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Re: [RFI] How dark is dark enough?

To: Bob Kozlarek WA2SQQ <wa2sqq@gmail.com>, RFI List <rfi@contesting.com>
Subject: Re: [RFI] How dark is dark enough?
From: Michael Carter <Mike.Carter@unh.edu>
Date: Wed, 4 Jan 2023 20:14:10 +0000
List-post: <mailto:rfi@contesting.com>
Thanks, Bob, for raising that question again.

The maximum solar irradiance on the Earth's
surface is about 1300 Watts/square meter.
A full moon produces about 1 mW/square meter,
six orders of magnitude less than the sun's
irradiance.  That makes a huge difference in
the available current from a PV array, which
is nearly linear with irradiance impinging
orthogonal to the plane of the PV array.

A photovoltaic module is essentially a current
source, i.e. capable of sourcing a fixed
current at any terminal voltage up to nearly its open-circuit
voltage where the available current depends on
the solar (or lunar) irradiance as well as the module
ratings.  A series string of PV modules could present
a high open-circuit voltage even under full moon illumination, but
the string (or an array of strings) would have virtually
no current generation capability, and the voltage across
the 'load' (human) would be much less than the open-circuit
voltage.  it is the current, of course,
that represents the electric shock hazard if it passes
through the torso near the heart.

73,
Mike, K8CN


________________________________
From: RFI <rfi-bounces+mike.carter=unh.edu@contesting.com> on behalf of Bob 
Kozlarek WA2SQQ <wa2sqq@gmail.com>
Sent: Wednesday, January 4, 2023 2:35 PM
To: rfi@contesting.com <rfi@contesting.com>
Subject: [RFI] How dark is dark enough?

CAUTION: This email originated from outside of the University System. Do not 
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In response to:

Thank you for your clear and specific reply to my question.

I will investigate whether residual RFI continues when microinverters are
shut down.

Best regards,

Michael, W9IP

de WA2SQQ
Our fire inspector attended one of our home owner organization meetings
where solar panels were discussed. The fire fighter’s safety was their
first priority.  He mentioned that the light from a full moon was enough to
produce voltage levels that could present a danger to the fire fighter. I
guess my question is, just how dark does it need to be to have these
devices truly turn off?
--



*Best 73 de WA2SQQElmwood Park, NJ"The only dumb questions are those we
don't ask"*
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