DIY Solar Panels

Did you know that you can easily make your own solar panels?  It needs no specialized equipment or skills.  All you need to have are some basic woodworking and soldering abilities.  Even if you have never done these things before, you can quite easily learn them.  That was my experience.  I had never soldered anything together in my life and the only woodworking I have done was sawing some wood apart.  So if a DIY idiot like me can do it, so can you.

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Here is my own experience in constructing a solar panel.

First I bought a set of 36 mono-crystalline solar cells from eBay.  These are either blemished or chipped cells that cannot be sold commercially and therefore, they are much cheaper.  Usually, you can get them for under $200.  There are 2 types available – tabbed or untabbed solar cells.  If possible, buy the tabbed ones; they will save you a lot of work.  Tabbed solar cells are those with tab wires already attached to the front, along the 2 white strips (called busbars) down the cells.  Untabbed ones are those without tab wires attached so you will have to solder them yourself.  Tab wires are special flat wires you attach to solar cells to conduct the electricity they generate.  The act of soldering the tab wires onto the solar cells is called ‘tabbing’.

Before working on the solar cells, I constructed the solar panel box, which was basically a shallow box that holds the solar cells that are linked together.  I measured the size of the box that was needed to fit my 36 solar cells into a panel of 6 cells by 6 cells.  Then, I sawed the lengths of plywood I needed.  Make sure that the sides of the box are not too high so that it does not shade the solar cells when the sun shines on it at an angle.  The next step was to paint the wood with weather-proof paint. 

I also used a piece of softboard as the substrate on which to glue the solar cells.  I cut the softboard so that it would fit into the solar panel box and painted it also.  Instead of softboard, you could use anything thin and flat as a base as long as it is not a conductor.  I applied 2 layers of paint and left the plywood and softboard for 2 days to dry completely.  In the meantime, I worked on my solar cells.

I bought untabbed solar cells so I had to do the tabbing myself. 

Before you actually do the soldering, there are 2 things you need to do to prepare the tab wire.  Firstly, I had to apply solder onto half of each length of tab wire (the length of each tab wire is double the length of one solar cell).  I used fine electronics rosin-core solder.  This process is called ‘tinning’.  This part of the tab wire will be soldered onto the busbar at the front of the solar cell.  Secondly, I applied flux onto the busbar of the solar cells using a flux pen.  After tinning my tab wire and adding flux, I was ready to tab my solar cells by soldering the tab wire onto the busbars of each solar panel.  You will need 2 tab wires for each cell as there are 2 busbars.  After soldering, I used a toothpick to press it down and make sure the connection between the tab wire and busbar is strong.

After tabbing my solar cells, I had to string them together.  Stringing solar cells together is to solder the remaining length of tab wire onto the solder points at the bottom of the next solar cell.  That’s why you need tab wires that are twice the length of each solar cell.  I placed each solar cell upside down with the tab wires coming out from underneath.  Then I soldered the tab wires of one solar cell onto the solder points of the next solar cell.  This is called wiring the cells in series.  A crystalline solar cell’s negative side is at the front and its positive side is at the back.  I had joined the negative side of one cell to the positive side of the cell next to it (like how batteries in a flashlight are arranged).  I strung 6 cells together and then started another string until I had 6 strings of solar cells with 6 cells each.  I made sure that each solar cell has tab wires tabbed to its front and its back.

By the time I got my 6 strings of solar cells done, my wooden solar panel and softboard substrate was all ready.  I marked out the positions for my strings of solar cells on the substrate and placed them according to my markings.  The solar cell strings are to be wired in series, so each string had to be facing opposite sides of the solar panel.  The first string faced the top, the second faced the bottom, the third faced the top and so on.  I then glued the solar cell strings onto my softboard substrate using some double sided tape at the center of each cell (flipping the entire string over was a challenge). 

The next step was to wire the solar cells in series with each other.  I took some copper wire and soldered it perpendicularly to the 2 tab wires at the end of the first string and the 2 tab wires at the start of the second string.  Once again, I made sure I had the solar cells in series; the negative side of the last cell in one string is connected to the positive side of the first cell in the next string.  Alternatively, you could use extra tab wire or any wire instead of copper ones.

Before I put my softboard substrate containing the cells into my solar panel box, I used a voltmeter to test it.  I brought it out into the sunlight and my 36 solar cells produced 18.2 volts.  It worked! 

Now I attached a blocking diode in series with my solar panel because I didn’t want the solar panel to discharge my batteries that will be attached to it when the sun did not shine.  I recommend Shottky diodes as they have a lower forward voltage drop than other brands of diodes so they waste less electricity.  Once everything was in working order, I placed the substrate into my solar panel box.  I now had 2 wires from the 2 ends of my solar panel strings – one positive and the other negative – exiting the solar panel box.  I drilled a hole at the side of the box for the wires to exit and sealed it inside and outside with silicone caulk. 

Once the silicone caulk had dried completely, it was time to seal the box and cover the solar cells.  I used a piece of plexiglass and screwed it onto the front of the solar panel box.  To prevent rain water from seeping in, I sealed all the edges with silicone caulk.  Thus, my DIY solar panel was completed.

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