17v Vmax NewPowa vs 18v Vmax Renogy with Victron MPPT

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  • Naruto
    Junior Member
    • Aug 2021
    • 25
    #1

    17v Vmax NewPowa vs 18v Vmax Renogy with Victron MPPT

    Hi,
    I am working a RV solar application with very limited roof space, the standard 100W panels won't fit. My goal is to have at least 200w panel on the roof so my panel options are as following. (due to AC unit shading, panels will have to be connected in parallel).
    (Vmax/Voc)
    1. Renogy 100w + 50w x 2(21.6v/17.9v), total of 200w. consistent Vmax and Voc.
    2. NewPowa 75w x 3 (17v/20.3v) x 3, total of 225w. consistent but lower Vmax.

    They will be used with a Victron SmartSolar 20A MPPT controller.
    #2 is my preferred config, as it provides 25w more and would be simpler to install and better aesthetics as well. But I don't know the 1v drop in Vmax would have any negative impact on output. My Victron MPPT charger requires Voc 5v over battery voltage to start charging and 1v over battery to stay in charging mode. My lithium battery (3.4x4) has 13.6v near full charge, so I am looking at minimal 14.6v Vmax and 18.6Voc, which is within 17v and 20.3v.

    But my questions is, in practice, would this reduce the duration of a day that I get solar charging from these panels? compared to Renogy panels which has about 1v Vmax over NewPowa?

    Thanks!
    Last edited by sdold; 10-18-2021, 09:35 AM. Reason: Removed links
    Tags: None
    • Mike90250
      Moderator
      • May 2009
      • 16020
      #2
      What is the minimum MPPT voltage for the Victron ? 17.9V is barely enough voltage to charge with a cheap PWM controller, MPPT may need 25-30V to activate.
      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

        • chrisski
          Solar Fanatic
          • May 2020
          • 547
          #3
          With that 17 volt panel, when its warm or cloudy or both, panel voltage can drop below the panels rating. I have 18 - 22 volt panels and have not had problems with them, but 1 less volt could mean the SCC won’t work. THe 18- 22 volt panel I mentioned is my observed output. THe panel has 18 volts on it.

            Comment

            • SunEagle
              Super Moderator
              • Oct 2012
              • 15125
              #4
              Originally posted by chrisski
              With that 17 volt panel, when its warm or cloudy or both, panel voltage can drop below the panels rating. I have 18 - 22 volt panels and have not had problems with them, but 1 less volt could mean the SCC won’t work. THe 18- 22 volt panel I mentioned is my observed output. THe panel has 18 volts on it.
              If those 3 panels are wired in series then the voltage below 17V is mute.

                Comment

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