Application experience and field performance of silvered polymer reflectors Page: 3 of 12
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
APPLICATION EXPERIENCE AND FIELD PERFORMANCE OF
SILVERED POLYMER REFLECTORS'
Paul Schissel, Gary Jorgensen, and Roland Pitts
National Renewable Energy Laboratory"
1617 Cole Blvd.
Golden, CO 80401
The solar-weighted hemispheric reflectance of unweathered silvered acrylic mirrors exceeds 92%, and
specular reflectance into a 4-milliradian, full-cone acceptance angle is greater than 90%. Comparison of
outdoor and accelerated tests suggests that the protected silver can resist corrosion for the five-year life
that is the current goal. An installation of parabolic troughs has been cleaned monthly for two years, and
reflectance is regularly returned to within a few percent of the initial retlectance values. In the presence
of moisture, the silver/acrylic bond can delaminate to form a maze of tunnels and destroy specular reflec-
tance. Proper edge preparation and protection delay the initiation of tunnels.
Silvered polymer mirrors, weathering, durability.
For most applications, silver is the reflective material of choice. The hemispheric reflectance of freshly
deposited silver weighted over the solar spectrum (0.3-3.0 pm) is greater than 97%. A transparent layer
is required to protect the silver from abrasion, soiling, and corrosion. An acrylic polymer with ultraviolet
(UV) absorbers (to inhibit UV-photon-activated degradation) can he used. The solar-weighted hemispheric
reflectance of new, unweathered, silvered acrylic material exceeds 92%.
The composite mirror is shown schematically in cross section in Fig. 1. The performance goals for sil-
vered polymer films are a five-year life with a specular reflectance greater than 90% into a 4-mrad,
full-cone acceptance angle. The optical goals for unweathered mirrors have been met, and current
emphasis is on durability in the environment (Susemihl and Schissel, 1987).
Experimental mirrors are tested in accelerated weathering tests. Laboratory results have led to a series
of production materials called ECP 300 followed by ECP 3(XA and ECP 305 from the 3M Company. The
production materials also are undergoing accelerated weathering tests and outdoor tests near Denver,
Albuquerque, Miami, Phoenix, and other sites.
This work was supported by the U.S. Department of Energy (DOE) under Contract
No. DE-AC02-CH 10093.
--A U.S. DOE facility.
Here’s what’s next.
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Schissel, P.; Jorgensen, G. & Pitts, R. Application experience and field performance of silvered polymer reflectors, article, April 1, 1991; Golden, Colorado. (https://digital.library.unt.edu/ark:/67531/metadc1310751/m1/3/: accessed May 20, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.