Building solar panels

I have stopped writing on my blog for more than two months due to my work heavy load, so I was very tired, but now, I have received the rest of my solar system's components and I again have the urge to write. At this moment when I'm writing these lines, I have my PC fed from solar energy. YES! I have completed my solar UPS and I have made a successful test run.

But first I should resume from where I stopped earlier. I will talk about building my solar panel.

I purchased a a pack of 108 solar cells from ebay (on the right picture and I have to say I expected them to be larger) and I have also purchased tabbing wire to connect solar cell together (this was a time consuming job). The solar cells I bought has a dimensions of 6"x6" each produces 0.5V DC and 8A DC (that what was written on ebay).

I wanted to assemble some of them to produce 18V DC (as standard panels produce) so the calculation will be: 18V DC/0.5V DC = 36 cells. 

Note: These cells are extremely fragile and brittle, I broke about a dozen, but they are still functional.

First thing I did is to put one in the sun and measure how much power does it produce. I measured a 0.55V DC and 1.1A DC. I thought something was wrong as it should produce 8A DC, but I think I could not hold it right or my hand shadow affected the current. Anyway I decided to go on with experimenting. I connected two of them and measured 1.1V DC and also 1.1A. I thought that since they are imported from China, they should be not good, but I couldn't stop at this phase. In the picture the measurement is away from the sun.

I had to connect those 36 cells in a rectangular pattern of 9x4 by connecting each positive side (dark side) to its neighbor's negative side (shiny side)

The frame is made of aluminium angles (3cm x 3cm thickness 3mm) joined together and in the middle is a glass sheet (thickness 6mm) glued to the frame with silicone. I had to line up the cells to be neat and have a nice look. I welded all the 36 cells and extracted the far terminals to be the positive and negative. I covered the back of the cells with a PVC tape to isolate them from humidity (I should use a piece of plexiglass or any isolating sheet for the back of the panel because the PVC tape is not solid, thus sagging a little bit).

The final panel look is in the picture on the right. I measured the voltage output and it was 18.8V DC. I measured the short circuit current and I was very pleased to read 6.5A DC.

My panel initial design was 144 Watts, but practically it is 122 Watts. It's okay for me and this result satisfies me for my first home built solar panel.

After doing some research about which direction to point my panel and which angle is the most suitable to extract the biggest amount of juice from the sun, I reached some very easy numbers. Since I live in Egypt in the Northern hemisphere, then I should point my panel to the true South. Also in Cairo the suitable tilting angle in summer is 15 deg and in winter is 45 deg (I have made an extension leg to increase the tilting angle to 45deg). Sure a tracking device will be much more efficient, but I don't want to bother myself with mechanical designs at this stage yet.