Building Your Own Solar Panels – Part 3

Building Your Own Solar Panels – Part 3

Here’s Part 1 and Part 2

Greetings. How’s your solar panel project coming along? Are you ready to finish it off this week? Well, I am. Now that you’ve got a working solar panel, it’s time to encapsulate it to protect it from the weather. This consists of putting glass on it and a frame around it.

The first step is to install a spacer around the edge of the panel. This is going to perform two functions for us. The first is to keep the glass from touching the solar cells and breaking them. The second is to act as something to hold the glass to the panel. To do this, we’re going to use double-sided adhesive mounting tape; you know, that foam stuff that’s hard to get off walls, after you stick a picture up with it.

That mounting tape is about 1/16″ thick. So, to be sure that I have enough clearance to avoid damaging the cells, I like to use a double layer, all the way around the perimeter of the panel. I also put some small pieces in between the rows of cells, in order to keep the glass from flexing and hitting them.

Your wires need to come out of the panel, through this mounting tape. The easiest place to do this is in one of the corners, where the tape has to join together anyway. Just leave a small gap for the tape, as small as the wires will fit into. Later, when you put the glass on the panel, put a little bit of silicone caulking in this gap, to seal off around the wires. It’s important that he panel be watertight, to prevent the inside of the glass from fogging up.

The next step is to install the glass itself. This can be a little tricky, because we have to protect the cells from damage, at the same time we are aligning the glass. You really only get one try with this, as once the glass is in place, it can’t be moved. Lots of people recommend using dowel rods as spacers in a case like this, but I’ve found something better.

What I did was to make a perfect corner out of some scrap I had in the workshop. I used a thin piece of plywood, about 18″ square, with a perfect 90 degree corner as the base (that 90 degree corner was that way from the lumber mill; I trust their cutting more than my own). Then I attached a couple of pieces of 1″x 4″ to the corner, to act as a fence, nailing them to each other and to the plywood base. After a final check with a framing square, the jig was ready to use.

Placing the solar panel in the corner of this jig gives me a way of aligning the glass to the panel, before lowering it down to touch. So, after peeling the protective cover off the adhesive, at least on the sides that are going into the corner, it is placed in the jig. Then the glass is set in place, a couple of inches above the panel to align it. Once aligned, it can be lowered into position and then the rest of the protective paper can be removed.

SOLAR PANEL CORNER
Solar panel set in jig. Note that it would have to be all the way in the corner to work.
Foam mounting tape shown, for attaching glass to the panel.

Let me talk about glass for a moment here. Most solar panels are made with tempered glass. That’s because it is about two times as strong as regular glass. Considering the possibility of hail, that’s a good idea. But you can do even better than tempered glass, by going with plastic substitutes.

  • Standard Acrylic (Plexiglas) is 10 times as strong as glass.
  • Impact-resistant Acrylic is 50 times as strong as glass (it’s somewhat rubberized).
  • Polycarbonate (Lexan) is 250 times as strong as glass.

Please note that when I’m saying “strong” here, I really mean “impact resistant.” The flip side of this coin is that they are less scratch resistant than glass. But then, what’s going to scratch a solar panel on your roof? The other little detail is that any of these, tempered glass, acrylic or polycarbonate is going to be more expensive than plain old glass. You get what you pay for, you know?

Okay, so now the glass or plastic is stuck to the mounting foam. Run your fingers over it, applying light pressure, just to make sure it is stuck well. Then seal the edge with silicone caulking, to make the whole thing waterproof. You don’t need to glob it on, just a thin coating, smoothed out by a wet finger. You still need to cover that up with a frame. But before doing that, you need to let the silicone dry.

There are several ways of doing a frame, including buying commercial solar panel frames. My favorite is to use an aluminum C-channel. You can buy this in different sizes. I always look for one that has an inner dimension of 1/2″ between the two arms of the C. If it’s smaller, it’s hard to fit the panel in. My best results have been with a 3/4″ C channel that’s 1/8″ thick. That gives me exactly 1/2″ inside dimension and it’s thick enough to tap for screws. But you’ll have to buy that online; the home improvement centers don’t carry that size.

You’ll need to cut the C channel at a 45 degree angle to make the frame. This can be done on a power miter saw, a radial arm saw or even a table saw. If you don’t have any of the above, you can use a hand miter box with a back saw. Remember, neatness counts.

You actually need to cut the frame pieces longer than the actual dimensions of the panel, to make up for the extra length taken up by the thickness of the metal. So, for a 1/8″ thick frame, the sides need to be 23/64″ longer than the panel. That will make the inside dimension match those of your panel. Drill a clearance hole through one of the sides, for your wires to go through.

The frame pieces are stuck to the panel with more silicone caulk. Simply put a couple of beads of caulk in the frame and press it into place. Hold it with bar clamps or by taping the corners with masking tape (after making sure they are aligned well) until the silicone dries.

Technically, you can stop here, but I’ve gone one step further, adding corner braces to the back side of the frame, just to give it a bit more strength. Since the plywood is so thin, it’s more or less impossible to use wood screws to screw into it. So it’s better to drill holes in the aluminum frame and tap it, and then use machine screws. That will make a much stronger joint.

SOLAR PANEL CORNER 2
Corner bracket attached to the back side of the frame with #6-32 flat head machine screws.
You can also see the wires coming through the frame.
The hole (3/8″) has been filled with clear silicone to seal it.

For #6-32 machine screws, you’ll need a #36 drill, which is 0.1065″ in diameter. I don’t have numbered drill sizes, so I substituted and used a 7/64″ drill bit; at 0.1009″, it’s close enough. Use a light cutting oil with the tap, to help it cut easier and keep it from binding in the hole.

There you have it, your solar panel is now ready for use. All you need to do is hook it up to a solar charge controller, and start charging batteries with it. Then you can use that power for anything you need. I’d recommend building some more panels, as one really doesn’t give you a whole lot of power. But now you’re one step closer to being ready to survive.

So keep your powder dry and your survival equipment, including your solar panel, close at hand.

solar panel

 

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