[RFI] Covering Solar Panels To Assess RFI

[Tony Brock-Fisher]

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
>
>
>