What's in a Name? ASTM Subcommittee on Glass
for Solar Applications Sets Terminology
July 2, 2010
The ASTM E44.20 Subcommittee Glass for Solar Applications met yesterday
in Kansas City to further discuss the creation of standards and
guides for the solar glazing industry.
The group began with a review of work item "Edge Classifications
for Glass Used in Solar Applications," led by Wayne Boor of
PPG Industries. During the group's last meeting it had heard a proposal
to use SAE J673 on edge classifications to define edges for solar
glass. "It's an auto standard that describes the different
edge types used in the auto glass industry," Boor explained.
However, the challenges to using SAE come in the terminology, since
it was quickly realized that the players in the room from the architectural
glass, solar module and even aluminum industries had different terms
to describe various edge shapes, finishes and defects.
The group's task is to provide names for these edge characteristics,
rather than to provide information on edge strength, which should
be a work item for the future, suggested subcommittee chair Doug
Hall of Corning Inc. Hall noted that the point was to classify the
terms, not set tolerances, in order to be able to have conversations
with others about tolerances and specifications.
"There's so much confusion about the naming of these things
that we really need to come up with new names," said Hall.
He proposed defining edge shapes in terms of a picture and geometry,
using generic names, new to all industries, to make this clearer.
His concern is that even members of the architectural glass industry
use different names to describe the same shapes.
The group agreed on five edge shapes to begin to classify. Julie
Schimmelpenningh of Solutia Inc. posed a request that the group
look to the Glass Association of North America's Glazing Manual
to gather terms already in use for these shapes, as well as for
the finishes and defects.
The group also began to discuss descriptions and terms for the
treatment of glass corners. "This is an area that's new to
the glass industry. Generally speaking, there really is no corner
designation in any standard I've ever seen. However in the solar
industry it is important," Boor said.
The group came up with a list of the terms they've seen used to
refer to corners and then whittled it down to twodubbed and
rounded--upon agreeing that most names agree to one of these two
Terms for glass classification came up again later in the meeting
as the group met to discuss a guide to solar glazing terminology.
The guide defines types of glass by its composition, but when it
came to the portion of the outline setting out to define iron composition,
specifically, what percentage of iron makes a glass mid-, low- or
ultra-low-iron, the glass industry spoke out. Representatives of
AGC, Cardinal and Guardian agreed that what customers request is
a certain visible light transmittance, not iron content, and that
to get to those specifics of the iron composition would be to share
what sets their solar glazing products apart from competitors.
The subcommittee addressed several other issues in this second
meeting. Daryl Myers with the National Renewable Energy Laboratory
gave a presentation urging the group to consider supporting the
reinstatement of ASTM E903, Standard Test Method for Solar Absorptance,
Reflectance and Transmittance of Materials using Integrating Spheres.
This test method, which essentially "died" in 1996 due
to lack of re-balloting, covers the measurement of spectral absorptance,
reflectance and transmittance of materials using spectrophotometers
equipped with integrating spheres. Myers noted that these properties
are important in performance of all solar energy systems, from passive
building systems to central receiver power systems. He noted that
anyone interested in working on updating the standard doesn't necessarily
have to be part of ASTM.
The group also heard a presentation from Joel Feingold of Strainoptics
Inc. providing background for its work item on minimum surface compression
requirements in heat-treated glass used for solar cell modules and
HERE to read about this presentation during this week's Solar
The group also began the first steps in drafting a "New Guide
for Durability and Reliability Issues of Glass and Coated Glass
Used in Solar Energy Products." The current work item is intended
to serve as an educational document for manufacturers of solar energy
products and to help E44.20 learn where future standards might be
needed. The group began by starting to identify durability issues
during the glass and module manufacturing process and in field use.
HERE to learn more about the subcommittee and how you can be
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