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Building a solar panel |
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The solar panel project was to build a panel using 36 cells purchased on e-bay. These cells are extremely delicate and require a very gentle touch. To test them I first measured the voltage on one to confirm what I thought to be the positive side and what was the negative. I was able to confirm that the three small solder tab on the back were the positive terminals and the lone wire from the top was the negative.
I also found that oxidation on the pads requires a very delicate scraping with a hobby knife to clean an area to solder to. I used some wide copper tape to attach the bus for the positive and gently soldered two cells together for a test. Later I found that using an eraser is just as effective and much easier in cleaning the solder pad.
Success ---- I got a bit over 1 volt DC and I was happy.
Next was to build a holder for the cells.
A simple wood box was the plan. I used what materials I had on hand ….. a half inch sheet of plywood cut to 36” by 16”. This size was calculated but adding up the 3.5” X 3” solar cells – 4 rows with ¼ inch spacing between each cell and ½ inch between rows. Add one and a quarter inches on each side to reduce the shadow from the side rail and you get 16 inches by 36 inches.
While I do not think it is necessary to add all the dimensional information I have learned that many people are not able to visualize a project like this but can follow directions. However, the actual dimensions for the box will depend on what size solar cells you purchase.
I scientifically selected the color …… I had white available …. The side rails were 1X2’s because that is what I had. The cell holder, with the paint can on it, is set up to have the solar cells glued to it and then dropped into the box. A clear piece of Plexiglas will finish out the design. Vent holes are drilled in the bottom and brass bolts are used as the power connection point.
Oh yes, credit must be given to the job site supervisor who was critical in overseeing the technical aspects of preparing the box. Shadow is indispensable as a source of technical know-how and is always there to encourage me should I hit a bump in the road.
Putting the cells together:
I worked on an assembly line concept with each of the cells. They were strung together one at a time and soldered. They were wired in series with 9 cells to a string and four strings across. As each cell is very delicate a good bit of care went into the assembly.
I used 60/40 rosin core solder and an adjustable heat soldering iron set to about 30 watts. The cells came with one half of the connectors attached so it was easy to solder to the next cell. I used copper foil for the end connection and to link each of the strings together. The foil is used in stain glass work and I had some on hand. I put a small dab of silicone calk under each cell (in the center) to hold them in place but not anchor them so tight that they break if the panel is flexed a bit
The cell carrier is put together and the first measurements taken in the late afternoon in Dallas. The output current is disappointing. Only 400Ma, short circuited with about 20 VDC. This is much less current then I had expected but the panel does work. However, as I was using a Radio Shack DVM I had a concern as to the accuracy of the current reading and changed to my old, but very worn, Fluke. It gave me a reading of 900 Ma with about 20 VDC. As I trust the Fluke and have questions regarding the Radio Shack I have elected to go with the Fluke. |
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Frame for solar panel—1/2 inch plywood and 1X2 sides |
Two types of panels were made but the basic construction technique is the same. |
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A row of cells is soldered together in series. The orientation of the cells is reversed for the next row so that I can continue hooking them in series. |
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Copper foil is used for the buss and interconnection between the cells. |
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Finished panel being tested |
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Job site supervisor Shadow |
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Failed Solar Panel story |
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Herb & Barbara our interests and family |
