Mixing panels

momofgcmmomofgcm Solar Expert Posts: 35
I have (4) 63W (VOC17v?) panels that are older and am buying (4) new 208W (Voc37V?).

Can I somehow use all of these panels together in the new system? Maybe an old panel and a new panel in a string? Then the string in parallel?

Kim

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,697 admin
    Re: Mixing panels

    What is the Vmp/Imp of the panels and what battery bank voltage? I assume you are currently running a smaller PWM type charge controller.

    We need to know Voc (voltage open circuit) so that we don't over voltage the charge controller-but we need Vmp to make sure that it is high enough to charge the battery bank and make sure that we match within 10% of their Vmp voltage when connecting them in series.

    Need to know your battery bank voltage (12/24/48 ) to figure out the Vmp>Vbatt+2 volts or so.

    By the way, you are adding a new MPPT controller for the new panels?

    If you end up with two controllers--it may be easiest to leave the existing panels on the small PWM controller and just setup the array for the 205 watt panels on the new controller.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • momofgcmmomofgcm Solar Expert Posts: 35
    Re: Mixing panels

    Sorry.

    They are feeding an unknown controller (still trying to figure out if one is there already or if we have to order one) to a 12V battery bank. I assume the Vmp is similar to the Voc. The panels are poorly mismatched in terms of V's.

    63W (Voc = 17v?) panels that are older and am buying (4) new 208W (Voc = 37V?).
  • BB.BB. Super Moderators, Administrators Posts: 29,697 admin
    Re: Mixing panels

    With a 12 volt battery bank and a Vmp or Voc = 37 volts--you are going to have to use an MPPT charge controller.

    Perhaps I should move this thread into your other thread?

    I am sorry--but it is easier for my poor old brain if the details of the system design are in the same thread as the questions--or at least in this thread give us the basic system setup (I know that one thread with 10 different discussions about your system can be confusing to you)...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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