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Talesin West glazing (C) Daniel FriedmanPolycarbonate Solar Panel & Window Glazing Properties

Polycarbonate solar panel or window glazing:

This article discusses the properties of polycarbonate glazing used in solar applications, including its impact resistance, thermal movement, scratching, discoloration, and solar transmittance.

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- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

Polycarbonate Glazing for Solar Applications, Windows, Greenhouses

Accompanying text is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. Our photograph (left) shows an interesting sloped window installation on the roof of a barn silo that had been converted to living space. Conventional wood-frame double-hung windows were set into the sloped silo roof - this was not a successful installation and the windows rapidly rotted, leaked, and disintegrated. Our photo of sloped glazing at page top was taken by the editor (DF) at Taliesin West in Scottsdale, AZ.

The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.

Topic: What is Polycarbonate glazing, does it prevent "ultraviolet radiation seepage", Where can I get some?

Question:

I recently (1985) read an advertisement fdor a product that touts its covering as being made of "polycarbonate," which prevents ultravoilet radiation seepage. What is this stuff and where can I buy it? - Gary Allen, Palo Alto, CA.

Illustration showing a cross-section of a window, with parts labeled.

Notes on the sketch above:

Double-paned glass is shown to have a low-e and/or solar control coating, a gas fill between the double panes, and a spacer at the base of the window between the panes.

On the interior of the house is a strip of wood at the bottom edge of the window labeled the stop, and just in front of it is a step-like shelf labeled the stool. Beneath the stool and on top of a two by four is a thin pipe labeled the backer rod.

On the exterior of the house, the illustration shows the frame of the window labeled the sash, and the shelf in front of the window labeled the sill.

Weatherstripping is shown to be between the sill and sash. Beneath the sash, vertical against the house, is a strip of wood called the apron or flange, and the jamb is on the end of the sill. The caption reads: Energy-efficient window technologies are available to produce windows with the U-factor, SHGC, and VT properties needed for any appl ication.

- This article series combines, quotes from, supplements, and expands energy efficient building suggestions for new and older homes, provided by the U.S. Department of Energy. In the text we add commentary, photographs, and links to related material beyond the U.S. DOE content.Sketch, U.S. Department of Energy.

Answer:

Polycarbonate is one of several thermplastic glazing materials used in solar applications. Polycarbonate glazing is also used in greenhouse construction and hurricane-damage-resistant windows. Manufacturers assert that polycarbonate glazing is "200 times stronger than glass" (Gallina) and the material is lighter in weight than glass as well.

Greater resistance to impact is a main advantage of polycarbonate glazing over acrylic or glass glazing materials, but it is more expensive than either of them. Some manufacturers (Gallina, below) offer tongue-and-groove sheets, modular polycarbonate roof panels, insulated polycarbonate windows, and related glazing products.

Like all plastics, polycarbonate glazing expands and contracts under thermal stresses, so glazing stops must accommodate a fair amount of movement.

Also, polycarbonate glazing can abrade and discolor ovcer time, thus losing a certain amount of solar transmittance. And like other plastics, it is vulnerable to deterioration caused by ultraviolet radiation.

Polycarbonate sheet products that have been well known since the mid 1980's and are available through glazing distributors. Some sources of polycarbonate glazing products include:

  • ARCAT lists current manufacturers of polycarbonate sheet glazing, including Polygal Inc., SABIC (Originally General Electric Plastics), Sheffield Plastics, CO-EX, C.R. Laurence- Retrieved 11/29/2010, original source: http://www.arcat.com/divs/sec/sec08841.shtml
  • General Electric (Lexan, now produced by Sabic - see below). According to GE, Daniel W. Fox, a GE Chemist who was seeking an improved wire enamel, first discovered and discovered the polycarbonate resin used to produce Lexan in 1953. Lexan and related plastics have become widely used in the ensuing half-century and include products well beyond glazing, such as the production of CDs.
  • Lasco Industries ( Lascolite)
  • Cy/Ro (Cryolon SDP)
  • Gallina USA LLC. (Arcoplus) 4335 Capital Circle, Janesville, WI 53546 Tel: 608-531-0450., Email: todd@gallinausa.com - Retrieved 11/29/2010, original source: http://www.gallinausa.com/
  • Professional Plastics, (Acrylite) distributes products from 35 manufacturers. Tel: 888-995-7767. Quoting:
    Lexan polycarbonate resin is an amorphous engineering thermoplastic, characterized by outstanding mechanical, optical, electrical and thermal properties. The Lexan portfolio provides broad design versatility through its wide range of viscosities and product options such as: environmentally conforming flame retardancy, scratch resistance, toughness, heat resistance, weatherability, biocompatibility, optical quality, and compliance with stringent FDA and USP requirements. - Retrieved 11/29/2010, original source: http://www.professionalplastics.com/MAKROLONGP-polycarbonate
  • Sabic (originally GE Plastics) produces Lexan - Retrieved 11/29/2010, original source: http://www.sabic-ip.com/gep/Plastics/en/ProductsAndServices/ProductLine/lexan.html

Readers who are building their own windows or who are installing factory-built windows should also

see SLOPED GLAZING DETAILS

and VERTICAL GLAZING DETAILS. For suggestions about how to diagnose and repair leaks in existing skylights,

see SKYLIGHT LEAK DIAGNOSIS & REPAIR.

Also see THERMAL EXPANSION of MATERIALS and see if you are constructing site-built storm windows using this or any other glazing product, see our discussion of storm window weep holes and why they are critical: STORM WINDOW WEEP HOLES

Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

The link to the original Q&A article in PDF form immediately below is preceded (above) by an expanded/updated online version of this article.

...


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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: is polycarbonate glazing safe?

Nick said:
Is it safe, or is it like other plastics such as BPA? (Feb 16, 2012)

Reply:

Nick, BPA concerns mainly deal with plastics used to store and re-heat food or beverages. Theoretically, polycarbonate, a #6 plastic, would give you BPA if you microwaved food on it (BTW, styrofoam is 'air-entrained' polycarbonate). But since we don't use PVC pipes for our potable hot water, I'd say this is not a window topic.


...

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Citations & References

In addition to any citations in the article above, a full list is available on request.

  • Solar Age Magazine was the official publication of the American Solar Energy Society. The contemporary solar energy magazine associated with the Society is Solar Today. "Established in 1954, the nonprofit American Solar Energy Society (ASES) is the nation's leading association of solar professionals & advocates. Our mission is to inspire an era of energy innovation and speed the transition to a sustainable energy economy. We advance education, research and policy. Leading for more than 50 years. ASES leads national efforts to increase the use of solar energy, energy efficiency and other sustainable technologies in the U.S. We publish the award-winning SOLAR TODAY magazine, organize and present the ASES National Solar Conference and lead the ASES National Solar Tour – the largest grassroots solar event in the world."
  • Steve Bliss's Building Advisor at buildingadvisor.com helps homeowners & contractors plan & complete successful building & remodeling projects: buying land, site work, building design, cost estimating, materials & components, & project management through complete construction. Email: info@buildingadvisor.com
    Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com
  • Engineering Toolbox website, provides a more extensive table of coefficients of linear expansion at http://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html
  • Western Washington University Thermal Expansion is described and defined in a clear article that also gives both linear and volumetric coefficients of thermal expansion at 20 degC. for a variety of materials at http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Thermal/ThermExpan.html
  • General Electric Corporation, Silicone Products Division, Waterford NY 12188, 518-237-3330 also see www.ge.com/ [Beware of online web-links to the GE Silicone Products Division - the company's contact information for silicone products will redirect to a not-helpful website on silicone products hosted by supplier Momentive.
  • Tremco, 10701 Shaker Blvd., Cleveland, OH
  • Identification of Silicone Oil/PETN Interaction, PDF information from General Electric Corporation, Silicone Products Division, Product Information. Pamphlet RHB-4B. c A General Electric polydimethylsiloxane, document from the U.S. Department of Energy at http://www.osti.gov
  • Idea Development, Inc., PO Box 44, Antrim NH 03440 603-588-6544. Updated contact: www.bigideagroup.net, Manchester NH, 03101 603-641-5955 - Bigideagroup is a network of inventors assisting in marketing products.
  • Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
  • In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested

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