making a microgrid by connecting two systems

marscan
marscan Registered Users Posts: 1 ✭
in Off Grid Solar & Battery Systems #1
I have two complete and separate 12V off grid solar charging and battery bank systems, one a Xantrex system and the other an Outback system. They are separated by about 100 yards. Both have generator back up, One system supplies the house and the other supplies the barn.
I would like to balance the two battery banks by connecting them together. I have tried to connect the two battery banks directly with a 6awg cable, but there is insufficient transfer. Since both inverter systems are generating 110V I was considering connecting the two systems with a 110V suicide cable, basically plugging a male 110V plug into the house on one side and male 110V plug on the barn side. Theoretically, This would backfeed 110V back and forth, to and from the two inverters depending on the battery state of charge.
1. Is this doable?
2. Can the Xantrex and Outback inverters be backfed one to the other without internal damage?
Mark
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    Don't do this! It require special inverters to sync the sine wave!
    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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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #3
    marscan said:
    I have two complete and separate 12V off grid solar charging and battery bank systems, one a Xantrex system and the other an Outback system. They are separated by about 100 yards. Both have generator back up, One system supplies the house and the other supplies the barn.
    I would like to balance the two battery banks by connecting them together. I have tried to connect the two battery banks directly with a 6awg cable, but there is insufficient transfer. Since both inverter systems are generating 110V I was considering connecting the two systems with a 110V suicide cable, basically plugging a male 110V plug into the house on one side and male 110V plug on the barn side. Theoretically, This would backfeed 110V back and forth, to and from the two inverters depending on the battery state of charge.
    1. Is this doable?
    2. Can the Xantrex and Outback inverters be backfed one to the other without internal damage?
    Mark
    NO.  There is no way to sync the 2 different brands of inverters.  I guess you could try it with a phase light or meter, but you still have the problem of one unit will ALWAYS have 0.002V higher than the other, and hog all the load !

    Read these 2 threads about simple generators, and realize transistors make little noise when fried
    http://yarchive.net/car/rv/generator_synchronization.html
    https://www.smokstak.com/forum/showthread.php?t=72038




    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 ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #4
    Do you have two separate systems by, or did it sort of just work out that way?

    What are you trying to do in " balancing" the banks? Are you trying to load share so you can use capacity remaining on a bank after you have depleted the other? Do you want to run bigger loads than one system by itself can handle?

    Unless there is a good reason for the separate systems you may want to head in a direction that gets you to a single system properly sized for both your house and barn loads. An interim solution might be to put the systems together in one location and parallel the banks using short beefy cables, depending on your setup and what it is you're trying to accomplish.

    It would help to know more about loads, batteries, existing equipment, and what your goals are.
    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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