[RFI] SolarEdge Finds New Source of Solar System RFI

[Roger (K8RI)]

It should, normally, but "I think" it's possible as we are dealing with 
semiconductors, that on rare occasions it could develop a self resonant 
frequency and if it's in a series of cells  providing power ??

Theoretically, it's possible for spot contamination along with other 
influences to develop a not very efficient transistor.  I believe solar 
grade Silicon is the least expensive grade but we are still dealing with 
a couple parts per billion and even parts per trillion purity.  During 
fabrication, if a photographic mask slips even a fraction of a mm a 
whole batch could develop strange characteristics [ I've been out of the 
loop since 87 so I'm not sure what manufacturing process is now being used]

As these appear to be occasional, it's likely caused by a bad batch of 
cells.
I've seen the following analogy used to describe parts per billion.  
Take a cube of bricks one city block on a side. In this pile are one or 
two yellow bricks representing parts per billion.

  I heard that CPU fabrication is using X-Rays to get the size down.

One additional point: The semiconductor industry and particularly the 
first stage which is the poly-crystal growing stage, is a feast or 
famine industry and it is going into one of those shakeout periods.  
This means they are really squeezing pennies and at the end of these 
cycles there are usually only 3 to 5 poly manufacturers able to survive

73, Roger (K8RI)


On 6/8/2019 11:29 AM, r55stan at gmail.com wrote:
> Wouldn't the noise from semiconductors tend to be random (broadband white noise) in nature?  Much like the added noise from an amplifier due to its noise figure value?  The RFI I have experienced from SolarEdge systems falls at regular intervals in frequency, the harmonics of a switching frequency.  As for choking the optimizers having little effect, there is a good chance they missed one or more of them.  It took four visits at a house 200 feet from me for the technicians to find all of them.  Even a single optimizer without ferrites makes a lot of RFI.
>
> 73, Randy KQ6RS
>
> -----Original Message-----
> From: RFI <rfi-bounces at contesting.com> On Behalf Of Roger (K8RI)
> Sent: Saturday, June 8, 2019 5:59 AM
> To: rfi at contesting.com
> Subject: Re: [RFI] SolarEdge Finds New Source of Solar System RFI
>
> Having been involved with the semiconductor industry since early 1961with everything from poly crystal Silicon growth, single crystal production, to device production at the experimental, impurity problems, analysis of chemicals involved, as well as the maintenance and development of that equipment, I can think of many possibilities that would cause noise generation in individual solar cells.
>
> 73, Roger (K8RI)
>
>
> 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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> --
> Roger (K8RI)
>
>
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-- 
Roger (K8RI)