[RFI] Enphase Solar System RFI Tests

[James Jordan]

Scott has handled this in a very strong, proactive but cooperative manner. As energy saving and alternative energy generating devices become the norm for modern life, finding ways to embrace the technology will keep ham radio as a positive force and keep us from being seen as just a bunch of reactionary OF’s. 
Well done Scott. 
73,
Jim K4QPL

Sent from my iPhone

> On Jul 19, 2022, at 11:47 AM, K9MA <k9ma at sdellington.us> wrote:
> 
> My next door neighbors recently installed a solar system, with the panels no more than 60 feet (18 m) from my antennas. The primary antenna is a tribander at 70 feet, with a 40 meter rotatable dipole 6 feet above it. I'm in an urban area, surrounded by overhead power lines, so the noise level is fairly high. At best it's about -130 dBm/Hz on 20 meters. So far, I have been able to detect no RFI from the solar system from 1.8 to 28 MHz. Details below.
> 
> The solar system consists of 14 320W panels, each with an Enphase IQ7+ microinverter. It is a grid-tied only system, with no batteries or standalone operation.
> 
> At my request, ferrite snap-on split cores were installed. Each short DC lead from panel to inverter had two Fair-Rite 0431178281 cores attached near the inverter. On the AC cables, Fair-Rite 04311164181 cores were used. On 9 of the inverters, one core was attached the the input lead and one to the output. On the remaining 5 inverters, a core was attached only to the output lead. (Two, at the ends of the chains, had no input connection, and I ran out of cores for the other 3.) One additional core was attached to each AC cable to the junction box, about 5 feet from the closest inverter.
> 
> I checked out a couple other Enphase systems in the area with a small 20 meter loop and preamp. No RFI was detected but, of course, the small antenna is not very sensitive.
> 
> There is no way to know from this data whether all the ferrite cores were necessary. Even if they were, however, it shows that fairly simple and inexpensive mitigation measures are adequate with this Enphase system, at least in an urban noise environment.
> 
> Both the neighbors and contractor were very cooperative. I paid for the $300 worth of ferrites, in the interest of maintaining good relations, but I shouldn't have had to do that. If the contractor had had to remove all the panels to attach the cores after the panels had been installed, it would have cost them much more than that. If I were to install my own Enphase system, or if another close neighbor were to, I would insist the installer pay for the ferrites and install them initially, or agree to retrofit them later if necessary. I would, however, waive my customary enormous consulting fee.
> 
> 73,
> 
> Scott K9MA
> 
> -- 
> Scott  K9MA
> 
> k9ma at sdellington.us
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