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Author Topic: Solar Panel RFI  (Read 310 times)

W7QHH

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Solar Panel RFI
« on: May 17, 2021, 09:36:52 AM »

   After searching for some time for a very high noise level on 80 and 40 meters, I think I have come across a possible source. I took a portable radio tuned to 7.275 mhz. and walked around my neighborhood. About a half block from my QTH, I came across a residence loaded with solar panels on the flat roof. The noise level on the radio went up about 3 S units and declined as I walked away from the property. Can anyone on the forum thats been through this give me some advice as to how to deal with it? I'm in a CC&R controlled area. I'm 82 years of age and would like to enjoy the hobby again. Thanks, Clyde, W7QHH
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KF4HR

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Re: Solar Panel RFI
« Reply #1 on: May 17, 2021, 10:16:24 AM »

Unfortunately some solar systems do radiate RF.  It seems the suppression of RFI is not high on the priority list for many solar equipment companies. This is one of the main reasons I haven't installed solar at my qth.  Being local RFI you may be able to use a Noise Reduction device such as the Timewave ANC-4 or DX Engineering NCC-2 to reduce or eliminate your local noise.  Butch KF4HR
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N1UK

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Re: Solar Panel RFI
« Reply #2 on: May 17, 2021, 11:42:52 AM »

Does the interference go away at night ?


Mark N1UK
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W7QHH

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Re: Solar Panel RFI
« Reply #3 on: May 17, 2021, 11:44:30 AM »

   Mark, No it does not. It's 24/7
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K6AER

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Re: Solar Panel RFI
« Reply #4 on: May 17, 2021, 12:28:00 PM »

Typical solar systems being sold to home owners are daytime only with inverters located on each solar panel. Electricity is sold back to the electric provide via a income electric meter unit. You monthly bill is the difference between what you use and what you put back onto the grid.

Solar inverters have to meet part 97 radiation requirement but that amounts to a S9 signal at 100 feet at HF frequencies. Every time you double the interference sources your signal level goes up 3 dB. With 30 panels on a house with unshielded wiring you could radiate for more than a mile.

If the interference happens at night they probably are using a battery back up system.
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W9IQ

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Re: Solar Panel RFI
« Reply #5 on: May 17, 2021, 02:01:43 PM »

Typical solar systems being sold to home owners are daytime only with inverters located on each solar panel.

Those are commonly called 'optimizers'. The series string of panels/optimizers are then connected to a grid tied inverter.

Solar inverters have to meet part 97 radiation requirement but that amounts to a S9 signal at 100 feet at HF frequencies.

I think you mean Part 15. Where does the S9 at 100 feet come from?

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

N6RLG

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Re: Solar Panel RFI
« Reply #6 on: May 17, 2021, 03:07:19 PM »

It depends on the kind of solar installation it is.  Micro-inverters on every panel result in serious noise (RFI) generation.  The single inverter system which has only the one inverter usually mounted on the side of the home near the main panel box create noticeably less RFI, but still produce it all the same.  The solar companies are aware that they have to mitigate the noise their system creates but will do so only when asked.  "Only when asked" because they have to do it for free since their system is in violation of FCC rules and is creating the RFI.  Let the homeowner know they can call their solar company and request the "fix."  It will not cost them anything.  I had several solar systems in my neighborhood, including my own, mitigated this way.
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W9IQ

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Re: Solar Panel RFI
« Reply #7 on: May 17, 2021, 03:28:09 PM »

It is encouraging that they are responsive.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

W9IQ

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Re: Solar Panel RFI
« Reply #8 on: May 17, 2021, 04:23:26 PM »

What did you offer as proof that they needed to do mitigation? Any idea what they did for corrective measures?

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

W4NBO

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Re: Solar Panel RFI
« Reply #9 on: May 17, 2021, 07:02:49 PM »

I always enjoy RFI threads. I snooped and you have underground utilities. I am jealous of that. Sounds like you might have found your rfi source. It was mentioned about the phasing boxes. Another showing up is called an XPhase QRM Eliminator. About 20 bucks for a kit w/o box/knobs and 45 assembled with box and knobs on that big auction site and I would imagine other places. Its getting 5 star reviews here on eham and good reviews on the web and youtube. Its best to fix the rfi source of course but the phasing boxes can help until that time especially for 1 rfi source. contesting.com has an active rfi board where I have seen solar rfi discussions if you seek more info than the wisdom here. So far........i have not had solar problems as solar, is rare around here. I am hoping being in the heart of TVA country with cheaper rates that will keep them out, lol. I mainly contend with old power lines here.

73
Chuck
W4NBO
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W7QHH

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Re: Solar Panel RFI
« Reply #10 on: May 20, 2021, 03:08:52 PM »

Chuck, W4NBO, Thanks for your info on the $20 boards. I can't seem to find an ad for them. Yes, I do have underground utilities Can you help??
   Also, thanks to all the others who have posted information.
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N1UK

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N0GV

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Re: Solar Panel RFI
« Reply #12 on: May 26, 2021, 01:52:44 PM »

I suggest that you also check for LED or fluorescent lights that are on at all times at that house, the solar may not be the problem, I'm not seeing too many microinverter systems in my area and the larger systems generally do not run at night if they are grid tied, they switch over to utility power then.

LED drivers and some of the "efficient" solid state fluorescent ballasts are really wide spectrum jamming devices.....

Grover
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