In this instructable I will explain how I built a solar panel using 2 panes of glass. I am not the first person to do this, there are other instructables and youtube videos that show how this is done also, but this is how I did it. If you have looked at my first solar panel project, I say this one is an easier way of constructing a panel. The down side is that you need 2 pieces of glass for this, the other one I built only used one.
These are my other related instructables:
The tools and materials needed for this project:
1. 2 panes of tempered glass. I got them free from some one changing windows.
2. FRP board
4. Wood screws
5. Silicone, I used this kind.
6. Tile spacers, like these.
7. Wire, I used 14awg black and red because I have it around. But you need to get the wire that is the corect gauge for the wattage your panels produce.
8. Welding gas
9. Air pump needles, these, like you use to fill sports balls.
10. Caulk gun, like this.
11. Wood working tools; I used a table saw, router, and miter saw
12. Solar cells already soldered together, from first instructable.
13. Soldering iron, budget, midgrade, best.
14. Solder flux
15. wood glue
So lets get started……..
1. Clean and dry the glass very well. Anything that is on the glass now will be on there forever inside your panel.
2. Lay your cells face down and you can put a drop of silicone, or a stripe of silicone like I did, on the back side of the cells. This is to keep the cells from moving around inside the panel.
If you know exactly where your cells will be laying on your glass you could put the silicone on the glass and not on the cells. I didn’t try that because I knew I would not get it in the right place.
3. Then I carefully picked up the cells and placed them in the middle of the glass as centered as possible.
Another option would be to take the second piece of glass and lay on the cells, carefully without breaking them, and then flip the glass with cells over so they are face up and stuck to the bottom glass.
4. After I laid the cells on the bottom glass I used a paper towel to lightly press the cells down into the silicone, carefully not to break any cells.
1. Now that the cells are silicone down to the bottom glass it is time to put spacers in. You can’t just lay the top glass on the cells, you will break them. To keep the top glass from touching the cells I used rubber tile spacers, the white X’s in the picture. These are thicker than the cells, and since they are rubber they will absorb the shock of something impacting the glass such as hail. To place these I put a small spots of silicone around the cells, then placed a tile spacer on the silicone. This keeps them from moving around. Between the rows there was not enough room for an entire spacer, so I cut one in half.
2. Next I soldered the red and black wires onto the bus leads. Do it now, once the top glass is on its too late!
3. Trying to keep an even distance I ran a bead of silicone all around the edge of the glass about ¾ of an inch in from the edge. Not out to the edge, but about ¾ of an inch in so that there is an empty space between the edge of the glass and the bead of silicone.
4. Now it’s time to put the top glass on. Carefully place the top glass on. Make it even around the edges with the bottom glass. Press it down so that the silicone is contacting the glass all around the edges. Measure the total height of the panel; keep the same measurement all around the edges. I laid some old books on the glass to keep the top glass from lifting up and loosing contact with the silicone around the edge. Then left it this way for about 2 days to let the silicone cure.
At this point the functional part of the panel is done and it would be a good time to test it to be sure that it is working. If something needs fixed, better now then after its all finished.
The reason for doing this is that there is air inside the panel contains moisture. There are 2 major reasons you need to get the moisture out; 1, it will make the cells rust and 2, it may condense on the top glass and block light from getting to the cells.
To purge the air out it needs to be replaced with another gas that has no moisture in it, I replaced it with welding gas, argon and CO2 mix. I used welding gas because I have a welder at hand to use. And for those that do not know, welding gas is NOT flammable. That’s why I use a lighter as part of the purge cycle.
The hardest part is knowing when the panel is truly purged of air, I could not find information on how to do it accurately without scientific instruments in a lab. If you have a local company that repairs double pain windows they may be able do this step for you.
This is how I did it.
1. I used 2 needles for inflating sports balls like footballs and basketballs. First I grounded the round tip they come with to a point, like a medical needle.
2. With the gas valve closed I removed the line from my welder and taped the needle to the end of the line. In the future I plan to put a T in the gas line so I don’t have to remove the line from the welder every time, just have a second line with a valve ready to fill more panels.
3. I set the panel on a bench upright. I placed the needle connected to the gas supply in the bottom right, and the other needle in the top left for a vent. There may be better places to put them, but this is how I did it.
4. Then open the gas valve so that there is only about ½ a PSI of gas entering the panel. If you push the gas in to fast you will stir up the air and may not get the moist air out. This is a long process, but necessary.
5. After giving the gas some time I held a lighter over the top vent needle. If there is a normal flame then there is no gas coming out, as you can see in my picture there is a small blue flame that kept going out that means that there is welding gas coming out. If the welding gas is coming out then the panel must be full.
6. Now that the panel is full, turn off the gas and remove the fill needle. Immediately seal it with silicone! By the time you do that the top needle should have had time to vent any pressure that may be in the panel. If there is any pressure coming out of the panel let it vent, you do not want pressure in your panel. Remove the vent needle and seal this with silicone also.
7. Now that the panel is purged you will want to fill the remaining empty space around the outside of the panel with silicone. This makes a double seal around your panel. 1 seal is good, 2 is better.
First I cut a piece of FRP board the same size as the glass. I put some random silicone globs on the back of the panel and place the FRP on them. Press it down for a good seal. I put this on the back side of the bottom glass for 3 reasons.
1. It looks better than an all clear panel in my opinion.
2. It will reflect the light that is not hitting the cells also reflecting some heat.
3. Since the light is not passing through the panel to the black roof under the panel, the back side will stay cooler because that part of the roof will not heat up as much. And the heat will not radiate up against the back of the panel. Heat lowers efficiency.
Now for the frame. To do this I started with a 10 ft. long 2x4.
1. Cut it in half so that there are 2 pieces 10 ft. long and almost square.
2. I got measurements from the panel and cut the 4 pieces for the frame, if you don’t know how to do this get someone to help with this step. I recommend using a 45 degree cut for the corners.
3. After getting the 4 frame pieces cut I put the grove in them for the panel. This grove needs to be large enough for the panel and the FRP board to fit into.
4. The place where the wires come through will need to be cut out.
5. Using wood glue and screws put 3 sides of the frame together.
6. Slide the glass and FRP board panel into the grove of the frame.
7. Put the final side of the frame on, be sure your wires are not being cut into by the frame.
8. Using silicone seal the top glass to the frame, and the FRP board to the frame. I also filled the wire cut out to be sure the wires are sealed in. Then I used a wire staple to hold the wire in place so that the wire does not get pulled on and break the seal between the glass panes.
To finish up the panel and get it ready for mounting I had 2 things to do.
1. I painted the panel with a product called Flex Coat. It is made for outdoor use, it’s the same thing I used on my other panel.
2. Solder a diode in the positive wire. Some people put these diodes inside there panel. I don’t because if it is damaged then the entire panel needs to be taken apart to replace it. I put these diodes about 10” from the end of the wire. Not where the wire comes out of the panel, but the other end. The diode needs to be installed the correct direction. If it is installed backward you will have no voltage pass through it. There is a stripe on one end, that stripe needs to be on the end that is going to connect to the device being powered by the panel.
When it is all dried it is ready to be mounted.
This is the first time that I have built a panel in this style. I made a small one to test. If this style seems to last then I will most likely make more panels this way.