Building a solar panel, EVA film style. This is a continuation of my other instructable “How to solder solar cells together”. https://www.instructables.com/id/How-to-Solder-Solar-Cells-Together/
The picture above is of the completed panel. This panel was put up July of 2013, if produces an average peak of 40 watts. It is set at an angle of approximately 35 degrees and facing south.
Now for the materials:
- Wood for the frame
- Wood screws for the frame
- Wood glue for the frame, I like this kind.
- Finishing coating for the frame, I used a product called Flexcoat. It is foundation coating that I had left over, but it worked to seal the wood. Find it here.
- Silicone, I used 100% Silicone sealant. Something like this.
- Tempered glass, I got this free from someone that was replacing windows in their home.
- EVA film, This is the film that is used to seal the cells to the glass. Find it here.
- Heat gun, I recommend a gun with a high and low heat. This is a recommended gun because it comes with deflectors, find it here.
- Sheet of FRP, this is a wall covering found at home improvement stores. See it here.
- Soldered solar cells, from other instructable.
- Brad nailer and nails, find it here, and brads here.
- Table saw, I just have a small portable saw similar to the one here.
- Miter saw, I use one similar to the one here.
- Vacuum, You can use your home vacuum, or a small shop vacuum like the one here.
- Other tools and materials.
This is what I used to put this together; you may come up with different materials and methods.
Disclaimer. When working on this project use your head, don’t do anything to hurt yourself. I used nail guns, heat guns, power saws, soldering irons, and other tools that can hurt you. If you don’t know how to use any of the tools I talk about then get someone to help you that does.
Now on to the fun!
Before you begin any assembly you need to have your materials around and ready. I had all my solar cells soldered together and tested before for the piece of glass that I was using before I went any further. Before I can put those cells on the glass I built the frame.
To build the frame I used one 2x4 10 foot long. I ripped the 2x4 down the center so that I had two 10 foot pieces of almost square material on my table saw. Then I cut a rectangle piece out of that, and kept it for later.
Then cut the 4 pieces to fit the glass that you are using, remember the ledge that you made from your cuts will go to the inside to support the glass.
Also cut a piece of FRP the same size as your glass. This will cover the back of your panel.
Now I begin to assemble the panel. First I cleaned the glass, very well! Then I set it on saw horses to start applying the EVA film.
1. Lay out a layer of the EVA film. This comes in a milky white color and has divots on one side. From the information I read the divots go against the glass side to help spread the sunlight going through the film to your cells.
2. I folded all the edges over and taped them to the bottom of the glass, except 1 corner.
3. That one corner that is not taped I connect to a vacuum cleaner so I can vacuum all the air out from between the glass and EVA film.
4. I used a heat gun to lightly melt the film to the glass, it turns clear when it is heated. Be sure not to melt through the film!
5. After it cooled I laid the solar cells on the film and positioned them.
6. Lay out another layer of EVA film over the cells, then tape them down to the bottom side of the glass as before. Then reconnect the vacuum.
7. Use the heat gun again to melt the film over top the cells and to the first layer that was applied to the glass. Be sure to get all the air out, work them toward the vacuum.
8. Then I trimmed all the edges even with the glass.
Now to put the cells in a frame. I already had the frame assembled. The pic above has the frame lying face down.
1. Run a bead of silicone along the ledge that the glass will lay on.
2. Carefully lay the glass/ solar cells in the frame.
3. Run a few beads of the silicone on the back of the cells, I suggest 1 bead down the back of each row of cells.
4. Lay the FRP on top the cells and LIGHTLY press it down onto the silicone. You will have to make a notch in the FRP for your wires.
5. Using that piece of wood that was cut out of the 2x4 to make the ledge for the glass, cut them to put along each side of your frame to hold the layers of glass/ cells and FRP to the frame. It needs to be tight, but not so tight that you break any cells.
6. These wood pieces I glued in, then I used some brad nails to secure them. Be sure to put your nails into the frame and not try to put them through the glass!
To finish the panel I painted the frame with a product called Flex Coat. It has a stucco type of finish, but it is made for outdoor use over brick/block, insulation, wood, and other materials.
I also put a diode in the positive wire about 10 or 12 inches from the end of the wire. I have seen other people put the diode inside the panel, but if it burns out you have to take the panel apart to change it. Also I don’t put it close to the panel because you want as much wire as you can get coming out of the panel just in case you have to cut the wire off because of damage. This is why I put it at the end of the wire and not close to the panel.
Here I have it mounted on a framework that has it setting at approx. 35 degrees from level to the ground. At the moment I have it strapped to the chimney that it sets against. I am still in a testing period, so it is not permanently mounted yet.
You can also see that it has a white look to it. I think that I did not get a good seal to the glass and it has dropped away a little. I will be adding some bracing to the back to keep the cells closer to the glass. But the panel does work. On a good day around 12 noon I get 18-19 volts, and 2.5 amps giving about 45-46 watts. The amount of cells that I have in this panel is rated for 60 watts, but that’s in a laboratory in perfect conditions.
If you decide to try building a panel using EVA film please let me know how it worked for you.