PV degradation [RE-wrenches]

Bob-O Schultze, Electron Connection econnect at snowcrest.net
Fri Dec 15 08:14:22 PST 2006


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Hiya Gang,
Mitsubishi claim that their "no lead" approach to module  
interconnections will reduce degradation due to lead solder  
oxidation. Maybe so.
I'll let you know in 10 years or so, Buddha willing and the creek  
don't rise.
Merry Christmas to all.
Bob-O
On Dec 12, 2006, at 12:07 PM, Bruce Roush wrote:

>
> Windy,
> The figures used by BP are from 1/2 to 1% per year degradation. Of  
> this
> power loss, 1/2 is voltage and 1/2 current.
> Most modules are warrantied to produce 80% power output after 25 years
> (this equates to 0.8% per year).
>
> Significantly, the warranty is for the wattage adjusted to the stated
> tolerance factor of the module. For a module with 9% power tolerance,
> you would first multiply the wattage times .91, to adjust the  
> rating to
> the guaranteed minimum. Then the 80% would be applied.
>
> As to the reason for the loss, I have heard that is is a result of the
> development of resistance in the cell junctions and between crystal
> boundries within the cells.
>
> Bruce Roush
>
>
>
> Windy Dankoff wrote:
>>
>> Wrenches,
>>
>> Perhaps you can help  me answer a question for "Ask The Experts"
>> column in Home Power. It regards degradation of PV modules.
>>
>> There seems to be some agreement on a norm of about 1/2% per year
>> degradation (not due to dirt). This is a rough average, of course.Is
>> there any general agreement on WHY this happens?
>>
>> I think it's the average of a variety of factors, but if you have
>> data on this issue, it may be helpful.
>>
>> Also, if you have factual data on percentages of failures rates of PV
>> over a long period, that will help too.
>>
>> Thanks!
>> Windy


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