I’ve completed soldering 24 of the 36 cells yesterday. I’m not quite sure if I’m making great connections or not. Here is an enlargement of one of the soldered connections on the cell. I’m using a lead free flux with the tabbing wire.

The top part of the cell is the negative terminal and the bottom is the positive. I’ll start the positive soldering after all the negative soldering is complete.  The flux helps the tabbing wire stay down but it also helps the solder make a good connection.

The plan is to make three rows of twelve cells for a total of 36 cells. This should produce about 18 volts. My question is if this will be too many volts to charge a 12 volt deep cycle battery.

As you can see, I’m using latex gloves because it’s not good to touch the cells with your fingers as the oils from your skin are damaging to the cells. The cells are very fragile and I broke one of them by pressing too hard with the hot iron. I’ve adjusted my technique and I only apply a light pressure. It just takes some time getting used to soldering.

I’m checking my wiring diagram on how to connect all the positives with the negatives going from one column to the next. I need to use the thicker bus wire to make this connection. That will be my next challenge. Part two is here.

The trim wood was attached using 3/4 ” x 3/4 ” using screws from the back. We drilled small holes to make sure we didn’t split the wood. I think I had about five different kids each having a turn with the drill. We then painted it white with two coats of paint. I have a 2 foot x 4 foot piece of plexiglass ready to put on top. I’ll drill small holes around the perimeter to hold it down. I’ll also put some clear outdoor calk around to make it waterproof.

I ordered the solar cells from ebay for $ 129.00. This included some solder, flux and tabbing wire. Everything came in a box, and nothing was broken. I lined up three rows of 12 cells for a total of 36 cells. This should give about 18 volts, more than enough to charge a 12 volt battery. I hope this is not too much to charge the battery, but I’ll look into this and find more information about charging.

The next step is to solder all the cells in series. I’ll start this soon. I have a few 8th grade students that want to help but I may do most of it at home. The only tool that I need to buy is a pencil style soldering iron. I’ll get this at the store today so I can start to solder this week. I hope to have this completed in two weeks.

Edit: Part one is here

I have started to build a solar panel to use for a class project here, and eventually in the Philippines. I searched the web and found that it’s possible to build a lower cost 60 watt PV panel, possible less than $200.00. One of my goals in building this panel is to learn more about this technology and to refine my skills. I also have a few of my middle school students that are eager to help and this will be a good learning experience for everyone involved.

I would also like to incorporate the solar panel into my large Mars Habitat project at the end of the school year. Maybe we will be able to generate enough power to run one of the fans. I’m not sure where all this will go, but I think it will be a fun project.

I already bought a piece of wood 3/8 inch thick, 2 feet by 4 feet plywood at the local store. This size wood is precut and easy to bring back to school. The only problem is that it’s a little warped. I’m not sure if this is critical or not. I plan to trim the perimeter with 1″ trim wood to add strength. Today I started to paint it and I’ll finish painting it tomorrow. So far, the cost of the wood, trim wood, paint and brush cost $38.00. Tomorrow I want to finish painting both sides and add the perimeter trim to strengthen the panel.