Confusion around VOC for MPPT

LuluBelle
LuluBelle Registered Users Posts: 2 ✭
in Caravan, Recreational Vehicle, and Marine Power Systems #1
Hi there. I recently purchased a new MPPT for my camper and am purchasing new panels to go with it but it stipulates that the maximum VOC must be 32Volts. I am struggling to find anything "stronger" than 160W that doesn't run higher than 32Volts VOC. Is there a way to get around this, besides purchasing a new MPPT  :(
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited October 2020 #2
    Welcome aboard 

    That's a very low voltage for an MPPT controller, I would suspect it's not an MPPT at all, there are many online which claim to be MPPT but are in fact PWM, please share an image or link to what it is you have.
    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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  • LuluBelle
    LuluBelle Registered Users Posts: 2 ✭
    #3
    Thanks so much.

    This is the item that I procured. 

    https://www.redarc.com.au/dual-input-25a-in-vehicle-dc-battery-charger

    I believe that it has a built-in MPPT. 
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    You bought a battery - battery charger, not a solar charge controller

    You need to return it, as it cannot work for your described use.

    Then come back here, and let us know what your loads are and how much space you have for PV panels.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • mike_s
    mike_s Registered Users Posts: 156 ✭✭
    #5
    It says it does MPPT, but also says it's designed to work with "12V" solar panels, which would typically have a VOC of 20-25V. If you can't find a single panel with the watts you want, you can parallel multiple panels. If you parallel more than 2, you need to fuse the individual panels.
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  • DZL
    DZL Registered Users Posts: 4 ✭
    #6
    @LuluBelle There is not a way to "get around" the Maximum Voc without buying a second controller. But you can work within that constraint. 32V means you are limited to "12v" panels (which have a Voc in the low 20's). But you can wire multiple panels in parallel up to the current (amps) or power (watts) limit of the controller. You can find specifics in the documentation.

    While it may be hard to find <32 Voc panels above 160W or so, combining multiple panels in parallel would for the most part be functionally the same as fewer larger panels.

    @M@mike95490 the description states clearly that this product is a combination MPPT controller and DC-DC (B2B) charger.
    REDARC said:

    The REDARC BCDC1225D In-vehicle Battery Charger is the next generation in REDARC's DC to DC charging technology, with additional features that make it the most advanced dual battery charger on the market.

    Featuring a Maximum Power Point Tracking (MPPT) solar regulator, the BCDC1225D will charge from both solar and the alternator simultaneously. And, with built-in Green Power Priority it will select solar charging first, meaning less load on the alternator.




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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #7
    Guess I was wrong and you have no worries
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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