[RE-wrenches] Voltage degradation

[Drake Chamberlin]

What is the documentation for 10% module voltage degradation?  I have 
heard different ideas on what will degrade over how much time.  For 
direct grid tie, I shoot for a voltage drop 1% maximum on the DC side.

Thanks,

Drake

At 11:08 AM 4/8/2010, you wrote:
>I usually keep in mind that the modules will degrade by 
>10%  However, if you are one of those wrenches promoting 3% DC 
>Voltage Drops, maybe you should add some more.
>
>Nick Soleil
>Project Manager
>Advanced Alternative Energy Solutions, LLC
>PO Box 657
>Petaluma, CA 94953
>Cell: 707-321-2937
>Office: 707-789-9537
>Fax: 707-769-9037
>
>
>
>From: Drake Chamberlin <drake.chamberlin at redwoodalliance.org>
>To: re-wrenches at lists.re-wrenches.org
>Sent: Tue, April 6, 2010 1:58:56 AM
>Subject: [RE-wrenches] Voltage degradation
>
>Esteemed Wrenches,
>
>How much voltage overhead should we have available on our arrays to 
>allow for inverters not to fall out of their DC voltage operating 
>range?  Since the module power degradation is 20% over the warranty 
>period, I usually shoot for a module voltage that can drop 20% and 
>still be within the MPPT range of the inverter under the average 
>high temperatures, since most of the degradation is in voltage.
>
>Am I being too conservative with this number?  It always pushes the 
>number of modules to the top of what is allowable on the string for 
>the extreme low.
>
>Thanks,
>
>Drake Chamberlin
>Athens Electric
>OH License 44810
>CO License 3773
>NABCEP TM  Certified PV Installer
>Office - 740-448-7328
>Mobile - 740-856-9648
>
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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648  
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