PV Gap

Geraldine Said:

how are the solar cell made?

We Answered:

I generally find that Wikipedia is a good source of information on most subjects, and in the case of photovoltaics it has what looks like a good site for general information, with lots of links to more detailed info... Hope this helps... (The relevant url is en.wikipedia.org/wiki/solar_cell)

Jenny Said:

what are solar cells made of?

We Answered:

Materials you will need…

A sheet of copper flashing from the hardware store. This normally costs about $5.00 per square foot. We will need about half a square foot.
Two alligator clip leads.
A sensitive micro-ammeter that can read currents between 10 & 50 microamperes. Radio Shack sells small LCD multimeters that will do, but I used a small surplus meter with a needle.
An electric stove. My kitchen stove is gas, so I bought a small one-burner electric hotplate for about $25. The little 700 watt burners probably won't work -- mine is 1100 watts, so the burner gets red hot.
A large clear plastic bottle off of which you can cut the top. I used a 2 liter spring water bottle. A large mouth glass jar will also work.
Table salt. We will want a couple tablespoons of salt.
Tap water.
Sand paper or a wire brush on an electric drill.
Sheet metal shears for cutting the copper sheet.

The first step is to cut a piece of the copper sheeting that is about the size of the burner on the stove. Wash your hands so they don't have any grease or oil on them. Then wash the copper sheet with soap or cleanser to get any oil or grease off of it. Use the sandpaper or wire brush to thoroughly clean the copper sheeting, so that any sulphide or other light corrosion is removed.
Next, place the cleaned & dried copper sheet on the burner & turn the burner to its highest setting.
As the copper starts to heat up, you will see beautiful oxidation patterns begin to form. Oranges, purples, & reds will cover the copper.
As the copper gets hotter, the colors are replaced with a black coating of cupric oxide. This is not the oxide we want, but it will flake off later, showing the reds, oranges, pinks, & purples of the cuprous oxide layer underneath.
The last bits of color disappear as the burner starts to glow red.
When the burner is glowing red-hot, the sheet of copper will be coated with a black cupric oxide coat. Let it cook for a half an hour, so the black coating will be thick. This is important, since a thick coating will flake off nicely, while a thin coat will stay stuck to the copper.
After the half hour of cooking, turn off the burner. Leave the hot copper on the burner to cool slowly. If you cool it too quickly, the black oxide will stay stuck to the copper.
As the copper cools, it shrinks. The black cupric oxide also shrinks. But they shrink at different rates, which makes the black cupric oxide flake off.
The little black flakes pop off the copper with enough force to make them fly a few inches. This means a little more cleaning effort around the stove, but it is fun to watch.
When the copper has cooled to room temperature (this takes about 20 minutes), most of the black oxide will be gone. A light scrubbing with your hands under running water will remove most of the small bits. Resist the temptation to remove all of the black spots by hard scrubbing or by flexing the soft copper. This might damage the delicate red cuprous oxide layer we need to make to solar cell work.
Cut another sheet of copper about the same size as the first one. Bend both pieces gently, so they will fit into the plastic bottle or jar without touching one another. The cuprous oxide coating that was facing up on the burner is usually the best side to face outwards in the jar, because it has the smoothest, cleanest surface.
Attach the two alligator clip leads, one to the new copper plate, & one to the cuprous oxide coated plate. Connect the lead from the clean copper plate to the positive terminal of the meter. Connect the lead from the cuprous oxide plate to the negative terminal of the meter.
Now mix a couple tablespoons of salt into some hot tap water. Stir the saltwater until all the salt is dissolved. Then carefully pour the saltwater into the jar, being careful not to get the clip leads wet. The saltwater should not completely cover the plates -- you should leave about an inch of plate above the water, so you can move the solar cell around without getting the clip leads wet.
now place in the sun with the magnified on top.
The solar cell is a battery, even in the dark, & will usually show a few microamps of current.
That’s it it’s that simple. If you’d a more detailed process & some pics (couldn’t put them here) it’s available along with some other DIY alternative energy projects at www agua-luna com

Hope this helped, feel free to contact me personally if you have any questions if you’d like assistance in making your first self sufficient steps, I’m willing to walk you step by step threw the process. I’ve written several how-to DIY guides available at http://www.agua-luna.com/diy_guides.html on the subject. I also offer online & on-site workshops, seminars & internships to help others help the environment.


Dan Martin