Forum Discussion

jayw900's avatar
jayw900
Explorer
Jul 11, 2016

PV upgrade decision

Right to the point: should I upgrade to a bigger panel or to an mppt controller?

More info for those that take the time to read:

I have a 100 watt, 21 ish volt panel and a pwm controller right now. I'd like to get a 345 watt, 39ish volt panel and mppt controller but they can't happen at the same time. Would it be better to go with the bigger panel knowing I'll lose out on some power right now or get an mppt controller to try and squeeze any extra out of my current 100 watt?

Right now I'm thinking the larger panel would be better even with the losses but want to make sure I'm not missing anything.
  • KD4UPL's avatar
    KD4UPL
    Explorer
    Jul 11, 2016
    Where exactly are you going to find a 345 watt panel? I haven't seen any bigger than 325. I'd love to get my hands on some if they exist.
    If the controller will handle the voltage of the big panel I would get that first. It would still probably be around a 60% increase from what you have now. The Voc of a panel will increase by as much as 25% when it's really cold. Make sure your current controller can handle that voltage.
  • 2oldman's avatar
    2oldman
    Explorer II
    Jul 11, 2016
    jayw900 wrote:
    I have a 100 watt, 21 ish volt panel and a pwm controller right now. I'd like to get a 345 watt, 39ish volt panel and mppt controller but they can't happen at the same time.
    They can, if ...

    a) the panels' amperage is about the same
    b) you wire them in series
  • pianotuna's avatar
    pianotuna
    Nomad III
    Jul 11, 2016
    As SMK said it depends on whether the existing charge controller can tolerate the higher voltage of the new panel.

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