2 inverters wired to 1 subpanel??

I have a Xantrex ProWatt 2000 inverter going to a 6/12 100amp sub-panel..

It has 2 positive load lugs on the top.. 3 leg/circuits per positive lug.. and shared ground.. and shared neutral.. (separately as I have GFCI on the inverter and don't need any issues.. LoL). (The BOND screw (green) is not in.. the picture was before I removed it..)

All is working well at this point.. both + load lugs are tied together so all 6 breakers have shared access to the measly 18-20 amps.. :blush:

connectLOADhots.jpg

If I undo the 6AWG jumper I used from + load lug to the other + load lug.. Can I then use the + side from another inverter for that 1/2 of the box (aka 3 of the 6 cirucuits), thereby creating 40 amps of service for my cabin (20 on 1 leg and 20 amp on the other)??

Logically it makes sense as the + would be separate and all the wiring in the cabin is separated as well..

The question is will the neutral or ground lugs when doing this give me issue?? I read that 110v is really 55 on the Positive and 55 on the Neutral. (or something like that)..

Would or should I cut the Neutral bar in half to be safe??

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 2 inverters wired to 1 subpanel??

    It all depends. :p

    With sine wave inverters it is not a problem to have a shared neutral both bonded to ground.

    Unless someone crosses the wrong wire or connects a 240 VAC load, et cetera.
  • BB.BB. Super Moderators, Administrators Posts: 32,608 admin
    Re: 2 inverters wired to 1 subpanel??

    With two inverters--I would get two "main" panels--That way, there is never any confusion. There is no real "need" to tie the two inverter output together or run them in the same breaker panel (other than connecting the neutrals to the common ground rod--if that is what you are going to do).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • NorthGuyNorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: 2 inverters wired to 1 subpanel??

    If these are completely separate inverters and are not be synchronized in any way, you won't be able to use 240V loads.

    Otherwise it depends on the inverters. If one is GFI and another has a neutral-to-ground bond, this will trip the GFI. If both are GFI, or both have neutral-to-ground bond then there shouldn't be any problems.
  • ywhicywhic Solar Expert Posts: 621 ✭✭
    Re: 2 inverters wired to 1 subpanel??
    NorthGuy wrote: »
    If these are completely separate inverters and are not be synchronized in any way, you won't be able to use 240V loads.

    Otherwise it depends on the inverters. If one is GFI and another has a neutral-to-ground bond, this will trip the GFI. If both are GFI, or both have neutral-to-ground bond then there shouldn't be any problems.

    No 220-240V loads planned (ever).. Their was rumors that neutral-ground bonding on a panel attached to a GFCI inverter would cause 'tripping' issues (covered last year abit on here).. so I left the neutral-ground bonding screw OUT on the AC sub-panel and also did a separate ground bar in the sub-panel..

    So.. Cariboocoot your saying it should be alright to have all the 'neutrals' on the same bar..?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 2 inverters wired to 1 subpanel??
    ywhic wrote: »
    No 220-240V loads planned (ever).. Their was rumors that neutral-ground bonding on a panel attached to a GFCI inverter would cause 'tripping' issues (covered last year abit on here).. so I left the neutral-ground bonding screw OUT on the AC sub-panel and also did a separate ground bar in the sub-panel..

    So.. Cariboocoot your saying it should be alright to have all the 'neutrals' on the same bar..?

    GFCI will cause problems if there is an N-G bond in the distribution panel because there will already be one at the inverter before the GFCI equipment.

    Excluding that, two pure sine wave inverters can be wired to share a neutral bus bar and ground connection. Two MSW inverters ... most likely not.
  • PhotowhitPhotowhit Solar Expert Posts: 5,806 ✭✭✭✭✭
    Re: 2 inverters wired to 1 subpanel??
    ywhic wrote: »
    ...Can I then use the + side from another inverter for that 1/2 of the box (aka 3 of the 6 cirucuits), ...

    On most breaker boxes, it isn't one side and the other, breakers are fed from either side of 240V feed, so every other one is fed from one side so a 240 breaker uses both sides while sitting in 2 side by side spots.

    Perhaps one of the mods can make this more understandable...

    With your small system, I would be surprised if you will want to try having 40 amp available, until your battery bank and array grow.
    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.
  • ywhicywhic Solar Expert Posts: 621 ✭✭
    Re: 2 inverters wired to 1 subpanel??

    Here Lug #1 it handles breaker 1,3,5..

    Lug1.jpg

    Here Lug #2 handles breaker 2,4,6

    Lug2.jpg

    Red wire is shown for pointing to the + lug.. (this is also currently tied together so all 6 breakers will be fed by the current 1 inverter I have)..

    If I get above the 660ah to say 800ah. I think having the ability to have 40 amps of service their (if even not used) couldn't hurt..
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 2 inverters wired to 1 subpanel??

    Or you could change the inverter to a larger unit if/when needed - including upping the system Voltage. 40 Amps @ 120 VAC is 4800 Watts, and that's not really in the 12 VDC realm (draw 400 Amps from the batteries? No thank you!)
  • ywhicywhic Solar Expert Posts: 621 ✭✭
    Re: 2 inverters wired to 1 subpanel??

    I get what your saying truly I do.

    For arguments sake lets suppose I want an A/C on 1 inverter and the other for say the small fridge and Sureflo pump.
    A single inverter rated for 2k would cry for sure with both heavy loads on one inverter, especially if both compressors kick at the same time.
  • NorthGuyNorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: 2 inverters wired to 1 subpanel??
    Or you could change the inverter to a larger unit if/when needed - including upping the system Voltage. 40 Amps @ 120 VAC is 4800 Watts, and that's not really in the 12 VDC realm (draw 400 Amps from the batteries? No thank you!)

    That's right. The more you're going to grow your system, the more difficult it'll be to stay with 12 V. If that's what you're going to do over time, it's a good idea to go to 24 (or 48) volts right now. If you do, you will immediately save some on breakers and MC4 cables. When you buy more panels, you will not need another solar controller. You'll need thinner cables and smaller breakers throughout. Cost of these small things piles up really fast making 12V system more expensive.
  • ywhicywhic Solar Expert Posts: 621 ✭✭
    Re: 2 inverters wired to 1 subpanel??

    NorthGuy.. I hear you..

    Funds are tight as I am driving 2100 miles to get their from my current NJ/PA location.. (did I mention the 93' Bronco with 351 V8..)

    I will have initially like $1200 to spend once I get their.. so batteries, insulation, small fridge, and fans to start with will be key at this point and be picked up out their in El Paso..

    I have the 8 panels, 2000w ProSine Inverter, breaker box for DC side, breaker box for the 110v side, 10 outlets and Romex in-hand already..

    As well as the plumbing fittings, valves, PEX (and cutter).. I even bought a sink with pedestal and Sureflo 110v pump (0.9amp max and 3.3 gpm/45psi)..

    So water, electric, and stove (propane for now) are covered..

    The solar and plumbing are going to be the projects for me and my 11 yo son for the 3 weeks he will be with me.. (no worries we found a KOA nearby to stay at every few days).. LoL
  • PhotowhitPhotowhit Solar Expert Posts: 5,806 ✭✭✭✭✭
    Re: 2 inverters wired to 1 subpanel??
    ywhic wrote: »
    For arguments sake lets suppose I want an A/C on 1 inverter and the other for say the small fridge and Sureflo pump.
    A single inverter rated for 2k would cry for sure with both heavy loads on one inverter, especially if both compressors kick at the same time.

    You should be fine, in my 4 years at the cabin and the last week here, I've been running a small A/C and fridge at the cabin, and a full size and a/c here on a single 1800 watt inverter, along with other items. If your thinking when turning on loads, you should be fine, and it will be the heavy draw from the battery bank that will be the problem. I use to turn off the A/C at the cabin if I was going to run the Foreman grill or microwave, but other than that, I didn't have larger loads at the cabin. I do have a larger battery bank here and the last little bit at the cabin, but before that I ran on 4 golf cart batteries. running the A/C once they reach float and some at night. I did turn the fridge off the first and last summer, for longer run time at night, the first year I only had 900 watt array and the last summer the batteries were loosing some capacity.

    I would live with what you have and see how it works out. You may find your fine or that you would rather invest in a larger array to give you more day time energy.

    If you know where I can find some plinking 22lr brick PM me!
    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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