Panel glass expansion question

a1bigtuna
a1bigtuna Registered Users Posts: 21 ✭
in General Solar Power Topics #1
Does tempered glass require space for expansion for high temperatures? Is there a preference for the thickness of tempered glass for solar panels? Mine will not be in any hail storms and will only be out while out in camping sites. Will just cover it when bad weather comes in. Just don't want to make an aluminum frame out of 1/8" stuff and crack the glass? Any advise on the thickness, will have the cells covered with EVA sealant and Tyvek tape just for more protection.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Panel glass expansion question

    Commercial panels seem to use 1/8" (single weight?) tempered glass... They also use "low iron" glass for transparency. Thicker glass will be stronger but also a lot heavier.

    Also, do you have a place that will cut and temper the glass for you (at a reasonable price)? Or are you going to find "used glass" (old tempered glass windows from homes) for your project?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Slappy
    Slappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    #3
    Re: Panel glass expansion question

    http://www.newton.dep.anl.gov/askasci/eng99/eng99303.htm read the 7th paragraph, but glass will expand, but very little, but encasing the boarder of the glass with weather striping something like this http://www.lowes.com/pd_66674-81-02279_4294858100_4294937087_?productId=1096045&Ns=p_product_price|1&pl=1&currentURL=%2Fpl_Weather%2BStrip_4294858100_4294937087_%3FNs%3Dp_product_price|1%26page%3D4 to protect the glass that sits inside the frame, it will give it room to expand, and "shock" from the frame being bumped. or you could use other things as you prefer. I just used those just for examples. and according on the materials used and assembly. But I think that glass will expand 0.02%
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  • a1bigtuna
    a1bigtuna Registered Users Posts: 21 ✭
    #4
    Re: Panel glass expansion question

    Thanks for the replies, I will buy the glass as my figures come out to, am not really concerned about costs, I am only making one of these set ups. Could care less about the cost/watt, just need it to meet my traveling needs. Just do not want to get thicker and heavier glass than I need, because it is just for a camping application.
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #5
    Re: Panel glass expansion question
    a1bigtuna wrote: »
    Could care less about the cost/watt, just need it to meet my traveling needs.

    My want to look at those folding thin-film panels.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #6
    Re: Panel glass expansion question

    Tempered glass panels (like patio door blanks 28X76 or 34X76 units) should always be set with neoprene setting block available from any glass shop for nearly nothing. They are little dense rubber blocks that are about 1/8" thick. This allows the glass to expand against the blocks. I suspect there is a co-efficient of expansion table out there for glass, but setting blocks have worked well in glazing for years.
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #7
    Re: Panel glass expansion question

    The setting blocks are to keep the glass from touching the frame. Temper glass can take a heavy blunt impact on its face. But the slightest impact/nick on the edge will shatter it.

    This is what happens when glass and metal meet:
    http://www.facebook.com/#!/video/video.php?v=1062788822877

    We just installed this door a week before this happened.
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  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
    #8
    Re: Panel glass expansion question
    a1bigtuna wrote: »
    Could care less about the cost/watt, just need it to meet my traveling needs. Just do not want to get thicker and heavier glass than I need, because it is just for a camping application.

    You can try potting cells in transparent urethane resin on fiberglass sheet for durability. There is UV stable urethane resin that seems scratch resistant. I have one cell that I potted and it has been laying in the yard exposed to elements for past few months. So far still clear. Best part is that it weighs 4 times less per Watt than glass solar panel. I am also looking to make lightweight, foldable solar panels for camping.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #9
    Re: Panel glass expansion question
    n3qik wrote: »
    The setting blocks are to keep the glass from touching the frame. Temper glass can take a heavy blunt impact on its face. But the slightest impact/nick on the edge will shatter it.

    This is what happens when glass and metal meet:
    http://www.facebook.com/#!/video/video.php?v=1062788822877

    We just installed this door a week before this happened.

    Actually, only partially true. Neoprene setting blocks allow the glass to expand, compressing the block, so that it doesn't hit the frames. Stress on tempered glass edges is fatal as Ken suggests.

    Tony
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