Microsoft Outlook SignatureIn addition to STC plus/minus 10% being skewed to
minus most of the time, lab testing accuracy is plus/minus 5% (Keith Emery at
NREL).
----- Original Message -----
From: Jerry Caldwell
To: RE-wrenches
Sent: Tuesday, December 02, 2008 10:18 AM
Subject: Re: [RE-wrenches] CEC module rating testing
Gents, thanks for the responses.
Joel's spreadsheet indicates that the CEC at least was at one time simply
using the NOCT & temperature coefficient of power to determine PTC rating.
Dave, if your attachment is anything different from what Joel sent I welcome
you to send it my way.
My brother who works for a manufacturer sent me the following response:
"We send our modules out for testing at ASU's Photovoltaic test lab (now
TUV-PTL) I just looked at a report. Seems data is taken from 3 different test
conditions: STC (1kw/m2 & 25C cell temperature), NOCT (800W/m2, 20C ambient
temperature), Low irradiance (200W/m2, 25C cell temperature). This data is
used to establish the temperature corrections to report data for the PTC
conditions (1kW/m2, 20C ambient).
The report says that the NOCT data was taken outdoors. The other tests
require that the cell temperature be 25C, and I think for that they must do
indoor testing."
But as Anthony pointed out, if STC is the basis for PTC then it all hinges on
the manufacturer's +/- tolerance. This makes it difficult to accurately
estimate and compare system performance of different modules, which is becoming
increasingly important for large systems and PPA's.
Best,
Jerry Caldwell
------------------------------------------------------------------------------
From: David Katz <[EMAIL PROTECTED]>
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>; [EMAIL PROTECTED]
Sent: Monday, December 1, 2008 6:48:16 PM
Subject: Re: [RE-wrenches] CEC module rating testing
Jerry,
The CEC formula for PTC uses the NOCT of the module, the STC rating, the
power temperature coefficient and the aperature area of the module.
The data is supplied by the manufacturer but must make sense. Starting July
1, 2009, this will have to be certified by an acredited testing lab.
Let me know if you want the exact formula and i will send it to you. i can't
attach anything to this email
David
David Katz
President
AEE Solar
1155 Redway Drive
P.O. Box 339
Redway, CA 95560
Tel (707) 825-1200
Fax (707) 825-1202
[EMAIL PROTECTED]
www.aeesolar.com
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Jerry Caldwell wrote:
Wrenches,
Can anyone tell how PTC ratings are determined for modules on the CEC list
of eligible modules? I seem to recall having heard that the manufacturers
provide this data on the honor system. Can anyone verify this?
The test is obviously more involved than flash testing at STC. Even though
PTC is supposed to simulate more real-world conditions, it must still require a
controlled environment. How exactly is this done, and how long does it take?
Best,
Jerry Caldwell
Recurrent Energy
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