Solar Cell Glass: Hardness of glasses
Solar Cell Glass: Hardness of glasses
(OP)
Hello,
I am choosing glasses for a novel solar cell design, and part of the criteria is if the glass will be able to withstand hail and other things (?) falling from the sky, since this glass will be the cover glass for the entire solar cell. I can gather information on the glass including Knoop/Moh's hardness, Young's modulus, etc., but 1. I'm not sure which of these structural properties translates to being able to withstand things like hail and 2. If it's hardness, how hard is hard enough/how can I determine this?
Any help is greatly appreciated. Thanks.
I am choosing glasses for a novel solar cell design, and part of the criteria is if the glass will be able to withstand hail and other things (?) falling from the sky, since this glass will be the cover glass for the entire solar cell. I can gather information on the glass including Knoop/Moh's hardness, Young's modulus, etc., but 1. I'm not sure which of these structural properties translates to being able to withstand things like hail and 2. If it's hardness, how hard is hard enough/how can I determine this?
Any help is greatly appreciated. Thanks.





RE: Solar Cell Glass: Hardness of glasses
If it flexes you can't make it strong enough, you need a balance of the two.
But fist you should be looking at the optical properties of the glass, you don't want to block usable wavelengths of light.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Solar Cell Glass: Hardness of glasses
RE: Solar Cell Glass: Hardness of glasses
If it's only 5 cm across, then the obvious answer is to increase the thickness of the glass. A 1/8-inch thickness would probably resist the majority of impacts, barring those that would crush everything around your solar cell. Note also, the smaller gap between the cell and the cover glass, the less opportunity for breaking the cover glass.
TTFN

FAQ731-376: Eng-Tips.com Forum Policies
Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers
RE: Solar Cell Glass: Hardness of glasses
The short answer is that there is no single property like hardness or modulus that translates into x amount of resistance to hail. Impact conditions, whether it is from hail, a dropped hand tool like a hammer, or something else entirely, is a complicated, dynamic event governed mostly by fracture mechanics. Fracture of brittle ceramics like glass depend a great deal on the presence of microscopic flaws, and designing for impact either requires knowledge of the statistical distribution of these flaws (within a part, lot-to-lot variation, etc.) or considerable product testing under realistic conditions.
RE: Solar Cell Glass: Hardness of glasses
http://en.wikipedia.org/wiki/Gorilla_Glass
RE: Solar Cell Glass: Hardness of glasses
separate comment: I do not think there is usually a gap above the solar cell, clear adhesive used
RE: Solar Cell Glass: Hardness of glasses
Impact testing.
Something along the lines of ASTM F3007 (though it's specific to architectural laminated glass, it gives you the idea. Drop a steel ball from a known height and see what happens!)
RE: Solar Cell Glass: Hardness of glasses
- you want glass both as thin as possible and low iron for optical performance
- tempering will increase impact resistance, as will chemical strengthening. Tempering is much cheaper.
- Partly in response to the needs of the solar industry, the tempering machines now available are designed for thin glass. I don't have a number at hand, but I believe they can temper down into the 1-2mm thick range for relatively large panels.
- Alumina silicate glass with chem strengthening like Gorilla or Willow glass would be the Cadillac for this application, but is likely to an order of magnitude more expensive than tempered soda lime glass.