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<DIV>Thanks for the responses.</DIV>
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<DIV></SPAN>I want to share another response I got for this query, which seems to go further in accounting for partial shading:</DIV></DIV>
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<DIV>>>> Andre Mermoud <A href="mailto:andre.mermoud@cuepe.unige.ch> 10/4/2004 6:31:24 AM >>">andre.mermoud@cuepe.unige.ch> 10/4/2004 6:31:24 AM >></A><BR><BR>>Dear Mr. Gupta,<BR><BR>A friend of mine transmitted your request to me.<BR><BR>I have a partial answer to your question.<BR>My software PVsyst performs PV system simulations with partial shadings <BR>(3D tool).<BR>It takes the partial shadings on the PV array into account, in the usual <BR>"linear" way (i.e. Shading loss factor proportional to the shaded area).<BR>But you may also divide the PV array in "rectangles", each supposed to <BR>cover about a module string. The program computes the shading factor by <BR>supposing that when hitten by the shadow, the entire rectangle is <BR>invalidated. This is of course a rough approximation, but it gives an upper <BR>limit to the shading losses. The real situation should lie between these <BR>two values.<BR><BR>In practice, the shading factor applies on the beam component. The diffuse <BR>attenuation is calculated with the linear one, as it is not specular. <BR>Therefore the difference between the two values is usually not so important <BR>(at least under our middle-latitudes climates with 50% diffuse yearly).<BR><BR>You can download PVsyst from <A href="http://www.pvsyst.com,">www.pvsyst.com,</A> and use it with full <BR>capabilities during ten days. You will find more details in the contextual <BR>"help" (which may be invoked from anywhere in the software by typing F1).<BR><BR>Regards,<BR><BR>Abdré Mermoud<BR><BR>NB: You may put this answer on your forum if desired. I don't have access <BR>to it.<BR><BR>>_____________________________________________________________<BR>>Hi,<BR>><BR>>A PV related query again. This time I would like to find out if anyone<BR>>can suggest an algorithm or tool that accounts for the effect of partial<BR>>shading on an array. From what I understand, EnergyPlus and eQuest<BR>>algorithms factor the effect of shading through adjusting the effective<BR>>irradiation incident on the surface to which the array is attached.<BR>>Please correct me if I am wrong in understanding this.<BR>><BR>>But the effect of partial shading is quite different depending on the<BR>>location of the actual cell in series. The shaded cell depending on its<BR>>location in the series can degrade the performance a lot more than<BR>>proportional to the % of area shaded. Can anyone confirm if any tool or<BR>>algorithm takes into account his fact.<BR>><BR>>Any help and advise regarding this issue is appreciated.<BR>><BR>>Thank you,<BR>><BR>><BR>><BR>>PS-eQuest output for PV performance states that<BR>>"NOTE: PARTIAL SHADING OF A PV ARRAY CAN SEVERELY DEGRADE ITS<BR>>PERFORMANCE, BUT IS NOT TAKEN INTO ACCOUNT SEE REPORT LS-SH FOR SHADING<BR>>INFORMATION"<BR>><BR>>Smita Gupta<BR>>Energy Analyst, LEED AP<BR>><BR>>Buildings & Appliances Office<BR>>California Energy Commission<BR>>1516 Ninth St. MS-25<BR>>Sacramento, CA 95814<BR>>Phone: (916) 657-4034<BR>>Fax: (916) 654-4304<BR>><BR>><BR>><BR>><BR>>======================================================<BR>>You received this e-mail because you are subscribed<BR>>to the BLDG-SIM@GARD.COM mailing list. To unsubscribe<BR>>from this mailing list send a blank message to<BR>>BLDG-SIM-UNSUBSCRIBE@GARD.COM<BR>><BR>>----- Fin du message transféré -----<BR>><BR>><BR>><BR><BR>André Mermoud<BR>CUEPE - University Centre for Study of Energy Problems<BR>University of Geneva<BR>Battelle, bât. A, 7, rte de Drize<BR>1227 Carouge/Geneva<BR>Switzerland<BR><BR>Tél +41 22 379 06 61<BR>Fax +41 22 379 06 39<BR>e-mail andre.mermoud@cuepe.unige.ch<BR><BR><A href="http://www.unige.ch/cuepe/">www.unige.ch/cuepe/</A><BR><A href="http://www.pvsyst.com">www.pvsyst.com</A><BR><BR></DIV><PRE>
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