2 different Array sizes one controller

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benewt
benewt Registered Users Posts: 3
in Solar Beginners Corner #1
Ok I have the following:

Outback FX 2548 Inverter 48volt input
MX60 MPPT charge controller

8 Kyocera 130w PV (string size would be 4 in series x 2 parallel)
6 Mitsubishi 190w PV (string size would be 3 in series x 2 parallel)
2 Shell 175w PV (string size would be ?)

I have looked at the Outback String Sizing tool for all 3 arrays.
I live in the tropics at 18 degrees S. Pretty warm here!

I am having a hard time understanding if I can run the different size arrays through the same controller. can anyone out ther give me some advise on this?

Thanks!
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: 2 different Array sizes one controller

    Welcome to the forum.

    The Kyocera's are Vmp 17.5: you need four of these in series for a 48 Volt system (string Vmp 70).
    The Mitsubishi's are Vmp 25.1: you need three of these in series for a 48 Volt system (string Vmp 75.3).
    The Shell's are Vmp 35.4: you need two in series for a 48 Volt system (string Vmp 70.8 ).

    The biggest difference is with the Mitsubishi's, and that string will be only 5 Volts off the other so it won't make much difference.

    All together you have 1040 Watts from the Kyocera's, 1140 Watts from the Mitsuibishi's, and 350 Watts from the Shell's for a total array size of 2530 Watts. That would be enough to support 400 Amp hours +/- @ 48 Volts under typical conditions.

    It should work on an MX60 providing the wiring between array and controller is large enough to minimize Voltage drop; the heat in the tropics will cause some loss there anyway, so you want to try and keep it as low as possible.
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  • benewt
    benewt Registered Users Posts: 3
    #3
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    Re: 2 different Array sizes one controller

    Thank you for that!! would you recommend a solar combiner before the controller or can I run the wires from the 3 different strings straight to the controller?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: 2 different Array sizes one controller

    You will have five parallel string connections: two of the Kyocera's, two of the Mitsubishi's, and one of the Shell's.
    Each one needs circuit protection on it. Your best bet is a MidNite combiner like this: http://www.solar-electric.com/mnpv6.html

    Your total current is going to be around 40 Amps max, so be sure the wire from combiner to controller can handle that current with as little V-drop as possible over the distance.
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  • Jamaican cherubim
    Jamaican cherubim Registered Users Posts: 9 ✭
    #5
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    Re: 2 different Array sizes one controller

    Sounds like with this small charge controller compared to your pv array you will be losing a lot of power, the cc stated here depending on your location may limit the amount of currrent that your array is able to produce. It also depends on ur battery bank size, if it is a small battery bank then you should not have anything to worry about.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
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    Re: 2 different Array sizes one controller
    Jamaican cherubim wrote: »
    Sounds like with this small charge controller compared to your pv array you will be losing a lot of power, the cc stated here depending on your location may limit the amount of currrent that your array is able to produce. It also depends on ur battery bank size, if it is a small battery bank then you should not have anything to worry about.

    :confused:
    2530 Watts total producing about 40 Amps on his 48 Volt system.
    MX60 is a 60 Amp controller, regardless of system Voltage.
    Not a small charge controller and no power loss.
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