Announcement

Collapse
No announcement yet.

Mixing different Wattage Solar Panels

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Mixing different Wattage Solar Panels

    Hi i have two 55w (22.4Voc. 3,19A Isc. 18,67Vmp. 2,95Imp) panels connected in series to my MPPT charge controller on my boat... they have only been in use a few months. Unfortunately they don't deliver enough power to all my equipment.
    I have been offered a band new 100W (22.5Voc. 5.92A Isc. 18.5Vmp. 5,41Imp) panel cheap.
    Is it possible to parallel the two 55w panels to make 22,4V Voc, 3,19A Isc*2=22,4Voc 6,38A Isc and then series connect those with the one 100W. 22,5Voc, 5,92A Isc panel and get 22,5Voc+22,4Voc=44,9Voc and 5,92A Isc. and only loose the last 0,46A Isc?
    or is it a better choice to just parallel all 3 of them and only loose the 0,1Voc? (as i calculate it i get 9,7Watt more out of the last option)?
    Last edited by DennisTheMenace; 05-06-2020, 11:05 PM.

  • #2
    Originally posted by DennisTheMenace View Post
    Hi i have two 55w (22.4Voc. 3,19A Isc. 18,67Vmp. 2,95Imp) panels connected in series to my MPPT charge controller on my boat... they have only been in use a few months. Unfortunately they don't deliver enough power to all my equipment.
    I have been offered a band new 100W (22.5Voc. 5.92A Isc. 18.5Vmp. 5,41Imp) panel cheap.
    Is it possible to parallel the two 55w panels to make 22,4V Voc, 3,19A Isc*2=22,4Voc 6,38A Isc and then series connect those with the one 100W. 22,5Voc, 5,92A Isc panel and get 22,5Voc+22,4Voc=44,9Voc and 5,92A Isc. and only loose the last 0,46A Isc?
    or is it a better choice to just parallel all 3 of them and only loose the 0,1Voc? (as i calculate it i get 9,7Watt more out of the last option)?
    Since your current setup is series, the controller can apparently handle voltages in the range of 36-45 V. Would it work properly with 18-22.5 V available in a parallel connection? That may be the deciding factor. It should be possible to wire the two 55 W panels in parallel then connect the 100 W in series.

    Neither connection is going to allow all three panels to operate at their "optimum" point. The parallel connection requires all three to operate at the same output voltage and whatever current they can each muster at that voltage. The series connection forces the same current, and whatever voltage each can muster. The short circuit current won't mean enough, but you only have open circuit and one loaded voltage/current point. You would probably need the whole load curve (a graph) to decide which optimizes output from the solar array. However, I would look at what voltage range is best for your controller too.

    Are you sure your present connection is series? A lot of controllers seem to handle 18-20 V loaded and optimize into "12 V" battery banks. If that is the case, parallel would be your only option.

    Comment


    • #3
      John S Yes they are operating in series at the moment. My MPPT controller can handle op to 100PV in. I have testet and measured witch setup is working best with the two 55W panels i currently have and measured on the charge current it is trowing out to the battery, I seem to get a little more out of series connecting them to the 37,34-44.8 V. There my MPPT controller trow out around 7,2A 13,8V to my battery. Where as when I parallel connect the two panels to 18,67-22.4V 5,9A my MPPT controller seem to trow around 13,8V 7A charge current to my battery. the difference is "only" around 0,2A on the battery side, but as i said... just a nip more in series......

      I do know that if i want to get the absolutely most out of the array if i buy that 100W panel from my friend would be to buy one more MPPT controller for that panel too.... but then it is not a cheap solution anymore.... :/

      There fore my original question... which setup would be the best with my current MPPT controler and the 3 panels?
      Last edited by DennisTheMenace; 05-07-2020, 05:10 AM.

      Comment


      • #4
        Originally posted by DennisTheMenace View Post
        John S Yes they are operating in series at the moment. My MPPT controller can handle op to 100PV in. I have testet and measured witch setup is working best with the two 55W panels i currently have and measured on the charge current it is trowing out to the battery, I seem to get a little more out of series connecting them to the 37,34-44.8 V. There my MPPT controller trow out around 7,2A 13,8V to my battery. Where as when I parallel connect the two panels to 18,67-22.4V 5,9A my MPPT controller seem to trow around 13,8V 7A charge current to my battery. the difference is "only" around 0,2A on the battery side, but as i said... just a nip more in series......

        I do know that if i want to get the absolutely most out of the array if i buy that 100W panel from my friend would be to buy one more MPPT controller for that panel too.... but then it is not a cheap solution anymore.... :/

        There fore my original question... which setup would be the best with my current MPPT controler and the 3 panels?
        Without the detailed curves, no way to be absolutely 100% sure; you could try both.

        However, my bet is on the series connection. Using just the two 55 W panels, series and parallel, you get more with the series connection. That tells me the controller is "happier" with the higher voltage (more efficient). Ignoring losses, the series and parallel panels should be identical, so the controller must have an efficiency difference at the two voltages.

        Wiring the two 55 W panels in parallel then the 100 W panel in series will come closer to that high efficiency operating voltage. At least, that's my theory. But if you like to experiment, no harm in trying both, and there is certainly a chance my theory is wrong.

        Comment

        Working...
        X