Question - 350V MPPT controller

bill von novak
bill von novak Solar Expert Posts: 891 ✭✭✭✭
in Advanced Solar Electric Technical Forum #1
Question for all of you -

I have a grid tie system that has 3 strings total, each string with an max power point of 290 volts. Open circuit voltages run around 350 volts. Two of these feed one inverter, the third string feeds a second inverter. 3200 watts per string.

I would like to set up a standby system that I can connect via an additional DC disconnect purely for power outages. (i.e. power goes out, disconnect the array via the primary disconnect, connect it to the standby system via a second DC disconnect.) That means a charge controller that can drop 290-350 volts to 24 volts to run a smallish 24 volt battery system - around 200 amp-hours.

There seems to be a hole at that voltage, though. The Classic 250 charge controller goes to 250 volts but no higher. The only controller I can find out there is the Schneider 80-600, which at $1300 is a bit steep. I also don't need that much current since this will be for backup only, and since I'd like to keep battery charge rates below C/3.

Does anyone know of a charge controller that works at that voltage, either existing or upcoming?
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Question - 350V MPPT controller

    Welcome to the forum.

    This is a very popular question in fact. Maybe we should have a "Top Ten Things We Want" list. :D

    As far as I know only Schneider Xantrex makes a controller for such an application. You already know the problem there.

    The other option some have opted for is to make it possible to split off or re-wire the array easily to feed a standard MPPT controller like the 250 Volt Classic.

    There just doesn't seem to be any inexpensive or easy way to do this. :cry:
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Re: Question - 350V MPPT controller

    unless you will be constantly robbing that inverter of power to charge a battery it won't work anyway. a battery will not be good to leave alone without a charge to it until the power goes out.

    you could just opt for a backups type thing with an inverter/charger and add enough batteries to power the backed up circuits. it will lower the net sold to the grid no matter what, that is, unless you buy more pvs just to charge those batteries with and that will operate when the grid goes down too. for the pvs on the gt system i suppose there could be a tap at the appropriate number of pvs for a good voltage that the controller could take to add a charge to the batteries, but this will not fly for operation with the gt inverter while it's operating.
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #4
    Re: Question - 350V MPPT controller

    Check out this solution from a Jan. 2012 thread: "Vicor Batmod as an inexpensive alternative to a full-blown hybrid system" http://forum.solar-electric.com/showthread.php?14972-Vicor-Batmod-as-an-inexpensive-alternative-to-a-full-blown-hybrid-system
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #5
    Re: Question - 350V MPPT controller

    Another alternative is to leave your GTI in place and connect it to the output of a bi-directional battery inverter and charge the batteries that way. SMA sunny island and Xantrex XW support this configuration. Every other bi-directional inverter/charger also supports this configuration but with the addition of a diversion load controller across the battery.
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  • 65DegN
    65DegN Solar Expert Posts: 109 ✭✭
    #6
    Re: Question - 350V MPPT controller

    The Schneider 80-600, I believe, will not operate at 600 VDC. It reads more like a hyper VOC.
    This from the Schneider web site;
    "Input voltage 195 V DC -
    open circuit <= 600 V "
    Looks like the operating voltage is nothing special at 195 volts.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #7
    Re: Question - 350V MPPT controller

    The MPPT range for the Xantrex 80 600 is up to 510V. This from the install manual:
    Attachment not found.
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  • offgrid me
    offgrid me Solar Expert Posts: 119 ✭✭
    #8
    Re: Question - 350V MPPT controller

    You are not correct about this. The operating voltage range is 195v to 550v. Shut down is 600v. Mine runs consistently at an input of over 400v
    Ned
    65DegN wrote: »
    The Schneider 80-600, I believe, will not operate at 600 VDC. It reads more like a hyper VOC.
    This from the Schneider web site;
    "Input voltage 195 V DC -
    open circuit <= 600 V "
    Looks like the operating voltage is nothing special at 195 volts.
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #9
    Re: Question - 350V MPPT controller
    offgrid me wrote: »
    You are not correct about this. The operating voltage range is 195v to 550v. Shut down is 600v. Mine runs consistently at an input of over 400v
    Ned

    Shutdown at 600 volts ?? what is shutdown ??

    boB
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Question - 350V MPPT controller
    boB wrote: »
    Shutdown at 600 volts ?? what is shutdown ??

    boB

    Turns off because of the over-Voltage state ... and doesn't turn back on again until you reset it? :p
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #11
    Re: Question - 350V MPPT controller
    Cariboocoot wrote: »
    Turns off because of the over-Voltage state ... and doesn't turn back on again until you reset it? :p

    Yeah... Having to reset it might be right.
    I'd just let it turn on again when Voc drops below 550 or whatever it is.

    I'm not sure why they'd need to keep it from running unless maybe the input voltage goes
    above 600V everytime the CC turns on ? Or after a few times of doing that ?
    Having to reset the CC might be a royal pain.

    boB
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  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    #12
    Re: Question - 350V MPPT controller
    stephendv wrote: »
    Another alternative is to leave your GTI in place and connect it to the output of a bi-directional battery inverter and charge the batteries that way. SMA sunny island and Xantrex XW support this configuration. Every other bi-directional inverter/charger also supports this configuration but with the addition of a diversion load controller across the battery.

    Interesting idea. I wonder if that would work with an Outback GTFX series inverter.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #13
    Re: Question - 350V MPPT controller
    bill von novak wrote: »
    Interesting idea. I wonder if that would work with an Outback GTFX series inverter.

    Yep, should do. Here's outback's tech note on the subject: http://www.outbackpower.com/pdf/tech_notes/AC_Coupling_WHT_Paper.pdf
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