2 Enphase Meter collars - Typical split panel 400a service

[mikeames]

I am sure this has been discussed but curious (not job specific) since Enphase is coming out with the new IQ Combiner 6C which consolidates their controller and combiner.

Typical 400A service with one meter base and 2 - 200 MB panels.
PV system with battery backup and grid. No generator.

Enphase has the 200A meter colar that simplifies the grid interconnect control. Not all utilities approve it and its a no go for 400 amp services. What would be the result if 2 were installed on the load side of the meter where each fed just 1 of the 200 amp panels? Could you parallel the control and CTs? Would it be transparent to the 6C Combiner? The CTs should be additive right? Regardless I know its not legal but I am trying to think if its easy for Enphase to come out with a supported solution for a 400A residential service. I don't think this will work because i think the comms is a CAN bus, but it seems like its easy to implement on Enphases part. Thoughts?






6C Install PDF here - https://enphase.com/download/iq-combiner-6c-quick-install-guide

Original pic below.

 

[jaggedben]

Install 2 completely separate systems or only back up 200A. (Who really needs 400A in a power outage situation? That's 96kW.)

 

[mikeames]

I know there are ways. Adding an additional system adds unnecessary costs and/or reduces capacity for backup since it segregates the systems to respective panels.

Don't need it. convenience of distribution. If using the literal max ampacity of the service equipment, who really needs even 200 the utility doesn't size the lateral to the ampacity of the service.

So this isn't about needing the ampacity, this is about the distribution of branch circuits being in multiple panels. The hoops the industry jumps through for 400 amp services that only consume marginally more then a 200 (if any), is silly.

 

[jaggedben]

....

Don't need it. convenience of distribution. If using the literal max ampacity of the service equipment, who really needs even 200 the utility doesn't size the lateral to the ampacity of the service.

...

Well, exactly. I bet in the majority of cases you could do a load calc and move all of the load to a 200A panel. It does suck that you have to re-wire everything instead of just installing the meter collar. Someone shouldn't have wasted money on a 400A service panel.

I mean, I get what you're saying, I really do. But there are no easy workarounds. Among other things, I doubt that the extra cost of a 400A rated meter collar would be justified by the market, and I bet the utilities would be a lot less likely to approve it.

As far as what would happen with your idea, I think you would probably fail inspection for illegally paralleled conductors? I can't speak to whether there are engineering difficulties coordinating parallel MIDs or not. But if there are, that could also make it non-functional or unsafe.

 

[Zee]

This is a very valid question......for Enphase. Definitely call Enphase sales/tech support (maybe ask for level 2/ smarter guy).
As for now, this is either not allowed or I am not smart enough to know how.

Couple separate facts:
--Yes, CT's can be paralleled (do it all the time) although usually to capture various loads that are not easy to fit in one CT......but they total 200A - not 400A.
--Dont know about paralleling Enphase control wire!
--Enphase can handle multiple Envoy systems on one page on their portal, so.....
This fact leads me to wonder about installing 2 separate systems, which means 2 meter collars, 2 combiners 6C, which means 2 Envoys......and then you may at least have all the data displayed on one page.

 

[Zee]

Install 2 completely separate systems or only back up 200A.

Exactly.

You may find one sub panel contains almost all the loads they really want backed up. If some critical loads remain on the other 200A panel, maybe you can even move some over? This is a PITA usually though! How far are panels 1 and 2?

More ideas:
- Maybe feed panel 2 from panel 1? Or vice versa? This will limit these 2 panels to 200A overall.

-- Although.....you can still stick (or leave) some giant, and non critical, loads in the 400A panel - and thus outside the backup.
(yes this load can also be measured with external CTs per Enphase. It wont be backed up though. It will be offset as part of self consumption mode. Well, again, all of this is true up to 200A!)

--- Also the Combiner 6C can shed up to 80A of loads. A "Load Contoller" is integrated. A spot for up to an 80A brkr integrated.

Please follow up with us.
This is interesting.

 

[mikeames]

Well, exactly. I bet in the majority of cases you could do a load calc and move all of the load to a 200A panel. It does suck that you have to re-wire everything instead of just installing the meter collar. Someone shouldn't have wasted money on a 400A service panel.

I agree the 400A is a waste but the size of the houses 6,000sf + essentially require it based on the service load calcs. Practically unnecessary but necessary in the eyes of the NEC.

I mean, I get what you're saying, I really do. But there are no easy workarounds. Among other things, I doubt that the extra cost of a 400A rated meter collar would be justified by the market, and I bet the utilities would be a lot less likely to approve it.

That's what I was thinking. My thought was that exactly with a 400A meter collar. More specifically the utilities not approving it. From a product design standpoint it seems like it would be minimal internal changes so may be feasible for enphase, but if there are a limited amount of 400A residential services that also want PV backup possibility for all circuits, and a utility that accepts it, the profit may not be worth it.

As far as what would happen with your idea, I think you would probably fail inspection for illegally paralleled conductors? I can't speak to whether there are engineering difficulties coordinating parallel MIDs or not. But if there are, that could also make it non-functional or unsafe.

I thought about the parallel issue but none of the conductors are parallel. They originate at the same places but terminate at different locations. More like taps. My thought was it violates the manufacture's installation instructions. Its not supported officially. I don't know about safety or functionality either. It looks likes the meter collar uses a CAN bus (looks like there is a termination resistor), and I am not sure how the systems addresses the the meter collar. My thinking is expects a voltage from a CT (red + black) which could be paralleled, and then controls a solid state relay in the collar to make or break the utility interconnect (yellow + blue)? I don't know.

You may find one sub panel contains almost all the loads they really want backed up. If some critical loads remain on the other 200A panel, maybe you can even move some over? This is a PITA usually though! How far are panels 1 and 2?

Yea, this is not a real job, just me thinking. So for distance of panels assume the usual 400 am split 200MB panel service so both panels are next to each other. I realize the critical loads can be moved between the panels. Even though that's a pain in the ass its definitely feasible, but it still doesn't solve the problem of backing up the whole house for convenience. All the general lighting loads not in the back up panel will be dead. So miscellaneous branch circuits that feed bedroom lights, laundry room lights, bedroom receps etc, will be dead. With LED lighting these are all small loads but still reasonably important. Not including dishwashers, washer, dryer,etc.... For convenience its nice to be able to choose how to use backup power instead of being limited to what's hard wired. During the more pleasant months big loads like AC may not be needed so using that capacity for convenience in other areas of the house is a plus.

Since this is a 400A service with a 6000 sf house, having just one of the panels backed up leaves a lot to be desired. Half the house wont have lights or power at the receps even though the PV system could support it. It makes me think, turn the second 200A panel into a subpanel. Feed it off the first. Silly, but it solves the problems. Nothing would be unbalanced. 400A meter base feeding a 200A MB panel. Actual load is well below the 200A.

Again not a real job but based on experience of this scenario many times.

 

[Zee]

Yeah I also prefer to back up more loads than not and leave it up to the customer to manage them.

 

[jaggedben]

The control wire cannot be paralleled but there is that extra port in the combiner (number 4) that I'm sure could be used to extend the daisy chain to a 2nd meter collar. I don't think comms hardware would be the issue, it's a system design and engineering/listing/safety issue.

You can also have more than one Gateway in a system as far as the customer's app display goes. But again, that doesn't solve the physical problem of having two separate backups. Not sure how the app would display things if one of those systems were off grid and the other wasn't.

 

[Zee]

Just took the Enphase University online "designer" training for this Enphase 4th Gen stuff. Enphase says you must install 2 independent systems, with 1 meter collar (in a new meter pan) and 1 IQ6 Combiner each, each system feeding one of the two (200A) sub panels.

"2 partial home systems which, in total, will provide whole home backup."

 

[Zee]

another scenario might be this if you have a dual lug meter socket:

Like always for 400A, there must be 2 complete and independent Enphase Gen 4 systems.

 

[Zee]

3rd and final 400A scenario is this:


Note external CT locations for measuring 400A whole home loads.