DIY Solar Panels...What kind of glass?

[BilljustBill]

What type of tempered glass would you use to make a PV panel? Source?

I realize this is "Out There", but I ran across several metal-framed glass shower doors. Having enough cells to make a panel, would this type of glass work?

I've used a sealant called LexCell in sealing my dual 3 Hp. suction fans and 1/4" thick Plexiglass windows on the side of my two 55 gallon waste barrels. It's a water-clear sealant that dries rather hard, but somewhat flexible. Sealing a metal framed glass isn't a problem using that product.

Adding the equal of two panels under the glass of one shower door "seems" workable.... ;>)

Bill

[Mike90250]

Glass is called Low-Iron, high transmitivty .

[scheek]

I used a double pane glass. It's about twice as thick as single that goes in windows. Any glass supply house will have it. I don't think Lowes carries that thick. Too, they are twice as high. I got (2) 27" x 32" pcs for a total $14. Lowes wanted $15 for one pc/single.

After using a 1/8 tile spacer for alignement of my cells, the total thickness of both panes, with silicone is exactly 1/2". My angle aluminum is 1-1/2" for the frame.

[philpaine]

Has anyone any idea of how good plexiglass is at transmitting light?

Are there any other downsides to using plexiglass instead of low-iron glass?

Phil

[scheek]

I considered it but was afraid of the flex. Those cells are fragile.

[philpaine]

Hi
Well, I found I could get two 1/4inch 2' x 2' Plexiglass sheets for $34, and 1/4in shouldn't flex that much. If I used the plexiglass, I was going to use 3/4in ply 2' x 4' for the rear. I would have thought that screwing the two together sandwiching a 1" x 1/4" softwood frame would have given a pretty stiff structure. One could always put some 1/4" spacers in the middle of the panel if there were were still concerns re. flex.

I like the fact that it is easy to drill plexiglass.

What I don't know is what the light transmission issues are, if any.

Phil

[Jason]

moving this thread to the DIY section

[BilljustBill]

Hi
Well, I found I could get two 1/4inch 2' x 2' Plexiglass sheets for $34, and 1/4in shouldn't flex that much. If I used the plexiglass, I was going to use 3/4in ply 2' x 4' for the rear. I would have thought that screwing the two together sandwiching a 1" x 1/4" softwood frame would have given a pretty stiff structure. One could always put some 1/4" spacers in the middle of the panel if there were were still concerns re. flex.

I like the fact that it is easy to drill plexiglass.

What I don't know is what the light transmission issues are, if any.

Phil

Just a question with using Plexiglass: I thought you had to use a Polycarbonate so it won't yellow?

Back in the early 1980's, I built the batch water heater from plans in "New Shelter" magazine. It used plywood, standard sizes of lumber, and for the reflector, it used Masonite so foil or Mylar would follow the double curve. Storm windows were the big energy-saving thing back then, so I had a large window made with a single layer of two large panes side-by-side of glass and a center support. I could use the heater from the last frost until the first one (April-November). During the summer heat up to 104 in July-August, I was always worried about a fire, even with using the 40 gallon pressure tank as a stable heatsink...and when a hailstorm hit 3 years later, I was glad to remove it during the re-roofing.

That feeling has stayed with me all these years. When I do build my panels from the shower door, all sun/heat exposed areas will be made from Hardyboard type materials that are concrete and fiber based as well as fire resistant. Heavy, yes, but stable and fire resistant!! Maybe I should use a layer of glass over the cement board to prevent any corrosion to the solder connections or the cells. Any advice?

I saw one DIY video on You-tube where the fellow mounted his cells on a suspended layer of pegboard as well as used standard lumber for the framing.... After seeing the panel fire pictues (THANK YOU), building a PV panel gives me new respect for the U/L label and the prices of the higher quality panels....

Bill

[miernik]

What I don't know is what the light transmission issues are, if any.

Any updates on that?
I would also want to use Plexiglas, but can't find any info on light transmittance.

If anyone knows anything, please message me.

[sunnysun]

Plexiglas transmits 92% of visible light and over 10 years in the harshest sunlight will lose about 2% - which you can't really detect with your own eyeballs.

Sounds like a pretty big efficiency loss!

[russ]

Like sunnysun points out - wiki says 92% light transmittance. The stuff is used on green houses where light transmission is important.

If you don't buy a type that is UV stabilized it will discolor quickly and you won't get those numbers.

[miernik]

Let me make sure I understand you correctly:

With a new Plexi I will get 92% of power I could get without it, with a 10-year old one 90% and about 87% with a 25-year-old?

That's not too bad, let's say a new panel without Plexa is 4.9A, a 25-year old panel itself will degrade to about 4 A and with a 25-year old Plexa will give about 3.4 A, which is not so bad after 25 years.

Glass, besides being breakable, would be very difficult for me to mount on my panel, because of it's weight and fragile-ness. I don't imagine myself handling a 1.6 meter x 0.8 meter sheet of glass on the roof of my van. And no - I won't take the panel off the roof - it's too much work and would require a forklift which I won't have access to.

[russ]

Before getting too excited and taking action you might visit a local nursery that uses the stuff and ask them for input. They will know better than anyone.

They will use a thinner material that is not flat but has a profile to it so that will be different.

They can tell you how often they replace the sheet and what their criteria are for replacement.

[miernik]

What exactly do you mean by "nursery" and what would they use a Plexiglass for, and why would they use a UV-stabilized version - you mean these called "Lexan"?

http://en.wikipedia.org/wiki/Nursery_(room)

A nursery is usually, [...], a bedroom within a house or other dwelling set aside for an infant or toddler.

???

You mean you tell me to go to someone's house to see their bedroom or what?

[russ]

Look again and you will see a variation of the definition under science - Plant nursery, a place where young plants or trees are raised

They would be by far the biggest consumer of this type of covering. Some use plastic sheet because it is cheaper but the better quality houses are covered with plexi-glass.

This stuff is not cheap, especially in the quantities a commercial greenhouse uses. They know how to get the best value for their money.

The UV in sunlight causes plastic to degrade rather rapidly. Plastic of this grade/type designed for exposure to sunlight is UV stabilized.