[aprssig] FW: Solar Ham Radio Interference

Robert Bruninga bruninga at usna.edu
Fri Nov 18 20:11:55 EST 2016


Previously QST and my emails discussed the rise in the noise floor from home
solar and my suggestions to avoid purchasing a system with micro-invrters or
elecronic "optimizers" on every panel on the roof, and stick with the
wuieter or easier-to-fix all DC wiring and central inverters.

THAT’S NOT ALL!   It was pointed out at the ARISS meeting this weekend that
one must also watch out for their NEIGHBORS!  That is, if you want to keep
your clean noise floor for your own hamming and your own solar, you must
also be vigilant of your surrounding neighbors.

The time to make friends so you can guide their future investment is NOW,
well in advance before they make an irreversible decision.

Ill try to remember to go out and see how far the noise radiates from some
of the other solar panels in my neighborhood.  Although my DC system with
central inverters is much quieter, I should go out and see how far beyond
these houses, the various system's interference can be detected.

Bob, Wb4APR

-----Original Message-----
From: Robert Bruninga [mailto:bruninga at usna.edu]
Sent: Sunday, October 23, 2016 12:55 PM
To: Amsat BB
Cc: bruninga at usna.edu
Subject: Solar Ham Radio Interference

Not Satellite related, but people often ask about any RFI from my solar
arrays at home.  Interest stems from an RFI issue in April QST and my letter
in Sept 2016 QST.

Well, FINALLY, the jury is in.  For the first time since installing solar, I
finally got all my full-sized dipoles up in the air again. And listened with
the arrays on and off.

Yes, I have inverter noise about 12 dB above the noise floor every 38 kHz on
80 meters,. But couldn't really find anything on 20 meters.  I did not do a
thorough search, but enough to finally say, "yes, there is some noise..."

I post this because my 16kw of arrays are conventional series string arrays
and much quieter than the  "optimizers" on every panel all over the roof
noted in the April QST article.  I always thought my string array was quiet,
but now I have some data noted above.  This could easily be fixed with some
clamp-on ferrites down in the basement on the wires going into the

But for my rare HF operating, the solar AC disconnect switch is about 3 feet
from the kitchen door.  Easy enough to pull if I want HF silence.  I could
also install a 40 amp disconnect relay from a switch in the shack...  But
with my rare operating style, I'll probably do nothing.  Of course it is
perfectly quiet at night ;-)

It took me 6 years to get around to this test, so don't hold your breath
waiting for me to add some clamp-on filters to the inverter wires and see
what that does.

For those into solar, come join us on SolarDIY at yahoogroups.com Bob, WB4APR

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