This is an attempt at explaining a simple method to make a solar panel at home. This panel is an array of solar cells, a cell is a device that converts energy, radiated by the Sun, in the form of small bundles of light called photons, into electricity.
How does it happen? Solar cells exploit a phenomenon called the 'photoelectric effect'. A photon is a packet of pure energy, and light from the sun is a flood of trillions of such photons. When these photons strike the surface of certain metals and semiconductors, they are absorbed by the bound electrons, until then, confined to moving around the atom.
To break the strong electric force that binds them to the atom, electrons require a lot of energy. Therefore, when photons of just the right energy come along, they absorb them and get liberated from confinement, becoming available for conduction. That is how electricity is produced in a solar cell.
How to Build a Solar Panel?
Normally, these panels are manufactured out of silicon, a semiconductor. The process of purifying silicon; however, is very costly. Silicon is not the only the material or semiconductor that displays the photoelectric effect. Cuprous oxide is a well-known semiconductor, which has been in use, even before the advent of silicon as a semiconductor.
How is making solar panels possible without silicon? The clever use of cuprous oxide, instead of silicon, does the trick. The efficiency of cuprous oxide is much lower than silicon, but the cost of manufacturing is comparatively negligible. So, what we do is, create a thin film of cuprous oxide over copper metal, and use it as a solar cell.
The procedure for creating this thin film of cuprous oxide is to literally burn copper in air, creating a layer of cuprous and cupric oxide over it. You will need a very high wattage (1000 watts or more) electric coil type heater, with a wide base.
Buy a square piece of copper flashing of such a size, that it is lesser than the coil diameter, and fits inside it. Scrub the plate thoroughly with sandpaper and clean it.
The procedure then starts with heating the square plate, using a burner. You will see a beautiful potpourri of oxidation patterns forming on the plate, after a sufficiently high temperature is reached.
The color will change from pinkish red to brown, and ultimately black, as you go on heating it. The black layer that forms is cupric oxide (CuO) and below that, the reddish layer formed is cuprous oxide (Cu2O). The red film is what we are interested in. The black layer is more like soot, that can be cleared off carefully after cooling.
Once the surface is sufficiently black, stop heating and let the copper plate cool. As it cools, the copper plate contracts differentially, that is unequally, and therefore, patches of the red pinkish layer are exposed.
After the plate has totally cooled off, rinse it carefully and remove the black soot. Do not scrub the plate as it may remove the red cuprous oxide film too. Thus, the main part of the procedure is over.
Cut the top of a large water bottle or can and place the oxidized sheet of copper in it. Let the oxidized film part face the outside the bottle. Place another same sized piece of copper in the bottle, without letting the two plates touch each other.
Fill the bottle with salt water, till about 80% of the plates are submerged. Attach two crocodile clips to the plates, and connect the positive lead of a microammeter to the copper plate, and the negative lead to the oxide-coated plate. Keep the whole apparatus in the Sun.
As you place it in the Sun, you will see the ammeter reading going up. This shows that there is current flowing through the apparatus and you have succeeded in making a solar cell. This cell can give you an approximate power output of around 10 microwatts. It is not sufficient for lighting even a bulb but it's a start.
Thus, you can make your own solar panel at home and enjoy the process of creating something new. This method is not feasible for commercial production currently, but shows an alternative to silicon, as a solar cell. In future, an advanced form of this method may make cheap and affordable solar cells possible.
Make sure that you use adequate safety equipment, while conducting this experiment. Children are advised to take help from an elder, while attempting this experiment.