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Yet, Another RF Noise Question...

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  • #16
    The Inverters generate Differential Mode Noise. That makes it Line Noise. Regardless of the Mode an In-Line Filter on each Micro-Inverter will attenuate both Differential and Common Modes. Common Mode is the radiated noise in reference to Ground.

    My Belly Ache is the damn manufactures could spend $2 in parts to include decent line filters. We are talking 4 capacitors and 2 coils of wire. You can build them easy enough, except they would not comply with local codes and void warranty.

    It took me all of 15 minutes to build one in my Ham Shack installed on the Input of the CC and output of Panels. Tightly twisted conductors and two capacitors work wonders.
    Last edited by Sunking; 06-30-2016, 07:57 PM.
    MSEE, PE

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    • #17
      It is all FM to me.

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      • #18
        I'm not talking about low frequency line harmonics; these will not bother the HAM. Radio frequencies need to be contained at the interference
        source, or not at all. Mfrs meet a legal requirement, but it isn't strict enough for a sensitive receiver right there. Often it can be done. When
        my Moms vacuum would wipe out my radio in the 50s, I got hold of it and added some shielding/filtering; no more interference. My 62 car
        generated all sorts of noise in my radio, but I fixed them all. The ignition was the challenge; all the wires had to be shielded all the way
        to the base of the plugs, and power came through feed throughs. Like an aircraft engine. But multiple, unshielded sources are difficult,
        esp on a roof. No need to re invent the wheel; plenty of good filters are available off the shelf. Bruce Roe
        Last edited by bcroe; 06-30-2016, 10:18 PM.

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        • #19
          I installed a small (3kw) solar system on the roof of my house using Enphase M-215 microinverters. I am also a ham, and was very interested in the RFI / interference issue and researched it prior to my installation. On Enphase's tech support section they discuss their recommended installation practices. I followed them, and also added additional ferrite chokes on the output of each microinverter prior to installing the microinverters. My lowband antenna is about 25 ft above my solar panels, and I get no RF interference on my Icom 745 ham radio.

          Here is a link that explains in more detail what I did to reduce the RF interference from my Enphase microinverters I hope this helps!

          -- Mike
          Last edited by wb8erj; 08-30-2016, 08:52 PM.

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          • sdold
            sdold commented
            Editing a comment
            I really liked reading your blog, Mike. I like your "Conserve first, then generate" approach. I'm a ham too and will be setting up an HF station near my Enphase installation at some point, so I appreciate you putting your experiences online. I DIYed mine too.

        • #20
          Filters can be home built, but off the shelf designs will be more thoroughly proved effective. They start getting a lot
          more expensive after passing perhaps a 20A rating. Inductors work, but they work a lot better when combined with
          capacitors. Just search a little of EMI FILTERS. Bruce Roe

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          • #21
            Hello, in re-reading this thread, I would like to clear something up with the Enphase M-215 microinverters that I am using, and probably other Enphase products work this way as well. what they do is track the 60 hz sine wave coming from the power company and generate power that tracks that. I don't believe this is the cause of the RFI from the Enphase microinverters.

            I believe the issue with the Enphase creating RFI is coming from their ethernet over power line technology they use to allow the homeowner to monitor their solar panels on the web,. This has a carrier that is injected in to the house power system at 144 kHz. Again, by following Enphase's installation recommendations, and also adding a split core ferrite on the output of each microinverter, seems to kill any harmonic interference generated by the 144 kHz carrier / data transfer that causes interference.

            Here is a link to my page that shows my Enphase M-215 microinverters with an EMI ferrite core installed.

            -- Mike

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            • #22
              A spectrum analyzer could reveal the nature of your noise. The process of tracking the 60 hZ waveform is done by switching
              back and forth in a controlled way, at an ultrasonic frequency. Because the switching is done at the FULL POWER level of the
              inverter input, there is considerable opportunity for harmonic radiation and interference. The right filtering and shielding can
              contain it.

              The communication signal is done at a far, FAR lower power level, though that does not remove it from suspicion. Bruce Roe
              Last edited by bcroe; 08-30-2016, 11:40 PM.

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              • #23
                Originally posted by wb8erj View Post
                I believe the issue with the Enphase creating RFI is coming from their ethernet over power line technology they use to allow the homeowner to monitor their solar panels on the web,. This has a carrier that is injected in to the house power system at 144 kHz. Again, by following Enphase's installation recommendations, and also adding a split core ferrite on the output of each microinverter, seems to kill any harmonic interference generated by the 144 kHz carrier / data transfer that causes interference.
                A split-core filter will filter common mode noise but will not be effective against differential noise. The data signal is differential. EMI due to power switch operation is both differential and common mode, but the common mode noise is far more aggravating in real world applications.

                So from your experiments it sounds like the issue is not due to the PLC interface.

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                • #24
                  Originally posted by bcroe View Post
                  A spectrum analyzer could reveal the nature of your noise.
                  Just exactly where doe s HO get one of those at? Who is going to teach them how to use it?
                  MSEE, PE

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                  • #25
                    Originally posted by Sunking View Post
                    Just exactly where doe s HO get one of those at? Who is going to teach them how to use it?
                    I bought several on Eb*y. The prices today are way down, esp as the older ones are pensioned off. Just spotting the
                    fundamental and harmonics of the largest signals isn't very hard. Those who don't really want to know won't make the
                    effort, that includes most home owners. Bruce Roe

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                    • #26
                      Hey guys. I started a new thread over here: https://www.solarpaneltalk.com/forum...o-interference before seeing this old thread. I am not sure if it's impolite on this forum to restart the old thread or start a new thread for my question?

                      But from the first post you can see I'm trying to decide which solar design to go with for a new house that will not cause HF/VHF interference for my amateur station.

                      On the M215 Enphase units, does anyone have a similar experience on with the new iq units? I need rapid shutdown for NEC 2017 compliance, as well as wanting to use 300+W panels...

                      Thanks, and happy to participate on this or the new thread.

                      thanks
                      mike


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