manual Transfer Switch and the 200 Amp Feeder Tap Breaker? Isn't that messy versus having everything separate?

I'm not seeing much of a difference between separating the main breaker from the main panel vs. a combo panel. Either way there is a conduit out of the main breaker and a conduit for the feeder going into the main panel. It's still 2 conduits regardless if the main breaker is packaged into a single combo enclosure vs. 2 separate enclosures.

 

[SurferJon]

So would these be all the "boxes" outside, all next to each other? Can any of them go inside the house in the utility closet where the inverter will be?

200 amp combo meter/breaker box
PV AC disconnect
Manual transfer switch
Feeder tap breaker
Rapid shutdown switch
PV DC disconnect

 

[BentleyJ]

Obviously the combo meter/breaker box outside. Although going back to your question above, a separate meter base with means of disconnect outside would allow the breaker panel to be inside. This is atypical for CA but should meet code.
The disconnects and RSD need to be outside.
Feeder Tap Breaker or separate disconnect may not be necessary depending on the distance from the tap to the Inverter with built in breaker and if the feeder could be shut off from outside with the main AC disconnect or breaker. In other words, if the tap is in front of that outside means of disconnect.
Manual transfer switch could probably be inside.

Any additional details or corrections from our resident electricians would be helpful.

 

[SurferJon]

I just managed to get hold of my city department that approves all the plans and sends out the solar inspectors. The head guy basically told me the wiring is overdesigned for other states. He said the PV AC disconnect isn't necessary because the breaker box is right there and they can just shut off the main switch. He said he's never heard of anyone using a feeder tap breaker. He said all they want to see is the RSD button outside and that's it. He also said firefighters go on your roof to cut a hole, but no local firefighter will go on a roof with solar.

 

[BentleyJ]

Sounds like your chief building official has some sense. I can tell you in our neighborhood all the solar installations have an AC disconnect within a couple of feet or less from the main breaker panel.

 

[SurferJon]

Do you think I should have that too or any of the other "boxes" in the wiring diagram? Is the transfer switch even necessary?

EDIT: What do we think of this?

200 amp combo meter/breaker box

PV AC disconnect
-Not necessary, just shut off the main breaker

Manual transfer switch
-Not necessary, only helps keep the house powered in the event the inverter fails

Feeder tap breaker
-Not necessary apparently?

Rapid shutdown switch
-Necessary, shuts off the panels in case of fire or maintenance, put outside

PV DC disconnect
-Necessary(?), cuts power for incoming wires from solar panels, can be in utility closet?

 

[BentleyJ]

In the proposed wiring configuration per the drawing, a more accurate description would be "Maintenance Bypass" and yes I would recommend it. If the the Inverter malfunctions, and they can, it really makes life easier to simply pull the handle and go to straight utility power. You know Murphys Law. The inverter will only fail in the middle of the night or during some kind of major weather event.

At this point, you should be discussing these options with your electrician, he should have a much better idea of local code requirements.

 

[BentleyJ]

200 amp combo meter/breaker box.

I believe in an earlier post I mentioned considering a Schneider Pulse panel. It has split bus bar design so critical and non-critical loads can be separated without having to install a subpanel. Not sure if that would be necessary in your case, it depends on your peak demand and if a 12K inverter is sufficient for the whole house in an outage. They are a bit pricey also.

PV AC disconnect
-Not necessary, just shut off the main breaker

Agreed, If the Electrical Inspector will approve plans without it.

Manual transfer switch
-Not necessary, only helps keep the house powered in the event the inverter fails

See previous answer.

Feeder tap breaker
-Not necessary apparently?

This is a Depends on a few details kind of answer.
1) Where the Feeder Tap is located. Does it originate before Main Breaker or after. In other words does the main breaker de-energize the feeder tap also?
2) Is the RSD also an Emergency Power Off (EPO) that shuts down the inverter and all AC output as well as the PV DC?

Rapid shutdown switch
-Necessary, shuts off the panels in case of fire or maintenance, put outside

Yes, code required accessible outside. See #2 above.

PV DC disconnect
-Necessary(?), cuts power for incoming wires from solar panels, can be in utility closet?

The inverter may have input breakers or a built in DC disconnect. Another one in the closet seems redundant although could be a convenience if the inverter wiring needs to be removed. Alternate method would be to use the RSD to kill DC then disconnect the PV wiring upstream either on the roof or J box, if there is one. Don't want to work on live high voltage DC.

 

[SurferJon]

This is a Depends on a few details kind of answer.
1) Where the Feeder Tap is located. Does it originate before Main Breaker or after. In other words does the main breaker de-energize the feeder tap also?
2) Is the RSD also an Emergency Power Off (EPO) that shuts down the inverter and all AC output as well as the PV DC?

1. You're saying the feeder tap should be after the main breaker switch so that it can be de-energized, right?
2. Looks like 18kPV has an e-stop feature that turns off everything when you hit the RSD button, such as the AC output: https://eg4electronics.com/blog/news/supporting-safety-eg4s-total-e-stop-feature,

The inverter may have input breakers or a built in DC disconnect. Another one in the closet seems redundant although could be a convenience if the inverter wiring needs to be removed. Alternate method would be to use the RSD to kill DC then disconnect the PV wiring upstream either on the roof or J box, if there is one. Don't want to work on live high voltage DC.

Yep it looks like the 18kPV has a DC disconnect on the side.

Also general question: does RSD completely kill all voltage from the panels? I thought I saw in a video somewhere that it only brings it down to a safe voltage.

 

[BentleyJ]

1. You're saying the feeder tap should be after the main breaker switch so that it can be de-energized, right?

Yes, If the building official is going to consider the breaker satisfactory as a means of disconnect then it actually has to de-energize ALL the feeders downstream of it.

2. Looks like 18kPV has an e-stop feature that turns off everything when you hit the RSD button, such as the AC output: https://eg4electronics.com/blog/news/supporting-safety-eg4s-total-e-stop-feature,

That should be sufficient. In cases where the inverter may not have an E-stop or remote On/Off connection. A shunt trip DC breaker or Contactor can be used to interrupt the battery connection thus disabling the inverter and its ability to produce AC.

Yep it looks like the 18kPV has a DC disconnect on the side.

Good.

Also general question: does RSD completely kill all voltage from the panels? I thought I saw in a video somewhere that it only brings it down to a safe voltage.

The code only requires below 30V outside the perimeter of the PV array. There are different brands of RSD modules and their specifications may vary so you may still be able to measure some voltage above 0 even if the RSD is activated.

 

[SurferJon]

One thing I'm confused about. Do you know why the wire diagram above includes the "200 Amp Feeder Tap Breaker" after the main breaker when the Feeder Taps are also after the main breaker? My taps would also be after the main breaker, so how come I don't need the feeder tap breaker?

 

[BentleyJ]

There is an explanation on the right hand side of the diagram. It's related to the Main Panel (new 200A, the link you posted) having its own 200A breaker or not. The Idea is that if the Transfer Switch is in the position where power is flowing from the Service Breaker at the Utility Meter directly to the Main Panel (Inverter load output is disconnected by the transfer switch) AND the 2 pole fused disconnect is in the ON position. The Main Breaker panel could be subject to the full 200A from the utility as well as the full 50A Sell Back amperage from the Inverter. This would be a total of 250A feeding into a panel with 200A bus bars. Highly unlikely scenario but the 200A Beaker in the new panel would be the protection device.

On the other hand if the new Main Panel was a Main Lug Only type with no breaker then the feeder tap breaker would be necessary.

 

[zanydroid]

In the OP it wasn’t clear what the desired loads layout was supposed to be.

Do you want to use the 200A bypass and do whole backup? If so you need either the hipster split bus combo main or separate meter and main

It would be hilarious if the chosen meter main for new build can’t fit the CTs

 

[SurferJon]

Dumb question, but is this basically how I would wire the breaker to the inverter?

- Putting the "GRID" wires after the 200 amp breaker so the inverter can be shut off if you flip that breaker
- Putting the "LOAD" wires before the 200 amp breaker since the inverter's output can be shut off with the inverter's load breakers?

 

[zanydroid]

This looks like a terrible idea. If you close the breaker you directly connect output to grid which defeats the disconnect relay inside the inverter.

In general, you have to do something clever with combo mains. Either some kind of meter ring device (proprietary at present, and EG4 decided to go with Grid Boss next instead of a meter ring), or you use a split meter / main, or you move everything in your combo to a subpanel. Now this subpanel is load side of your inverter (load connection). While your inverter (grid connection) is load side of the combo.

FWIW you already got three posts in this thread talking about the benefits of splitting meter from main for whole house backup

 

[Quattrohead]

If you are having to do this work anyway I would definitely split the meter and panel from each other. Also investigate the grid boss.

 

[SurferJon]

Problem is my electrician already ordered that Square D meter box for my panel upgrade. Is there any way that box is going to work with my solar installation? I haven't installed solar yet.

 

[zanydroid]

Problem is my electrician already ordered that Square D meter box for my panel upgrade. Is there any way that box is going to work with my solar installation? I haven't installed solar yet.

Already described above. Combo is good for grid tie and for holding circuits you don’t want backed up on inverter in emergency mode. If you don’t want any circuits excluded all the time from backup then combo main is not helpful.

Eat the restock / return fee / permit redo fee seems much more pound-wise. But you can spreadsheet it into cost benefit and decide that way. I believe 90%+ of the inputs have been shared with you.

Maybe this helps with the analysis paralysis. With things changing so much in solar and automatic load shedding it’s not uncommon to have to reconfigure for $1000-2000 of throwaway work. And add noob tax to that, we’ve all been there. Actually I personally burned way more than that on noob tax so $1000-2000 of redo is a bargain.

 

[SurferJon]

So my electrician said we should still install that Square D combo panel on the exterior wall to hold the meter and 200 amp breaker. He said there really aren't any smaller combo boxes available than the one we're getting. I'm getting all of this for free through SoCal's Charge Ready program, which requires a solar-ready panel to be installed.

Then he said on the interior wall (behind that panel), he could install a new load center that has all of the home's breakers. He said it'll be like $400-500 to do that. This panel would be powered by the inverter's load, obviously.

How's that sound?

So I believe my setup would be:

• Exterior 200 amp combo box (link): meter -> CT -> 200 amp breaker -> lugs (sold separately) that output to inverter's "grid" ports
• EG4 18kPV inverter: "load" ports -> manual transfer switch -> 200 amp subpanel
• Interior 200 amp subpanel: breakers for the whole house

Thank you everyone for your continued help!

 

[zanydroid]

Yes, that makes sense. You have to have a 200A exterior breaker to meet code for the building disconnect, and combo mains could well be the cheapest things you can get for this due to the volume.

If the 18kpv is inside, you'll need to plumb the external e-stop button of the inverter to an outside location that your AHJ is happy with, but that is fine.

 

[SurferJon]

One more thing I still don't understand.

We said I don't really need the "200 Amp Feeder Tap Breaker." Let's also say I exclude the "Manual Transfer Switch." Let's say I don't care if the system goes down when the inverter fails in 15 years and I just don't have power for a few days.

By removing those two "boxes" from the diagram, isn't the load from the inverter going straight to the feeder tap, which is also where the wires are going to the inverter's grid?