[RE-wrenches] Module frames

[Joel Davidson]

I have never seen a warped anodized aluminum frame. I've seen frame stock in handling, but it was not used to build modules. Does anyone have a photo of a warped module frame?
  ----- Original Message ----- 
  From: Peter Parrish 
  To: 'RE-wrenches' 
  Sent: Wednesday, July 01, 2009 12:58 PM
  Subject: Re: [RE-wrenches] REC Solar melt-down


  Let's make sure we are making a distinction between "differential coefficient of expansion" and "(heat induced) warping". All material (Al alloy and low-Fe glass among them) undergo a change of dimension as a function of temperature. Pure aluminum and many of its alloys have a differential coefficient of expansion of 2.30e-5 per degree centigrade difference from 0 degrees centigrade. Low iron tempered glass has a lower coefficient of 0.84e-5. As a result, both aluminum and glass expand when heated but glass does so more slowly. Over a 45 degree centigrade temperature increase (from 25 deg C) there will be a 0.65e-3 change, or less than 1/10th of 1 per cent. Usually this does not create a problem unless the aluminum and glass are pinned together in some fashion and the length of the bond is long enough to produce unmanageable changes in dimension. For example a 150 cm length (long dimension of a PV module) would produce a relative dimension change of 0.1 cm (40 mils). This is manageable I understand given the elastomeric sealant that PV module manufacturers' use when applying the frame to the glass/Si/Tedlar sandwich.  



  What I suspect is the problem is warping, caused by heating of the aluminum frame. Work hardened metals (including extruded metal) often have built in stresses due to the forming process. This stress can be relieved by long term high temperatures, resulting in the metal piece deforming. I have seen warping as much as 5% in long extruded parts. If in fact what is happening is warping, then I suspect that warping cannot be overcome with something like an elastomeric sealant. 



  I honestly don't know if manufacturers of extruded metal parts put their parts through an annealing cycle to remove stresses or not.



  - Peter



  Peter T. Parrish, Ph.D., President
  California Solar Engineering, Inc.
  820 Cynthia Ave., Los Angeles, CA 90065
  CA Lic. 854779, NABCEP Cert. 031806-26
  peter.parrish at calsolareng.com  
  Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885                                                                                                   




------------------------------------------------------------------------------

  From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Joel Davidson
  Sent: Tuesday, June 30, 2009 9:06 PM
  To: RE-wrenches
  Subject: Re: [RE-wrenches] REC Solar melt-down



  What frame material has that high a coefficient of expansion?

    ----- Original Message ----- 

    From: Nick Vida 

    To: wrenches 

    Sent: Tuesday, June 30, 2009 8:45 PM

    Subject: [RE-wrenches] REC Solar melt-down



    wrenches,


    the defect in REC panels is the frame expands past the panel and can contract and break the glass. Unfortunate, but no big deal in a lot of ways. I dont know if there is another defect, but that one would warrant a recall instead of replacing a lot of panels. There was also an article about their Oregon plant breaking a couple hours after it went online. Im glad to see they have done a recal. I think it is proper and good business. I think thier silicon and wafers are fine and well made, and we would hopefully find out if they werent because they are a major supplier of wafers to several manufactures. 




----------------------------------------------------------------------------

    _______________________________________________
    List sponsored by Home Power magazine

    List Address: RE-wrenches at lists.re-wrenches.org

    Options & settings:
    http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

    List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

    List rules & etiquette:
    www.re-wrenches.org/etiquette.htm

    Check out participant bios:
    www.members.re-wrenches.org



------------------------------------------------------------------------------


  _______________________________________________
  List sponsored by Home Power magazine

  List Address: RE-wrenches at lists.re-wrenches.org

  Options & settings:
  http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

  List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

  List rules & etiquette:
  www.re-wrenches.org/etiquette.htm

  Check out participant bios:
  www.members.re-wrenches.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20090701/41f388a3/attachment-0004.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image003.gif
Type: image/gif
Size: 4274 bytes
Desc: not available
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20090701/41f388a3/attachment-0007.gif>