Flash Test Data [RE-wrenches]

[Bill Brooks]

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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