Sealing the panel

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A good frame will keep the cells sturdy and should seal the cells in a waterproof material. Common sealing methods include EVA film, a glass face, silicon and epoxy based sealants. Each method has their pros and cons. For this panel I decided to use epoxy because it was easy and was a non-glass method of strengthening the wood. Also, I had a lot of it around from a project that my dad is currently working on.

The main disadvantage of using epoxy is that it yellows, and you never fully know when or how much it is going to yellow. The plan was to give the epoxy 3 days of drying time and then cover it with a clear UV protection coat.

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Applying silicone:

To make sure the cells are properly attached to the base, and do not buckle, silicone is applied in a thin layer underneath the cells. I used a squeegee to spread it inside the area of each cell. Applying the cells now, make sure to apply silicone generously to the two wire leads. Those leads will stick out of the surface a bit, but this is okay since the epoxy will cover them.

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Mixing the epoxy:

I used a marine grade, indoor (ironic), and most importantly, self leveling epoxy. It needs to be self leveling or it will leave air bubbles. Almost all epoxies need to be mixed with a 1:1 ratio (for two part epoxy). In my case I used 400mL or epoxy, so 200mL of hardener and 200mL of epoxy. I mixed the epoxy for aprox. 10 minutes and poured it thoroughly over the cells, starting with the cracks, ending with the surfaces.

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The pour:

The cables and cells are now attached to the back plate now. I leveled the panel out on our table by adjusting several wooden blocks. The leveling of the panel is critical, otherwise the epoxy will pour out one edge.

I ended up using about maybe 400ml of epoxy, I wasn’t quite sure how much is enough so I had to do several pours. During this time the use of a flame such as a propane torch is required. Heat raises the air bubbles to the surface where they pop, leaving a smooth surface.

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Building the frame

Wooden Frame

For this panel I decided to go with wood as my back-plate. Not only is wood cheap, it is surprisingly water-resistant if treated properly. The plan was to spray-paint the wood, apply a layer of epoxy, put the cells on top, then somehow attach wires and cover the surface with epoxy. While it was a nice idea maybe, I found a much better way that will be covered in my next post.

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Cutting the back-plate:

I cut a nice 4mm thick piece of pine (I think) to 61 cm by 40 cm. Then with my dad’s careful assistance and help; I cut a 2.5 mm strip to match the outside dimensions of the back-plate. Then I cut matching 45 degree slants into that strip. One of the strips was marginally shorter than the others so I shaved a bit off one side of the back-plate to compensate.

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Gluing the “margins”:

Now that everything is cut out, I needed to glue the margins on. Doing to ended up a slightly messy, yet solid result. I used wood glue for this, just so you know, and I applied it to the margins in a very very shallow layer. Pressing down with some books now, I let the glue dry for several hours.

In the pictures above you can see that I have put the cells on the unfinished base just for looks really. I also learned that the best way to transfer these cells is by flipping and flipping requires the strings to be taped together.

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Painting:

Painting is simple, just spray an overlapping coat from ~8 inches away, flip and repeat. After the paint dries I put the cells back on and drilled two holes, 1 mm apart between the two top tabs. I made a slight mistake of not pushing extra delicately and ended up with a few splinters near the holes.

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Materials for my first solar panel

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Hi! One of my newest projects is a 12 watt solar panel made for charging my phone. Now that I have successfully tested the panel in the shy Vancouver sun, I have decided to share the build process on this website. Here is a list of things that I did:

  • Gathered materials
  • Prepared the cells (tabbing)
  • Connected solar strings using bus wires
  • Prepared the frame
  • Covered the cells in epoxy
  • Made the power connections
  • Tested it out

Things I needed:

  • Solar Cells (0.5v each at 1+ amp)
  • Tab wires (3-5 mm wide tin wires)
  • Bus wires (5-7 mm wide wires)
  • 4mm thick board
  • Wires (2)
  • 5v power regulator (I used the COM-00107)
  • Electrical Tape and/or shrink tubing
  • Rosin core solder
  • White spray-paint
  • Clear automotive coat
  • Self leveling epoxy resin
  • USB micro cable
  • Silicon

Tools I used:

  • Voltage reader
  • Flux pen
  • Table saw
  • Miter saw
  • Soldering Iron
  • Pliers/tin snips
  • Propane torch
  • Lighter

Most of these materials I had at home and did not need to buy them. However, I later realized that not many people have solar cells and spare electronic parts laying around; so I made a handy list with references to eBay:

Keep in mind that if you were to buy more efficient solar cells (say like 2 amps each) then you would need to buy a more powerful voltage regulator, otherwise your voltage regulator would overheat.

You may have noticed that I did not include all of the materials in the eBay list; this is because I personally bought them from either Home Depot or The Source (Radioshack in the States). It’s much cheaper to drive to one of these stores than pay for the extra shipping online. Also, I highly recommend searching for a solar kit as it may be slightly cheaper than buying all of the items separately.

Here is a blueprint that I made in inventor:

Solar Panel 12v Blueprint

As you can see, the solar cells are aligned in two rows and are connected in series (I will go over this in more detail later). This means that the voltage is added from every single panel, yet the current stays the same. A drawback of doing this is that if one of the cells break, then the entire current might be disrupted, and then the solar panel wont work.

These solar cells can be connected in series by connecting the bottom side (the anode or positive) to the top side (the cathode or negative). This is usually done by connecting two strips of tin to the top side of a cell, and then have it connected to the bottom side of a cell. This process is called tabbing and will be covered in the next post.

Be sure to leave a comment if you have any questions! I’ll be happy to update my post with any information I missed.

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