How To Build A Solar Cell
Here are step by step instructions for your DIY solar cell project
Before starting to build a solar cell, it might be worth reading about the effeciency, longevity and cost rational for homemade solar cells.
Clue: It is NOT motivated at all from a cost perspective to make your own solar cell.
If you still want to build a solar cell, you'll get detailed instructions below. Of course it can be a fun project ot carry out even if it won't make you rich...
Step By Step Instructions To Build A Solar Cell
Note: As the copper starts to get hot, beautiful oxidation patterns begin to form when you build a solar cell. You will see a variety of colors emerge and cover the copper including oranges, purples, and reds. As you continue heating the copper the colors are replaced with a coating of black cupric oxide. This is not the oxide you need. It will flake off later, revealing the reds, oranges, pinks, and purples of the cuprous oxide layer underneath.
Note: This is important, since a thick coating will flake off nicely, while a thin coat will stick to the copper.
Note: The copper shrinks as it cools. The black cupric oxide also shrinks but they shrink at different rates, which makes the black cupric oxide flake off. The little black flakes usually pop off the copper with a strong enough force to make them fly a few inches. Be prepared for a little more cleaning around the stove.
Note: The solar cell is a battery, so even in the dark, it will usually show a few microamps of current.
How does it do that? Cuprous oxide is a semiconducting material. A semiconductor has properties that lie somewhere in between a conductive material where electricity can flow freely, and an insulating material which binds electrons tightly to their atoms and does not allow any free flow of electrons.
In a semiconductor, there is a hole, called a bandgap between the electrons that are bound tightly to the atom, and the electrons that are farther away from the atom. In the bandgap electrons can move freely and conduct electricity. Electrons cannot however, stay inside the bandgap. An electron cannot gain just a little bit of energy and move away from the atom's nucleus into the bandgap. An electron must gain enough energy to move farther away from the nucleus, outside of the bandgap. Similarly, an electron outside the bandgap cannot lose a little bit of energy and fall just a little bit closer to the nucleus. It must lose enough energy to fall past the bandgap into the area where electrons are allowed.
When sunlight hits the electrons in the cuprous oxide, some of the electrons gain enough energy from the sunlight to jump past the bandgap and become free to conduct electricity.
The free electrons move into the saltwater, then into the clean copper plate, into the wire, through the meter, and back to the cuprous oxide plate.
As the electrons move through the meter, they perform the "work" or provide the energy required to move the needle. When darkness or a shadow falls on the solar cell, there are fewer electrons available to move through the meter so the needle dips back down and less current is produced.
If you want to see how a solar cell can be made, have a look at this video clip, where the instructor will build a solar cell similar to ours above.
Instructions: When watching the video clips, start the videos by clicking the small arrow down to the left, not the large one in the middle of the screen. If you're using Internet Explorer and your browser and the video doesn't start, try clicking twice on the small arrow.
More About Solar Cells
Want to try other DIY solar projects? Have a look at the list to the right for more inspiration.
Once you're done with the project to build a solar cell or with some other solar DIY project, please take a moment to brag about it here.
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