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  • Newbie Questions

    Hey Folks
    New to solar systems and learning as I go so bear with this newbie my system is
    2 - 245w Panels
    1-Renogy 20amp Mppt Tracer Charge controller
    4 - Powerware 200ah batteries hook up in parallel
    Batteries I have were given to me and I know they are at least 8 to 10 years old
    I am powering a off grid cabin and only useing led lights plus ceilings no fan and tv
    I have a couple of issues
    1:I believe my panels are to big for my solar controller and I should go with a larger in 40amps perhaps
    2: I know my batteries will have to be replaced before winter
    Everything seems to be working great other than fact batteries drain to about 35 % by morning we been running without generator for 3 days with no issues but just wondering if I risk overheating or overcharging my batteries battery temp is 25 to 30 Celsius
    Thanks for any advice
    Attached Files

  • #2
    Battery / PV ratio is wrong, if I understand your battery size. Sounds like you are using 12V @ 800ah battery ( 4 twelve volt batteries in parallel )
    Ideally, that much battery wants 80A to recharge. You only have 30A from the 2 panels with a MPPT controller. You need 3x the panels you have (1500w ideally)

    Better, would switch up to a 24 or 48V system, and avoid the problematic parallel batteries.
    48V @ 200 A would only need a 20A controller ( at 48V ), but would still want about 1.5kw of PV panels

    parallel battery problems addressed http://www.smartgauge.co.uk/batt_con.html
    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

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    • #3
      Batteries are 12v 200ah ea but as I mentioned they are old probably will just go with 2 new 200ah batteries
      thanks for the reply

      Comment


      • #4
        Originally posted by Bobbler View Post
        Batteries are 12v 200ah ea but as I mentioned they are old probably will just go with 2 new 200ah batteries
        thanks for the reply
        You don't have enough solar power to keep that bank charged.

        Actually, what it really comes down to is the amount of energy you're using vs the amount of solar power you have. But I think its safe to say that Mike is correct.. You have 12x800ah = 9600 watts of storage, and only 245w x2= 490 watts of power generation...

        That's like trying to power a concrete truck with a lawn mower engine....

        To make matters worse, since you don't have the ability to fully charge the batteries in 5 hours, it means your batteries are in a constant state of discharge and sulfating... which is going to kill them very fast.. lucky to get even a year out of them. Won't matter what lead acid batteries you buy, if you can't keep them charged, they're going to die.

        If you're going to run a large battery bank and not power it with enough solar to keep it charged, I would suggest you switch to a different battery chemistry that doesn't mind being run down all the time. Lithium batteries love sitting at 50% SOC or less.. They don't mind being partially charged one bit.

        So either switch to lithium, or buy more panels. and not a couple more panels, you need at least 1500 to 2000 watts of solar to keep those lead acid cells happy, and that's assuming you're in the lower latitudes during summer. If you're in the north and using the system in the winter, you'll need at least 3000 watts of solar at a minimum.

        Comment


        • #5
          Thanks for your reply I was given the batteries so I thought why not use them lol
          i guess I would be better to just useIng two battery bank for now and then look at buying a couple in spring we use very little power as I mentioned led lights and ceiling fan plus tv
          I appreciate the advice

          Comment


          • #6
            Originally posted by Bobbler View Post
            Thanks for your reply I was given the batteries so I thought why not use them lol
            i guess I would be better to just useIng two battery bank for now and then look at buying a couple in spring we use very little power as I mentioned led lights and ceiling fan plus tv
            I appreciate the advice
            Yup.. much better to use a smaller bank and keep it charged than to allow a big bank to remain discharged.

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