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MPPT charge controller rated for 140w panels, can i go bigger?

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  • MPPT charge controller rated for 140w panels, can i go bigger?

    Hey guys, my first post so go easy on me... :P

    I just picked up a Victron 75/10 MPPT controller to run on my camper trailer. At the moment i run a 50watt panel mounted on my carport just to float my 100Ah AGM during the day when the camper isnt being used.. The plan was to pick up a 180/190w panel off gumtree for around $50 to use when out camping. (gotta keep the beers cold). Now according to the MPPT specs (which i overlooked) the charger can have a maximum of 140w solar panel connected. However i have found larger panels out there which come in well under the max specs of the charger in terms of Pmax,Vmp, Isc. So.... Can i go a little bigger, or just stick with 140w?.

    attached are the specs of my charger and a example of one of the many panels i have found in the buy sell pages.


    Cheers
    Tez

    Attached Files
    Last edited by Terry10amps; 10-15-2018, 06:12 AM.

  • #2
    Originally posted by Terry10amps View Post
    Hey guys, my first post so go easy on me... :P

    I just picked up a Victron 75/10 MPPT controller to run on my camper trailer. At the moment i run a 50watt panel mounted on my carport just to float my 100Ah AGM during the day when the camper isnt being used.. The plan was to pick up a 180/190w panel off gumtree for around $50 to use when out camping. (gotta keep the beers cold). Now according to the MPPT specs (which i overlooked) the charger can have a maximum of 140w solar panel connected. However i have found larger panels out there which come in well under the max specs of the charger in terms of Pmax,Vmp, Isc. So.... Can i go a little bigger, or just stick with 140w?.

    attached are the specs of my charger and a example of one of the many panels i have found in the buy sell pages.


    Cheers
    Tez
    The problem is that your CC is only rated for 10A output. That limits your pv watt input to 140watts. Even if you wire up more panel wattage you will not get more then 10 amps of charging.

    If you need more panel wattage then you will need to increase the rating of your CC. Go find a 30Amp MPPT and you should be able to go up to almost 400watts of panels.

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    • #3
      Your other choice would be to up your system voltage to 24 volts.. Being an RV this likely isn't practical. Simpler to get a higher amp rated CC as recommended by SunEagle.
      2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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      • #4
        Thanks for the responses guys,

        So wouldn't a larger panel at least get me closer to running at 10 amps?

        Cheers
        Tez


        Comment


        • #5
          You can over panel your controller to some extent as long as you do not exceed your max. Voc., based on the coldest expected temperature for your area. People do this to get better performance early and late in the day, as well as in hazy/cloudy conditions. Your controller will just not put out more than it's rated power.

          One thing that doesn't make sense to me is why they even make such low powered MPPT controllers. With typical crystalline panels there are few combinations that work in their limited power ratings. About the only sensible use for a low power MPPT controller would be for using a higher voltage, low current , thin film panel.
          2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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          • #6
            Yep fair cal​​​​​​l.

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            • #7
              Originally posted by littleharbor View Post
              One thing that doesn't make sense to me is why they even make such low powered MPPT controllers.
              Because as PT Barnum said; "There is a Sucker Born Every Minute". Exact same reason people buy Pet Rocks and Chia Pets.

              MSEE, PE

              Comment


              • #8
                Victron has a great Solar Calculator you can customize for any panels to any of their CC's. It is how you can determine if your panels would produce too much voltage when cold. Too much amperage is less common due to fewer watts being produced than rated unless they are perfectly aligned to the sun. I would think you could put a 180 watt panel on their 75/10 CC. -Bill

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                • #9
                  Yes. I was playing around with that spreadsheet last night. I also spoke with victron rep who said he same thing.

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