Announcement

Collapse

Need help?

Please include the year, make and model of your GDRV ("2019 Reflection 315RLTS") along with the make and model of the component with the issue ("Dometic RM1350 refrigerator", "Furrion FMCM15-BL microwave", etc) in your question.
See more
See less

Question about plugging in a Portable Panel through existing MPPT

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Question about plugging in a Portable Panel through existing MPPT

    Hello all,

    I am planning on installing two 120watt "24 volt" panels in parallel on my roof top. These panels are from NewPowa and are 120W 40.5Voc and 3.7Isc each.

    I have a third identical panel that I would like to use as a portable panel occasionally. And when it is deployed, all 3 panels will be in parallel and all feeding into my MPPT charge controller. I want to be sure folks understand this is just a panel and not a solar suitcase with its own built-in controller.

    My concern is with plugging in the portable panel. Even if the Circuit Breaker is open, so that the roof top panels are disconnected from the charge controller, there will still be ~40 volts on that connector junction. Will this arc when the portable panel is plugged in? Am I going to char up the connectors over time? Is there a better way to do this?

    Thanks,
    Billm321

    Click image for larger version

Name:	Andersen.jpg
Views:	210
Size:	62.3 KB
ID:	43451
    Bill M.
    2021 Imagine XLS 22MLE
    2016 F-150 3.5L Ecoboost

  • #2
    Originally posted by BillM321 View Post
    Hello all,

    I am planning on installing two 120watt "24 volt" panels in parallel on my roof top. These panels are from NewPowa and are 120W 40.5Voc and 3.7Isc each.

    I have a third identical panel that I would like to use as a portable panel occasionally. And when it is deployed, all 3 panels will be in parallel and all feeding into my MPPT charge controller. I want to be sure folks understand this is just a panel and not a solar suitcase with its own built-in controller.

    My concern is with plugging in the portable panel. Even if the Circuit Breaker is open, so that the roof top panels are disconnected from the charge controller, there will still be ~40 volts on that connector junction. Will this arc when the portable panel is plugged in? Am I going to char up the connectors over time? Is there a better way to do this?
    You probably know this...but just in case the "24 volt" designation is referencing the number of cells in series that make up a string and not the output or battery configuration in the trailer. If that's confusing, please see https://gdrvowners.com/forum/solar/4...2598#post42598

    For the panel insertion I'd have two cutoff switches in the PV circuit (input side of the controller). Turn off the primary (electrically near the controller input) to turn off all PV going into the controller. Then turn off the secondary (electrically near the permanent, stationary panels). The junction for the portable panel is inserted between the two cutoffs. (Make sure and cover the portable panel so there's no voltage on it's connector when hooking up.) Once the new panel is inserted in the path, uncover the portable panel, turn on the secondary cutoff and then turn on the primary cutoff.

    Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

    Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

    Comment


    • #3
      Thank you Howard !!

      Never in a million years would I have thought of putting in two disconnects. And on that note....do you think circuit breakers necessary or can the disconnects just be normal on/off switches? These are 40v panels so I was thinking DC circuit breakers would be able to kill the arc better than those red Blue Sea switches. But I don't' know if it makes a difference or not.

      And yes, I am aware that the 24 volt designation is just that. That is why I put it in quotes. I am fairly new to the solar game, but I figured that a portable panel that was 20 feet away with a few connectors and switches in between each causing another voltage drop would be better served with a high voltage panel. I figured a higher voltage pushing a small current would be the most efficient way of getting the power to the MPPT.

      Thanks again ! This forum is the best !!

      Billm321
      Bill M.
      2021 Imagine XLS 22MLE
      2016 F-150 3.5L Ecoboost

      Comment


      • #4
        I just had another thought as I was re-drawing my diagram to include two breakers. If the "portable panel" is always covered when connecting and disconnecting so there is no voltage across its connector.....could I just wire its input to the output of the first breaker? Wouldn't this be the same as wiring it to the input of a second switch? The output of one is the input of the other and electrically the same point right?


        Click image for larger version

Name:	Andersen_2_switches.jpg
Views:	97
Size:	65.0 KB
ID:	43468

        Click image for larger version

Name:	Andersen_1 switch.jpg
Views:	87
Size:	62.4 KB
ID:	43469

        Billm321
        Bill M.
        2021 Imagine XLS 22MLE
        2016 F-150 3.5L Ecoboost

        Comment


        • #5
          Originally posted by BillM321 View Post
          I just had another thought as I was re-drawing my diagram to include two breakers. If the "portable panel" is always covered when connecting and disconnecting so there is no voltage across its connector.....could I just wire its input to the output of the first breaker? Wouldn't this be the same as wiring it to the input of a second switch? The output of one is the input of the other and electrically the same point right?

          Billm321
          Doh! Yes, that makes sense and does the same thing. Good catch! Helps to "see" it, doesn't it?

          For the Anderson connector that stays attached to the circuit I suggest a good protective cover to ensure when the portable isn't connected there's no chance of an accidental short.

          Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

          Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

          Comment


          • #6
            BillM321 -- it's interesting that NewPowa claims on the website the panels are built "for a 24V system". That doesn't make any sense to me at all--it's the output of the controller that's connected to a system's battery setup, not the solar panel.

            Am I missing something?

            Your three panel setup looks like (to me) like it is ideally configured to maximize your MPPT with the third panel. Hopefully some others look this over and chime in if I did miss something.

            https://www.newpowa.com/products/new...cy-solar-panel

            Click image for larger version

Name:	newpowa.JPG
Views:	88
Size:	73.8 KB
ID:	43474
            Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

            Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

            Comment


            • #7
              BillM321

              Thought about this a bit more. For the cost of an extra switch and a bus bar, this is probably what I'd do to implement the proposed system. It gives a way to isolate a single path or both paths as needed. It also provides a method of isolating the portable connector when a panel is not connected (so live voltage isn't sitting on the open connector.)

              I'm JAO ("Just Another Owner") like yourself--I'm not an engineer....


              Click image for larger version

Name:	Third Method.jpg
Views:	70
Size:	80.9 KB
ID:	43479
              Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

              Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

              Comment


              • #8
                OK...I think you have sold me on the idea of two breakers But I think I might just tie the two outputs together like this.

                Click image for larger version

Name:	Anderson2switches_take2.jpg
Views:	71
Size:	66.8 KB
ID:	43493

                Billm321


                Bill M.
                2021 Imagine XLS 22MLE
                2016 F-150 3.5L Ecoboost

                Comment


                • #9
                  BillM321 -- That will work! Based on the Blue Sea switches I used in my setup I'd expect there to be enough "post" for the two wires.

                  Please post how it works out once actually in use.
                  Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

                  Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

                  Comment

                  Working...
                  X