Plexiglass UV resistance

[Mike90250]

Thanks for the nifty update. Got any pics of the assembley ?

[mrfrisky]

Here is a pic. White splotches are cloud reflections.

[dogsbody]

Did similar on solar hot water panels in 1970's. Many still working but slight crazing of the surface, which does not apparently affect the solar gain

[woodypynes]

Tomorrow, I am about to install my first solar panels. I have the accessories (battery, charge regulator, inverter, etc)...but I am curious about something. Will it hurt or help if I "protect" them with a piece of plexiglass or tempered glass? I only considered this option b/c of hail and "weathering" in general. They just look SO pristine right now, I'd hate to see them rusted (frames) or cracked (hail). I'll take any suggestions, as this is my first go-around with SP.
Thanks guys!!

[Mike90250]

"Factory Built" commercial panels have tempered glass fronts and are generally resistant to small hail. Adding another sheet of glass or anything, will reduce the light, increase heating, and lower output power.

[woodypynes]

Thank you for the advice, Mike! I'm about to go outside and begin the installation. We're so excited! We really could have used this setup during/after Hurricane Irene last summer (we live in NC).
Thanks again, Mike.

[Bratan]

Started making panels back in '08 for use in the tropics where it rains a lot. Here is the correct procedure for plexiglass after 3 years of tinkering.

1. We use 1/16" aluminum sheet for the back, framed by 3/4 x 1/4" aluminum bar. We use U/V resistant .093" thick plexiglass. We do not enclose with aluminum channel (c-bar) and will explain why below.
2. After attaching to the panel, you must encapsulate cells with Sylgard, Corning, etc, applying a good layer of liquid encapsulant, using a brush. One batch of encapsulant is good for every two panels that are 36" x 30". (36 3x6 cells)
3. Must glue plastic, transparent "necklace beads" in the middle of panel, in between the strings of cells, so that plexiglass does not touch the cells upon contraction.
4. Everything is held in place with stainless steel screws (#10).
5. When attaching plexiglass to the panel, only apply silicone GE-II to the top. Leave sides and bottom attached only by the screws/nuts/washers. These are the areas that cannot be totally sealed.
6. Channeling will only destroy panel. It is impossible to get a 100% waterproof seal here, so panel needs to "breath". When we used channeling, the panels developed moisture/condensation and when daytime brought the sun at its hottest, water became hot vapor and the plexiglass literally exploded outward, became brittle and did not last weeks.
7. After testing for many weeks and months, panels are now totally moisture free and working at its highest rating. Whenever it rains or condensation forms, it quickly dissipates as soon as the sun starts shining.

I'm very interested in this method as I'm also trying to use plexiglass. In #2 you encapsulated cells to the aluminum backside?
In #3 how exactly did you make "necklace beads"? I'm not sure I understand that part Did you add some drops of Sylgard to the plexiglass and let it dry and then put panels on top of it? Is plexiglass not attached to cells in any direct way (i.e. you can remove it later)?

[natel]

I'm interested too. I'd love to see a video of this whole process if you ever get around to making on someday.

I'm very interested in this method as I'm also trying to use plexiglass. In #2 you encapsulated cells to the aluminum backside?
In #3 how exactly did you make "necklace beads"? I'm not sure I understand that part Did you add some drops of Sylgard to the plexiglass and let it dry and then put panels on top of it? Is plexiglass not attached to cells in any direct way (i.e. you can remove it later)?

[Bratan]

I'm interested too. I'd love to see a video of this whole process if you ever get around to making on someday.

That seems unlikely looks like OP hasn't been back for a long time (only 2 posts). Anyway I'm trying to develop my own method of "floating encapsulation". It involves wax paper and liquid latex I will let you know how it goes...

[sermormo]

I planning to built my first one and I found all this info very helpfull. Thanks