[RFI] SolarEdge Finds New Source of Solar System RFI

[Tony Brock-Fisher]

Randy-

I've done some testing on the optimizers. If you apply DC to the panel 
input leads, the internal switcher will start up and power the internal 
microprocessor. However, after that, to put it into operating mode 
requires some communications via the output leads from the central 
inverter, or a special controller/tool that is not generally available. 
Without this command sequence, the optimizer will stay in 'Safe Mode' 
where it outputs 1 volt DC. In this mode it is not converting much power 
and not generating as much RFI as it normally does in operating mode.

The internal switcher runs at ~200kHz, which explains the spurs commonly 
seen at 13.997, 14.197, ... I'm pretty sure this is also the frequency 
used on the converter when handling the full load,

Testing in this manner was what allowed me to develop the 3-turn bifilar 
choke that is recommended in the QST article. Despite only being able to 
test in 'Safe Mode', the chokes were very effective in actual installations.

-Tony, K1KP

On 6/3/2019 12:32 PM, r55stan at gmail.com wrote:
> Hi Ed,
> I would be interested in anything you discover regarding the interaction
> between solar panels and SolarEdge optimizers (DC to DC converters).
>
> I just picked up a SolarEdge optimizer, model P320 on eBay and was planning
> to open it up to get a rough idea of how much EMI filtering (if any) it has
> on the input and output leads, and also to measure the RFI it generates
> feeding it with around 30 VDC from a bench supply.  After I am done with it,
> I could donate it to you to study.
>
> 73,
>
> Randy KQ6RS
>
> -----Original Message-----
> From: RFI <rfi-bounces at contesting.com> On Behalf Of Hare, Ed W1RFI
> Sent: Monday, June 3, 2019 9:30 AM
> To: Wes Attaway (N5WA) <wesattaway at bellsouth.net>; 'Tony'
> <dxdx at optonline.net>; 'Tony Brock-Fisher' <barockteer at aol.com>; 'RfiList'
> <rfi at contesting.com>; Cianciolo, Paul, W1VLF <pcianciolo at arrl.org>
> Subject: Re: [RFI] SolarEdge Finds New Source of Solar System RFI
>
> I will.  Tony is pretty good with RFI, but there are always a lot of
> variables in residential environments, and we can take the panel to a few
> different locations, just to eliminate confounding factors.
>
> Ed
>
>
> -----Original Message-----
> From: Wes Attaway (N5WA) <wesattaway at bellsouth.net>
> Sent: Monday, June 3, 2019 12:28 PM
> To: Hare, Ed W1RFI <w1rfi at arrl.org>; 'Tony' <dxdx at optonline.net>; 'Tony
> Brock-Fisher' <barockteer at aol.com>; 'RfiList' <rfi at contesting.com>;
> Cianciolo, Paul, W1VLF <pcianciolo at arrl.org>
> Subject: RE: [RFI] SolarEdge Finds New Source of Solar System RFI
>
> Ed .... please keep us posted on results.
>
>     -------------------
> Wes Attaway (N5WA)
> (318) 393-3289 - Shreveport, LA
> Computer/Cellphone Forensics
> AttawayForensics.com
>     -------------------
>
> -----Original Message-----
> From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Hare, Ed W1RFI
> Sent: Monday, June 03, 2019 11:22 AM
> To: Tony; Tony Brock-Fisher; RfiList; Cianciolo, Paul, W1VLF
> Subject: Re: [RFI] SolarEdge Finds New Source of Solar System RFI
>
> There are a number of possibilities here.
>
> Yes, the panels themselves could be generating noise by any of a few
> different mechanisms.  What is not really known is whether this is an
> extreme near-field phenomenon, heard only very close to the panel, or
> radiated more effectively. Any panel noise could also conduct onto
> electrical wiring connected to the panel.  A common-mode choke is only going
> to be effective if it includes hot, neutral and ground for ac wiring and +,
> - and ground for dc.
>
> If the ground lead is not choked off, common mode noise from any source
> could be conducted to the panels and radiated from both the conducting
> wiring and the panels.
>
> Other noises could be present, confounding any findings.
>
> And, of course, the panels could be creating and radiating noise.
>
> I am going to see if they can send us a panel and microinverter that we can
> set up here for testing purposes.
>
> Ed, W1RFI
>
>
>
> -----Original Message-----
> From: Tony <dxdx at optonline.net>
> Sent: Sunday, June 2, 2019 4:28 PM
> To: Tony Brock-Fisher <barockteer at aol.com>; Rfi List <rfi at contesting.com>;
> Hare, Ed W1RFI <w1rfi at arrl.org>; Cianciolo, Paul, W1VLF
> <pcianciolo at arrl.org>
> Subject: Re: SolarEdge Finds New Source of Solar System RFI
>
> Tony:
>
> I asked if they were sure about their findings and the answer I got was that
> they were still seeing RFI with the system turned off and the array
> disconnected and disassembled. I'm assuming disassembled means they removed
> the optimizers from the panels.
>
> They found that the noise dropped significantly after they applied ferrites
> to the panels, but I'm not sure if they tested a stand-alone panel with and
> without chokes or if they ran the test with the system completely
> reassembled and turned on. I'll asked that question the next time I speak
> with them.
>
> The engineer mentioned the diode theory as well. If there is ambient RF
> exciting the panel diodes, is it possible that it would come from the
> inverter?
>
> Tony -K2MO
>
>
>
> On 6/2/2019 8:51 AM, Tony Brock-Fisher wrote:
>> Tony et al-
>>
>> This sounds pretty hard to believe to me. The panels normally contain
>> no active circuitry, so it's hard to see how they could be generating
>> RFI.
>>
>> The panels may have a series diode. Additionally, the cells themselves
>> are really, really large diodes. The only thing I can think of is that
>> they could be getting excited by high ambient RF, and then rectifying
>> that RF to produce harmonics or possibly cross modulation products.
>>
>> I have an AM BC station that is less than a mile, line of sight, from
>> my QTH. During the day they transmit at 44kW. I have tons of RF all
>> over the place, and it does cause lots of products with other BC
>> stations and AC line modulated direct-diode supplies.
>>
>> Just my opinion here...
>>
>> -Tony, K1KP
>>
>> On 6/1/2019 5:59 PM, Tony wrote:
>>> All:
>>>
>>> I recently spoke with an engineer from SolarEdge who said that they
>>> discovered a previously unknown source of RFI which turned out to be
>>> the solar panels themselves. They found that the panels were
>>> producing noise while physically disconnected from the system at a
>>> few installations.
>>>
>>> They are now working with the panel manufacturers Hanwha and Trina to
>>> determine why a certain batch of their panels are producing RFI. The
>>> goal is to locate installations with the defective panels and replace
>>> them.
>>>
>>> Cumulative RFI from multiple panels is apparently enough to cause
>>> serious RFI and may be the reason why my neighbors installation still
>>> makes noise during?? the day while the system is turned off. It could
>>> also be the reason why the choking the Optimizers had little effect.
>>>
>>> Tony -K2MO
>>>
>>>
>>>
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