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Mppt or copper

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  • Mppt or copper

    My pwm 4 100 watt 12 volt array is 66 ft on 8 awg 10% drop. Mppt puts me at 2%. I'm currently seeing 310 watts and 22 amps midday at 32c on pwm.With Mppt what should I see??
    Last edited by Ho jo; 06-09-2018, 06:04 PM.

  • #2
    Your question makes no sense at all, nor does the title. If you have a MPPT controller with a Voc input of at least 100 Volts, panels wired in series, using 12 AWG wire with a 1-way distance of 66 feet only looses 1% with 33 amps into a 12 volt battery.

    So how in the world do you loose 10% using 8 AWG?

    Let me guess, you wired your panels in parallel?
    MSEE, PE

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    • #3
      10% loss for all in parallel? Then going to 2 in series in parallel with 2 more in series, your
      loss will drop to around 2.5% with MPPT. If you can tolerate the voltage of all in series, even
      10 gauge will have less loss, no fuses needed. Bruce Roe

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      • #4
        What i meant to say On pwm to go 66 ft I'd need 2 awg for a 2% drop. Or I could buy a mppt controller.

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        • #5
          Originally posted by Ho jo View Post
          What i meant to say On pwm to go 66 ft I'd need 2 awg for a 2% drop. Or I could buy a mppt controller.
          With PWM even if you control voltage drop to 2%, you still loose over 40% of the power. Right now you have to wire your panels in parallel which gives you around 20 amps. With MPPT wire all panels in series and you can use 12 AWg wire between the panels and controller (less than 2% loss) and on the output of the controller you will have 30 to 33 amps. Keep the 8 AWG, loose the PWM controller, and rewire your panels in series.
          MSEE, PE

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          • #6
            With 4 22.5 voc panels 90 volts x 25% safety puts me at 112 volts. 150 volt cc are more expensive. If I did 2s 2p 38 volts 10.58 amps I could use a 100 volt cc and still be in the 2% volt drop. And wouldn't all in series 90 down to 12 volts compared to 38 to 12 be less efficient for the charge controller?

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