Inverter/module Testing [RE-wrenches]

Fri Apr 19 13:43:48 PDT 2002

The wrenches and our customers are often guinea pigs for the photovoltaic
module and component manufacturer. To the pioneers go the arrows and to the
settlers goes the land. Two suggestions- stay off the bleeding edge- the
first pioneers- use components, products at least one year after their
introduction. Second- ask yourself how long the manufacturer is backing the
warranty. When you become a solar contractor with years of experience, you
know your customer's future expectations for your choice of modules, etc.,
hinges on your judgment. That is why I am glad the big oil companies are
manufacturing modules. It means two things:
1. The homeowner can count on a 25 year warranty.
2. They know we are at the apogee of hubberts curve for the oil industry- I
believe we are past the apex. I have to have something to sell soon-and
quickly. We are now extracting and depleting 4 gallons for every new gallon
found. Fourteen million more net addition gas guzzlers hit the road this
year and supply can know longer met demand.
The good times are around the corner- its lights out on growth due to cheap
oil.
Gator Tom
----- Original Message -----
From: "Antony Tersol" <tony at appliedsolarenergy.com>
To: <RE-wrenches at topica.com>
Sent: Friday, April 19, 2002 1:51 PM
Subject: RE: Inverter/module Testing [RE-wrenches]

There is the Testing Centre for photovoltaic components (TISO-LEEE) in
Switzerland (see http://leee.dct.supsi.ch/PV/Welcome_TISO.htm) that
seems to do much if not all that is being suggested.  The only
limitation is that they do not buy large numbers of each module.  They
are purchased anonymously.

>From a paper I downloaded from their site last year, presented at the
16th EPVSEC,Glasgow, May 2000, I have excerpted the Introduction, a
paragraph from within the report, and part of the conclusion:

"18 TYPES OF PV MODULES UNDER THE LENS

1.INTRODUCTION
The nominal electrical parameters supplied by the
manufacturers normally refer to typical parameters
recorded during the manufacture of the modules which use
specific or even calculated measurements. Project planners
and installers are increasingly asked to provide production
and behaviour estimates for the systems they install, in
particular when they involve Solar Grants and Contracting.
They therefore ask the following questions:
1. Is the electrical data supplied by the manufacturers
useful for our purpose?
2. Do the modules degrade over time? In what way?
3. Is there a difference in energy production (Wh/Wp)
between the different types of modules?
4. What is the actual energy output of the different
modules?
5. Does the high voltage between frame and cells of a
module in a plant influence its efficiency?

In order to answer such questions the LEEE-TISO
testing centre for PV components has, since 1991, carried
out systematic tests, under real operating conditions, on the
most important modules currently on the market ([1 ] to
[5 ]). At Lugano-Trevano,the modules for each cycle of
tests are exposed on stands tilted at 45° and 7° south of
azimuth and kept at maximum power point (MPP). Each
module is equipped with a Maximum Power Tracker
adapted for its power range.

In more recent times, 18 modules divided into two
cycles with 11 (cycle 5) and 7 (cycle 6) modules
respectively have been test.  They were selected from those
most commonly found on the market or which had
interesting innovations. In order to guarantee impartiality
and neutrality regarding measurements, the modules were
purchased anonymously unknown to the manufacturer.
Two examples for each kind of module were acquired."

from within:

"The PWX 500 and ASE-50-PWX-modules,
produced by the same manufacturer but with a different
label,have a similar PR with respect to Peff.;but,since
Photowatt (PWX500)declares a higher nominal power,
there is a difference in production of 8% between the two
modules. In cycle 5 the BP580 module shows better
performance due to a correct declaration of power. The
good energy rating of the old ASI16-2300 module with
respect to other cycle 6 modules should be noted: after 18
years of exposure,and with nominal power being equal,
this module produces more."

from the conclusion:

"Stabilized power after 12 months of exposure to light is
lower than the guarantee limits for 12 out of 17 modules
purchased."

----- Original Message -----

Date: Fri, 19 Apr 2002 05:37:27 +0000
From: Brad Bassett <bsbassett at earthlink.net>
Subject: RE: Inverter/module Testing

...

This points out that there are two ratings question that need to be
addressed. One is an equal STC rating between mfg's instead of just
their own internal rating. The other is a rating that indicates real
world performance of a system so customers have a better idea what they
are buying. I support Bill and Endecon in getting ratings systems in
action. Do wrenches have the ability to do these ratings? I do think
that reports from the field on reliability are very valuable, and I
don't think you really get that from a test facility, but I have not
seen too much side by side comparison. Home Power has done some, and I'd
like to see more.

One more note, it's important that testing be done on off the shelf
units, not gifts or known deliveries from the manufacturer, which will
always be at the top of the 10% rating window. Also, a large enough
sample needs to be tested so that anomalies are spotted.

Thanks

Allan Sindelar wrote:
> If one module manufacturer were to rate their modules honestly, I would
> support the effort by using their modules where I can. I would soon be
> reporting here and elsewhere that "hey, this thing puts out more than
> Brand
> S's equally rated module!" I would like to believe that the combined
> publicity would shame the other manufacturers to follow suit. But I have
> always been a little naive that way...
> Allan
>

Brad Bassett
Schott Applied Power
Tumwater, WA office
bsbassett at earthlink.net

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