Paul, here is some information from one of the eBay sellers that kind of wraps up a lot of the basic information for you. I have about 1800-2000 of the same types of cells that you have. Those 3x6's sound like evergreen. The tips that the other folks gave you is good stuff. There are some ebay sellers that also provide 1 hour videos on DVD showing you how to put together the cells. However, do a search on Youtube.com and you'll get a lot of interesting hits.
Good luck!
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The standard cell specifications are the following, though the individual cells can be above or below these standards.
Cell Specifications:
Average Power (Watts): 1.50 Wp (We lower the wattage power just as a precaution, in reality many of them are going to be higher than 1.5 watts. We like to underpromise)
Average Current (Amps): 3.0 Imax
Average Voltage (Volts): 0.5 Vmax
Thickness 200 μm = 0.2 mm
Exact dimension: 3 1/4 inches x 6 inches, or 80 mm by 150 mm
Weight: Just above 6 grams, or 0.2 oz.
Some useful information in making solar power:
How to make sense of the above numbers:
The basic and very important formula you need to know to make sense of solar cells is this:
Power (P) = Current (I) Multiply by Voltage (V), or P=I*V
Power's unit of measure is watt,
Current's unit of measure is amp,
Voltage's unit of measure is volt.
So in our solar cell's specific example, if each solar cell is rated at 1.75 watts on average, and the voltage is 0.5, you do a little algebraic math, then to get the amps (I), since P=I*V, so I = P / V , therefore I (amps) = 1.75 watts divided by 0.5 volts = 3.5 amps.
It's important to understand the concepts of series connection and parallel connection when stringing these solar cells together to make a solar panel. Series connection of the cells increases voltage but not amperage; parallel connection of the cells increases amperage but not voltage. Series connection is when you connect the positive terminal of a cell with the negative terminal of the next cell. Parallel connection is when you connect the positive terminals of all cells in the set of cells with a tabbing wire and all the negative terminals of all cell in the same set. You can use a combination of series and parallel connections to get the right voltage and amperage for your solar panel.
The cell specifications above were given to us by the manufacturer as averages. Variations are possible. To make a 18 volts panel, for example, you connect 36 cells in series (36 cells times 0.5 volt each = 18 volts). And 36 * 1.75 (each cell in theory averages 1.75 watt) watt = 63 watts. The amps you will be getting is 63 watts divided by 18 volts = 3.5 amps.
Solar cells basics:
The front of the cells (blue side, aka Sunny side) has two thick white lines, called bus bars. They are the negative terminals of the cell. The back side, where the 6 square dots are, are positive terminals. Connect the tabbing wires from the bus bar of the first cell on one side to the three dots of on the back side of the next cell. That way you have a series connection. Repeat the process on the other side of the cells. In panel making you should connect all the tabbing wires on the front for all the cells first, then flip the cells over to solder the back side in a second step. Some solar cells such as SunPower cells have both positive and negative terminals at the back of the cells, but we don't have to worry about them. Most cells are negative on the front and positive on the back.
The white color bus bars on front and the contact points on the back are made out of silver, and you should keep them intact. Apply solder on your them and the wires should bond.
Testing:
Make sure that you test the cells under strong sun light with the front of the cell facing the sun, at the same time connect your meters to the right terminals. If you are inside the building, make sure you shine your sun simulating lamps onto the front of the cell while testing.
Panel configuration:
For those who are new to solar panel making or if you don't have an engineering background, here is our recommendation:
- Make small panels first so you gain experience.
- In most situations, make either 36 or 72 cell panels, and connect them in series. 36 cells give you 17.5 or around 18 volts or so. And 72 cells doubles that. These panels are very useful, and you will find a lot of matching products that will want to buy! For example, you almost always want to use a charge controller if you make your panels to charge batteries. Charge controllers usually come in 12 or 24 volt settings, which match your panels' 18 and 36 volts very nicely. Yes, your panel voltage should be 1.5 times the voltage of the battery you intend to charge. Connect more panels together if you want to tie to the grid, in which case, always use an inverter.
- For a lot higher voltage panels and configurations, consult a professional. Just don't fry yourself.
Soldering:
If you want to become a serious panel maker, buy a good soldering iron whose temperature can be adjusted. Don't get a cheap iron. It's one of the most important tools you need to have. Get those that have a flat soldering tip / head.
