Solar Panel is collection of solar cells interconnected together either in series or parallel to give the desired output voltage and current rating. They convert sunlight energy into electrical energy. Solar cell is made up of different materials such as monocrystalline silicon, polycrystalline silicon, cadmium telluride, amorphous silicon and copper indium selenide. Most of the solar cells in the market are composed of monocrystalline silicon and polycrytalline silicon. Monocrystalline silicon is more expensive to produce but it is more efficient. Polycrystalline silicon is less expensive to produce but it is less efficient. Therefore, types of solar cells selected depends on the application of the solar cells. How does solar cell work? The photons from the sunlight once hit the solar panel, they will are absorbed by the silicon. Electrons are broken from their bonds creating a potential difference. To cancel this potential difference, current starts flowing through the material and this electrical energy is captured. The electrons are only allowed to flow in one direction due to the special composition of the materials.
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In order to get the maximum output energy from the sun, the sunlight rays should hit directly or perpendicular to the solar panel. As the sun moves from east to west from day to day, the position of the solar panel has to be adjusted or the tilt angle of the solar panel is varied in order to maximize the energy capture from the sun. A device called solar tracker is invented for this purpose which constantly moves the solar panel in desired angle according to the sun position. However, solar tracker is too expensive to be implemented than installing extra solar panel to compensate for the loss of energy capture. Particularly in solar charger for mobile phones, a solar tracker is not needed. This is because the mobile phone will start charging even under low light condition. Solar tracker however is useful for the solar panels installed on the roof top used for supplying electricity to the house in certain countries.
