Mixing panels

unyalli
unyalli Solar Expert Posts: 121 ✭✭
in Solar Beginners Corner #1
After reading about this topic quite a bit I'd like to open this can of worms one more time. I have in my possession 4 Solartech SPM130P-S-N's I will mount on the roof of my RV and wire in series/parallel two sets of two. The specs are Vmp 18.1 and Imp 7.38 so two of them in series is Vmp 36.2. These will connect to my Midnight Classic 150. I also have two Solarland SLP90-12U's I will use as a portable array with Vmp 17.2 and Imp 5.23 so two in series is Vmp 34.4.

If I connect them all to the classic will the portable array cause too much loss in efficiency of the big array? or Should I connect the portable array to my also existing Sunsaver MPPT and attempt balancing the battery voltages and temp compensations? I have battery temp sensors for both controllers.

Jeff
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Mixing panels

    I wouldn't worry about it much. The Vmp difference between the strings is just a bit over 5%:

    (36.2 - 34.4) = 1.8 * 100 / 34.4 = 5.2%

    On the whole the panel Voltage will probably sag that much in the heat anyway.
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  • unyalli
    unyalli Solar Expert Posts: 121 ✭✭
    #3
    Re: Mixing panels
    Cariboocoot wrote: »
    I wouldn't worry about it much. The Vmp difference between the strings is just a bit over 5%:

    (36.2 - 34.4) = 1.8 * 100 / 34.4 = 5.2%

    On the whole the panel Voltage will probably sag that much in the heat anyway.
    Thanks Coot.

    Jeff
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