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Disconnect switch between solar panels and solar charge controller

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  • Disconnect switch between solar panels and solar charge controller

    I search for this and re-learned that I need a disconnect switch between my panels and the MPPT solar controller. However the details of what folks have used are sparse.
    Some videos and posts are using a bin rail circuit breaker to act as a switch.
    https://www.amazon.com/uxcell-Low-vo...7KNQHJ8K&psc=1
    and the box
    https://www.amazon.com/Fielect-Switc...7ZQZBL2Z&psc=1
    or
    https://www.amazon.com/Flameer-Circu...productDetails

    Others have used just a switch like the following

    https://www.amazon.com/BEP-701-Batte...540330&sr=8-61
    or
    https://www.continuousresources.com/...ery-switch-red

    The circuit breakers would be cheaper, but I am leaning towards the Blue Sea switch. Its durable and positive.

    If I may ask what are folks using for this application?

    Thanks for the help

    Ye-per back to my corner again
    Keith

    Cumming up inverter charger decision. I will be posting a side by side comparison of my choices - don't hit me I was asked to do it I am still on the fence and if I go one way SWMBO may put me in the dog house
    2018 Reflection 150 Series 220RK 5th wheel. Reese R20 Titan hitch, Steadyfast system, 2004 F350 King Ranch dually

  • #2
    Yoda I used a blue sea. Like you say, nice and positive. Breakers are not really meant to be turned on and off. Not that said I do not turn off the panel disconnect often enough, but I believe in the right part for the job.
    Neil Citro
    2018 Reflection 28bh
    2019 F350 6.7L Long Bed Crew Cab

    Comment


    • #3
      Originally posted by ncitro View Post
      Yoda I used a blue sea. Like you say, nice and positive. Breakers are not really meant to be turned on and off. Not that said I do not turn off the panel disconnect often enough, but I believe in the right part for the job.
      Thanks Neil
      2018 Reflection 150 Series 220RK 5th wheel. Reese R20 Titan hitch, Steadyfast system, 2004 F350 King Ranch dually

      Comment


      • #4
        Originally posted by Yoda View Post

        Thanks Neil
        As shown in the Master Diagram for my system...Blue Sea. If you look at AMSolar's diagrams that I've referenced in the past, you'll also see they use the Blue Sea in their configurations. Don't think too hard on this one, Keith.

        Click image for larger version

Name:	Blue Sea Switch.JPG
Views:	158
Size:	62.6 KB
ID:	47294
        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


        • #5
          I had the same Blue Sea switch for my panels shutoff but decided to add 2 more panels (going from a 2S2P to a 3S2P system) that raised my voltage from 48V to 72V - this exceeds the Blue Sea Switch rating, so I replaced it with a double pole DC breaker rated at 250VDC (and much lower amps - 63 amps versus 300 amps that the Blue Sea was rated). I think I am code-compliant now

          So check the voltage of your system (note that the charge controller can handle up to 150 Volts, and depending on how you wire your panels you can run into potential issues (first is getting shocked .... the Blue Sea Switch does not full protect the terminals from human contact unless flush mounted ... and when working from the back one can still put their fingers on a live DC wire. I think that is the reason for the 48VDC rating on the Blue Sea switch. Physically I am pretty sure it can easily handle shutting off the up to 20 amps of current at 72V DC ...

          The following video was educational .... https://www.youtube.com/watch?v=HOXnWXvLXko

          Comment


          • #6
            I found the following on the Explorist.life website while researching the design of my solar system:

            1- Is a Dual Pole Disconnect Necessary for a DIY Camper Solar Array?
            Yes… And here’s why:

            NEC 2020 Article 690.13 section (E) States that “ The PV System disconnecting means shall simultaneously disconnect the PV system conductors that are not solidly grounded from all conductors of other wiring systems." Since camper electrical systems are generally NOT grounded, this means that both the positive and negative conductors from the solar array need to be able to be simultaneously disconnected, and a dual pole breaker does exactly that where those other breakers and switches do not.

            2- Can’t I just use one of the commonly used 12V DC resettable breakers/switches like this?
            (note by me - pictures were shown of common switches and breakers used in solar systems)

            No. You shouldn’t. For two reasons…

            1: Those switches/breakers do not satisfy the “Must disconnect both the positive and negative wire” requirement set by NEC 2020 Article 690.13 section (E)
            2: Those switches/breakers have a max operating voltage of 48V, 48V, and 24V (respectively, top to bottom) and a properly designed solar array controlled by an MPPTcharge controllerwill VERY MUCH LIKELY exceed 48V.


            I used a 50A, 400V dual pole breaker in my system.
            Last edited by bertschb; 03-24-2021, 09:30 AM.
            Brian & Kellie
            2020 Grand Design Solitude 310GK-R, FBP, MORryde IS w/ disc brakes, 1,460w solar
            2020 Ford F-350 Platinum SRW PSD Tremor, 60g TF fuel tank, Hensley BD3-F air bag hitch

            Previous setups:
            2019 Grand Design Solitude 373FB-R, 2019 Ford F-350 Platinum DRW Powerstroke, Hensley BD5 air bag hitch
            2016 Grand Design Reflection 318RST, 2016 GMC 3500 Denali SRW Duramax, Hensley BD3 air bag hitch

            Comment


            • #7
              Originally posted by openrangeowners View Post
              I had the same Blue Sea switch for my panels shutoff but decided to add 2 more panels (going from a 2S2P to a 3S2P system) that raised my voltage from 48V to 72V - this exceeds the Blue Sea Switch rating, so I replaced it with a double pole DC breaker rated at 250VDC (and much lower amps - 63 amps versus 300 amps that the Blue Sea was rated). I think I am code-compliant now

              So check the voltage of your system (note that the charge controller can handle up to 150 Volts, and depending on how you wire your panels you can run into potential issues (first is getting shocked .... the Blue Sea Switch does not full protect the terminals from human contact unless flush mounted ... and when working from the back one can still put their fingers on a live DC wire. I think that is the reason for the 48VDC rating on the Blue Sea switch. Physically I am pretty sure it can easily handle shutting off the up to 20 amps of current at 72V DC ...

              The following video was educational .... https://www.youtube.com/watch?v=HOXnWXvLXko
              I am at 45V (open circuit) in series with my 2 190W panels - so I should be good
              Thanks for the input,
              2018 Reflection 150 Series 220RK 5th wheel. Reese R20 Titan hitch, Steadyfast system, 2004 F350 King Ranch dually

              Comment


              • #8
                Originally posted by howson View Post

                As shown in the Master Diagram for my system...Blue Sea. If you look at AMSolar's diagrams that I've referenced in the past, you'll also see they use the Blue Sea in their configurations. Don't think too hard on this one, Keith.

                Click image for larger version

Name:	Blue Sea Switch.JPG
Views:	158
Size:	62.6 KB
ID:	47294
                Howard - you did it again. I looked at their diagrams, but just found generic images, and looked at some of their packages to try and identify the switches they used. I guess I did not look hard enough. I think Blue Sea it is.
                2018 Reflection 150 Series 220RK 5th wheel. Reese R20 Titan hitch, Steadyfast system, 2004 F350 King Ranch dually

                Comment


                • #9
                  Originally posted by openrangeowners View Post
                  I had the same Blue Sea switch for my panels shutoff but decided to add 2 more panels (going from a 2S2P to a 3S2P system) that raised my voltage from 48V to 72V - this exceeds the Blue Sea Switch rating, so I replaced it with a double pole DC breaker rated at 250VDC (and much lower amps - 63 amps versus 300 amps that the Blue Sea was rated). I think I am code-compliant now

                  So check the voltage of your system (note that the charge controller can handle up to 150 Volts, and depending on how you wire your panels you can run into potential issues (first is getting shocked .... the Blue Sea Switch does not full protect the terminals from human contact unless flush mounted ... and when working from the back one can still put their fingers on a live DC wire. I think that is the reason for the 48VDC rating on the Blue Sea switch. Physically I am pretty sure it can easily handle shutting off the up to 20 amps of current at 72V DC ...

                  The following video was educational .... https://www.youtube.com/watch?v=HOXnWXvLXko
                  howson bertschb

                  So the Explorist life guy is saying that BOTH the positive and negative from the solar panels should be switched. Brian is this how you see it? Howard if the video is correct why would AM solar only switching the positive side? I may want to contact them on this - more to learn. But then again I may be overthinking on this - Ya think?

                  He also promotes using ferrals for connections. I happen to have those available from another project. Is this a better way, or just a different way of doing things?

                  Being a sponge here

                  Thanks Keith
                  2018 Reflection 150 Series 220RK 5th wheel. Reese R20 Titan hitch, Steadyfast system, 2004 F350 King Ranch dually

                  Comment


                  • #10
                    Originally posted by bertschb View Post
                    I found the following on the Explorist.life website while researching the design of my solar system:

                    1- Is a Dual Pole Disconnect Necessary for a DIY Camper Solar Array?
                    Yes… And here’s why:

                    NEC 2020 Article 690.13 section (E) States that “ The PV System disconnecting means shall simultaneously disconnect the PV system conductors that are not solidly grounded from all conductors of other wiring systems." Since camper electrical systems are generally NOT grounded, this means that both the positive and negative conductors from the solar array need to be able to be simultaneously disconnected, and a dual pole breaker does exactly that where those other breakers and switches do not.

                    2- Can’t I just use one of the commonly used 12V DC resettable breakers/switches like this?
                    (note by me - pictures were shown of common switches and breakers used in solar systems)

                    No. You shouldn’t. For two reasons…

                    1: Those switches/breakers do not satisfy the “Must disconnect both the positive and negative wire” requirement set by NEC 2020 Article 690.13 section (E)
                    2: Those switches/breakers have a max operating voltage of 48V, 48V, and 24V (respectively, top to bottom) and a properly designed solar array controlled by an MPPTcharge controllerwill VERY MUCH LIKELY exceed 48V.


                    I used a 50A, 400V dual pole breaker in my system.
                    Since I'm not an engineer I can't speak to the NEC code or it's applicability. All I know is there's not a single diagram drawn by Garret Towne (an electrical engineer) at AMSolar that does not use a single Blue Sea switch on the + between the combiner and MPPT.

                    I don't know the qualifications of the Explorist individual, but even if he's a NASA rocket scientist that doesn't change that when there's more than one engineer in a room they will argue over the "correct" implementation of a code standard.

                    OPINION: Having an additional disconnect on the negative won't hurt anything, but it does nothing additional to actually disconnect the solar panels from the system. No power will pass from the MPPT to the rest of the trailer's circuits once the + is disconnected between the panels and the controller.

                    Sample AMSolar diagram...

                    Click image for larger version

Name:	Example AMSolar Diagram.JPG
Views:	159
Size:	88.6 KB
ID:	47333
                    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


                    • #11
                      Originally posted by howson View Post

                      Since I'm not an engineer I can't speak to the NEC code or it's applicability. All I know is there's not a single diagram drawn by Garret Towne (an electrical engineer) at AMSolar that does not use a single Blue Sea switch on the + between the combiner and MPPT.

                      I don't know the qualifications of the Explorist individual, but even if he's a NASA rocket scientist that doesn't change that when there's more than one engineer in a room they will argue over the "correct" implementation of a code standard.

                      OPINION: Having an additional disconnect on the negative won't hurt anything, but it does nothing additional to actually disconnect the solar panels from the system. No power will pass from the MPPT to the rest of the trailer's circuits once the + is disconnected between the panels and the controller.

                      Sample AMSolar diagram...

                      Click image for larger version

Name:	Example AMSolar Diagram.JPG
Views:	159
Size:	88.6 KB
ID:	47333
                      Thanks Howard
                      BTW the picture you posted is an example of the generic switch shown in their diagrams - thus my question on what to use.

                      Thanks again
                      Keith
                      2018 Reflection 150 Series 220RK 5th wheel. Reese R20 Titan hitch, Steadyfast system, 2004 F350 King Ranch dually

                      Comment


                      • #12
                        For our home Solar setup, the disconnect is for both poles. The reason is for human safety. Lets say there is 150 volts DC being supplied by a panel array.

                        The potential for shock if one side is still energized is greater than if both sides are blocked. Voltages greater than 48VDC can be very deadly to a human.

                        48V is the practical and LEGAL definition of the maximum voltage to be considered "low voltage" and intrinsically "safe". Certainly 48V delivered UNDER your relatively insulating skin surface could kill you if delivered in the "right" place. But we are assuming people aren't walking around with subcutaneous electrodes exposed to accidental contact with "LV" wiring. 48V is reasonably safe for most people under normal conditions.

                        Comment


                        • #13

                          howson openrangeowners bertschb ncitro
                          AM solar responded

                          Keith,
                          There’s actually no code regarding mobile solar systems. But prior to working at AM Solar, I worked at a company that did do off-grid systems that required code compliance. Since electric current flows in loops, a disconnect added to the negative, when there is already one on the positive, would be redundant. It’s not that there are two different types of electricity flowing through the two lines. Cutting off the positive is going to cut everything off.

                          Anyone recommending this is likely not familiar with electricity, or following rules established by someone who is not familiar with electricity (which actually happens all the time).

                          One switch is fine.
                          Garret Towne, Electrical Engineer
                          3555 Marcola Rd., Springfield, OR 97477
                          t: 541.726.1091
                          e: garret@amsolar.com
                          w: www.amsolar.com
                          running back to my corner now
                          Keith
                          Last edited by Yoda; 03-24-2021, 02:58 PM.
                          2018 Reflection 150 Series 220RK 5th wheel. Reese R20 Titan hitch, Steadyfast system, 2004 F350 King Ranch dually

                          Comment


                          • #14
                            I found a couple of links about mobile install of solar panels and most MPPTs having common ground between the MPPT's PV Input and the Battery Output terminals.
                            They make is sound like our solar PV conductors are grounded (Neg DC Busbar and then to trailer frame.)
                            I see there's numerous questions about the PV disconnect of Positive or Positive & Negative conductors.

                            Grounding MPPT 100/50 - https://community.victronenergy.com/...ppt-10050.html
                            Guy Stewart (Victron Community Manager) answered · Jan 30 2019 at 6:44 AM Best AnswerACCEPTED ANSWER
                            You should connect the solar panel negative to the solar panel negative terminal on the MPPT

                            Victron Wiring Unlimited:
                            7.7 System grounding
                            Off-grid system grounding
                            Do not ground the positive or negative of the PV array. The PV negative input of the MPPT is not isolated from the negative output.

                            Do my panels need Double Pole breakers? If so, why?
                            https://forum.solar-electric.com/dis...kers-if-so-why
                            Gene and Kim
                            2015 Grand Design Reflection 317RST
                            2017 RAM 3500 CC, LB, 4x2, 6.7L CTD

                            Comment


                            • #15
                              I agree with what AM Solar stated. The only reason I changed my cutoff was because I exceeded the Maximum Voltage rating (48VDC) of the single switch. I was able to source a double pole breaker rated at 250VDC. I was not able to easily source a quality single switch with a higher voltage rating - something above 75 volts.

                              What if I cut power from the + side of my panels and was working on the system (with just a single switch cutting power to the + side)?

                              Now lets say I accidentally touched the hot side of the switch with my finger and my leg was up against the frame of the camper. Since the panels - line is going ultimately to camper ground (assuming it becomes grounded in the Charge Controller - that can actually be debated in an MPPT controller ...) I could get a nice shock.

                              With a double pole shutoff, touching the same + side with my finger and with my leg grounded - I would not complete the circuit with my body because the - is also disconnected. The breaker is in a box and the connections are more protected as well, so I have no regrets. I was fine with the single high quality switch I had before adding more panels in series.

                              "Do not ground the positive or negative of the PV array. The PV negative input of the MPPT is not isolated from the negative output." - so the scenario above what be present.

                              Comment

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