what size diode do I need for 165w 18v flexible solar panel?

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  • khanh dam
    Solar Fanatic
    • Aug 2019
    • 391
    #1

    what size diode do I need for 165w 18v flexible solar panel?

    There are some 165w flexible solar panels for sale that are 32x32" 1kg and 18v, but they are missing mc4 connectors and diodes. How do I determine the correct diode rating for these panels? I will be using them for camping or an ebike and Yes I know flexible solar panels fail easily but their light weight is important for my application.
    The history of these panels is pretty interesting they were used by Loon to provide internet after natural disasters. via weatherbaloons that acted like cell towers: https://sunpower.maxeon.com/int/case...ng-world-above

    would these work well: 50v 10amp diodes: https://windandsolar.com/10-amp-50-volt-blocking-diode/

    Each maxeon sunpower solar cell is around 3.5Watts, 0.6Volts and 5.9Amps and the 36 cells are all wired together in series so each panel is 5.9amps @ 21.6 volts
    Last edited by khanh dam; 10-23-2021, 09:34 PM.
    Tags: None
    • Mike90250
      Moderator
      • May 2009
      • 16020
      #2
      The diodes you linked to should work fine. I believe it takes 3 diodes per panel, and maybe you should get some spares at that price . Does the J-box have mounting locations for the diodes?
      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

        • khanh dam
          Solar Fanatic
          • Aug 2019
          • 391
          #3
          Originally posted by Mike90250
          The diodes you linked to should work fine. I believe it takes 3 diodes per panel, and maybe you should get some spares at that price . Does the J-box have mounting locations for the diodes?
          there is no junction box. which is good because it would get in the way when folding the panels for travel. I'll just put diods inline with the cord. Hmm. how do I calculate how many diodes I need? I guess an extra one or 2 can't hurt?

            Comment

            • Mike90250
              Moderator
              • May 2009
              • 16020
              #4
              The bypass diodes internally bypass segments of the PV panel. If there is no J-box with taps, there is nothing for the bypass diodes to do. Modern charge controllers have backfeed diode function built in.


              PV bypass diode.png
              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

                • SunEagle
                  Super Moderator
                  • Oct 2012
                  • 15151
                  #5
                  I am guessing that the diodes are either built into the flexible panel or the cells in each panel are all wired in series to obtain the Vmp value. Then maybe wiring diodes external to the panels or maybe just using a combiner box to isolate each panel will work.

                    Comment

                    • khanh dam
                      Solar Fanatic
                      • Aug 2019
                      • 391
                      #6
                      THESE ARE INCOMPLETE PANELS, THEY NORMALLY HAVE A JUNCTION BOX AND MC4 CABLES BUT WERE NEVER FINISHED. I DO NOT THINK DIODES ARE BUILDT INTO THE PANEL. PLAN ON WIRING UP 2 IN SERIES FOR A SINGLE 43.6V PANEL AND A SINGLE GENASUN CONTROLLER. i'LL EMAIL GENASUN AND SEE IF THEY CAN TELL ME.

                      path.png

                        Comment

                        • khanh dam
                          Solar Fanatic
                          • Aug 2019
                          • 391
                          #7
                          https://www.youtube.com/watch?v=5rYy0gHZepI


                          this video explains it very well. guess I won't need the diodes since both panels will either be in full sun or shade most of the time.

                            Comment

                            • chrisski
                              Solar Fanatic
                              • May 2020
                              • 571
                              #8
                              Originally posted by khanh dam
                              folding the panels
                              Flexible panels don’t actually fold. If the panels are CIGS they may, but the panel you pictured looks like the flexible panel I have. THose can bend a little to mount to a roof, but would crack if consistently done so,

                              If these are so cheap you can throw them away, would be worth the try.

                              If you’re folding the two like a suitcase, that would work.

                                Comment

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