35 kVA 3 phase system?

islandboy43444
islandboy43444 Solar Expert Posts: 45 ✭
in Advanced Solar Electric Technical Forum #1
K can you help me put together a 3ph 120/208 35kva system with battery backup for 2days and to tie in a 35kva generater
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: 35 kVA 3 phase system?

    I've moved this to its own thread because it's quite a different topic.

    I don't know of any inverter that can handle that kind of power requirement. Were it single phase that would be one thing (four 8kW Radians = 32kW). If it were 1/10 the kVA it could be done (three Outback FX 3648 ). The combination of the two is outside the normal realm of off-grid power supply (hence placing this thread in the Advanced section).

    If it is possible to divide the loads up into more manageable amounts that would be different, although the thought of ten individual 3.5 kW 3 phase set-ups is a bit unsettling too (30 FX3648's at $2,000 each = $60,000 just for inverters). Depending on how long this would have to operate, the outlay in batteries would be daunting as well. To say nothing of the amount of PV and controllers needed to recharge with. Basically you'd be looking at ten sets of batteries around 400 Amp hours @ 48 Volts, each with roughly 2kW of PV on it.

    As I said, not your typical O-G install.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,626 admin
    #3
    Re: 35 kVA 3 phase system?

    I would suggest that you are pretty much in the range of needing a real power engineer to design/oversee the installation and acceptance testing of your system.

    Here is a similar sized system and the ongoing problems the folks are currently having (not yet resolved).

    Is the system set up right

    Large/Poly Phase systems are a whole order of magnitude of system design issues (and cost of mistakes). I would suggest that you let us know (roughly) where the system would be installed (and/or where you would buy the equipment if intended to be exported) and ask for suggestions of suppliers/engineers that may be up to the job.

    One question I would have--Is this a pretty balanced 3 phase system, or is most of the power going be single phase with a bit of 3 phase thrown in. Also, is this US or Europe, 208/230/240/277/440/480 VAC 3 phase, Delta or Wye preferred?

    Knowing your loads is the first step here (including is this seasonal and/or backup power/grid power and net metering available, etc.)... Conservation should be the next few steps (smaller the system, the lower the fixed/installation/maintenance costs).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #4
    Re: 35 kVA 3 phase system?
    islandboy43444 wrote: »
    K can you help me put together a 3ph 120/208 35kva system with battery backup for 2days and to tie in a 35kva generater

    SMA do a multicluster box which will do 120V/208V 3 phase up to 72kW: http://www.sma-america.com/en_US/products/off-grid-inverters/multicluster-box.html

    You can then AC connect sunny boys for the solar panels to each of the phases, or use normal DC charge controller on the batteries, or a combination of the two.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
    Re: 35 kVA 3 phase system?

    i'm glad you put this to the forum as you will get more input than just pming me about it. for the record the inverter you cited xantrex no longer carries.
    http://www.altestore.com/store/Inverters/Grid-Tie-Inverters/8kW-and-Commercial-Grid-Tie-Inverters/Xantrex-Pv45208-45Kw-208Vac-Inverter/p2225/

    as you can see they do carry others of various capacities though. few here would have experience with something quite this big and it would be advisable, as was already said, to get professional engineers in on this in addition to involving your local utility as well.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #6
    Re: 35 kVA 3 phase system?
    stephendv wrote: »
    SMA do a multicluster box which will do 120V/208V 3 phase up to 72kW: http://www.sma-america.com/en_US/products/off-grid-inverters/multicluster-box.html

    You can then AC connect sunny boys for the solar panels to each of the phases, or use normal DC charge controller on the batteries, or a combination of the two.
    EDIT: The inverters have a generator support feature so they can augment the generator power if needed, i.e. with 35kW of battery inverter and 20kW of generator power, you can draw 55kW from the loads.
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