It is a known fact that the amount of energy that reaches earth everyday in the form of sunlight is enough to supply the entire planet with all the electricity it needs and more than just one time around at that. Now, to turn the energy contained in sunlight to usable electrical energy, a semiconductor is required which is capable of transforming the sun’ rays to electricity when sunlight hits it. Such a device is known as a solar panel or a photovoltaic cell. The oldest and the first photovoltaic cells were made of silicon, one of the most common elements that are found on our planet. The capability of silicon to convert light energy into electrical energy had made it an important discovery, but it is also quite expensive to use this element for capturing solar power. Unfortunately, common and efficient as the element certainly is, it is difficult to make large silicon crystals necessary for creating photovoltaic cells capable of capturing the sun’s energy. Alternatives were found later in the form of flexible films made out of copper-indium-gallium-selenide (CIGS), but these “thin-film” crystals does not have as high a solar energy conversion rate as silicon crystals. Still, the comparatively low-priced Copper-indium-gallium-selenide thin film photovoltaic cells have increased the popularity of solar energy by decreasing the cost associated with installing a solar grid system.
In order to understand how exactly the photovoltaic cells convert raw energy of the sun to usable electrical energy, a scientific explanation is required. In a silicon crystal, the bond that exists between its atoms are composed of electrons and all the atoms within the crystal, share these electrons. What happens is that when the light (photon) falls on a photovoltaic crystal, the electrons start to heat up and when they reach an energy level which is higher than the existing bond, the electrons move about freely producing current, ready to be collected as electricity. The process is known as the photoelectric effect and it is this principle of photoelectric effect that we depend on to convert solar energy into electrical energy.
Although companies may use slight alterations to customize their signature solar panels to be more efficient, the basic principle for all solar panels are more or less the same. Made mostly out of silicon crystals, solar panels usually have two sheets or layers known as the N-layer and the P-layer. The N-layer is the sheet with excess free electrons that move about in it, while the P-layer is the sheet that is deficient in electrons. The electrical field that separates the two layers, allows one way migration of free electrons from the P-layer into the N-layer each time photons hit the P-layer and frees an electron, but when sunlight hits the N-layer and frees an electron, the electron is not allowed to move across the electrical field and into the P-layer, thus the N-layer ends up with most of the free electrons in it. The circuits attached to the N-layer first supplies the current flow to the solar powered appliances and then the electrons are taken back to the P-layer to continue the process for as long as there is sufficient light.
Now that the procedure for the application of photoelectric effect in harnessing and converting solar energy is explained, it is time to understand how solar energy works to help us with our power needs and also to reduce pollution. What the world depends on today as the primary source of energy is coal and oil, otherwise known as fossil fuel. The fossil fuels are made up of decayed plant and animal matter, fossilized due to the pressure of the overlying strata of landmass over hundreds of millions of years. As it took millions of years to form the coal and petroleum that we harvest and use today, it is not difficult to understand that it is only a matter of time before we run out of these. Since it is impossible for us to wait for millions of years until the fossil fuel supply is restored again naturally, we will at that point in future, be forced to either utilize an alternative source of energy or return back to the dark ages. Solar energy, wind energy, hydro electricity and bio-fuel are some of the alternative sources of energy that have surfaced, but among them, solar power remains the most promising source of energy for us in the future. Solar energy is virtually unlimited as long as the sun rises to shed its light on earth every day and harnessing it with the help of photovoltaic cells also does not cause carbon gas (carbon dioxide and carbon monoxide) pollution, a harmful side effect of using fossil fuel. In spite of these advantages of solar energy, it is yet not that efficient at replacing the use of fossil fuel. The main problem is the cost that is associated with producing solar energy; it has come down immensely over the decades, but still is significantly more expensive than the energy obtained from burning fossil fuels. Other disadvantages include the lack of power production during the night and also the influence of climatic conditions which may render solar energy apparatus completely useless. It is hoped that man will be able to overcome most of these obstacles to establish solar energy as a dependable source of energy in the near future, but even today, solar power is used by us for a number of purposes. Solar water heaters and especially pool heaters are the most common and popular household solar appliance today. In fact it is actually cheaper than using a conventional water heater, because the cost of a solar appliance is almost always equal to what you pay to install it, meaning that the appliance will never be responsible for electricity charges. In Japan and also up to a degree in certain states of the US, solar energy supplements both residential needs as well as business needs. From simple solar calculators to high-tech space satellites, solar energy is used vastly, even today.
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