Off-grid wiring schematic - How does this look?

Kgelles
Kgelles Solar Expert Posts: 25 ✭
in Off Grid Solar & Battery Systems #1
Hello, I have learned a lot about wiring in the last few months but I still need some help with grounding my off-grid system, especially the grounding relating to the inverter and ac wiring. I included notes from the inverter's manual in the diagram. Please let me know the changes I need to make. Thanks everyone in advance...everyone's been really helpful so far.

One other question...Should I connect the battery's negative post to the ground rod with 6wag copper wire? The manufacturer seems to want me to do so...



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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Off-grid wiring schematic - How does this look?

    My eyesight is not the best, but I see nothing wrong with it at all. No ground loops, only one neutral-ground bond, circuit protection in the right places, very neatly drawn.

    6 AWG should be sufficient for negative to ground wiring. Manufacturers usually know what they're talking about.
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  • Caneman
    Caneman Solar Expert Posts: 71 ✭✭✭✭
    #3
    Re: Off-grid wiring schematic - How does this look?
    Kgelles wrote: »
    Hello, I have learned a lot about wiring in the last few months but I still need some help with grounding my off-grid system, especially the grounding relating to the inverter and ac wiring. I included notes from the inverter's manual in the diagram. Please let me know the changes I need to make. Thanks everyone in advance...everyone's been really helpful so far.

    One other question...Should I connect the battery's negative post to the ground rod with 6wag copper wire? The manufacturer seems to want me to do so...



    Attachment not found.

    nice drawing, one of the best ones I have seen for a home system.

    do you want to add breakers to your combiner box? you may want to add more panels/strings later and if you put in a combiner box that can accomodate 4 to 6 breakers then it will be easy to do that...

    one more thought, do you want to add in a bus bar off the battery bank and have the CC and loads tie in to that instead of at the battery bank?
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  • Kgelles
    Kgelles Solar Expert Posts: 25 ✭
    #4
    Re: Off-grid wiring schematic - How does this look?
    Caneman wrote: »
    nice drawing, one of the best ones I have seen for a home system.

    do you want to add breakers to your combiner box? you may want to add more panels/strings later and if you put in a combiner box that can accommodate 4 to 6 breakers then it will be easy to do that...

    one more thought, do you want to add in a bus bar off the battery bank and have the CC and loads tie in to that instead of at the battery bank?

    Thanks for the reply. I'm glad the drawing was clear.

    As far as adding combiner box fuses...I think that's a great idea. And besides, I may add two more panels in the future so....

    I attached a new screen grab of the schematic with combiner box fuses and a busbar off of the battery positive. Should I add one to the grounded negative post wire as well?

    Thanks again.

    Attachment not found.
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  • Caneman
    Caneman Solar Expert Posts: 71 ✭✭✭✭
    #5
    Re: Off-grid wiring schematic - How does this look?
    Kgelles wrote: »
    Should I add one to the grounded negative post wire as well?

    Thanks again.

    Attachment not found.

    that is what i have seen, and you can run your (-) ground off of that as well...

    do you have a (+) battery disconnect switch?
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  • Kgelles
    Kgelles Solar Expert Posts: 25 ✭
    #6
    Re: Off-grid wiring schematic - How does this look?
    Caneman wrote: »
    that is what i have seen, and you can run your (-) ground off of that as well...

    do you have a (+) battery disconnect switch?

    Wonderful. This is a great forum Thanks Caneman.

    I will add a negative busbar and ground off that. And I will add a disconnect switch near the battery positive terminal.
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  • wide-raft
    wide-raft Registered Users Posts: 5 ✭
    #7
    Re: Off-grid wiring schematic - How does this look?

    I am connecting a Magnum MS-PAE 4024 inverter to a 100a main panel which will distribute power to my cabin.

    The instructions for the 100a main panel obviously (but unfortunately for me) did not include any useful information for off-grid setups.

    Everything just said that the sub-panel shouldn't be neutral-ground bonded but the main panel should; rather, the first point of entry should be neutral-ground bonded. But in my setup I was confused, because the first point of entry would be the inverter, but I couldn't find anything about this in the instructions.

    Now it seems like I should bond the inverter ground with the inverter neutral as indicated by this drawing. Yes? And do not bond neutral to ground in the main panel but instead connect a grounding bus bar inside the panel.



    Kgelles wrote: »
    Wonderful. This is a great forum Thanks Caneman.

    I will add a negative busbar and ground off that. And I will add a disconnect switch near the battery positive terminal.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #8
    Re: Off-grid wiring schematic - How does this look?

    welcome to the forum.
    you may be needlessly confusing yourself. normally your standard entrance cb box is the first thing as the utility power would just come straight into it. the buses for neutral and ground are usually prebonded straight to the metal box itself. you can open your box and see this for yourself. if, on a lark, it isn't and one is insulated from the box then you can just add a jumper to bond the 2 buses.

    as you figured this is where most have the neutral/ground bond and this goes off to the ground rod as well. the magnum should not have the neutral ground bond being it is in the main panel.
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  • wide-raft
    wide-raft Registered Users Posts: 5 ✭
    #9
    Re: Off-grid wiring schematic - How does this look?
    niel wrote: »
    welcome to the forum.
    you may be needlessly confusing yourself. normally your standard entrance cb box is the first thing as the utility power would just come straight into it. the buses for neutral and ground are usually prebonded straight to the metal box itself. you can open your box and see this for yourself. if, on a lark, it isn't and one is insulated from the box then you can just add a jumper to bond the 2 buses.

    as you figured this is where most have the neutral/ground bond and this goes off to the ground rod as well. the magnum should not have the neutral ground bond being it is in the main panel.

    OK. My main panel, a homeline 100a, came with a mysterious bonding screw but it isn't attached. I do not know where to put this screw. So, just to be clear, the magnum inverter will not bond neutral with ground, but the main panel will (once I figure where to put the screw).

    I still do not understand this.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #10
    Re: Off-grid wiring schematic - How does this look?

    can you link to the panel in question or show us a pic?
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  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #11
    Re: Off-grid wiring schematic - How does this look?

    I guess that you know that youre well into "should be using an electrician" territory here. But as the others said the earth neutral bond is usually made in the main ac breaker box. The earth bus and the neutral bus usually have a solid copper link between them. So the link on the inverter should not be used as well. While it /may/ amount to the same thing, better to do it explictly in ac breaker breaker box, where it is guaranteed to remain intact. It is after all a safety feature.
    Around here (240V country) breaker boxs are plastic so both buses are otherwise insulated from the case.

    The only other thing id add is that the midnite mini dc box is worth every penny, gets all the DC stuff neatly tucked away, and comes with a proper inverter breaker.

    http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=8&productCatName=Mini%20%20DC%20Disconnect
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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  • wide-raft
    wide-raft Registered Users Posts: 5 ✭
    #12
    Re: Off-grid wiring schematic - How does this look?

    That's what I have -- the midnight dc disconnect box. I haven't been using it for the inverter yet because currently I'm just using a xantrex square wave inverter and extension cords.
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  • wide-raft
    wide-raft Registered Users Posts: 5 ✭
    #13
    Re: Off-grid wiring schematic - How does this look?

    It sort of looks like it should go in the top center but the hole is not threaded there.

    Attachment not found.
    Attachment not found.

    It's a homeline 100a outdoor load center class 1100
    1.jpg 73.2K
    2.jpg 88.6K
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #14
    Re: Off-grid wiring schematic - How does this look?

    Ground bus bar is bonded to the box itself. Neutral bus bar is not. The long, green screw replaces one in the neutral bus bar causing it to make contact with the box and thus create the N-G bond.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #15
    Re: Off-grid wiring schematic - How does this look?
    wide-raft wrote: »
    That's what I have -- the midnight dc disconnect box. I haven't been using it for the inverter yet because currently I'm just using a xantrex square wave inverter and extension cords.

    Keep that power source away from any grounds, unless they have a specific ground terminal on the case of the inverter.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #16
    Re: Off-grid wiring schematic - How does this look?
    wide-raft wrote: »
    It sort of looks like it should go in the top center but the hole is not threaded there.
    Attachment not found.

    It's a homeline 100a outdoor load center class 1100

    Read the instructions on the green screw carrier.
    Look for a hole in the neutral bar which has a hole in the panel behind it which the screw will reach.
    The hole in the neutral bar will probably not be threaded, and the hole in the panel case may not be threaded either, relying on the green screw to cut its own threads to assure a tight metal-to-metal contact.
    SMA SB 3000, old BP panels.
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  • wide-raft
    wide-raft Registered Users Posts: 5 ✭
    #17
    Re: Off-grid wiring schematic - How does this look?

    Yep. Worked like a charm. I just had to push the screw in kind of hard and then it started to thread.

    Everything since has been connected and is working great.

    Thanks!!
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