Compatibility of Xantrex XW-MPPT80-600 Charge Controller & solaredge optimizer!!

90cummins
90cummins Solar Expert Posts: 57 ✭✭
in Grid Tie and Grid Interactive Systems #1
Advice needed on the addition of a Solar charge controller as an alternate (backup) to my current grid tied system.
I have a 6.3kw grid tied solar installation which works beautifully but I would like to have a backup plan that would allow me to use my existing Solar Panels in the event of a prolonged power outage. The solar panels are YINGLI SOLAR YGE-Z60 series panels with SolarEdge power optimizers and the output is 377v.
I have a Xantrex XW 4024 inverter and 4 Trojan L16-RE-B batteries as a backup. If a long term outage happened I would like to use the output from my solar panels to charge my batteries.
I would like to use the Xantrex XW-MPPT80-600 Charge Controller because it will communicate with my system and it is the only one I have found that accepts a 377v DC input.
If a long term outage occurred I would move the PV output from the SolarEdge Inverter to the Xantrex Solar Charge Controller.
Will the Xantrex charge controller have a conflict with the SolarEdge power optimizers?
Thanks
90cummins
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #2
    Re: Compatibility of Xantrex XW-MPPT80-600 Charge Controller & solaredge optimizer!!

    MorningStar now makes 600 Volt input controllers too:

    Morningstar TriStar 600 Volt 60 Amp MPPT Solar Charge Controller
    Morningstar TriStar 600 Volt 60 Amp MPPT Solar Charge Controller with Disconnect Box

    Not cheap either at $1,300 to $1,525.

    I don't know anything about them otherwise (relatively new product, nobody here has reviewed them, that I remember.

    Your other option is to get a Radian or Magnum or SMA >6,000 Watt TSW AC inverter and connect your GT inverters to the output of the off grid inverter.

    The Off Grid inverter provides the "utility power" for the GT inverters. And the OG inverter supplies the 120/240 VAC @ 60 Hz for the loads.

    If the loads exceed the GT inverter's output power, the OG inverter will supply additional energy to the loads. If GT inverter power is greater than the loads, the OG inverter will run in "reverse" and recharge the battery bank.

    If the batteries are full, the OG Inverter will alter its frequency by +/- 1.0 Hz or so and "knock" the GT inverters off line (5 minutes minimum).

    Either method would work. I probably would prefer the MPPT charge controllers over the GT+Inverter system--But either would work.

    With the 60 amp charge controllers, the maximum "cost effective array" per controller would be:

    60 amps * 59 volts charging * 1/0.77 panel+controller derating = 4,597 Watt array "cost effective" maximim

    So--You might want a single controller or two controllers with the array split across the two (in general, you should connect two MPPT controllers to a single array). And put a transfer switch between the GT inverters and MPPT controllers.

    Some options... Do a paper design both ways and see what works best for you. If your backup power needs are less--A MPPT solar charge controller will support a smaller battery bank.

    The full size GT array would require a minimum of 630 AH @ 48 volt battery bank (my recommendation). An 8 kWatt AC inverter would work nice with a 800 AH @ 48 volt battery bank minimum (if you need that much power).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #3
    Re: Compatibility of Xantrex XW-MPPT80-600 Charge Controller & solaredge optimizer!!

    If you have SolarEdge optimizers, they are only compatible with the SolarEdge inverter. Your array cannot be used for anything else without totally rewiring it to bypass the optimizers. You could rewire a few panels to a transfer switch and have them reconfigured to a lower voltage during an outage so as to work with a standard low-voltage charge controller. Other option is to try AC couple the GT inverter to a SMA Sunny Island inverter that would keep the SolarEdge inverter up and running during an outage. (although I don't think you'll get anyone at either company to guarantee this will work).

    "What! - you mean my $20,000 solar system won't work during an outage and I can't show off to my neighbors?"

    Did the solar city people talk to you at all about this problem?
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  • 90cummins
    90cummins Solar Expert Posts: 57 ✭✭
    #4
    Re: Compatibility of Xantrex XW-MPPT80-600 Charge Controller & solaredge optimizer!!

    I initially though it would work if there was an outage but realized early on that wasn't the case.
    So I'm looking for a plan B to utilize my solar panels off grid.
    What is it that prevents a grid tie system to powered up be utilized off grid?
    90cummins
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #5
    Re: Compatibility of Xantrex XW-MPPT80-600 Charge Controller & solaredge optimizer!!

    Standard GT inverters are not voltage sources--They are designed to "follow" the AC voltage sine wave that is supplied by a voltage source (utility, off grid inverter, etc.). Technically, GT Inverters are "current sources" designed to inject current into the AC mains (the utility power keeps the voltage and frequency stable).

    It a bit like an automotive electric system. The car can run without the alternator working by drawing power from the battery, but the alternator cannot run correctly without a battery connected (alternator spinning too slow/too much loads like car head lights, DC voltage falls towards zero. No loads, alternator spinning fast, the DC bus voltage can exceed 100 VDC and wipe out the lights/electronics/etc.).

    It is also how GT inverters are designed--If they do not see stable 240 VAC +/- 10% and 60 Hz +/- 0.5%, the GT inverter shuts down to prevent electrocuting the utility lineman, trying to power other houses down the street, etc.

    To use your GT array--You have to make your array wiring reconfigurable so that it will work with other type of MPPT charge controller.

    Or, you can do something else--Reconfigure your 6 kW array into an ~4 kWatt array (can you disconnect a string?), and connect the GT inverter to the output of your 4kWatt XW 4024 inverter. The XW (with the right firmware and configuration) should be able to properly manage the power from a 4 kWatt array and GT inverter system (the Off Grid inverter has to be the same size or larger Wattage rating than the GT inverter feeding it).

    It is a pain--But pure GT systems simply are not designed to operate in utility fail situation unless you can play some sort of game.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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