[hfsig] Fwd: The end of daytime HF?

Robert Bruninga bruninga at usna.edu
Thu May 3 22:22:50 EDT 2018

I don't want to be an alarmist, but we need the Hams with the proper
knowledge to get involved in this disturbing news.

The National Electric Code now requires electronics on every module of a
solar array communicating  via signalling on the DC power lines to assure
EACH pair of panels can shut down independently.  This is to make all
possible faults never allow more than 80 volts anywhere in the system.
This is effective 1 Jan 2019

This is the nail in the coffin of simple DC series string arrays which are
the quietest systems and almost demands microinverters or optimizers on
every panel.  Refer to the QST article a few years ago about how disastrous
optimizers are to RFI and HF operations with modules all over the roof..

Here is the Solar news:

Also, what is going to happen to an array that has signaling all over it in
the near field of HF?

Although you can avoid it by going solar before then, you may have problems
when your neighbors go later.

I hate  to be an alarmist but we all know what happens when ham radio and
commercial systems are incompatible and even though Ham radio might be in
the right, we are only 1 in 600 and no one is going to side with us.

We took on broadband over power and squelched that dumb idea, but now this
has the potential for equal demise of Ham radio.  It should be fixable, but
we also know that there is high competition in the solar market and the
modules that are made the cheapest  will be popular and will likely not be
adequately filtered.

If nothing else, we need to find out what systems are terrible emitters and
nip them in the bud.  Maybe all it takes is driving by solar systems you
see and turing on your AM radio on a weak signal channel and seeing if the
background noise peaks near that home.  But also it has individual peaks,
so it might also be nice to tune around too find the max and then check the
range.  I find the noise can go hundreds of feet along the power lines....

You cant miss  em... just sounds like a 60 Hz buzz on all the harmonics of
the inverter switching frequency.

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