PV to THNN/ THWN connection

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  • nwdiver
    Solar Fanatic
    • Mar 2019
    • 422

    #16
    Originally posted by badwithusernames
    Thank you for the input. I agree that having multiple points of shutoff is pointless. With the inverter based shutoff, and Tigo RSS, you can shut it down at the panel end, or the inverter end; having a disconnect mid way serves what purpose?
    I have forwarded a bunch of info to my inspector and am waiting for a response. PITA, as he's the kind of guy that doesn't like to be told what to do, so I have to carefully choose my words. I know if I tell him the disconnect doesn't need to be there he'll want me to install three of them, just to be a dick.
    SD
    ??? You have RSS AND he wants an additional DC disco ? Jeeze that's idiotic. Does he know about the RSS?

    Comment

    • badwithusernames
      Member
      • Jun 2020
      • 44

      #17
      Well, after a tense few emails we had a discussion that ended favorably for me. In the end he agreed that the manual DC disconnect at the barn would serve no real purpose, and I get to have a junction box after all.
      Thanks again
      SD

      Comment

      • Ddwarf
        Junior Member
        • Feb 2020
        • 5

        #18
        Interesting, I just went through this exact process myself. Ground mount with Rapid shut down. I contacted a solar installer to do the final hookup and they wanted to add dc disconnects at the array(would need 3 disconnects for 3 strings). When I questioned the need, they insisted that "it's just how it's done". I ended up wiring it myself with a simple junction box per the three line. I used wire nuts.

        Inspector said it was fine. With RSS the need for one DC disconnect is questionable, why would I want another set??

        Comment

        • PVAndy
          Solar Fanatic
          • Aug 2014
          • 230

          #19
          Originally posted by Ddwarf
          Interesting, I just went through this exact process myself. Ground mount with Rapid shut down. I contacted a solar installer to do the final hookup and they wanted to add dc disconnects at the array(would need 3 disconnects for 3 strings). When I questioned the need, they insisted that "it's just how it's done". I ended up wiring it myself with a simple junction box per the three line. I used wire nuts.

          Inspector said it was fine. With RSS the need for one DC disconnect is questionable, why would I want another set??
          Remind the inspector that an MC4 connector is rated as a non load break DC Disconnect

          Andy

          Comment

          • Mike90250
            Moderator
            • May 2009
            • 16020

            #20
            Originally posted by Ddwarf
            ............... I ended up wiring it myself with a simple junction box per the three line. I used wire nuts..........
            Please consider replacing them with split bolts. Wire nuts will be seeing a hours long continuous load and can often overheat in a solar application,

            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

            • Ddwarf
              Junior Member
              • Feb 2020
              • 5

              #21
              What about using an MC4 connection - would they work better? Can they be used in a junction box?

              Comment

              • Mike90250
                Moderator
                • May 2009
                • 16020

                #22
                MC4 connectors work well when installed properly. Of course, the problem is, installing them properly without expensive crimp tools
                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

                • bob-n
                  Solar Fanatic
                  • Aug 2019
                  • 569

                  #23
                  I don't know about MC4 crimp tools, but there are some respectable Chinese crimp tools on the market now in the $20 price range.
                  7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV

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