Amps needed to charge a battery bank

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  • Smig52
    Junior Member
    • Feb 2011
    • 2

    #1

    Amps needed to charge a battery bank

    I cant seem to find what I am looking for on this GREAT web site.
    I would like to set up an emergency PV system to run my refrigerator. I have been researching panels and found what I think is a great deal, but after reading some of the threads here, I think I have found the fly in the ointment.

    Panel Specs:
    Power (W) 110 Watts
    Open Circuit Voltage (V) 141.70 Voc
    Short Circuit Current (A) 1.17 Isc
    Maximum Power Voltage (V) 110.40 Vmp
    Maximum Power Current (A) 0.98 Imp

    I have read on a thread that it is the amps that charge the batteries. Am I reading this correctly that this panel only provides 1 amp? Is this an inferior panel because of that or does the high voltage compensate for that. I am planning on getting an MPPT controller. Which I have read on this site that it may increase efficiency.

    My ultimate goal is to build a system that will provide electricity for both the refrigerator and a seasonal dehumidifier (summer).

    I havent hooked up my KILL-A-WATT meter up to these items yet to determine the exact watt hours that I will need, but I will.

    Are these panels decent or a waste of money.
    If anyone knows off the top of their head what should be a sufficient, (generic/ballpark estimate), sized system for what I'm looking to do, I would appreciate that as well. I would also like to make it an expandable system for the future.

    Thanks for you advice.
  • Sunking
    Solar Fanatic
    • Feb 2010
    • 23301

    #2
    They are made for grid tied systems. You can use them on a battery system if you use a MPPt controller. They will down convert voltage and up convert amperage. So at the output of the controller the output would be around 12 volts @ 9 amps.

    However not all MPPT controllers can convert that high of a voltage down to 12 volt system. But who says you have to use 12 volts. It is the worse choice you could make. 24 and 48 volt is a much better choice.
    MSEE, PE

    Comment

    • Mike90250
      Moderator
      • May 2009
      • 16020

      #3
      It's best to convert all measurements to watts. Look at the yellow energy tag on your fridge, it likely says 450KWh a year to run. that works out to 1.3KWh daily.

      So, in your 4 or 5 hours of good solar sun, you need to harvest enough to run and recharge the battery bank 1.3KWh. roughly speaking, you need to harvest 3 KWH over a 4 hour period. That needs about 750W of panels.

      Then a couple batteries, charge controller and an inverter.

      or a small gasoline genset.
      Powerfab top of pole PV mount (2) | 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

      Comment

      • Smig52
        Junior Member
        • Feb 2011
        • 2

        #4
        Thank you for the fast response

        Thanks guys. Love this site.

        Comment

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