[RFI] New Solar Panel System Causing Grief For Hams

Hare, Ed, W1RFI w1rfi at arrl.org
Fri Mar 25 20:55:21 EDT 2022

It is not correct that the systems do not need to comply with FCC regulations. They very much do.

Because they are essentially switching power supplies, they need to comply with the Part 15 limits for unintentional emitters.  Under those rules, they are classified as "digital devices."

They must meet the limits for noise conducted onto the AC mains below 30 MHz.

They must meet the limits for radiated emissions above 30 MHz. 

This means that there is no limits on radiated emissions below 30 MHz for solar systems.   The premise on which the rules are based is that on HF, devices are generally small and thus do not act as effective antennas, but the long wires that are the AC mains do radiate, so by controlling emissions onto the AC mains, historically, EMI has been controlled. 

In the case of solar systems, though, the wires from inverters to microinverters or to optimizers do not have specific emissions limits.  IMHO, this is a potential problem that needs to be addressed in the long run, but those kinds of changes to emissions limits that have been reasonably effective for decades are going to take years of time to resolve, if ever.

Meeting the limits is the responsibility of the manufacturer.   From all indications, the emissions above 30 MHz meet the limits, as do the conducted emissions below 30 MHz, meeting the limits for noise conducted onto the AC  mains.

The rules then go on to require that the operator of the device use is in ways that do not cause harmful interference to licensed radio services. It is on this basis that solar-system EMI has been addressed.  In one manufacturer's case, a design that did cause a lot of interference, it has retrofitted over 400 systems in the field to date.  

The problems come from a few issues. First, initial designs were not good, and the installation practices were worse, with panels with noisy wires daisychained into large loops.  The inverters and optimizers in present use are more quiet, and all manufacturers specify to their installers that they should connect all external wiring using twisted pair.  Ferrites are also added to the wiring. 

Not all installers are following the good practices, though, and although the number of complaints is staying pretty steady, this is in the teeth of an increasing number of installations.

Would we be delighted if every manufacturer of noisy devices created a program to address that interference and retrofitted or replaced hundreds of systems?  The manufacturer involved in most of the problems is continuing to look to improve the system, with design changes in the works that in some cases has made a difference, in other cases not but still being work that continues.

We will never get regulations that eliminate all possibility of interference. Those limits are not practically achievable.  The limits on amateur harmonics are also pretty high, with 50 mw harmonics being legal from HF transmitters.  Do we cant draconian regulations for ourselves, that prevent all possibility of TVI or other interference to other services? If so, we would need 100 dB more attenuation. If we demand that, the same principle would be applied to us and we'd be taking the position that the existing rules are fine.

Expect the same pushback from the industry if we were to try to get the emissions limits lower.  They are responding, as a rule, and in instance after instance over decades of time, I have seen  manufacturers start with  "case-by-case" solutions, but ultimately reduce the emissions from their products to be more than the rules require, just to cut down on the cost of field retrofits.

Yes, the League is working with manufacturers, and they are responding by replacing hundreds of systems, 95% to the satisfaction of the ham. We are convincing them to go after the remaining noise, and they are. We are poised to create an industry standard to specify limits and installation practices, and much of all of that might end if amateur radio takes a confrontational approach instead of one of mutual cooperation.

Having said that, yes, we are working on it, but there are bigger fish to fry, such as grow lights as much as almost 60 dB over the limits and a flood of imported devices that also exceed the limits.

This is amultifold problem that will take longer to resolve head on than by building trust and cooperation. And that is my decades of experience in this arena talking.

Ed Hare, W1RFI

-----Original Message-----
From: RFI <rfi-bounces+w1rfi=arrl.org at contesting.com> On Behalf Of David Eckhardt
Sent: Friday, March 25, 2022 8:31 PM
To: Tony <73guddx at gmail.com>
Cc: Rfi List <rfi at contesting.com>
Subject: Re: [RFI] New Solar Panel System Causing Grief For Hams

QUOTE:  "I stunned that these manufactures do not have to comply with an FCC
              regulations. "

Yep, so are most of us.  When in creation will FCC take a stand on these RFI polluters.  It's almost across the board on suppliers of home solar installations!!  FCC does nothing.

Take your complaints through the ARRL and their RFI division.  They are very competent and have the right equipment to measure these polluters.
They also have the ear of the FCC when it comes to these issues.  The sad part is that the ARRL and we who pay dues to ARRL are paying for a service which FCC was tasked to perform - test and regulate emissions under Part 15.  Yes, the members of ARRL are paying for something FCC was originally tasked to undertake.

Take your complaints through ARRL.  They can help, but it may take several years or so.  They are well aware of SolarEdge and are working with them, but still, RFI prevails with new installations.  ARRL doing the job of FCC.....  You and I who are members are paying for that.  It should be paid for through our tax dollars to fund the effort at FCC.  GGGRRRRRR......

Dave - W ØLEV

On Sat, Mar 26, 2022 at 12:18 AM Tony <73guddx at gmail.com> wrote:

> All:
> The list of complaints regarding solar panel RFI issues continues to 
> grow. I just received yet another message from a fellow ham who is 
> experiencing RFI from a GroWatt 3000TL system -- see below.
> Most of the complaints I heard about over the years involve systems 
> made by Solar Edge and Generac, but it looks like we can add GroWatt 
> to the list.
> Tony -K2MO
> Mike Dannhardt wrote:
> /I just installed a GroWatt 3000TL for an offgrid system. RFI is 
> horrendous! I just tried putting a 4 inch 31 mix ferrite donut on the 
> battery leads. I was able to get four passes through the donut. No 
> measurable suppression. So I might have to resort to disconnect the 
> panels when using the rig but what a sad situation. When I'm not using 
> the station I am going to be polluting the spectrum for others. I 
> stunned that these manufactures do not have to comply with an FCC 
> regulations. / _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi

*Dave - WØLEV*
*Just Let Darwin Work*
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