Ray,
The "solar constant" -- the average irradiance value at the edge of the Earth's
atmosphere -- is about 1360 W/m2. See the wikipedia article:
http://en.wikipedia.org/wiki/Solar_constant
You're pushing the edge of what's possible if you're getting 1400 W/m2. There
could be a slight calibration problem. The 1800 W/m2 must be the edge-of-could
effect, or something is definitely going on with your pyranometer.
Jeffrey Quackenbush
________________________________
From: R Ray Walters <r...@solarray.com>
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Sent: Wednesday, August 29, 2012 1:26 PM
Subject: [RE-wrenches] Max Insolation
Hi All;
I was recently at a mountain top solar site (11,000 ft), doing some testing,
and I measured insolation values that were averaging 1400w/m2, with a temporary
peak (edge of cloud effect) that hit 1800w/m2.
Do I need to my meter recalibrated? Its the Daystar, and seems to be
accurate, when we got some cloud cover, insolation dropped to 200-300 w/m2 as
expected.
Interstingly the aging Photowatt 1000 modules were running at only about 60% of
rated output current into a Blue Sky 3048 MPPT controller. So I'm also
wondering if I have faulty modules. Back of module temps were about 95 deg F.
Any help on both the high insolation reading or Photowatt troubles would be
great.
Thanks in Advance,
Ray Walters
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