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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