All-In-One AC wiring

medic149aj
medic149aj Registered Users Posts: 4 ✭
in Advanced Solar Electric Technical Forum #1
I am going around in circles trying to figure out how to wire my all-in-one inverter to my AC breaker box.

I am totally off-grid.  Have 2-EG4 48v batteries.  Generator to charge batteries when needed as the AC input to the all-in-one.  System is in a shed 60' from where I want to install a sub-panel in the cabin.  

I was planning on installing a 200 amp breaker box and running 100 amp sub-panel to the cabin.  Grounding rod or plate for the 200 amp box.

With one Line, one neutral, and one ground coming out of the all-in-one unit to the 200 amp box, how would I wire them in the 200 amp box?
I've seen some people go directly to a Main breaker.  Some people go directly to the lugs.  Some people back feed to a breaker.

Any thoughts???  I am stumped on which is the best and safest way to go.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    If it's 220(240) I would wire it to the main breaker.  Does the 'all-in-one' bond the neutral and ground? 
    Will the shed be heated for the batteries?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • medic149aj
    medic149aj Registered Users Posts: 4 ✭
    #3
    Photowhit said:
    If it's 220(240) I would wire it to the main breaker.  Does the 'all-in-one' bond the neutral and ground? 
    Will the shed be heated for the batteries?
    It's actually 120 coming out of the inverter.
    There is a bonding ground in the inverter.
    Planning on building a battery case with heating pads for cooler weather, but won't be used in wintertime.
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  • m151
    m151 Registered Users Posts: 39 ✭✭
    #4
    Is your generator 120 or 120/240? Do you run 240 volt loads?
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  • medic149aj
    medic149aj Registered Users Posts: 4 ✭
    #5
    m151 said:
    Is your generator 120 or 120/240? Do you run 240 volt loads?
    Generator is 120, but do have two that can be used.  No 240 needs right now, but probably in the future.
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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,485 ✭✭✭✭
    edited June 2022 #6
    You did not mention model of all-in-one inverter.  I am assuming it is a high frequency unit and not carried by forum host.

    Often these inverters have a neutral-ground bonding relay internal.  When there is no AC input they assume they are running totally off-grid and connect their internal inverter neutral to inverter chassis ground.  When they detect an AC input, like grid or generator, the internal neutral-ground bond relay is opened.  This turns over neutral-ground bonding responsibility to AC input source.

    Inverter case and all metal cases like breaker panels should be common chassis connected to a single point ground, usually from any incoming AC panel. This is non-negotiable.  You don't want to risk putting left hand on one metal box and right hand on another metal box and find out there is an AC potential between them. This should be a separate green ground wire.  Metal conduit between boxes does not count as ground connection and should not be relied upon for inter-case grounding.  Conduit clamp rings often become loose.

    Issue is difference between operating with AC input and without AC input on inverter, and where neutral is grounded.  When there is no AC input to inverter it is okay for the internal neutral-ground of inverter be grounded back at input AC breaker panel.  

    When there is AC input to inverter you just don't want neutral-ground bonding within inverter or anywhere on downstream AC output from inverter.  All neutrals comes through inverter neutral back to main breaker panel neutral bus bar where it is single point grounded.

    One unrelated but very important point.  Most of these HF inverters do not have their PV input pos and neg lines isolated from inverter AC output.  They are like transformer-less grid-tie inverters.  This means breakers to panels must use double pole DC breakers to break both the pos and neg lines to PV panels.
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  • medic149aj
    medic149aj Registered Users Posts: 4 ✭
    #7
    RCinFLA said:
    You did not mention model of all-in-one inverter.  I am assuming it is a high frequency unit and not carried by forum host.

    Often these inverters have a neutral-ground bonding relay internal.  When there is no AC input they assume they are running totally off-grid and connect their internal inverter neutral to inverter chassis ground.  When they detect an AC input, like grid or generator, the internal neutral-ground bond relay is opened.  This turns over neutral-ground bonding responsibility to AC input source.

    Inverter case and all metal cases like breaker panels should be common chassis connected to a single point ground, usually from any incoming AC panel. This is non-negotiable.  You don't want to risk putting left hand on one metal box and right hand on another metal box and find out there is an AC potential between them. This should be a separate green ground wire.  Metal conduit between boxes does not count as ground connection and should not be relied upon for inter-case grounding.  Conduit clamp rings often become loose.

    Issue is difference between operating with AC input and without AC input on inverter, and where neutral is grounded.  When there is no AC input to inverter it is okay for the internal neutral-ground of inverter be grounded back at input AC breaker panel.  

    When there is AC input to inverter you just don't want neutral-ground bonding within inverter or anywhere on downstream AC output from inverter.  All neutrals comes through inverter neutral back to main breaker panel neutral bus bar where it is single point grounded.

    One unrelated but very important point.  Most of these HF inverters do not have their PV input pos and neg lines isolated from inverter AC output.  They are like transformer-less grid-tie inverters.  This means breakers to panels must use double pole DC breakers to break both the pos and neg lines to PV panels.
    Thank you.  It's actually an MPP Solar LV6548
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