Dear Fellow Survivalist;
I don’t know about you, but I find it difficult to pay for all the survival gear and supplies that I need. That’s why I try to build as much of it as I can. Not only do I enjoy building things, but it saves me a lot of money along the way.
Take solar panels, for example. You can save about half the cost of a solar panel by building it yourself, over buying them from a dealer. Considering that you need a whole lot of them to do any good, being able to save that much money is great. So, I’m in the process of building my own. Eventually, I might even have enough to save on my energy bills.
So, what does it take to build a solar panel? First of all, you need a bunch of solar cells. The most common sizes of solar cells used for solar panels are 6″x 6″ and 3″x 6″. I’m using the smaller size, because it’s easier to work with a smaller panel; although building the bigger ones is actually cheaper per kilowatt-hour.
Before getting started on this, let me warn you that solar cells are extremely fragile. They are made on paper-thin glass, so you can imagine how easy it is to break them. Packages of cells usually come with a couple of extras, just in case you break one. Everything you do with them, must be done with extreme caution.
All solar cells, regardless of their size, produce 0.5 volts of power. The size affects how many watts of that power they produce. Since 0.5 volts isn’t enough to power much of anything, it’s necessary to string a bunch of them together, in order to have enough voltage to use. Typically, 36 solar cells are strung together in series, making for a total of 18 volts. That’s high enough for charging 12 volt batteries (like car batteries) even when clouds keep them from producing at 100% efficiency.
There are two ways of connecting solar cells together; in series and in parallel. To get the 18 volts, they need to be connected together in series. If you think of a flashlight, the batteries are connected in series. The positive end of one connects to the negative end of the other. That’s what we need to do.
For solar cells, the face side (the blue side) is the negative side and the back side (the grey side) is the positive side. So, we need to connect the face side of one cell to the back side of the next cell in the string. Ultimately, we need 36 of them strung together like this, although the string is usually broken in parts.
Cells are strung together with tabbing wire. This is a flat, uninsulated wire, about 2mm wide and very thin. It is coated with solder or “tinned” when you buy it, making it easier to solder. If your solar cells don’t come “tabbed” (with the tabbing wire already on them) you need to start by tabbing them.
This consists of soldering pieces of tabbing wire to the contacts. First, it is soldered to the negative side, then the positive. To do so:
- Draw a line over the electrical contacts, with a flux pen, to apply flux to the contact area. Please note that you need to push down on the point of the pen, before using it, to start the flow of flux into the tip.
- “Tin” the contacts, by applying a very thin coat of solder, using your soldering iron. Some people skip this step, as the tabbing wire is already tinned, but I find that it works better to tin the contacts; otherwise I get cells where I don’t have good contact.
- Set a piece of tabbing wire, twice the length of the contact area on the contact and hold it in place with a weight, as in the picture below.
Note: I’m using a large socket for a weight. If my other hand hadn’t been holding the camera, it would have held the other end of the tabbing wire in place with a soldering tool.
- The soldering iron is then run across the tabbing wire slowly, from the weighted end to the other, melting the solder and sticking the tabbing wire to the contact on the cell. You can easily tell when the solder is melted, because it will become shiny and wet looking.
- You’ll need to do the same to all the rest of the cells, before moving on to the next step.
- Once the cells are all “tabbed” it’s time to string them together. That means soldering the tabbing wires on each cell to the back of the next one in the string. So, everything is going to be done with the cells face down.
- Apply solder and tin the contacts on the positive side of all your cells. This will make sure that you get good contact with the tabbing wire. When tinning, use the least possible amount of solder; you don’t want it lumpy, but more like you’ve just painted it on.
- Lay the cells out in a line, face down, so that the tabbing wires from one cell overlap the back side of the next one in the string. It helps to use a straight edge, taped to your work surface, to ensure that you get a straight line.
Note: A typical solar panel, made from 3″x 6″ cells consists of four strings of 9 cells; so that’s what you want to make.
- Straighten the tabbing wire so that it naturally falls onto the contacts of the solar cells.
- Solder the tabbing wire to the back sides of the cells, just like you did the front side; using the soldering tool to hold your tabbing wire in place, while soldering (don’t use the weight).
- Cut tow pieces of tabbing wire and solder them to the back side of the first cell in the string, which doesn’t have any wires attached to it. This way, you’ll have wires coming out of both ends of the string; one set coming off the negative side and one set coming off the positive side.
Notice in this photo how the tabbing wire is coming from under the cell on the right side, as pointed out by the arrow. This piece of tabbing wire is soldered to the positive side contacts on the leftmost cell. The tabbing wire coming out from under this cell (from its negative side) can be seen on the left.
Okay, I think that’s enough work to keep you busy for a while. Make your four strings and get them ready, then next time I’ll talk you through how to put them together and turn them into a solar panel. In the mean time, keep your powder dry and your survival equipment close at hand.
Stay tuned for Part 2!