Hybrid Inverter and a Combo Meter/Panel: Full grid load through inverter practical?

[FilterGuy]

Sometimes panels are labeled as things like "suitable for use as service equipment". Or "Must be used as service equipment"

IE whether neutral and ground are permanently bonded.

Whether it's listed for it.

Presumably there are many All-in-one MSPs that are not convertible to a subpanel b/c how many people want to do that / look for that feature.

1) I don't know off hand if it is "suitable for use as service equipment". Something to figure out.
2) Since the inverter is designed to go immediately after the meter, I would think it would be "suitable for use as service equipment".

 

[zanydroid]

Isn't it rare to find a listed neutral bar accessory? And neutral bar is something UL probably cares a lot more about, wrt performance, than ground bar.

 

[zanydroid]

2) Since the inverter is designed to go immediately after the meter, I would think it would be "suitable for use as service equipment".

Right it's the first disconnect / service equipment. But now that means your previous MSP can no longer have a N-G bond.

 

[timselectric]

Everything between the first means of disconnect and the utility transformer must be "service equipment rated".

 

[FilterGuy]

All good questions.

As I mentioned earlier, I would probably put a breaker at the new meter box and that would become the first means of disconnect. With that "Everything between the first means of disconnect and the utility transformer must be "service equipment rated". should be achievable. However, where the NG bond must be could become an issue.

Ideally, I would move my grounding Electrode Jumper to the new meter box and put a system bonding jumper in the new box, However, the existing box has the grounds and neutrals mixed and does NOT have an isolated neutral bus or isolated ground bus. If it turns out I have to split the neutral and grounds in the existing main breaker box it is going to be a PITA.

Since the new meeter box is right next to the existing box.... I hope I can get away with leaving the NG connection in the existing box and run a EGC over to the new meter box to ground it (without a bond). If I can't, this gets to be a messy problem with no clean solution.

 

[rcht148]

I see what you mean now. Good question. e-gad!! I hope that does not become an issue.

The new meter box might be able to be put in a position that can use the existing wires and not require splicing.... but that remains to be seen. I also don't know if there is a no-splice rule here. The interesting thing is that there are splices on the wires coming out of the weather head to the wires going to the pole.... but those splices were made by the utility company (I think).

That part of the job is going to be tricky unless the Utility disconnects service at the pole.... and I am not sure what that will take or if they would be willing to do it because I share a transformer with neighbors. If the service is not disconnected, it means playing with those wires when they are hot.... and that is something I will leave to the electrition. Electricians have to deal with the utility connection all the time and know what the proper method is. (I am not willing to play with wires that I can't personally de-energize)

Once I have an electrition look at it and tell me what it will take, I will let everyone know.

Apologies to revive this old thread but I have a similar setup with a combo main meter panel. What did you end up doing?

 

[Hedges]

I have one like that coming up.
You may be allowed to connect a 40A PV breaker, even though main is in middle not at end.
But not enough for a large hybrid.

What I'm going to do is install a new sub panel adjacent to main panel, with its own main breaker. Transfer all branch circuits to it.
Install a 200A tap or breaker in main panel, no other breakers. The 200A output feeds new sub-panel and a disconnect switch for inverter (up to 200A). This uses existing panel as a "meter main" instead of a combined service entrance device.

 

[rcht148]

I have one like that coming up.
You may be allowed to connect a 40A PV breaker, even though main is in middle not at end.
But not enough for a large hybrid.

What I'm going to do is install a new sub panel adjacent to main panel, with its own main breaker. Transfer all branch circuits to it.
Install a 200A tap or breaker in main panel, no other breakers. The 200A output feeds new sub-panel and a disconnect switch for inverter (up to 200A). This uses existing panel as a "meter main" instead of a combined service entrance device.

Can you please clarify with a SLD? Wasn't clear to me where the inverter sits relative to the new subpanel.
As I understand it,
Meter-(200A breaker in main panel)- Disconnect- Inverter-New subpanel

 

[Hedges]

Can you please clarify with a SLD? Wasn't clear to me where the inverter sits relative to the new subpanel.

100% rule or Hawaiian Tie-in:

Post in thread '120% rule question. What if the load breakers are under 120%?'

Nov 1, 2024

So you transfer all branch breakers to a new breaker panel (maybe on inside of garage directly behind this one), and install a single 100A branch breaker to feed it.

100% rule or Hawaiian Tie-in:

Connection of Normal and Emergency Power Sources for Homes

iaeimagazine.org

• Hedges

Something like this, note inverter (and its disconnect) is NOT actually connected to a breaker in main panel, but to the wire coming out of main panel. And NO other loads are connected to the unused breaker slots in main panel. Where drawing shows "40A" circuit to inverter you might have 200A safety switch:

Solar Interconnection Methods (Full Guide) - Ecuip Engineering

Navigating solar interconnection methods with diverse configurations and rules is complex. Connecting your PV system demands understanding this landscape.

ecuip.com

As shown in that picture, the inverter isn't supplying any loads in sub-panel. So connect inverter's output to an interlocked breaker adjacent to main breaker in sub-panel. Then you can feed the loads either directly from grid, or through inverter.

As I understand it,
Meter-(200A breaker in main panel)- Disconnect- Inverter-New subpanel

That would be the electrical circuit order if you want inverter to supply everything in new sub panel.

Physical order might be what I wrote, due to length of branch circuit wires routing from existing panel to new sub-panel. Unless they are accessible for instance from inside garage to pull out of main panel and re-route into sub-panel, you might just run through a conduit between the panels. Good to keep a conduit run with many wires under 2' length, because ampacity derating is supposed to be applied if longer.

If you put new subpanel after inverter, best to have a bypass mechanism in case inverter fails. I use interlocked breakers.

Actually feeding all loads of a 200A panel through the bypass relay of an inverter capable of supplying 50A or 60A can be problematic, because of course if you happen to have higher loads active, the inverter will shut down after a while, or immediately. Better to have only loads it can actually handle automatically transferred to inverter. Excessive loads can be manually switched over, with you responsible for ensuring not all are active at once (e.g. turn off electric dryer if A/C is needed.)

I replaced my separate meter and main panel with meter and main breaker only. Similar to you just using 200A tap off your main panel and removing all branch breakers.
After my main breaker I run wires to 200A sub-panel with 200A breaker (excessive loads), 125A sub-panel with 100A breaker (backed up loads), 100A fused safety switch (for inverter).
Output of inverter will go back to interlocked breakers in both 125A sub-panel (normally feeding) and in 200A sub-panel (normally not feeding)

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

• 

In the photos shown, empty meter socket and old 100A main panel still shown, later replaced with 200A sub-panel.
All conduit goes through basement. In your case you might place all side by side and route externally. I was working with limited dimensions due to corner of house, window, crawl space.

 

[rcht148]

100% rule or Hawaiian Tie-in:

Post in thread '120% rule question. What if the load breakers are under 120%?'

Nov 1, 2024

So you transfer all branch breakers to a new breaker panel (maybe on inside of garage directly behind this one), and install a single 100A branch breaker to feed it.

100% rule or Hawaiian Tie-in:

Connection of Normal and Emergency Power Sources for Homes

iaeimagazine.org

• Hedges

Something like this, note inverter (and its disconnect) is NOT actually connected to a breaker in main panel, but to the wire coming out of main panel. And NO other loads are connected to the unused breaker slots in main panel. Where drawing shows "40A" circuit to inverter you might have 200A safety switch:

View attachment 287735

Solar Interconnection Methods (Full Guide) - Ecuip Engineering

Navigating solar interconnection methods with diverse configurations and rules is complex. Connecting your PV system demands understanding this landscape.

ecuip.com

As shown in that picture, the inverter isn't supplying any loads in sub-panel. So connect inverter's output to an interlocked breaker adjacent to main breaker in sub-panel. Then you can feed the loads either directly from grid, or through inverter.



That would be the electrical circuit order if you want inverter to supply everything in new sub panel.

Physical order might be what I wrote, due to length of branch circuit wires routing from existing panel to new sub-panel. Unless they are accessible for instance from inside garage to pull out of main panel and re-route into sub-panel, you might just run through a conduit between the panels. Good to keep a conduit run with many wires under 2' length, because ampacity derating is supposed to be applied if longer.

If you put new subpanel after inverter, best to have a bypass mechanism in case inverter fails. I use interlocked breakers.

Actually feeding all loads of a 200A panel through the bypass relay of an inverter capable of supplying 50A or 60A can be problematic, because of course if you happen to have higher loads active, the inverter will shut down after a while, or immediately. Better to have only loads it can actually handle automatically transferred to inverter. Excessive loads can be manually switched over, with you responsible for ensuring not all are active at once (e.g. turn off electric dryer if A/C is needed.)

I replaced my separate meter and main panel with meter and main breaker only. Similar to you just using 200A tap off your main panel and removing all branch breakers.
After my main breaker I run wires to 200A sub-panel with 200A breaker (excessive loads), 125A sub-panel with 100A breaker (backed up loads), 100A fused safety switch (for inverter).
Output of inverter will go back to interlocked breakers in both 125A sub-panel (normally feeding) and in 200A sub-panel (normally not feeding)

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

• 

In the photos shown, empty meter socket and old 100A main panel still shown, later replaced with 200A sub-panel.
All conduit goes through basement. In your case you might place all side by side and route externally. I was working with limited dimensions due to corner of house, window, crawl space.

Thanks for the detailed reply. I have a 125 amp service and was planning to add a single 125 amp breaker in the main meter and move the loads to a separate 200 amp sub panel.

I need to figure out now the inverter placement now:
1. In the middle of the grid and 200 amp subpanel with a manual bypass switch (to connect the loads to grid if the inverter is down)
2. Feeder tap like you suggested with interlocked breakers (to connect loads to inverter when the grid is down)

Not sure which option is better. Interlocked breakers seem like more work than a manual bypass switch. Also, I imagine and hope the inverter will be more resilient than the grid (which goes down about once in 2 years for me) so better to opt for a manual solution that I'm less likely to use

 

[Hedges]

What is a "manual bypass switch"? A non-interlocked switch shorting inverter output to inverter input (grid)? I wouldn't do that if I were me.
It should be impossible to do harm without tools.
A DPDT knife style transfer switch would be great, but expensive.

I used to think interlock at $50 was overpriced for a stupid piece of metal, but it is UL listed and does the job for a fraction the price of a transfer switch.

 

[rcht148]

What is a "manual bypass switch"? A non-interlocked switch shorting inverter output to inverter input (grid)? I wouldn't do that if I were me.
It should be impossible to do harm without tools.
A DPDT knife style transfer switch would be great, but expensive.

I used to think interlock at $50 was overpriced for a stupid piece of metal, but it is UL listed and does the job for a fraction the price of a transfer switch.

I meant to say transfer switch

 

[Will Prowse]

I just saw the review of the EG4 18K and it looked really interesting. The thing that got thinking was that Will said you can put your entire 200amp service through the inverter and place it between the meter and the panel.

My home has a combination meter and panel located outside the home. As a practical matter, what would the logistics of being able to place an inverter between the meter and panel look like? Example of what my panel looks like:

My house is actually configured in this way. We had to run two pieces of conduit to wire up my EP cube gateway. Was a pain. Covering this in my new video actually.

 

[mikeinmlb]

My house is actually configured in this way. We had to run two pieces of conduit to wire up my EP cube gateway. Was a pain. Covering this in my new video actually.

Yeah, I think at this point I have given up on finding a economic solution to this. The math makes a Tesla meter collar look so much better and a vastly cleaner approach. I'm just waiting to see if anyone else starts to offer something similar.

 

[mikeinmlb]

Yeah, I think at this point I have given up on finding a economic solution to this. The math makes a Tesla meter collar look so much better and a vastly cleaner approach. I'm just waiting to see if anyone else starts to offer something similar.

Maybe someone who reviews solar inverters and has the ear of manufactures could suggest more meter collar transfer switches are needed

 

[Lawrence_SoCal]

Maybe someone who reviews solar inverters and has the ear of manufactures could suggest more meter collar transfer switches are needed

Enphase and ConnectDER both have meter-collar MIDs. James at EG4 mentioned a few months back that meter collar support was high (but not top) on his priority list

I too look forward to more and better meter-collar MIDs... as I'll need one as well