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  • Siemens QO breakers DC rating?

    Hey Everyone,

    I came across a mention of QO breakers with a 125v DC rating. It mentions both 48v rated and 125v rated. I am not having any luck finding the 125v rated breakers. Can anyone point me in the right direction?

    I am considering a Siemens load center and breakers for my combiner. My Voc is going to be around 80v with two panels in series.

    Is there anything special I need to know about using QO breakers instead of Midnites DC breakers?

    Thanks.

  • #2
    Originally posted by PNW_Steve View Post
    Hey Everyone,

    I came across a mention of QO breakers with a 125v DC rating. It mentions both 48v rated and 125v rated. I am not having any luck finding the 125v rated breakers. Can anyone point me in the right direction?

    I am considering a Siemens load center and breakers for my combiner. My Voc is going to be around 80v with two panels in series.

    Is there anything special I need to know about using QO breakers instead of Midnites DC breakers?

    Thanks.
    I took a look at can't even find Simens QO breakers listed. Do you have a data sheet. Another issue if that the panel they go in also needs to have a DC listing

    Andy

    Comment


    • #3
      I thought that QO was the Schneider SquareD breaker tradename. SquareD QO are only rated for 48VDC.
      https://www.se.com/us/en/product-ran...egory-id=50310

      The important thing to remember is that interrupting DC is much more demanding than interrupting AC. That's why these 240V AC breakers are only rated for 48V DC.

      The Midnight Solar breakers are rated for 150VDC. Sounds like you need them.
      7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV

      Comment


      • #4
        Originally posted by bob-n View Post
        I thought that QO was the Schneider SquareD breaker tradename. SquareD QO are only rated for 48VDC.
        https://www.se.com/us/en/product-ran...egory-id=50310

        The important thing to remember is that interrupting DC is much more demanding than interrupting AC. That's why these 240V AC breakers are only rated for 48V DC.

        The Midnight Solar breakers are rated for 150VDC. Sounds like you need them.
        According to the Schneider website they make breakers rated for both 48v and 125v. I have not had luck so far finding the 125v rated breakers. The 48v won't work for me as my Voc is going to be around 80v.

        Comment


        • #5
          here - the 150VDC rated from Midnight, not sure who makes them.
          http://www.midnitesolar.com/productP...Order=13&act=p
          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

          solar: http://tinyurl.com/LMR-Solar
          gen: http://tinyurl.com/LMR-Lister

          Comment


          • #6
            Originally posted by Mike90250 View Post
            here - the 150VDC rated from Midnight, not sure who makes them.
            http://www.midnitesolar.com/productP...Order=13&act=p
            Thanks.

            Any clue where I can find the breakers I am looking for?

            Comment


            • #7
              I don't know about the Siemens-QO


              CARLING breakers rated for 150VDC

              http://www.midnitesolar.com/pdfs/CA1...-767-321-L.pdf

              Carling may make a Load Center version , these are bolt on.

              The C-Series hydraulic/magnetic circuit breakers are
              ideal for applications that require higher amperage and
              voltage handling capability in a smaller package. They are
              available in 1-6 poles, 0.02-100amps, UL Recognized up to
              480VAC or 150VDC, UL489 Listed up to 240VAC or 125VDC,
              with choice of time delays, terminal options, actuator
              styles and colors.
              Carling Technologies, Inc.
              60 Johnson Avenue • Plainville, CT 06062-1177
              Phone: (860) 793-9281 • Fax: (860) 793-9231
              Email: sales@carlingtech.comwww.carlingtech.com

              Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
              || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
              || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

              solar: http://tinyurl.com/LMR-Solar
              gen: http://tinyurl.com/LMR-Lister

              Comment


              • #8
                Originally posted by PNW_Steve View Post

                Thanks.

                Any clue where I can find the breakers I am looking for?
                https://www.altestore.com/energy/midnite%20solar

                Comment


                • #9
                  Doesn't look like they have them.

                  Thanks for trying.

                  Comment


                  • #10
                    Originally posted by PNW_Steve View Post

                    Doesn't look like they have them.

                    Thanks for trying.
                    I'm surprised/, Did you try calling them? I've bought them there many times

                    You an also try https://www.solar-electric.com/marin...akers.html?p=2

                    Andy

                    Comment


                    • #11
                      My apologies, I somehow turned "Schneider" into "Siemens"

                      The breakers that I am looking for are actually Schneider.

                      Stuck on stupid......

                      Comment


                      • #12
                        Why do you think you need breakers? You do know with the right design, no breakers or fuses are needed. Guess you want to spend the cash huh?
                        MSEE, PE

                        Comment


                        • #13
                          Breakers are handy as a switch, for combiners to compare string performance as a quick sanity check. Also useful as a switch to disconnect PV from charge controller

                          Most fuse/holder combos are NOT rated for circuit interruption (meaning the contacts will fry if you pull a fuse while circuit is live) (only for the fuse to blow and interrupt)

                          And it's good practice to protect the cable from the battery to charge controller, in the odd chance the controller fails.

                          While sizing strings and only using 2 parallel PV strings, protection is not required, it's handy
                          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                          solar: http://tinyurl.com/LMR-Solar
                          gen: http://tinyurl.com/LMR-Lister

                          Comment


                          • #14
                            Originally posted by Sunking View Post
                            Why do you think you need breakers? You do know with the right design, no breakers or fuses are needed. Guess you want to spend the cash huh?
                            I can't tell if you are joking or serious........

                            Apparently there are few to none when it comes "right designs". We use overcurrent protection on every circuit.

                            Comment


                            • #15
                              Originally posted by PNW_Steve View Post
                              Apparently there are few to none when it comes "right designs". We use overcurrent protection on every circuit.
                              Dead serious, I am a professional electrical engineer with 40 years of experience. A solar panel is a Current Source, not a voltage source. With one or two strings of panels, makes it impossible for a solar panel system to operate a fuse. A 250 watt panel with a dead bolt fault will only deliver roughly 8 to 10-amps of current. 8 to 10 amps of current on a 15 or 20 amps breaker or fuse is a normal load current and will never operate a fuse.That is why electrical codes do not require a fuse on solar panels unless you cross the line with 3 or more strings.

                              Look at any panel specification and look for the spec Isc and learn what it means. Isc = Current Short Circuit. A 200 watt panel Isc = roughly 8 to 10 amps. That is the absolute maximum current that panel can deliver with its output shorted out (two output wires twisted together tightly.) Please explain how 8 to 10 amps is going to operate a 15 or 20 amp fuse or breaker.

                              You can certainly use OCPD on the panels if you wish, but they are not required and an unnecessary expense.
                              Last edited by Sunking; 10-13-2020, 11:56 AM.
                              MSEE, PE

                              Comment

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