Two inverters one panel

Joe94Joe94 Solar Expert Posts: 42
I'm wiring my off grid house and was wondering if I can feed each bus in my main breaker panel with separate inverters. I have one suresine that feeds it right now. Can I run the hot from the suresine to one bus and the neutral to the neutral bus and the hot from a second inverter possibly like a pro watt to the other bus bar? My biggest question is can the neutral from both inverters go to the same neutral bus bar? Don't want to fry anything but recall hearing somewhere that it would work that way.

Comments

  • BB.BB. Super Moderators Posts: 26,872 admin
    Re: Two inverters one panel

    In theory, with most TSW AC inverters, yes you could (TSW inverters usually have fully isolated AC outputs) tie the two AC Inverter Neutrals together.

    I am not sure if it a good thing or not ("cross talk" between inverters?).

    You can get AC inverters that can be tied together (parallel for more current on 120 VAC lines, or "stacked" for 120/240 VAC mains).

    Most MSW inverters cannot have their outputs tied together or grounded for "neutral". It will short them out. As always check the manuals for details.

    Perhaps somebody here has experience doing this.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Two inverters one panel
    BB. wrote: »
    In theory, with most TSW AC inverters, yes you could (TSW inverters usually have fully isolated AC outputs) tie the two AC Inverter Neutrals together.

    I am not sure if it a good thing or not ("cross talk" between inverters?).

    It never occurred to me that you couldn't. I wired my house with the intention of adding a second (small) inverter to be on 24/7.

    My big inverter is bonded to ground in the ePanel. I intend to run the small inverter's neutral through the ePanel and bond its neutral to the ground buss in the ePanel. I have separate panels (technically, sub-panels) for the two inverters, but I don't see why the OP's scheme wouldn't work from electrical perspective... of course there's code to consider... I have no idea if the scheme is legal.

    Of course, since the two inverters are powered from the same battery bank, their DC negative inputs are also connected. I could see "cross talk" on the DC side if the wiring of the inverters was such that the demands of the big inverter caused voltage drop at the small inverter.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Two inverters one panel

    It's not a problem between two Suresines, nor a problem between two Suresines and a Xantrex Pure Sine 1800/12 inverter. I've had 2 Suresines, (one on 24/7) and the Xantrex running for over 5 years now, with common ground (of course) and Neutrals joined and grounded. So far, with these 3 units so tied together I've come across no problems, they all appear to be very happy living together. Can't of course speak about other inverters, as these are the only PS inverters I have any experience with. I do have several MSW inverters that were used before I got the PS units, and they of course could NOT be neutral tied, or neutral grounded, as their so-called neutrals were floating at half the AC output voltage. And yes, when I was running the MSW inverters, I got several shocks when working on live circuits and happened to touch Neutral and Ground at the same time. This happened not once, but several times. Seems some people are slow learners. Hahahaha
  • LandKurtLandKurt Solar Expert Posts: 41
    Re: Two inverters one panel

    A caution would be an AC wiring practice where two circuits run over the same 4 wire cable using a shared neutral. This requires the two circuits to be out of phase so that the neutral isn’t overloaded. If your two inverters aren’t synchronized out of phase this sort of wiring could be a problem if you have it.

    My house has a couple instances of this; two 120V circuits exiting the electrical panel in one cable. Not a 240V circuit, but two 120V circuits in the kitchen, for example. I had to take this in account when I hooked up a backup panel powered by a single phase 120V source. I had to make sure none of the 6 breakers I was putting on backup when over the same cable.
  • madmikealonemadmikealone Registered Users Posts: 2
    I am attempting a similar setup with 3 psw inverters. tow would run to one load bar, 1 would run to the other load bar, and all three neutrals would tie in the neutral bar. the ground bar is completely seperate. the purpose, for me, it to have one side of my panel with the breakers that will power surge appliances. I have a crude drawing I would like to share, and submit for your comments and help!
  • madmikealonemadmikealone Registered Users Posts: 2
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  • mike95490mike95490 Solar Expert Posts: 7,307 ✭✭✭✭
    Generally, a 300w suresine won't be able to trip a 15A breaker

    As was pointed out - you can overload the neutral return wire, since the inverters will never be sync'd out of phase.

    Don't ever plug in any 240V appliance
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  • EstragonEstragon Registered Users Posts: 1,616 ✭✭✭✭
    I don't quite understand how inverters #1 + #3, both connected to L2 will work without sync'd phase. Won't they conflict, being at different potentials to neutral/ground at any given time?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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