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Re: [RFI] Covering Solar Panels To Assess RFI

To: "jim@audiosystemsgroup.com" <jim@audiosystemsgroup.com>, "rfi@contesting.com" <rfi@contesting.com>
Subject: Re: [RFI] Covering Solar Panels To Assess RFI
From: "Hare, Ed W1RFI" <w1rfi@arrl.org>
Date: Wed, 26 Aug 2020 16:11:41 +0000
List-post: <mailto:rfi@contesting.com>
Although it seems intuitive that escalating these problems to the FCC or other 
actions with legal implications will speed things up, just the opposite it 
true. Right now, we have good contact with Solar Edge engineering and just 
today, managed to segue that into contact with another manufacturer to be named 
later.  They are interested in EMC solutions and want to fix problems.  I am 
just today thinking that with two manufacturers involved, we may be able to 
form a Working Group and write an IEEE standard Recommended Practice on good 
EMC design, installation and field solutions to any remaining problems.

When manufacturers are willing to work with us, we are much better to do that 
than to try to increase the pressure. One letter from the FCC and we often hear 
from the engineers that they can't talk to us any more but need to run all 
communication through their legal department.

Jim, if we get the WG formed, I will let you know. I think you could add a lot, 
especially in the area of ferrite suppression of existing systems and in proper 
treatment of grounds and neutral wires on the AC mains side of things.  One 
does not need to be an IEEE member to be in an IEEE Working Group, and in the 
other WGs I am involved with, we are doing all meetings virtually, opening this 
up to a much broader range of stakeholders..


-----Original Message-----
From: RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> On Behalf Of Jim Brown
Sent: Wednesday, August 26, 2020 11:17 AM
To: rfi@contesting.com
Subject: Re: [RFI] Covering Solar Panels To Assess RFI

I agree with Ed and Tony Brock-Fisher's observations. More than a year ago, I 
gave Solar Edge's guy, who lives in the SF Bay area, a tutorial on the topic, 
and told him that the solution was design effective suppression of conducted 
emissions (both DC and AC side) into their electronics.

73, Jim K9YC

> I think that it is highly unlikely that the panels themselves are creating 
> noise.
> Paul Cianciolo, W1VLF, has a Solar Edge system at his house.  He had found 
> the usual wiring, grounding and optimizer issues present at his QTH, from his 
> own system.  Solar Edge came out and replaced everything but the inverter.
>>From what Paul can tell, the remaining noise, significantly reduced, is 
>>coming from the inverter. I don't recall whether it was conducted onto the ac 
>>mains, which would be subject to FCC Part 15 and other conducted limits, or 
>>conducted onto the input wiring, which is not subject to specific emissions 
>>limits.  But Solar Edge is aware of the issue and is designing upgrades that 
>>it believes should cure the problem.  When that is complete, they are going 
>>to return to W1VLF and install the upgraded inverter.
> So far, Solar Edge has repaired about 200 systems, almost all successfully, 
> at its own expense.  Paul reported that a crew of two took all day to replace 
> panels, rewire them and replace the optimizers.  If we could see every 
> manufacturer respond like this, we would be happy.
> Ed
> -----Original Message-----
> From: Tony Brock-Fisher <barockteer@aol.com>
> Sent: Wednesday, August 26, 2020 6:54 AM
> 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: Covering Solar Panels To Assess RFI
> Tony-
> 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.
> Regards,
> -Tony, K1KP
> On 8/25/2020 8:44 PM, Tony wrote:
>> All:
>> 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.
>> Tony-K2MO
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