Flash Test Data [RE-wrenches]

Mon Jun 18 21:22:11 PDT 2007

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Hi Bill,

Manufacturers' "amazing accuracy in hitting their minimum ratings so 
consistently." I like that.

On average, approximately sincerely yours,
Joel Davidson

----- Original Message ----- 
From: "Bill Brooks" <bill at brooksolar.com>
To: <RE-wrenches at topica.com>
Sent: Monday, June 18, 2007 7:02 PM
Subject: RE: Flash Test Data [RE-wrenches]

>
> Joel,
>
> My personal experience is that accuracy has improved and collaboration 
> among
> labs is substantially better than it used to be. I was involved in the
> round-robin testing of several modules for a client and testing was done 
> at
> FSEC, NREL, and Sandia. The results were +/- 1.5% which can be considered
> almost too good to be true since it included both flash testing and 
> outdoor
> testing. I believe that with careful measurements, +/-3% accuracy is
> possible and should be expected. How come the manufacturers can achieve 
> such
> amazing accuracy in hitting their minimum ratings so consistently? It begs
> the question of whether or not they know how to rate their modules--I 
> think
> they do because a watt saved is a watt earned according to the MBAs.
>
> The PV industry has hidden behind the accuracy argument for decades and
> needs to grow up and act like the responsible 20-something year-old that 
> it
> wants everyone in the world to think that it is. If I hear another whiney 
> PV
> manufacturer BS on this subject, I'm going to take them outback and spank
> them like a six year-old. (sorry for the analogy for all you who don't
> believe in corporal punishment).
>
> Bill.
>
> Bill Brooks, PE
> Brooks Engineering
> 873 Kells Circle
> Vacaville, CA 95688
> office and mobile phone: 707-332-0761
> fax:707-451-7739
> email: billbrooks7 at yahoo.com
> web: www.brooksolar.com
>
> Ecclesiastes 11:7 Light is sweet, and it pleases the eyes to see the sun.
>
>
>> -----Original Message-----
>> From: Joel Davidson [mailto:joel.davidson at sbcglobal.net]
>> Sent: Monday, June 18, 2007 5:36 PM
>> To: RE-wrenches at topica.com
>> Subject: Re: Flash Test Data [RE-wrenches]
>>
>>
>> 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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>>
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