A Solar Cell Made in the Kitchen?

A solar cell is a device which converts energy from the sun into electricity. These solar cells are made from highly perfected and processes silicon which requires huge factories, high temperature, vacuum equipment and lots of money. They are highly efficient and can produce the required amount of electricity for a house.

Solar cells can also be made in the kitchen out of materials from the neighborhood hardware stores. But they may not be that efficient when compared with the silicon equipped solar cell. With all the materials at one place, a solar cell can be made within an hour.

The solar cells that are made from the kitchen contain cuprous oxide as the main ingredient. This may not have the efficiency that a silicon posses but will produce electricity. The theory was developed by Albert Einstein which has awarded him the Nobel Prize for Physics.

The materials which are needed for this homemade solar cell are a half a square foot sheet of copper flashing, two alligator clips, a sensitive micro-ammeter that can read between 10 to 50 microamperes, an electric stove that generates about 1100 watts, a large clear plastic bottle of which the top can be cut (usually the 2 liter water bottle will do), table salt, tap water, sand paper or a wire brush on an electric drill and a sheet metal shears for cutting the copper sheet.

The first step to build the solar cell requires the copper sheet to be cut into half the size of the electric stove burner. Once the sheet has been cut, wash in thoroughly to clear off any dirt or grease particles. Sand paper can be used to clean the copper sheeting to clear of any sulphide or other light corrosion particles. Once the cleaning is carried out, place the copper sheet on the electric stove burner and turn the burner to its high settings.

Once the copper sheet starts to heat up, oxidation takes place which are observed on the surface in different forms. While oxidation takes place the surface is covered with orange, purple and red forms. As the oxidation temperature rises, the red form of color on the surface is replaced with black coating of cuprous oxide. When the sheet is completely covered with the cuprous oxide, remove the sheet from the burner and allow it to cool down naturally.

As its temperature starts to decline the black coating of the cuprous oxide will flake off or “pop” off, showcasing the red inner of cuprous oxide underneath. For this, allow the copper sheet to burn more causing the black coating of the cuprous oxide to become thicker. When the coating is thick, flaking off takes place easily. If the inner of the black coating is thin, they are sure to stick on to the copper sheet.

Once the cooling has taken place completely, put the copper sheet under the running tap to clean the oxidation particles. Do not put more pressure while scrubbing as this will completely let go the cuprous oxide particles also. Make sure the scrubbing is performed lightly. The cuprous oxide is the main ingredient for the solar cell.

Now cut another sheet of copper which is similar to the past one. Now bend of the copper sheets gently such that they fit into the plastic bottle or jar without coming into contact with each other. Always ensure that the cuprous oxide sheet which is clean and shiny is faced outwards in the jar. To one end of the copper sheet, using the sand paper bring it to its original texture. To this solder one of the alligator clip rule. The other alligator clip rule is soldered to the other copper sheet that has been cut. Ensure that both the soldering is covered in glue. Now connect these both alligator clip rule to the meter one at the positive terminal and the other at the negative terminal.

Now mix the salt with some tap water and be sure that all the salt is dissolved completely. Once the salt water is ready, pour the combination into the jar containing the copper sheets. observe that it should not be completely filled. 1/4th of the copper sheet should be outside the saltwater. This will ensure that the alligator rule pins are not in contact with the salt water.

The ammeter reading will initially shows few micro amps. When the solar cell is taken into sunlight, the ammeter slowly rises to 50 micro amps, swing the needle all the way to the right. The solar cell is a battery and will show few amps already in the dark.

The reason behind this theory is that, cuprous oxide is the semiconductor material. Semiconductor is a state in between the conductor and the insulator. Conductor is the state here it allows free movement of electricity and insulator is the state where electrons are bound firmly to their atoms and which do not flow freely.

Electron which are bound to the atom and the electrons which are far away from the atom always have gap called as “band gap”. This band gap allows the free movement and conducts electricity. Electrons need more energy to come out of the band gap and move far away from the nucleus. In the similar way, they cannot stay outside the band gap and lose little energy and fall back. They will have to lose all the energy and fall back into the level they are accepted. It is simple; electrons cannot stay in the bang gap vicinity. Either they have to come near to the nucleus losing all their energy or cross the band gap with higher energy levels. This course of action continues and allows the conduction.

When sunlight falls on the cuprous oxide sheet, some of the electrons gain enough energy to move past the band gap. This makes them free to move. This free movement of electrons conducts the electricity. This is cycle in which the electrons emitted from the cuprous oxide plate returns back to the same plate after it has travelled by the salt water, to the clean copper plate and insulated wire.

As the electrons move by the meter, they perform the work needed to move the needle. When a shadow falls on the solar cell, fewer electrons move by the meter, and the needle dips back down.

This is just an experiment. Do not think of powering your house with such instrument as you would need acres of land.

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