How to Build Your Own Solar Cells
Building Your Own Solar Cells
First and foremost, building your own solar cells isn't a viable alternative to buying commercial solar cells off of the Internet; even buying scratch-and-dent is going to be less expensive than this. However, if you're looking for something that you can use as a science fair project, this can do the trick.
We're going to explore the photo-electric effect that got Albert Einstein the Nobel Prize (for Chemistry, not Physics, surprisingly. Einstein never won the Nobel for relativity.) The Photo-electric effect is what drives silicon wafer solar cells; it takes photons in to a semi-conductor layer and shakes loose electrons, creating a current. The original substance that this was observed in was cuprous oxide in the 19th Century, and we're going to recreate this experiment.
To do this, you're going to need to get two sheets of copper and an electric stove. You want a heating element that will get very hot - a gas stove won't do it. After cleaning the copper with a wire brush, and soaking it in dishwasher soap to remove your fingerprints and oils, put the sheet of copper on the burner and turn the heat up to the maximum. As it gets hotter, you'll see color patterns show up in oranges and purples and reds; eventually it will turn black.
The black covering is cupric oxide, which is what we don't want - but let it accumulate anyway; while it's accumulating, it's shielding the more valuable cuprous oxide from the air, and letting that form. After the sheet has gotten very black (about 30 minutes), turn the stove down and let it cool off slowly. This will have the black oxide crackle and flake off and leave the multi-colored oxide behind. Give it a light rinse in clean water - no scrubbing or flexing - to remove the last of the easily removed black oxide.
Now, we're going to put the copper plate in a clear container with some salt water, and the other copper plate. We need to put both of them into the salt water, with the lead going from the cuprous oxide plate to the negative terminal of our voltmeter. If you set this in sunlight, you'll see that the voltage increases; when it's in shadow, it'll still show some voltage, because copper plates in salt water are a very primitive battery.
Now, before you think about how you're free to buy copper plates and generate your own electricity, here's some numbers - this solar cell design is good for about a quarter watt of power. You'd need several acres of them to equal the efficiency of a rooftop solar array, and because they're made of copper and salt water, they're going to oxidize into uselessness in about 9 months. Plus, copper plates are more expensive in bulk than buying slightly dented solar cells off of ebay, which are more efficient and last longer.
So if you ask me it's better if you buy commerical produced solar cells, than try to build your own solar cells. What I would advise you to do is to buy the solar cells out of ebay and then make the solar panels yourself. You save hundreds if not thousands of dollars doing this.