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  • Does This seem right?


    This shows one leg (110 of the 220) of my four panels in full sun.
    The voltage seems correct but the amps should be about 8 (800 watts).
    Note how the CT hole is much larger than the #12 wire.
    Please Comment. Thanks.

    20180629_164008.jpg
    20180629_164033.jpg

  • #2
    Your batteries are likely nearly full and accepting little current.
    2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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    • #3
      There are no batteries. Each of the four panels have grid tie micro inverters. The panels are wired directly to the main panel through a double pole breaker.

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      • #4
        Originally posted by Aston72 View Post
        There are no batteries. Each of the four panels have grid tie micro inverters. The panels are wired directly to the main panel through a double pole breaker.
        What is the DC current into the inverters? What is the DC voltage into the inverters?

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        • #5
          What is the CT ratio? If it is very large (200/5) then you may not get a linear measurement if the load is small (<10% of primary amp rating).

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          • #6
            Originally posted by Aston72 View Post
            This shows one leg (110 of the 220) of my four panels in full sun.
            The voltage seems correct but the amps should be about 8 (800 watts).
            Note how the CT hole is much larger than the #12 wire.
            Please Comment. Thanks.

            20180629_164008.jpg
            20180629_164033.jpg
            Actually it looks like the numbers are correct.

            With 173 watts (.173kW) at 119.1 volts AC you should see about 1.45 amps.

            I guess the problem is that you have a lot more panel wattage in that system but for some reason you are not getting the full production output.

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            • #7
              Originally posted by SunEagle View Post
              What is the CT ratio? If it is very large (200/5) then you may not get a linear measurement if the load is small (<10% of primary amp rating).
              I do not know. Is there a way to find out?

              However, it does seem odd to me when the #12 wire size with insulation is 0.124" and the CT has a hole diameter of 0.643".

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              • #8
                Originally posted by SunEagle View Post

                I guess the problem is that you have a lot more panel wattage in that system but for some reason you are not getting the full production output.
                That is what I am wondering. I took these readings later in the afternoon. I will take new readings about noon tomorrow and report then.

                Thanks all for the replies.

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                • #9
                  Originally posted by Aston72 View Post

                  I do not know. Is there a way to find out?

                  However, it does seem odd to me when the #12 wire size with insulation is 0.124" and the CT has a hole diameter of 0.643".
                  Some CT's have the amp ratio rating printed on the side, others do not because it comes with the paperwork.

                  The location of the #12 wire may cause the readings to be slightly off if it is not "centered" in the CT hole but that should not be the problem.

                  Like I said the readings that you are getting work out mathematically (173 watts = 119 volts x 1.45 amps) so the issue is somewhere with the panel circuit wiring and not the CT.

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                  • #10
                    Originally posted by SunEagle View Post

                    Some CT's have the amp ratio rating printed on the side, others do not because it comes with the paperwork.

                    The location of the #12 wire may cause the readings to be slightly off if it is not "centered" in the CT hole but that should not be the problem.

                    Like I said the readings that you are getting work out mathematically (173 watts = 119 volts x 1.45 amps) so the issue is somewhere with the panel circuit wiring and not the CT.
                    Yes. I can see where they work out but I think in the readings the panels appear to be under producing.
                    Today, I waited until about 1 pm and then waited for full sun and got the readings shown in the picture.
                    I think that is more like what the amps should be for one leg of the 220V??? 4 amps for each leg? Is that how it works.

                    today.jpg

                    I will make a little insert of some nonconductor material to better center the #12 feed wire.

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                    • #11
                      Originally posted by Aston72 View Post

                      Yes. I can see where they work out but I think in the readings the panels appear to be under producing.
                      Today, I waited until about 1 pm and then waited for full sun and got the readings shown in the picture.
                      I think that is more like what the amps should be for one leg of the 220V??? 4 amps for each leg? Is that how it works.

                      today.jpg

                      I will make a little insert of some nonconductor material to better center the #12 feed wire.
                      It depends on how you wired the meters and CT.

                      Based on the readings of 487 watt / 119.1 volts = 4.08 amps. So what you are measuring seems correct.

                      If one leg is really 220V then you have either incorrect settings for your meters or incorrect wiring of the circuit because you are only getting 119 volts not 220 volts..

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                      • #12
                        Originally posted by SunEagle View Post

                        If one leg is really 220V then you have either incorrect settings for your meters or incorrect wiring of the circuit because you are only getting 119 volts not 220 volts..
                        Sorry. I confused you. One leg is 120V and reading as it should be. Just doing one leg for now for testing.

                        The readings were taken about noon time. By about 4 pm, I notice quite a decline in amps. About half, roughly. What should be expected?

                        On the CT, there are no numbers on it I can see nor is there any info in the documentation.

                        Thanks for your reply.



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                        • #13
                          Originally posted by Aston72 View Post

                          Sorry. I confused you. One leg is 120V and reading as it should be. Just doing one leg for now for testing.

                          The readings were taken about noon time. By about 4 pm, I notice quite a decline in amps. About half, roughly. What should be expected?

                          On the CT, there are no numbers on it I can see nor is there any info in the documentation.

                          Thanks for your reply.


                          You are welcome.

                          CT's don't cost that much so depending on the max amount your panels can generate the primary rating on it could be 40% to 60% more.

                          So depending on the panel rating or charge controller output rating will determine your primary CT rating + or - a percentage.

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                          • #14
                            Originally posted by SunEagle View Post
                            What is the CT ratio? If it is very large (200/5) then you may not get a linear measurement if the load is small (<10% of primary amp rating).
                            A trick I have used to verify small loads is to pass the wire through the CT a few times......then divide the measurement results by the number of windings through the CT. Works like a charm.

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                            • #15
                              Originally posted by DanS26 View Post

                              A trick I have used to verify small loads is to pass the wire through the CT a few times......then divide the measurement results by the number of windings through the CT. Works like a charm.
                              Yes it does, I used one to increase the sensitivity of my early KILL-A-WATT meter before the later ones
                              built in better resolution. Bruce Roe

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