Solar Panel RFI 18 Jul 2023

[Ray Lalleu]

- in my summer QTH now the band is dead. What's worse, every 20kHz in a very wide range there is a peak
  of interference, probably coming from the transducer of the solar panels adjacent to the fence.
  (check it out after dark)

[Ray Lalleu]

At last I have identified a new RFI : a solar panel with harmonics every 23 kHz radiated from about  5 up to 8 MHz. Located 200 meters away, but more than 1 km by the streets, and I walked more than 1 hour in the neighbourhood with my Sony in hand before finding the smallest trace of this RFI with only the telescopic antenna.
Had a friendly chat with that far away neighbour. We will try to find where the problem is exactly, as a close neighbour of him has the same hardware with just less power and no RFI near his electric meter box.
The RFI is only during daytime, but this could come also from another device just shut off at night.

[~SIGINT~]

Hello Ray,

Solar panel systems are notorious for generating RFI / EMI, primarily from the charge controller. Here is some reading to assist.

Solar System RFI
https://palomar-engineers.com/rfi-kits/solar-system-rfi

Can Home Solar Power and Ham Radio Coexist? (Chris, K8NVH)
http://rsgb.org/main/files/2014/02/QST20Solar20April2020165b25d.pdf

Solar Energy Basics (ARRL)
https://www.arrl.org/solar

[NJQA]

Some advice:

http://ka7oei.blogspot.com/2020/08/it-is-possible-to-have-rf-quiet-home-pv.html

[RobRich]

Some chargers and inverters could double as wideband signal generators. o.0

Since the two systems are similar, though with seemingly considerably different EMI/RFI profiles, perhaps start with checking the grounding situation on the affected system. For a quick example, the solar system might have its own ground electrode, but is that electrode bonded back to the common-point ground for the house?

As usual with EMI/RFI mitigation, also consider applying mix 31 and/or 43 ferrites on the various power wires and control wires in the solar system.

[NJQA]

I seem to remember something from a QST article years ago that talked about the impact of how the wiring was run from the panels making a difference.  In one case the wires were twisted together; and in another the two panel wires were separated and ran on different edges of the panel because this made it easier to connect up multiple panels.  The twisted wires radiated less noise as I remember.

[NJQA]

It was an article by K1KP in the April 2016 issue of QST.  The issue was all of the panels were connected in series and due to the geometry of the wiring you ended up with a large loop of wire which was more efficient in radiating noise.  The recommendation was to double back the wire (to eliminate the open surface area of a loop).  The downside is the additional length of wire and it’s IR drop.  You probably ought to look at the article; the explanation is clearer than mine.

It’s the same article as the RSGB file link in Sigint’s posting earlier.

[kris]

          Thank you for the very informative literature that explains the problems of RFI that plague us today.
Observation from this afternoon- after sunset, the panels do not work, but the photovoltaic installation can give energy to the home network from the batteries via "inverters", which still generates RFI for some time!

[~SIGINT~]

Wait until there is a growth in Electric Vehicle (EV) charging stations. That can't be good either.