A solar cell is a device that converts the sun’s energy into electricity. These solar cells are made from highly refined and processed silicon, which requires large factories, high-temperature and vacuum equipment, and a lot of money. They are highly efficient and can produce the necessary amount of electricity for a house.
Solar cells can also be made in the kitchen with materials from neighborhood hardware stores. But they may not be as efficient compared to silicon-equipped solar cell. With all the materials in one place, a solar cell can be made in an hour.
Solar cells that are made from the kitchen contain cuprous oxide as a main ingredient. This may not be as efficient as silicon, but it will produce electricity. The theory was developed by Albert Einstein, who has awarded him the Nobel Prize in Physics.
The materials needed for this homemade solar cell are a half foot square sheet of copper flashing, two alligator clips, a sensitive microammeter that can read between 10 and 50 microamps, an electric stove that generates about 1100 watts, a large clear plastic bottle from which the top can be cut off (usually the 2 liter water bottle will do), table salt, tap water, sandpaper or a wire brush on a power drill and sheet metal snips to cut the copper foil.
The first step in building the solar cell requires the copper foil to be cut to half the size of the electric stove burner. Once the sheet is cut, wash thoroughly to remove any particles of dirt or grease. Sandpaper can be used to clean the copper foil and remove any sulfide or other light corrosion particles. Once the cleaning is done, place the copper foil over the burner of the electric stove and turn the burner to its high position.
Once the copper foil begins to heat up, oxidation occurs which is seen on the surface in different ways. As oxidation takes place, the surface becomes covered with orange, purple, and red shapes. As the oxidation temperature increases, the red color forms on the surface is replaced with a black layer of cuprous oxide. When the blade is completely covered with the cuprous oxide, remove the blade from the burner and allow it to cool naturally.
As its temperature begins to decrease, the black layer of cuprous oxide will flake off or “pop”, revealing the red layer of cuprous oxide below. For this, allow the copper foil to burn more causing the black layer of the cuprous oxide to become thicker. When the layer is thick, it flakes off easily. If the black coating layer is thin, they will surely stick to the copper foil.
After complete cooling has occurred, place the copper sheet under running tap to clean oxidation particles. Do not apply more pressure while scrubbing, as this will also completely release the cuprous oxide particles. Make sure scrubbing is done lightly. Cuprous oxide is the main ingredient of the solar cell.
Now cut another sheet of copper that is similar to the previous one. Now bend the copper sheets gently so that they fit into the plastic bottle or jar without touching each other. Always make sure the cuprous oxide foil, which is clean and shiny, is facing out in the jar. At one end of the copper sheet, using the sandpaper, bring it back to its original texture. To this solder one of the crocodile clip wires. The other alligator clip wire is soldered to the other copper sheet that has been cut. Make sure both welds are covered in glue. Now connect these two alligator clip leads to the meter, one to the positive terminal and the other to the negative terminal.
Now mix the salt with some tap water and make sure all the salt dissolves completely. Once the salt water is ready, pour the mixture into the jar containing the copper sheets. Note that it should not be completely full. 1/4 of the copper foil should be out of the salt water. This will ensure that the alligator lead pins are not in contact with salt water.
The ammeter reading will initially show a few microamps. When the solar cell is brought into sunlight, the ammeter slowly increases to 50 microamps, turn the needle fully clockwise. The solar cell is a battery and will show low amps even in the dark.
The reason behind this theory is that cuprous oxide is the semiconducting material. Semiconductor is a state between conductor and insulator. Conductive is the state in which it allows the free movement of electricity and insulator is the state in which electrons are tightly bound to their atoms and do not flow freely.
The electrons that are attached to the atom and the electrons that are away from the atom always have a gap called a “band gap”. This band gap allows free movement and conducts electricity. Electrons need more energy to get out of the band gap and away from the nucleus. Similarly, they can’t stay out of bandgap and lose little energy and fall back. They will have to lose all energy and fall back to the level where they are accepted. It is simple; electrons cannot remain in the bang gap region. Either they have to get closer to the core losing all their energy or cross the band gap with higher energy levels. This process continues and allows driving.
When sunlight falls on the cuprous oxide sheet, some of the electrons gain enough energy to pass the band gap. This makes them free to move. This free movement of electrons conducts electricity. This is a cycle in which the electrons emitted by the cuprous oxide plate return to the same plate after having traveled through the salt water, to the clean copper plate and to the insulated wire.
As the electrons move through the meter, they do the work needed to move the needle. When a shadow falls on the solar cell, fewer electrons move through the meter and the needle goes back down.
This is just an experiment. Don’t think about powering your house with such an instrument, as you would need acres of land.