Tom, aka TJ, is pretty good.....you are correct, he doesnt like Tonys
article from Arpil 2020, not sure why, but the retrofit they did at my
neighbors was very similar except they used clamp on ferrites, big son
of a guns.....Paul is probably monitoring, he can chime in if he wants,
but the engineer I had was Mike, and was very familiar with the work
done at Pauls....I didnt get a good look at the ferrites, they were
already on the roof when I saw them, but they twisted the heck out of
the wiring, and replaced all the optimizers.....Paul thought they used
type 31 ferrite, but in an email from TJ, he said the used a type 75,
ECM-IN-66OHM (maybe their part #)...he also said they eliminated a
ground fault pitch point ?!?!?!?
------ Original Message ------
From: "Tony" <73guddx@gmail.com>
To: "Rfi List" <rfi@contesting.com>
Sent: 9/25/2020 8:03:23 PM
Subject: Re: [RFI] Question Regarding Variations In Solar Panel RFI?
Jim:
Tom Simpson (Solar Edge Engineer) will be visiting the site sometime in the
near future so I'm hoping he'll address the potential problems you mentioned.
The issues you describe may also explain why the suppression hasn't been very
effective. The noise was 15db over S-9 prior to the suppression being installed
and it's now S-9 plus a tad for a reduction of roughly 10db.
This installation may require the methods used by Tony Brock-Fisher which
includes chokes between the inverter and mains which is something Solar Edge
frowns upon. Not sure if it's a cost or a code issue.
Thanks Jim.
Tony -K2MO
On 9/25/2020 6:49 PM, Jim Brown wrote:
Tony,
There are MANY variables and wiring errors and system layout errors that can
contribute to how much RFI is radiated. One issue that Teff communicated to me
was that the framing holding the panels was bonded to ground on the other side
of the building from the power entry. If this is true, it creates a current
loop that could be causing or contributing to your problem.
Wiring can be prevented from radiating by shielding, IF, AND ONLY IF, the
shielding is continuous. In the real world that I'm aware of, the only shielded
AC wiring is that which is enclosed in steel conduit, that is continuously
bonded together. That's quite rare in residences, except in cities like
Chicago, where the Electricians Union has it written into the city's Electrical
Code as a means of providing more work to Electricians.
Running twisted pair for power can prevent radiation from the current-carrying
conductors (phase and neutral), but won't help with common mode RF current,
which is nearly always on the green wire. And the common mode current is there
because of bonding failures, either in the construction of the equipment
itself, or in the installation, or both.
The wiring inside the home could be hot with RF as a result of wiring errors at outlets,
at panels (double-bonded neutral), even bonding at equipment. At the home I bought in
California, I found an outlet wired with neutral and ground reversed, and I found outlets
in the kitchen of a "mother-in-law" garage apartment fed between phase and
green rather than phase and neutral. I also found no ground at all at the service
entrance -- it was bonded to a hose outlet that was fed by PVC pipe!
73, Jim K9YC
On 9/25/2020 3:22 PM, Tony wrote:
All:
The reports I've read suggest that the strength of interference caused by solar
panel systems can vary from one installation to the next EVEN when the distance
to the source is similar. That variation could be attributed to radiating
conductors tied to the system such as the house wiring.
We found high levels of RFI on the A/C lines throughout my neighbors home and
that's likely the case with all Solar Edge installations since there are no
chokes between the mains and inverter.
Given those facts, would a large home with long runs of un-shielded Romex
produce higher levels of interference compared to a smaller home with shorter
runs? Or does the resonance of the wiring play more of a role than length and
number of runs?
It's an oversimplification, but it seems logical to consider what's connected
to system and not just the system itself.
Tony -K2MO
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