wiring two 5000w inverters together



  • DavidS
    DavidS Registered Users, Users Awaiting Email Confirmation Posts: 2
    I am in the US and have two seperate 110vac systems.  Can they be combined at the breaker box by putting the two black load wires where tines came in from the utility and both white neutral connected together where the white wire is attached from the utility?  The utility will be disconnected completely.  
  • BB.
    BB. Super Moderators, Administrators Posts: 33,409 admin
    The answer is bit more complicated than yes or no. You have to read the manuals of your inverters to be sure (and many will not day).

    In general, no msw (modified sine/square wave) inverter can Jane its outputs tied together (NEVER CONNECT MSW OUTPUTS, OR GROUND BOND A NEUTRAL).

    In general, psw/tsw (pure/true sine wave) inverters can have one white leg ground bonded neutral, and the L1 and L2 can go to the bus bar inputs.

    Note, you can only get 120 vac (L1 to neutral, L2 to neutral) and nothing useful L1 to L2 (normally 240vac for 120/240 split phase systems in North America).

    You also can buy inverters that stack. Either to add there 120 vac outputs or different ones to make 120/240 vac systems.

    There are still a lot of details to talk about to do this safely. In general it would be better to have two 120 vac boxes (less confusion, less to go wrong later).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    You can't generally put two "seperate" 110vac systems together, as each system's ac phase needs to be aligned with the other's. You can't, for example, combine the output of a 300w 12v inverter with the output of a couple of 3500w 48v inverters by tying the hots and neutrals together.
    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
  • DavidS
    DavidS Registered Users, Users Awaiting Email Confirmation Posts: 2
    Thanks guys.  These are both 3000w to 5000w inverters, I already have the systems and am putting them together now.  I have one array, controllers and inverter working.  I've connected my water pump and workshop which are 110vac circuits  and have already pulled the utility meters.  I'm working on the second array now.  Will I be better off getting one large 10 to 15k 220 inverter and hooking both arrays and wind generators to it?  
  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited January 2018 #36
    Using a single large  inverter has its downside, generally the larger the capacity the larger the idle consumption, this can eat into the battery capacity, especially the cheaper examples. Largely it depends on loads, if for example overnight loads are light and intermittent, using an inverter with a search mode could be benificial. On the other hand using a small inverter to power essential loads overnight, along with a larger one during the day could work, however the downside is complexity. Consolidation, it would appear is your goal, one inverter connected to a split phase panel feeding both 120V and 240V loads in a seamless system. If this is the case perhaps a split phase  inverter charger is the way to go, a complete system designed for the purpose, which allows generator, and or grid support, in an  integrated manner. Obviously without knowing exactly what the loads are, when needed and most importantly budget limitations, it's difficult to know what's best for your particular situation. Considering all the various devices not designed to operate together, it's often false economy to go that route. My opinions, others may differ.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,034 ✭✭✭✭✭
    edited January 2018 #37
    DavidS said:
      I've connected my water pump and workshop which are 110vac circuits  and have already pulled the utility meters.    

     What is the reason you are pulling the utility meters? Off grid power is going to cost you considerably more than buying it from the utility.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.