Forum Discussion

CA_Traveler's avatar
CA_Traveler
Explorer III
Nov 16, 2018

Connecting Dissimilar 12V Panels In Parallel

My son has 2 Kyocera 80W 16.9V 4.97A panels in parallel with 30’ of 10 ga wire one way to the controller. And he has 2 new Renogy 100W 18.9V 5.75A panels. We’re planning parallel and running a second set of wires also 30’ 10 ga one way to the same controller input.

The wiring calculator shows the Kyocera panel would have 16.6V at the controller or the Renolgy panels would have 18.5V at the controller.

Clearly 1.9V difference between the two panel types is significant and one option is to use 2 controllers.

However if we connect both sets of wires to one controller what it the result in terms of power loss or any other considerations?

Thanks for your input.
  • RJsfishin's avatar
    RJsfishin
    Explorer
    Nov 17, 2018
    I am running 3 different brand panels in parallel, 2 100w, and 1 90w for 5 yrs w/o any problems. The specs were close, but not the same. Power loss is sure not enuff for me to be concerned about. Under less than perfect sun conditions, I have seen 14 amps output.
  • red31's avatar
    red31
    Explorer
    Nov 17, 2018
    pwm controller, panels operate at batt voltage + line loss.
    mppt controller, during bulk operates at the combined panels mppt.
  • full_mosey's avatar
    full_mosey
    Explorer
    Nov 17, 2018
    Compare the % differences based on the Volts. You will lose 2V because the array will operate at 16.9V. The 16.9V panels could appear as shaded and possibly overheat.

    Parallel equal Volts, series equal Amps.

    You would want to know about blocking and bypass diodes Video.

    I would go with a separate controller.

    HTH;
    John
  • red31's avatar
    red31
    Explorer
    Nov 17, 2018
    renogy 100w Vmp of 18.9v @ 5.29A = 100 w
    if you buy that combined peak power is @ 16.9v, can you read the power @ 16.9v? 95w? is that a 5% loss? for the 100w panel and ~1/2 for the combined?

  • time2roll's avatar
    time2roll
    Nomad
    Nov 17, 2018
    No issues as the whole thing will be at battery voltage and produce Isc.
    Strap them on and enjoy the additional power.
  • mike-s's avatar
    mike-s
    Explorer
    Nov 17, 2018
    You didn't say which brand/model controller, or even the type, so everyone's left to guess.

    I'll assume it's a PWM controller, because with an MPPT you'd be better off connecting the panels in series. As already stated, they run at the battery voltage. You won't lose any efficiency due to mixing panels in parallel.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Nov 17, 2018
    The controller is a Sunforce 30A model 60032 PWM controller. The panels are Renogy RNG-100D 100W and Kyocera KC 80-01 80W.

    I believe both panels have bypass diodes which normally would not be a factor for matched parallel panels.

    My main concern it parallel panels with a 2V difference and any possible effects on each other including overheating.
  • time2roll's avatar
    time2roll
    Nomad
    Nov 17, 2018
    CA Traveler wrote:
    My main concern it parallel panels with a 2V difference and any possible effects on each other including overheating.
    No issues, none.
  • RJsfishin's avatar
    RJsfishin
    Explorer
    Nov 17, 2018
    time2roll wrote:
    CA Traveler wrote:
    My main concern it parallel panels with a 2V difference and any possible effects on each other including overheating.
    No issues, none.


    X3
    Just amazing when there ain't a problem, someone will make up one !
  • 3_tons's avatar
    3_tons
    Explorer III
    Nov 20, 2018
    There will be a theoretical difference but no noticably deficient difference - more panels = better harvest over a shorter period of time..

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