[RFI] Question Regarding Variations In Solar Panel RFI?

[Jim Brown]

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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