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'best' glazing for solar hot air panels? - Page 2

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Posted by Bill Kreamer on December 3, 2006, 12:41 am
Installing on an angle is problematic for plastic glazings.  Plexiglas
(acrylic), is cheap and works well if the collector is vertical and has
decent air flow so as not to run overly hot.  Polycarbonate (TwinWall, etc.)
is strong, but may eventually yellow.  In general, double glazing can be
counterproductive; don't go to extra effort or expense to do that.

- Bill

Posted by SJC on December 3, 2006, 4:46 am

  Last time I looked, acrylic was more expensive than dual wall polycarbonate.
They use it on greenhouses by the ton, it is designed to be cheap and available.
As for acrylic, it softens at 160F, if you stagnate to 200f+, you will have a
As for yellowing, dual wall polycarbonate has UV protectant on one side that is
backed by the manufacturer for 10 years. Greenhouses would not use it if it

Posted by Bill Kreamer on December 7, 2006, 3:16 am
 Thanks, Paul, I stand corrected on the application of Twinwall. It always
seemed a bit pricey at about twice the cost of Plexiglas.  Plexiglas will do
well in a vertical air collector.  The recommended 160 degF continuous
assumes 160 on both sides of the sheet; but you're right about not letting
the collector stagnate.  Given that caveat, I've never had a problem with

Polycarbonate Twin-wall -
Thickness   Sheet Size   Price Per Sheet
6mm          4x8             75.36

Plexiglas® -
Heavy Duty .093 Acrylic Sheet
(for Glazing, Inside Storm Windows & Picture Framing) -
List Price/Pkg. of 10 -
48" x 96", 383.52

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