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mena661's avatar
mena661
Explorer
Jan 30, 2014

Rogue 20A MPPT Controller Question

Maybe Marc will chime in but maybe this question is generic enough that others might answer. I was perusing the Rogue 20A manual and saw the 320W limit for 12V systems. I'm wanting to put two 150W panels in series to up the volts and reduce current in an attempt to be able to use more panels on the controller at a later date. If my total amps is well under 20, can I go beyond the 320W max for the controller?

18 Replies

  • BFL13 wrote:
    In the manual above the 320w recommended limit guide it says:

    "....... Conversely, an array that is oversized will constantly push the MPT-2024 to its maximum limit of 20A. At and beyond this limit the power from the array is constrained and the MPPT algorithm is overridden so that the controller does not exceed its maximum current output. To avoid wasting available power, follow the guidelines given in Table 4.4.1 when sizing your array."
    Maybe I should read the whole manual next time. :) Thanks all, I'll get the bigger controller. And, yes, BFL I could get a cheaper (with higher amps) PWM Morningstar but I'm not sure if I'll be adding anymore panels. I'd have to do some more measuring on the roof to see if I could get more up there.
  • Mena,
    I live in AZ. I have checked my controller when it was 100+ out and the sun directly overhead many times with no excess heating observed. My son is a solar installer and I have watched him size many systems including two of my home systems. It is very common to size the PV array larger than the inverter.
  • Hi mena

    MPPT controller rating = Input Power (w/ a max voltage limit) & Output Current

    When the input power rating is exceeded (on quality controllers) typically the integrated "Processor controlled TRACKING function" is used to reduce the input power level, which then limits the output current to within the system specifications.

    Many folks run a higher power array than the controller is rated for with out issues.

    I suggest you do NOT
    Instead oversize the controller
    This oversize allows for -
    Future array expansion
    No wasted energy when the "clipping" occurs, wasted $ on power that is not used
    Reduced heat - higher the current higher the internal heat generated
    Longer life from running cooler
    Generally just a better system design
  • Mena, if you call them, there's a real good chance you'll get Marc on the phone. He's a good fella' and may take the time to answer all your questions. That was my experience, anyway.
  • smkettner wrote:
    The 20a rating is controller output amps to the battery.
    Ah crap, forgot about this. The controller will still put out 20A, series or not. I guess it will be the 30A then.

    CJ, is that 500W continuous? And will it do that in desert heat? I know it will just limit amps but I don't to run it on the edge.
  • I have 405 connected to mine with no issues. What you end up with is a curve that is flat on top on a full sun day but you will generate more power in the morning and evening than you would have if you kept your PV at or below spec. If I recall, Mark told me mine can handle 500 watts in reality.

    Oops, you said 20 amp controller. I didn't know Rogue made a 20 amp.
  • The 20a rating is controller output amps to the battery.
    Much more than 320w panel rating and the controller will just clip the power.
  • In the manual above the 320w recommended limit guide it says:

    "....... Conversely, an array that is oversized will constantly push the MPT-2024 to its maximum limit of 20A. At and beyond this limit the power from the array is constrained and the MPPT algorithm is overridden so that the controller does not exceed its maximum current output. To avoid wasting available power, follow the guidelines given in Table 4.4.1 when sizing your array."

    With 300w you should see 300/130 x8.2 = 19a with PWM and array pointed at a high sun. MPPT should be slightly more amps so the 320w recommended limit checks out with my formula (so Marc got his math right :) )

    So IMO, although you will not hit the 100voc limit with two 22v panels, there is no point adding more panels. You can get a second controller for another set of panels and put both controllers on the battery bank, or get a higher amp/watt controller.

    Or for a lot less money---- :)

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