[RE-wrenches] CEC module rating testing

[Joel Davidson]

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 <dkatz at aeesolar.com>
  To: RE-wrenches <re-wrenches at lists.re-wrenches.org>; solarcowboy at yahoo.com
  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

  david at aeesolar.com

  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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