MPP LV6548 AC Wiring Question

schmism

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If your trying to back feed the main panel with generator power and subsequently supply generator power to the inverters, then yes.
 

Tecnodave

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No you do not need to use a back-fed main for that panel, If you want a shutoff breaker on that panel then you can use the QOM60VH Main breaker in the bolt on main space but please note...this is a 24 space panel, not a 24/48 space.....i.e. it cannot accept QO twin breakers such as the QOT2020 twins but on the same Lowe’s page just under this one is a QO24/48L125S panel for $10 more that can accept singles or twins

A twin breaker is two breakers in one space, it’s not a 240 volt breaker

20 amp QO breakers
QO120 single 120 volt 20 amp breaker takes 1 space
QO220.........for 240 volt 20 amp service takes 2 spaces
QOT2020......for 2 each 120 volt service takes 1 space......but not for 240 volt 20 amps

The one you referred to is a QO24L125S
The one lower on the page is the QO24/48L125S

You can PM me if you want qualified answers, I will also accept emails from you but PM me for that email address

Someone else has posted an answer that does not relate to what you are trying to do
 
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davesmith87

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If your trying to back feed the main panel with generator power and subsequently supply generator power to the inverters, then yes.
That's the thing. I don't think I'm going to be back feeding.

2 Inverters.

"AC In" on Inverters (for grid assist) going from 60A breaker on main panel.
"Ac Out / Load" on the inverters going to new sub panel, with a 60A breaker.

I don't see why I would need the back feed kit, because the sub panel, would not have a direct connection to the main panel.

Wouldn't the inverters take care of any potential back feeding?

The priority I'm going to be using on the inverts is...Solar #1, if no solar then Battery, if no battery then Grid.
 

Tecnodave

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If you do what some one else has said then , backfeeding the main panel from the sub panel with a generator to power the inverter input then feeding the inverter output back to the sub panel the result would be shorting the inverter out by connecting the output back to the input as well as connecting the generator directly to the POCO mains thus destroying the generator as well.

I say again you are welcome to PM me privately or we can email but i will not post my email here, PM me and i will PM you back with my email address
 

Tecnodave

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That's the thing. I don't think I'm going to be back feeding.

2 Inverters.

"AC In" on Inverters (for grid assist) going from 60A breaker on main panel.
"Ac Out / Load" on the inverters going to new sub panel, with a 60A breaker.

I don't see why I would need the back feed kit, because the sub panel, would not have a direct connection to the main panel.

Wouldn't the inverters take care of any potential back feeding?

The priority I'm going to be using on the inverts is...Solar #1, if no solar then Battery, if no battery then Grid.
You are mixing up backfeeding the grid with using a branch breaker to backfeed the QO buss in the subpanel.

Not evenly remotely the same thing.......If you still dont understand reread the only your questions and my responses to your questions and skip over answers from others

Not trying to be rude but some people tinker with electricity, some do it professionally....

Again 29 years as an electrical engineer at General Electric Corporation and 20 years doing contracting....Stocking installer for Schneider Electric’s Square D division.....liscensed by the federal government and state liscensed, da,da,da
 

Sanwizard

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OK Reality check time. If I'm wrong forgive me, but I'd rather say this in case you haven't thought it through. First, with a panel that size you likely have 200AMP service at your house. That's 200 Amps per leg. Your inverters will give you about 55 Amps per leg. You will overload your system badly if you try to run your entire house on 2 of the 6548 inverters. Sorry it just isn't possible.

If you are going to use the panel you linked to, then yes you need to use the backfeed breaker kit, but that is, in my humble opinion, a bad idea. I suggest you pause, think about how much power & which circuits you want / need to move into the sub-panel, then spec from there
The LV6548's are off grid inverters. Nothing will be going back to the main panel. Main panel just feeds grid to the inverters.

I went through a similar thought process, and used the beautiful DanF install as a guide. He covers both the DC side and AC side in his youtube videos.

 

Sanwizard

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That's the thing. I don't think I'm going to be back feeding.

2 Inverters.

"AC In" on Inverters (for grid assist) going from 60A breaker on main panel.
"Ac Out / Load" on the inverters going to new sub panel, with a 60A breaker.

I don't see why I would need the back feed kit, because the sub panel, would not have a direct connection to the main panel.

Wouldn't the inverters take care of any potential back feeding?

The priority I'm going to be using on the inverts is...Solar #1, if no solar then Battery, if no battery then Grid.
You dont need a backfeed kit. Use a transfer switch like in the Danf(Dan Fitzpatrick) video I linked. He is an electrician by trade.
 

Tecnodave

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OK third time now....im not talking about a back feed kit to back feed the grid, What i said is if you use a branch breaker as a back fed main breaker you need a lockdown kit to secure it to the buss so it does not pop out .

Normal use..........branch breaker is fed from the buss and the output is from the terminals
Backfed use.........branch breaker is fed from the output terminals and the output is on the fingers that go on the buss which on the QO breaker are exposed....so the lockdown is to prevent the breaker from popping off the buss and exposing you to the live terminals on the back side of the breaker which now are exposed...

When a branch breaker is used in this fashion it is properly called a “Backfed main breaker”

Its very clear in Square D technical data as well as the UL listing and the NEC
 

Sanwizard

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I guess I should let the electricians reply, as I am NOT an electrician!
That being said, my install looks like the attached picture. It works, and no sparks, so I must have done something right. Again, I tried to copy DanF's design.

Split phase config with shared neutral. Ground bond ONLY main panel.
 

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Tecnodave

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OK.....very good but only one issue, everything should be bonded (ground) back to the main panel and only the main panel is bonded to the ground rod. so your subpanel and your inverters should be bonded back to the main panel. Ground only is not a complete circuit, its for your safety.....to prevent a short circuit in the equiptment to the frame of that equiptment which will now be live. The one place and only one place rule is to prevent circulating currents from the noise suppressors (in all electronic equipment) shunted down the ground wire thus tripping GFCI’s as it is seen by the GFCI’s as a leakage thus nuisance tripping the GFCI.


I have stated my qualifactions several times now....
 

davesmith87

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I guess I should let the electricians reply, as I am NOT an electrician!
That being said, my install looks like the attached picture. It works, and no sparks, so I must have done something right. Again, I tried to copy DanF's design.

Split phase config with shared neutral. Ground bond ONLY main panel.
Your diagram looks like 100% what my goal is.

Is this diagram, it almost looks like there 3 panels? Main, Power Panel, and Barn Sub Panel correct? The device labeled power panel, is that just a super small sub panel, with room for 2 breakers? If so where, does the "main" tie into that? Also as I'm reading it, (3) 60 amp breakers total? Did you use the "standard circuit breakers" (about $30) or the "main" (about $80)?

Just want to confirm the purpose of the transfer switch is to transfer load back to 100% grid in the event that the inverters would fail? Correct?

Thanks in advance.
 

Sanwizard

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Your diagram looks like 100% what my goal is.

Is this diagram, it almost looks like there 3 panels? Main, Power Panel, and Barn Sub Panel correct? The device labeled power panel, is that just a super small sub panel, with room for 2 breakers? If so where, does the "main" tie into that? Also as I'm reading it, (3) 60 amp breakers total? Did you use the "standard circuit breakers" (about $30) or the "main" (about $80)?

Just want to confirm the purpose of the transfer switch is to transfer load back to 100% grid in the event that the inverters would fail? Correct?

Thanks in advance.
Correct on all fronts. You can post the PM I sent you if you wish.
 

Sanwizard

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raurre

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I have a question about the panel being fed by the inverters. Is it not treated the same way you treat one fed from a transformer as a new source of power? If so the panel it feeds would then have the neutrals and grounds bonded. the reason I ask is that I'm building system using the same inverters. I saw in the videos posted that this has been an issue for the MPP lv6548.
 
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Sanwizard

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I have a question about the panel being fed by the inverters. Is it not treated the same way you would a transformer as a new source of power? If so the panel it feeds would then have the neutrals and grounds bonded. the reason I ask is that I'm building system using the same inverters. I saw in the videos posted that this has been an issue for the MPP lv6548.
I am not an electrician, and your setup may be different, but I believe only one ground bond should be used at the main. Subpanels are not bonded. Please check your local NEC code.
 
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