Build Solar Panel The DIY Style

Build solar panel to power your home needs.  Here are some simple steps to get you started to build solar panel.

Go buy some bricks of 3 X 6 mono-crystalline solar cells. It takes a total of 36 of these type solar cells wired

in series to make a panel. Each cell produces about 1/2 Volt. 36 of these in series would give about 18 volts which would be good for charging 12 volt batteries. (Yes, you really need that high a Voltage to effectively charge 12 Volt batteries) This type of solar cell is as thin as paper and as brittle and fragile as glass. They are very easily damaged too. The seller of these solar cells dips stacks of 18 in wax to stabilize them and make it easier to ship them without damaging them. The wax is quite a pain to remove though. If possible, find cells for sale that aren't dipped in wax. Keep in mind though that they may suffer some more damage in shipping. Notice that these cells have metal tabs on them. You want cells with tabs on them. You are already going to have to do a lot of soldering to build a panel from tabbed solar cells. If you buy cells without tabs, it will at least double the amount of soldering you have to do. So paying extra for tabbed cells is well worth the money spent.

Besides solar cells with size 3×6, there are lots of other sizes available too. You could use larger or smaller cells for your panel. Just keep a few things in mind when you decide.

-  Cells of the same type all produce the same voltage no matter what size they are. So the same number of cells is always needed.

-  Larger cells produce more current (Amps) and smaller cells produce less current.

-  The total power your panel can produce is determined by Amps X Volts.

So using bigger cells produces more power, but the panel will be large and heavy too. Using smaller cells keeps the panel small and light, but won't produce as much power as the bigger one. Also, mixing cell sizes is not a good idea. This is because the current your panel can produce will be limited by the smallest cell in the group and the larger cells won't work to their full potential.

Let's assume we use 3 X 6 inches in size and are rated at roughly 3 amps. You can wire 36 of them in series to get a little over 18 volts. The result should be a panel capable of delivering almost 60 Watts of power in bright sunlight. It doesn't sound like a lot of power, but it sure beats no power at all. And that is 60 Watts all day when the sun is shining. That power will go into charging batteries which will primarily be used for powering lights and small appliances for only a few hours after dark.

After you buy your solar cells, put them away in a safe place where they won't get dropped, played with by the kids, or eaten by the dog until you are ready to install them in the panel. These cells are very fragile. Rough treatment and excessive handling will turn your expensive solar cells into little, blue, shiny shards that aren't useful for anything.

Next build a box. I made the box shallow so the sides wouldn't shade the solar cells when the sun comes at an angle from the sides. It is made of 3/8 inch thick plywood with 3/4 X 3/4 pieces of wood around the edges. The pieces are glued and screwed in place firmly together. This panel will hold 36 3 X 6 inch solar cells. I decided to make 2 sub-panels of 18 cells each just so make it easier to assemble later. So there is a center divider across the middle of the box. Each sub-panel will fit into one well in the main panel.

Make sure you drilled holes in the edges of the well. These are vent holes to keep the air pressure inside the panel equalized with the outside, and to let moisture escape. These holes must be on the bottom of the panel or rain and dew will run inside. There must also be vent holes in the center divider between the two sub panels.

Next, cut two pieces of masonite peg-board to fit inside the wells. These pieces of peg-board will be the substrates that each sub-panel will be built on. They were cut to be a loose fit in the wells. You don't have to use peg-board for this. Just about any thin, rigid and non-conducting material should work well.

Protect the solar cells from the weather using plexiglass front. Here two pieces of scrap plexiglass have been cut to fit the front of the panel. I didn't have one piece big enough to do the whole thing. Glass could also be used for this, but glass is fragile. Hail stones and flying debris that would shatter glass will just bounce off the plexi. Now you can start to see what the finished panel will look like.

Next give all the wooden parts of the panel several coats of paint to protect them from moisture and the weather. The box was painted inside and out. The peg-board pieces were also painted. They got several coats on both sides. Be sure to paint them on both sides or they will curl when exposed to moisture after awhile. Curling could damage the solar cells that will be glued to them.

Next, bath in hot water to melt the wax and separate the cells from each other. Don't let the water boil or the bubbles will jostle the cells against each other violently. Also, boiling water may be hot enough to loosen the electrical connections on the cells. I also recommend putting the brick of cells in the water cold, and then slowly heating it up to just below boiling temperature to avoid harsh thermal shocks to the cells. Plastic tongs and spatulas come in handy for teasing the cells apart once the wax melts. Try not to pull too hard on the metal tabs or they may rip off.

Now it's time to start installing them in the panel.  Laid out the cells on that grid pattern upside-down and solder them together. All 18 cells on each half panel need to be soldered together in series, then both half panels need to be connected in series to get the desired voltage.

Repeat the above steps and soldered solar cells together until you have a string of six cells. Then soldered tabs from scrapped cells to the solder points on the back of the last cell in the string of six. Repeat the whole process two more times to get three strings of six cells for a total of 18 for this half of the panel.

Next, glue the cell in place.  The three strings of cells need to be wired in series. So the middle string needs to be rotated 180 degrees with respect to the other two.

Each solar panel in a solar power system needs a blocking diode in series with it to prevent the panel from discharging your batteries at night or during cloudy weather. I recommend a Schottky diode with a 3.3 Amp current rating. Schottky diodes have a much lower forward voltage drop than ordinary rectifier diodes, so less power is wasted. Every Watt counts.