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Positive voltage from PV reads -18v when connected to charge controller??

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  • Positive voltage from PV reads -18v when connected to charge controller??

    Quick question:

    I have a Meanwell tn-1500-112 solar inverter/charge controller
    and when I tested the pos/neg leads coming from my panel... they read +18v
    I then connected to wires to the solar DC input of the inverter
    Places my alligator clips on the wires and my multimeter reads -18v
    Does this sound right??
    The flow of electrons is reversed when connected to the charge controller??
    I'm sure my wires are all pos to pos... neg to neg... no crossing
    Any ideas on why this is??

    Thanks in advance!

    -Aaron

  • #2
    No polarity does not change. Assuming they are standard battery panels you should read about 22 volts open circuit. When connected to the controller and batteries taking charge will depend on what type of controller you have. If MPPT should be around 17 to 18 volts. If PWM about 1 volt higher than the battery.
    MSEE, PE

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    • #3
      A good friend of mine (who's an electrician)... just told me earlier that when sampling the current in parallel... the polarity will "reverse". It was very overcast and I was getting +18v from the panel.... so I expect it to go even higher when sunny. I'm still trying to visualize the flow of electrons and WHY it would "reverse" as such. I have a Meanwell tn-1500 inverter/charge controller... and if the PV input wires were reversed it would recognize.

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      • #4
        Originally posted by aaronfro View Post
        A good friend of mine (who's an electrician)... just told me earlier that when sampling the current in parallel... the polarity will "reverse". ....
        Your good friend is a great joker. Buy him a beer.

        Nowhere in any PV system, does the polarity of anything magically reverse.
        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


        • #5
          Originally posted by aaronfro View Post
          A good friend of mine (who's an electrician)... just told me earlier that when sampling the current in parallel....
          His license should be revoked. Do not listen to him, he does not know what he is talking about.
          MSEE, PE

          Comment


          • #6
            Originally posted by Mike90250 View Post
            Your good friend is a great joker. Buy him a beer.

            Nowhere in any PV system, does the polarity of anything magically reverse.
            Maybe he was thinking about the Earth's magnetic field. It reverses polarity every once in a great while.

            Comment


            • #7
              Ok I'm not trying to get y'all too excited.

              I have the manual for the inverter... that I got from a friend.
              The manual... and all the distributors for Meanwell tn-1500-122
              Don't disclose the exact pin info on the PV DC solar input for the inverter
              If you look at the manual... you will see that the pos and neg input on the inverter is labeled
              And the solar input is on top... it's a 6 pin molex connector
              When I connect the pos of the PV panel to the pos input on the inverter (and the neg respectively)
              The wires then read -18v
              Either the inverter has the solar input polarities reversed (as labeled)
              Or something else is going on that I don't quite understand

              I didn't want to hook up the panel in reverse because of obvious reasons
              And I didn't get a "reversed polarity" warning beep or light

              I'm curious to know if anyone with an offgrid system
              When tapping into the pos and neg inputs of PV into charge controller/inverter
              Have experienced the same thing??

              If Meanwell (Taiwan) has the polarity of the input different as labeled... I wouldn't be suprised

              Comment


              • #8
                I have wired up many inverters, charge controllers and batteries.

                You have a miss-wire somewhere if you are seeing polarity changes.

                All of mine, use individual wires to each terminal. Wire them + to a + and - to a -, and it's always worked right for me.

                Never worked with Meanwell. Maybe they mean well, but it just doesn't work out ?
                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


                • #9
                  Originally posted by Mike90250 View Post
                  I have wired up many inverters, charge controllers and batteries.

                  You have a miss-wire somewhere if you are seeing polarity changes.

                  All of mine, use individual wires to each terminal. Wire them + to a + and - to a -, and it's always worked right for me.

                  Never worked with Meanwell. Maybe they mean well, but it just doesn't work out ?
                  [CENTER]SunLight @ Night[/CENTER]

                  Comment


                  • #10
                    I have to ask. Why are you wiring the panel to the back of the inverter?

                    It should be wired to a charge controller then to the battery.

                    WWW

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                    • #11
                      It's a solar inverter (has a charge controller built in)

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                      • #12
                        According to the spec sheet from the companies site , the positive 3 terminals are on the side
                        of the plug with the rounded corners an the negative on the side with the square corners.

                        I take it you have your batteries hooked up to the DC input before you hook up the solar panels
                        to the six pin plug?

                        Comment


                        • #13
                          Originally posted by aaronfro View Post
                          It's a solar inverter (has a charge controller built in)
                          Never seen one like that. Mind sharing the make and model number.

                          WWW

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