MPPT Charger and Input Voltage

x0054
x0054 Registered Users Posts: 8 ✭✭
in Advanced Solar Electric Technical Forum #1
I have a 48V battery storage system (off grid) and an array with 2 panel strings. Each string is comprised of 2 35V panels, for total array voltage of 70V. Would I be able to pull more power out of this array if I reconfigured it into strings of 3 panels for nominal voltage of 105V. My charger can handle up to 150V. The theory being that there would be more headroom for the charger to find the maximum power point that is still comfortably above the charging voltage of the batteries (59-62V).

Thanks for any info.

 - Bogdan
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    x0054 said:
    I have a 48V battery storage system (off grid) and an array with 2 panel strings. Each string is comprised of 2 35V panels, for total array voltage of 70V. Would I be able to pull more power out of this array if I reconfigured it into strings of 3 panels for nominal voltage of 105V. My charger can handle up to 150V. The theory being that there would be more headroom for the charger to find the maximum power point that is still comfortably above the charging voltage of the batteries (59-62V).

    Thanks for any info.

     - Bogdan

    I think you may not have enough 'head room' above the charging voltage. What charge controller do you have! If you do strings of 3 you might have issues with the VOC on cold mornings, some allow for higher Voltage for those cold mornings, Schneider and Midnite I think. Which panels do you have? Did you actually have 12 strings? or did you intend to buy more panels?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited December 2016 #3
    If I'm not mistaken you have a Morningstar MPPT controller, in which case you can always go to Morningstar's string calculator enter your information and it will tell you what is optimal.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • x0054
    x0054 Registered Users Posts: 8 ✭✭
    #4
    Thanks! I looked that up, and the results suggest I need 3 panels per string:

    http://string-calculator.morningstarcorp.com/#manufacturer=142&module=3371&product=23&vmin=44&vmax=62&tmin=15&tmax=100&tminunits=f&tmaxunits=f

    I'll be rewiring that once the weather improves a bit. Thank you all for the help!
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