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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