[RFI] Question Regarding Variations In Solar Panel RFI?

[Cianciolo, Paul, W1VLF]

Tony,

Regarding your statement below:

"We found high levels of RFI on the A/C lines throughout my neighbor's home and that's likely the case with all Solar Edge installations .............since there are no chokes between the mains and inverter."

It is the last part that I take issue with.  See the attached photo.  This is the EMI filter on the SE inverter on my house.  Also see the attached PDF, look under page 3 COMPLIANCES  you will find part 15B
They could not legally connect these to a residential  AC line if it were not part 15b compliant. In addition I have a Corcom 25fc10 installed at my home.  See the data sheet and response curves here.  http://www.farnell.com/datasheets/1430489.pdf
The filter makes a barely detectable change in the any received RFI I have from the SE system.

What needs to happen here is to determine,  the source of the RFI first, not the radiating elements.    In the past you have mentioned that even with the inverter off, not producing power, you still had the interference. In fact you had covered the panels and the RFI went away.

With that in mind here are a couple of sources, or generators, and not he radiating element that I cab confirm in my testing.

1) The inverter itself. The original inverters SE used had an internal switching frequency of roughly 18 KHz and thus harmonics were found every 18 KHz 
2) The HD wave inverters operate at roughly 50 KHz and thus you can see harmonic energy at 50 KHZ intervals  Other manufacturers that I have worked with use 39 KHZ .
It is difficult to switch, in my case 6.5 Kilowatts of power in a box 12" x 12" by 8" 
3) The original optimizers as we all know had a serious 200 KHz problem.  In the next version, as I have in my installation that problem has been rectified.
4) This leaves the fact that the current optimizers, the SP350? I believe?  may still generate  some noise in the non-power generating state. I am pretty sure you sent me a video or photo comparison that Randy, sorry I forget his call at the moment,  but he did bench test on a non-power generating optimizer.

In that video, you showed the spectral waveforms looking similar I believe?

I don't think the inverter is the cause of your issues at that this point. The exact radiation mechanism of the RFI from your neighbors SE system is still unknown.
I also do not see the noise issue you have, as you previously described at my house. The again I only have a 275' open wire fed dipole that I tune on all HF bands 200 feet away from house.  I don not have a multielement beam design for 20 meters.

To me it would make the most sense to concentrate on the specific device generating your noise based on the RF signature.


73,

Paul Cianciolo, W1VLF
ARRL EMC Engineer

ARRL - The national association for Amateur RadioT
225 Main Street, Newington, CT 06111-1400 USA 
Telephone: (860) 594-0392 
FAX: (860) 594-0259
Email: w1vlf at arrl.org
World Wide Web: www.arrl.org








-----Original Message-----
From: RFI <rfi-bounces+pcianciolo=arrl.org at contesting.com> On Behalf Of Tony
Sent: Friday, September 25, 2020 6:23 PM
To: Rfi List <rfi at contesting.com>
Subject: [RFI] Question Regarding Variations In Solar Panel RFI?

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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