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Re: [RFI] Covering Solar Panels To Assess RFI

To: Tony <dxdx@optonline.net>, Rfi List <rfi@contesting.com>, "Hare, Ed W1RFI" <w1rfi@arrl.org>, "Gruber, Mike W1MG" <mgruber@arrl.org>, "Cianciolo, Paul, W1VLF" <pcianciolo@arrl.org>
Subject: Re: [RFI] Covering Solar Panels To Assess RFI
From: Tony Brock-Fisher via RFI <rfi@contesting.com>
Reply-to: Tony Brock-Fisher <barockteer@aol.com>
Date: Wed, 26 Aug 2020 06:53:32 -0400
List-post: <mailto:rfi@contesting.com>

Was this experiment conducted with the per-panel optimizers connected to the panels? This is a critical question.

It appears the conclusion of the experiment is that the panels themselves and by themselves are generating RFI. I am certain this is incorrect. I suspect the experiment was conducted with the optimizers connected to the panels, and that the panels powered up the optimizers and the optimizers are generating the RFI, which would be entirely consistent with my understanding and experimentation with a single panel and optimizer. Indeed, a 300W halogen lamp provides sufficient energy to a single panel to power up an optimizer such that it generates RFI, the characteristic being harmonics appearing at ~200kHz intervals through 20m and above.

It is highly unlikely the panels themselves generate RFI without the optimizers, unless they contain some sort of active circuitry that operates at RF frequencies. Electrically, they look like a huge diode which is back-biased by the voltage developed in the presence of sunlight. A solar cell, by itself, does not generate RF.

As is often the case, a poorly conducted or misunderstood experiment can lead to an erroneous conclusion, which then leads to a futile course of action yielding a lack of productive results and further frustration.

I hope you can clear up this discrepancy before many more wheels are uselessly spun.


-Tony, K1KP

On 8/25/2020 8:44 PM, Tony wrote:

The the inverter on my neighbors solar panel installation was recently replaced to reduce the RFI caused by the system. The swap only made a slight change in the interference.

This left the solar panels as the possible source of RFI so my neighbor and I conducted a test we've done previously which involves covering each panel with tarps to see what affect it would have on the noise.

We found that the RFI completely disappeared while the tarps were blocking the Sun from reaching the panels. The noise returned when we removed the tarps.

I reported this to SolarEdge and they now believe that the panels are the cause of the interference. They mentioned 2 other installations that had this same problem with panels that were manufactured in China by Hanwha and Trina.

The takeaway is that solar panel systems need to be checked from top to bottom when checking the system for interference. I'm hoping SolarEdge will keep this in mind when they address their next RFI case.

We also reported our test results to the company who leases the panels to my neighbor. No response yet.


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