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  • #16
    vacuum

    Originally posted by Mike90250 View Post
    if you are using 2 hot plates to heat the entire panel, you have to rely on the air inside to move the heat around. if you vacuum first, you will only melt 2 spots. (at each hotplate)

    Try it on a sample first. We freeze and bake stuff all the time here at work, and with huge 20x30' Ln2 cold plates and electrical heaters, it takes hours to change the temps in a vacuum chamber, when there is no air, it's real slow.
    .
    Hi mike , I never though about NO AIR when heating. My box will be only the most 4foot long x 4foot wide x 5 inches tall.

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    • #17
      vacuum

      Originally posted by Mike90250 View Post
      if you are using 2 hot plates to heat the entire panel, you have to rely on the air inside to move the heat around. if you vacuum first, you will only melt 2 spots. (at each hotplate)

      Try it on a sample first. We freeze and bake stuff all the time here at work, and with huge 20x30' Ln2 cold plates and electrical heaters, it takes hours to change the temps in a vacuum chamber, when there is no air, it's real slow.
      .
      Hello mike. I have been looking all over net and wacthing vid's of sealing solar panels.not much help. But like you said hear first them vacuum.
      I didn't get my EVA yet,so don't know what it looks like.
      Im trying to figure out the steps to do this. would this be correct.Put glass down,then EVA,then cells,then EVA.next heat to about 120 to 150 degrees,next turn on vacuum.
      Now if that is correct when do I put on the backing? I plan to use some kind of plastic, or if I could use "window security Film" here is the website http://www.geowindowfilms.com/clear4mil.php
      But I dont know if the EVA will Stick to it.
      Let me know if you think the sept's are in order.
      Thanks. { But I NEVER though about heating it up with No air in the box]ha ha ha .
      John

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      • #18
        EVA vs Sylgard

        May be or hope some one could let me know about these spec. for using this to cover the face of solar cells when making a panel.This would be in place of layer of eva on the blue side of the cell.
        ---------------------------Good or Bad
        Visible Light Transmittance 86%

        Total Solar Transmittance 74%

        Total Solar Reflectance 8%

        Total Solar Absorbance 18%

        Visible Light Reflectance 10%

        Winter U-Value 1%

        UV Rejected 99%

        Shading Coefficient 92%

        Total Solar Energy Rejected 20%
        ............................
        This would ease my mind alot, and save me money on wasted cells.
        Thanks
        John

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        • #19
          this is what I'm going to try.

          http://www.youtube.com/watch?v=QD5SY...layer_embedded

          He uses a heat gun, but that sounds slow and ineffcient.
          I think a piece of sheet aluminum on top with bathroom floor heating strips would work great.

          http://cgi.ebay.com/13-Sq-ft-120-Vol...item4ceb6c6cb6

          http://www.briskheat.com/p-152-rh-pl...ip-heater.aspx

          Yeah the heating wire is expensive but I actually have some already cause I'm gonna heat my bathroom floor latter on.

          Also to put pressure on the top to the cells and help drive out and seal the membranes I have a 1/4" thick piece of foam sheeting that is used with perforated laminated plastic. I used to laminated photographic canvas and the sponge helps helps squeeze out any air spaces and acts as a leveling agent. I'll let you know in a few months if my plans worked out.

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          • #20
            where to get tedlar?

            http://cgi.ebay.com/1m-10m-Solar-Pan...item1e60e9be3f

            why is this stuff so expensive? $15 per square meter?

            Is it just thick plastic?

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            • #21
              eva

              Originally posted by rollandelliott View Post
              http://cgi.ebay.com/1m-10m-Solar-Pan...item1e60e9be3f

              why is this stuff so expensive? $15 per square meter?

              Is it just thick plastic?
              =======================
              rolland .I agree,cost too much.But now dosen't everything.Watching that vid, I cant figure how he hooked up the vacuum cleaner to the Bottom side of the eva.Because he didn't have that in a vacuum Bag.I know he said he drilled a hole in the bottom of the table.
              Im going to start to make my "autocave" I guess that is what they call it.It's a box that i'll beable to put a bag with a vacuum line going to it and also I can add pressure to the inside of the box and also have heat source in it to bring it to about 150 deg.. One guy here use a comercial one and he said it worked out pretty good.My box will be big enough for a 36 cell panel. Hope it works.
              John
              I made one panel using Surf Board epoxy , the company said that in FL., that is what they use. Up here it's not good, because of the cold ,below 32.It cracks. Well it's a learning curve. lol

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              • #22
                he taped all four sides of the tedlar plastic to the top of the table making it air tight.
                He also raised the glass off the table surface using rubber spacers. to the vacuum wouldn't try to just suck on the glass, but would remove the air around it.
                then he hooked up his vacuum and got suction, not perfect, but it doesn't have to be perfect.

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                • #23
                  Just a thought.
                  For a vacuum source, how about a compressor out of an old refrigerator?.
                  Cheap, or free, and if it can get a pressure of about 200 psi+, it must have the corresponding vacuum.

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                  • #24
                    Originally posted by NeilTheCop View Post
                    Just a thought.
                    For a vacuum source, how about a compressor out of an old refrigerator?....
                    They work, but you have to keep the oil in circulation, or the motor burns out quickly..

                    There are little "Dentist office" vacuum/pressure pumps that run a couple 100 $ new, that will pull a pretty decent vacuum too
                    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                    solar: http://tinyurl.com/LMR-Solar
                    gen: http://tinyurl.com/LMR-Lister

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                    • #25
                      eva

                      Originally posted by rollandelliott View Post
                      http://cgi.ebay.com/1m-10m-Solar-Pan...item1e60e9be3f

                      why is this stuff so expensive? $15 per square meter?

                      Is it just thick plastic?
                      ......................................
                      rolland
                      I just bought a qt of liquid lamimate at this web site.Going to see what's it's like.Has uv protection also.Main thing is to cover the face of the cells,Then could use anything to protect the cell from what/ rain ,snow,hail,That could also be done I see now with "Security window film.
                      http://www.dtgweb.com/shop/search.php?mode=search

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                      • #26
                        return it.

                        I think you wasted your money. As a photographer who used to buy stuff from DTG all the time the clear coatings applied to photographers would in my opinion not be trusted to last ten years much less 25.

                        which one did you get?
                        http://www.dtgweb.com/shop/product.p...2&cat=0&page=4
                        is one and it's not that much of a cost savings over Dow 6100, maybe a few bucks cheaper.

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                        • #27
                          eva/Liquid Laminate

                          What do you think. I bought some " Liquid Lamination " and it has UV protection.Im thinking of ..Spraying.. this on the Front of the cells,and then lay the cells Blue side down on to Glass, next Put a sheet of EVA over the cells with an over hang so that it will Melt./stick to the glass. Now put this in an autocave, guess that is what they call it. First put the glass with the cells in a vacuum bag ,then put that in the autocave.Hook up a vacuum line to the bag,[that comes from outside the autocave].Then HEAT the inside of the box to 150 deg.F. Now turn on the Vacuum and suck any air out of the cells,.I don't know how many inches of vacuum to use. Now fill the box with about 10 psi. and turn off the heat/and let it cool down.
                          After this is done ,.Im trying to think of the cheapest way to put a back on to the eva.Could use another peice of glass,Now all I would have to do is spread silicon on the back and then lay the glass on top.Then if I want, put it back in the vacuum chamber,
                          Sure would like some input.
                          tks
                          John
                          Oh my vacuum box is 48 inches long by 36 inches wide and 9 inches tall.
                          I have HEAT LAMPS inside to create the heat.

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                          • #28
                            eva/Liquid Laminate

                            Originally posted by rollandelliott View Post
                            I think you wasted your money. As a photographer who used to buy stuff from DTG all the time the clear coatings applied to photographers would in my opinion not be trusted to last ten years much less 25.

                            which one did you get?
                            http://www.dtgweb.com/shop/product.p...2&cat=0&page=4
                            is one and it's not that much of a cost savings over Dow 6100, maybe a few bucks cheaper.
                            -------------
                            rolland
                            the name of it is clear sheild type LL .made by Clearstar http://www.clearstarcorp.com/clearshield.asp

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                            • #29
                              I've used that before. I still have some. It is pretty thin about the consistency of latex paint. I'd put on a few coats. Maybe if you put them behind glass and use eva it will work.

                              A silicon glass sandwich isn't very effective, unelss you get all the air out. Any air in there will expand and pop the seal in a day .

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                              • #30
                                eva/Liquid Laminate

                                rolland, I know about the air bubbles, they also Pop in the cold/freezing weather.With the Liquid Laminate, I plan to ..SPRAY.. it on the cells, that way I know that it will cover 100 percent and then cover with eva and Heat and vacuum.Im almost done with building my autocave.I hope it works.
                                I also have a chance to buy cheap some glass 40 1/2 x 28 1/2. But Im thinking of the best way to wire the cells, I think I'll put 36 in series and have them go through the rest that are in parallel. They will be 3x6 cells.
                                John

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