Completing the solar panel

I finished my solar panel project this week. I’ve been working on it on and off for the past two years and it’s finally done. The only thing I need to complete is to put the clear acrylic panel on top to protect the cells.

Here are my previous posts on building the solar panel. Part 1 gives information on the parts I bought to build the 18 volt, 60 watt PV solar panel. Part 2 describes my frustration of learning to solder the cells and the time needed to do this well. Part 3 describes my attempt to solder the tab wire to the negative part of the cell and how I’m going to wire the cells to produce the correct voltage.  This last post will summarize the task of completing the solar panel before school starts and what my future plans are with solar power panels.

Video of the completed solar panel

It took me a couple of days to complete all the soldering. I got better at it as I went along and only broke a few cells. Luckily I bought enough and I still have about ten left. The hardest part was dealing with corrosion that built up on the tip of the soldering pen and getting an even flow of solder to flow onto the three positive connections on the back of the cell. I had to scrap a few cells because of poor solder connections.

As you can see from this image, the back of each cell has six places that need to be soldered. This side is the positive side and was the hardest part to solder because each of the six squares needed to have a small piece of solder deposited before I could solder using the tabbing wire. Some people recommend that you hold down the tabbing wire with a small piece of wood when you are soldering them together, but I found that a small book worked better and was not too heavy.

 Assembling the cells

After all the cells were completed, I had three strings of twelve for a total of 36 cells. Each cell has 0.5 volts so this should give a total output of 36/2= 18 volts.

I was now ready to attach the cells to the inside panel. I put a small drop of silicone on the back of each cell and gently pressed them into place in the panel box. After I had them  lined up in three rows, I soldered the rows together in series using the larger tabbing wire. I then used some spare wire I had to make the final connection between the positive end and the negative end to complete the solar panel.

The big test

I actually completed the solar panel and wiring  in the middle of August, but I couldn’t test it as it was raining for days on end. I did take a quick reading inside by the window then and read 4 volts. I thought maybe one of the cells was not soldered correctly, but thankfully, it was due to the clouds and rain condition. This past Friday I went to school to test the solar panel as it was a bright sunny day. On the first measurement, I recorded 19.0 volts. It made my day knowing the solar panel was working correctly. It went up to 19.1 volts in all sun and down to 18.3 when a cloud passed by. The total cost for this project was about  $160.00. I didn’t need to buy some small pieces of wire, screws and paint as I already had some laying around. The biggest cost was the solar cells.

What’s next

My next task is to research and find a deep cycle battery and an inverter to connect to the panel. The battery is a very important part of the system as it stores the energy to power any appliances. This panel may only light a 60 watt bulb for a short time, but I will investigate other types of lights like LED lights and other small appliances to see how long they can be powered using one or two panels. I also may try and build another solar panel using all acrylic and no wood. This solar panel that I just completed would never hold up on a roof for very long and that was not the intention here. I will put in in the sun during the day and bring it in at night.

My goal was and is to learn as much as possible about manufacturing low cost photovoltaic systems (PV systems) that can be made and used in the Philippines. The Philippines already has some of the largest solar manufacturing plants producing the worlds solar cells. The problem is that the cells manufactured in the Philippines are exported to other countries because of the high cost and regular Filipinos not being able to afford these systems.

I believe that bringing this do-it-yourself solar panels, make-your-own-technology to the Philippines will help with innovation in making and using low cost panels. Professional made PV systems are expensive because of the very high manufacturing cost associated with the solar panels designed to last 20 – 30 years, or more. I believe the cost can be greatly reduced if more people are given a chance to experiment with ( play with) and design smaller systems to last in the 3-5 year range. These smaller systems could be brought in during the night to save on wear and tear due to moisture, rain, and general outdoor conditions.

This was a great project for me to build. It’s a good example of bridging the gap between theory and practice. Much is written on building PV systems and the electrical theory involved, but few people actually build the solar panels and experiment with them. Everything doesn’t have to last 30 years. I’m sure there are better and more cost efficient way to assemble these panels that haven’t been discovered yet. Filipinos are very resourceful and need to have solar electricity development in their economy. Given the Philippines’ abundant sunshine and its large work force, solar power and the Philippines is a perfect fit.