Flash Test Data [RE-wrenches]

[Joel Davidson]

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Hi David,

I like Evergreen modules and the company, but I question any PV module test 
that claims better than -/+5% accuracy. Even with a 3-way round-robin 
shipping calibration reference cells and modules every 6 months, the best 
NREL and 2 PV manufacturers could achieve was -/+5% accuracy.

In 1994, Keith Emery, NREL engineer and one of the most experienced PV 
testers in the world, wrote, "I would expect less than a 3% difference in 
Isc and 5% in efficiency between my measurements and measurement performed 
by another calibration laboratory. When I compare with other laboratories a 
difference in efficiency of 10% for cells or modules is often encountered 
unless we have had substantial interactions to reduce the uncertainty. Many 
of these differences are related to contacting (are wires attached, voltage 
contract to sample isolated from current contact), spectral mismatch error, 
and reference cell calibration."

Nothing of note has changed since then. More recently, see Keith's 
"Photovoltaic Efficiency Measurements" presentation at 
http://www.nrel.gov/docs/gen/fy04/36831l.pdf  His last slide says it all.

Best regards,
Joel Davidson


----- Original Message ----- 
From: "David Katz" <david at aeesolar.com>
To: <RE-wrenches at topica.com>
Sent: Monday, June 18, 2007 2:45 PM
Subject: Re: Flash Test Data [RE-wrenches]


>
> Evergreen Solar is starting a new trend with their new 195 watt modules 
> wit a tolerance of -0/+2.5%.  All modules will have a test at or above 
> their nameplate rating.  Their current modules are the best in the 
> industry with -2%/+4%.
> Regards,
> DAvid
>
> David Katz
> AEE Solar, Inc.
> formerly Alternative Energy Engineering
> 1155 Redway Drive - Box 339
> Redway, CA  95560  USA
> Phone 707-825-1200
> Fax 707-825-1202
> email dkatz at aeesolar.com
> www.aeesolar.com
>
>
>
> Don Loweberg wrote:
>>  In a message dated 6/17/2007 11:33:49 AM Pacific Daylight Time, 
>> atersol at owl.csusm.edu writes:
>>
>>
>> IF each module IS flash tested what is the exuse for the -/+ 5-10% 
>> warrantys? Isn't that just a way for the manufacturers to overcharge for 
>> what they are delivering?
>>
>>
>>
>
>
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