Author Topic: Assembling my first solar panel (Read 2747 times)

tcrenshaw · « **on:** December 09, 2004, 03:34:32 PM »

I've just started to assemble my first home built solar panel. I've created two cell clusters of 18 solar cells each. I'm getting acceptable power out of the clusters so I'm pretty pleased with that. I'm using the cells that were on eBay a few weeks ago. I'm pretty happy with the results and soldering these cells together was a piece of cake.

I have a 5/8" particle board which I have liberally painted with acrylic white paint. I've added a very thin foam type backing where the cells will be set. The cell clusters will be siliconed to the foam backing. Around the outer edge of the cells I've left about an inch of particle board. I plan on using a silicon bead to go around the entire cell area boxing it in and then laying the glass on top of the cells and silicon. This should seal the cells under the glass. I'll then go around the edge of the glass where there'll be a gap between the particle board and the glass. The silicon should do a great job of holding the glass in place. I also have aluminum L channel that I'll frame the entire panel with. This should help prevent flexing of the particle board as well as protect the edge of the glass.

My question is, what type of glass should I use?

What thickness of glass?

Also, I've been toying with adding in silica packs to absorb any moisture. Good, bad, waste of time?

Another thing I've been thinking about is to add two small connectors on the back and pushing helium into the panel which should force the air out, then putting stoppers over the connectors to keep the helium in the panel. This would also allow me to purge the air and moisture out later if I see condensation.

As always, your comments and suggestions are greatly appreciated. I'm not looking to make these panels last forever but if I can extend their life and improve performance with little extra work, well then why not do the extra.

Tom in NH · « **Reply #1 on:** December 09, 2004, 06:09:04 PM »

I built a couple panels along the same lines as you. They were 32 x 42 inches and I ended up using double strength glass, mainly for the price. If you want the highest light transmission, you'll go with low iron glass, or lexan, but both of these are quite expensive. I think the thickness of the glass I used was 3/16 inch. It would be interesting to see a comparison of different cover, materials measuring the cumulative panel output over 20 years, to see whether the additional cost of low iron glass is worthwhile in the long run. In your panels, what is the purpose of the foam backing?

I'm now building panels differently. Rather than try to seal moisture out, I'm leaving them open so they can ventilate. I'm using 1/2 inch plywood as a backing material, stiffened with two pieces of 1 inch aluminum angle stock on the back side. My solar cells are very thin and fragile so I'm affixing them with just one spot of silicone in the center of each. I was concerned that going around the edge of each one with silicone might cause stress when they warm up in the sunlight. I got a good deal on plexiglas sheets so I am screwing it down to my plywood, resting it on a gasket of closed cell foam tape that goes around the perimeter of the plywood. Rather than using channel stock as a frame (which I did in my first panels), I'm thinking about sealing three sides with wide vinyl tape and leaving the bottom side open to the air. The channel worked fine to stiffen the panels, but it is costly. The channel is also good protection for the glass edges. Now that I'm using plexiglas, I'm not so concerned with that. I could always add it later if necessary. --Tom

tcrenshaw · « **Reply #2 on:** December 09, 2004, 09:50:12 PM »

Hi Tom, thanks for the information and some new ideas are now forming.

The foam backing is about 3/1"6 or maybe 1/4" thick. It's pretty stiff foam but I wanted to use it to hold the cells in place. Like your cells, the ones I'm using are very thin and fragile. The foam should hold the cells in place while also giving them some ability to expand and contract without breaking. By using the foam I don't have to worry about any silicon on the cells themselves and if the particle board for some reason flexes the cells should be okay as the foam should absorb the flex. Also if it hails I'm hoping the foam will absorb the shock instead of the glass or cells.

I like your idea of the open panel. The only thing I would be concerned about is how are you going to stop corrosion? I can pickup plexiglas fairly cheap but am concerned about the yellowing or fogging that happens to plexiglas over time. What are you doing to prevent or slow down that process?

It sure would be easier if I were not to seal the panel. Right now it looks like I'm going to get have to go to a glass shop and have the glass cut. I was hoping to find a store like Habitat for Humanity's outlet store with glass but they didn't have any. I hope to have this first panel done by Saturday evening and testing with it by Sunday.

Tom in NH · « **Reply #3 on:** December 09, 2004, 11:01:45 PM »

Hi Todd,

I got my plexiglas for 10 bucks a panel. If it lasts 15 years thats less than a dollar a year. If I'm still around then and if the panels are worth upgrading, I won't figure that this plexiglas owes me anything.

Now I see why you're using the foam. That might work. The drawback to silicone is once you decide to use it, you're stuck with it. With foam, you can always change things around if need be.

At this point, I'm not concerned with corrosion. In an open panel there will probably be less than a sealed system when water gets in it anyway (which it always seems to do)

I was trying to upload a photo of my setup, but the board kept crapping out on me. Maybe another time.

--Tom

iFred · « **Reply #4 on:** December 10, 2004, 01:45:40 AM »

I have built 12 panels so far, 28 x 26 with 28 cells per panel. I am waiting for the silicon to dry then I intend to fill them with oil-mineral or oil-baby oil 3/4 full. This will prevent corrosion and other problems.

I have updated this page. Enjoy!

Click on - Building Solar

http://www.internetfred.com/

tcrenshaw · « **Reply #5 on:** December 10, 2004, 02:19:53 AM »

I'll have to re-think the plexiglas idea. I'm thinking though that you may only get a few years at best out of them before they start to fog over. You've seen the plexiglas headlight covers on cars? That's what I'm thinking will happen here. Of course the panels will not be hit with road dirt/salt and such so maybe they will last. They would be a lot more impact resistant than glass that's for sure.

Yep, that's why I went with the foam. It'll absorb impacts along with flexing and allow me to change out a single cell if I need to in the future.

I'm still considering the open system as it would be much easier to do. I'm also considering a closed system but with the silica packs inside to absorb any water. So many choices to make!

I'd like to see the picture. If you can send it to my home address that would be great. It's crenshaw_todd*comcast.net Replace the "*" of course with the "@" sign. That just keeps the web farmers from farming my email address from the board.

tcrenshaw · « **Reply #6 on:** December 10, 2004, 02:28:46 AM »

Interesting idea using oil but I don't think I want to introduce a liquid into the mix. Not that it won't work, I think it will but I'd be to concerned over leaks over time. I've gone the length route instead of a fairly square panel. My panel is 15"x60 1/2" with 2x18 cells. This better matches my Arco M51 panels. I think I'm going to stick with the helium gas to purge the air from the panel and the silica packs to absorb any excess or remaining moisture, but the plexiglas might be a good alternative to glass.

Joel · « **Reply #7 on:** December 14, 2004, 08:06:26 AM »

I do have a concern about you mentioning laying the glass on top of the cells.

I have been experimenting with the best way of mounting these fragil cells. My first 6V panel had 6 arrays of 3 cells. Each cell was mounted to a glass backing with a dab of silicone in each corner leaving about 1/8" space between each cell and the glass backing. My thinking was that the small dabs I was using would be flexible enough to allow the cells their minute expansion and contraction without breakage. The completed pannel was then placed in the trunk of my black car to similate the large temperature swings. The result was one cell with a small crack in it, split in two and I lost a 1/2" x 1/2" section of another.

My second 6V panel had the same cell arrangement but each cell was mounted with a large dab of silicon in the center of the cell. To keep the cell angles and rear spacing uniform, each array is mounted and allowed to fully cure before the next array is mounted. The arrays are spaced from the mounting plate using two strips of 1/4" x 1/2" glass. I then take another piece of scrap glass and lay it on top of the cells to keep them flat while the silicone cures. The result is a good solid mount with each cell facing a uniform direction. The downfall is you have to be VERY careful when removing the spacing strips so as not to break the cells. As the silicone cures, it shrinks which slightly concaves the cells and puts pressure on the spacers. This is why I am concerned about your placing your cover glass directly on top of the cells and siliconing the edges. You may run the risk of breaking your outside cells from the silicone sucking the top glass down.

For both panels, I used a single 8' strip of 3/4" C channel aluminum for the outside casing and a single 8' strip of aluminum "L" channel for the mounting strips. I simply cut a 90 deg. wedge in the C channel where each corner is to be bent, and heat with a MAPP tourch to bend creating a frame. Leave one edge un-bent to allow the panels to be placed in the frame. The glass with the cells gets placed in first, siliconed into place and allowed to cure. The top glass is then put into place with the pannel turned upside-down so as not to damage the cells. Once the silicone for the top plate has cured, the open end is bent closed and sealed.

The mounting strip is then measured, cut, and bent to fit around the frame. 1/8" pop rivits hold the mounting strip in place and are placed in such a way to give added structural support to the top plate of glass by supporting the edges. I will be flooding these panels with helium and then sealing them.

I have some pictures of variouse steps of assembly if anyone is interested in seeing them.

Joel

tcrenshaw · « **Reply #8 on:** December 16, 2004, 05:51:56 AM »

Something to think about that's for sure but my
arrangement is 2x18 so at least for the width there shouldn't be much flex in
the glass at all. Since the cells are laying on a foam backing and I have 1" of
surrounding space between the cells and the silicon on the glass I'm hoping that
the cell expansion will be fairly flat since they are not siliconed or glued in
place. The cells should slide under the glass as they expand and contract. I'll
have to run a few tests like you did to make sure this works before I build my
second panel.

Please do post those pictures. The more information the better. I have another
nine panels to build!

For anyone else like me that's using the cells from eBay I found a method that
allows the re-attachment of the leads to the front of the cell. This includes
those cells that appear to have never had any lead attached. With a razor blade
lightly scratch the tanish coating on the front of the cell where the lead is
supposed to be. It doesn't take a lot of pressure nor a lot of scraping. You'll
see silver underneath. It doesn't need to be cleared of all the tan coating,
just enough to where there's a silver line going from top to bottom. Take a lead
from a broken cell and clean it of all particles. I just use my thumbnail and
run down the lead. With a soldering iron (I use 35 watt iron) tin the half of
the lead that you'll be soldering on the cell (tinning is just placing a large
amount of solder on the tip of your iron and running it down the lead fairly
quickly). This will turn the lead a nice even silver. Let it cool for a few
seconds. Clean the tip of your soldering iron of excess solder. Place the tinned
portion of the lead directly on top of the cell where the lead is to be
attached, tinned side down of course. Now quickly run the soldering iron down
the lead from end to end. Don't touch the cell if at all possible. The solder
will adhere to the cell quickly. A few seconds to cool and the attachment is
complete.

The original method I tried actually was to tin the scraped area of the cell
then attach the lead. When I tried this the heat from the iron discolored the
cell. The cell still works and didn't seem to suffer any ill effect but it is
messy and didn't look good at all. The method above, tinning the lead instead
worked perfectly and it almost looks like the lead was attached at the factory.
This method also works for partly attached leads. Testing the output of the cell
shows absolutely no loss in output.

I have two very nice pictures of this but the Insert image feature of the board
is not working.

They can be seen during the day (Central Time Zone) at

http://24.1.150.230:83/P2060124.JPG

http://24.1.150.230:83/P2060125.JPG

foster · « **Reply #9 on:** December 16, 2004, 10:49:59 AM »

Hi Joel,

I haven't being reading through the discussion board for a little while, however in checking through I saw your posting on the construction of your panel and am requesting if you could please make your pictures available.

Many thanks

Andre

Joel · « **Reply #10 on:** December 16, 2004, 09:32:23 PM »

We'll see if this works.

Here is my first complete panel. I have created a web page with detailed instructions and will post it to my server this weekend, so consider this a teaser...

Joel

tcrenshaw · « **Reply #11 on:** December 17, 2004, 05:06:58 AM »

Looks great Joel! Yes please do post the other pictures where we can see them.

tcrenshaw · « **Reply #12 on:** December 18, 2004, 07:10:49 PM »

Well I finally got my first panel put together today. I must admit that it
took a lot longer than I had anticipated. Tomorrow is testing day to see just
how well it all works. Stripping the silver from the mirror seemed to work very
well. Cutting the glass to size was a lot more difficult. I'm going to look into
other alternatives.

The first picture (if they show up) of course is the panel. The second picture is my panel setting next to my Arco M51 panel. My panel is about a foot longer and slightly heavier. Now tomorrow, start on the second panel. One down, eleven to go!

ghurd · « **Reply #13 on:** December 19, 2004, 01:55:47 AM »

Looks great!

G-

foster · « **Reply #14 on:** December 22, 2004, 12:29:43 PM »

Hi Joel,

Great Stuff!!

Best regards

Andre

dongoetz · « **Reply #15 on:** May 11, 2005, 10:57:37 AM »

I am also building a solar panel, but am having trouble soldering them together. They're pretty small (.5v, .4a) and I'm looking to make the total voltage about 6v. does anyone have any suggestions? Thanks.

pyrocasto · « **Reply #16 on:** May 11, 2005, 01:24:11 PM »

Wow you picked an old thread! ;-)

If there are no leads on them, I would use conductive tape or epoxy with wire. I've played witht he conductive epoxy and I just couldnt get certain things figured out, but I'm gonna keep trying.

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