Forum Discussion

Bobbo's avatar
Bobbo
Explorer II
Jul 28, 2021

Best weatherproof MPPT solar charge controller

I am about to buy 200 watts of portable solar panels in a suitcase configuration. I was about to get a Renogy 200 watt unit that comes with a weatherproof 20 amp PWM controller, but I really want an MPPT controller so I can hook those panels up in series rather than parallel. That way I can reduce voltage drop by carrying half of the amps at twice the voltage, and putting the controller beside the batteries instead of beside the panels. Then I had a brainstorm. Instead of buying the 200 watt unit with a PWM controller that I don't need, and wires I have to cut and reconfigure to get series panels, I will buy two of their 100 watt suitcases without a controller. That will make it easy-peasy to put them in series configuration. However, I still need a weatherproof MPPT controller.

Question, can someone point me to a decent weatherproof MPPT controller, preferably negative ground? (Victron doesn't list any of theirs as weatherproof.)

Thank you in advance
  • BFL13's avatar
    BFL13
    Explorer II
    Jul 28, 2021
    Not clear why you need it weatherproof when you intend to put it near your battery bank. You can put it inside near the battery bank and run the array-controller wiring to, eg, Anderson connectors going to the controller array terminals.

    It doesn't matter for RV use if the controller is pos or neg "grounded". You don't chassis ground the controller or the panels.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Jul 28, 2021
    You can also make your own suitcase with non suitcase panels. Ideally the controller shouldn't be exposed to vented flooded batteries. AGMs should be OK. Vent a container if necesssary to keep the controller from overheating.
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Jul 28, 2021
    A controller positioned outside? Not the best plan in my opinion. My go to company is WindyNation and I don’t see a weatherproof MPPT option. They do have a weatherproof PWM. The tests I’ve seen, including RV Tito, show little if any difference series vs. parallel. The setup, takedown, setup, takedown turn me off from a suitcase.
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Jul 28, 2021
    Voltage drop can be greatly mitigated by short distances and larger gauge wire.

  • 2oldman's avatar
    2oldman
    Explorer II
    Jul 28, 2021
    I don't get the need for weatherproof either. You want the higher voltage wires to be longest (to the coach and controller), not have the controller at the panels with the long 12v wires.
  • Bobbo's avatar
    Bobbo
    Explorer II
    Jul 29, 2021
    Reason for weatherproof: set up suitcase panels with controller not in enclosed space and go sightseeing. It rains. Rain can happen when not expected.

    Voltage drop CAN be mitigated by shorter distances and larger gauge wire. However, putting a suitcase panel in the sun may require longer distance with a wire gauge that is, ummm, more flexible. Hence my desire to put panels in series for higher voltage/lower current, and, put the solar controller close to the batteries rather than at the panels. A voltage drop from 36 volts/5 amps is much lower than voltage drop from 14 volts/10 amps. Especially when the dropped voltage from 36 volts is then converted to 14 volts.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Jul 29, 2021
    My 3 series panels on the roof have 62' total of 10 gauge wire to the controller resulting in 0.4% voltage drop which is very low. ie The panels on the ground could be about 31' from the controller.
  • Bobbo's avatar
    Bobbo
    Explorer II
    Jul 29, 2021
    CA Traveler wrote:
    My 3 series panels on the roof have 62' total of 10 gauge wire to the controller resulting in 0.4% voltage drop which is very low. ie The panels on the ground could be about 31' from the controller.

    You say your panels are SERIES. That is exactly what I am trying to accomplish. The weatherproof PWM controller that Renogy sells can not handle the panels in series, only in parallel. That is why I am wanting an MPPT controller.
  • BFL13's avatar
    BFL13
    Explorer II
    Jul 29, 2021
    Bobbo wrote:
    Reason for weatherproof: set up suitcase panels with controller not in enclosed space and go sightseeing. It rains. Rain can happen when not expected.

    Voltage drop CAN be mitigated by shorter distances and larger gauge wire. However, putting a suitcase panel in the sun may require longer distance with a wire gauge that is, ummm, more flexible. Hence my desire to put panels in series for higher voltage/lower current, and, put the solar controller close to the batteries rather than at the panels. A voltage drop from 36 volts/5 amps is much lower than voltage drop from 14 volts/10 amps. Especially when the dropped voltage from 36 volts is then converted to 14 volts.


    Yes, so just put the controller inside with short wires to the battery and long wires to the array.

    Instead of clamping the portable to the battery you clamp/plug to the terminals on the array side of the controller. Eg, run wires with connectors on them from the array side of the controller to where you can get at the ends to connect the portable array wires with matching connectors on them.

    In one set-up with the 5er we had, I put a "cable hatch" in the cargo bay door to pass wires through while still having the door locked shut. Others here have rigged Anderson connectors externally from wires going inside to the controller array side.

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