OUTBACK Flex 60A parallel wiring ?

hamlet_jones
hamlet_jones Registered Users Posts: 12 ✭
in Solar Beginners Corner #1
Can I series/parallel my pv side so I don't over-volt the Outback MMPT charge controller?

What I have:

Ten 12v/4..45A BP275's (75watts each, total of 750watts)

I want to series/parallel them into two groups of five panels, about 105v open circuit each string. Then I want to join the the two strings into the Outback in parallel.

The Flex60 is good for a nameplate wattage of 750, so good there. Max voltage is 150v, so that's okay.

Is this acceptable, or to clever? I don't want to buy two Outbacks!
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: OUTBACK Flex 60A parallel wiring ?

    No worries.
    The OB MX60 or FM60 will handle up to 1000 Watts on the input for a 12 Volt system.
    It is entirely doable to wire up two strings of panels (serial connections) and then connect them in parallel to the charge controller's input. Just don't exceed the maximum input Voltage of 150 on the panels' Voc.

    If you parallel more than two strings you will need to fuse each string to prevent the possibility of one failed string (short) receiving too much current from the remaining ones.

    Not sure what the Voc is on those panels. 23 perhaps? That would be 138 Volts per string of six. Could be dicey if you experience very cold temperatures.
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  • hamlet_jones
    hamlet_jones Registered Users Posts: 12 ✭
    #3
    Re: OUTBACK Flex 60A parallel wiring ?

    Cool, thanks. Five panels, OCV is 21, Hawaii, no worries.

    IF I added another string, I'd need the Flex80, which has got me thinking to order that model of MMPT, because I might want to expand in the future.

    Would a blocking diode in series with the fuse on each string beneficial in any way?

    Thanks guys!
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: OUTBACK Flex 60A parallel wiring ?

    A separate blocking diode should not be necessary. The charge controller will isolate the batteries from reverse current flow (draining through the panels at night).
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  • hamlet_jones
    hamlet_jones Registered Users Posts: 12 ✭
    #5
    Re: OUTBACK Flex 60A parallel wiring ?

    Okay, thank you. I'm trying to make sure my assumptions are correct, and it's always good to have someone look over your work, however simple.

    Question: If I want to add 1000w of pv in the future, do I just parallel another outback60 into the battery bank? I'm sizing my battery bank just a little larger, so I can add on more pv in the future and still be in the ballpark. I think this will allow me to use whatever pv is on sale at some future time, and not have a headache over matching the pv side.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
    Re: OUTBACK Flex 60A parallel wiring ?

    outback says this on the flexmax 60,
    "12 VDC systems 900 Watts / 24 VDC systems 1800 Watts / 48 VDC systems 3600 Watts / 60 VDC Systems 4500 Watts"

    and says for the flexmax 80 this,
    "12 VDC systems 1250 Watts / 24 VDC systems 2500 Watts / 48 VDC systems 5000 Watts / 60 VDC systems 6250 Watts"

    all watts are stc.

    also note that if you do happen to use a pv configuration that uses more than 2 strings that you must fuse each string.
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