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In the first article of this series we learnt a few basic concepts and facts about the power of the sun while the second article dealt with the concept of “Radiation Budget” of the Earth. We also saw the amount of solar power which is available on different areas of the globe in watts per unit of surface area. In this article we will learn more about the solar radiation conversion into electricity.
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No matter how much amount of energy is present in the solar radiation, it is of no use to us unless it is converted into the desired form namely electrical energy (of course direct sunlight is also extremely useful but I am talking from the context of solar power generation). There are several methods and arrangements which are used to convert this solar radiation available from the sunlight. In general these arrangements are known by the name of solar power plant which like wind power plants and tidal power plants perform the function of converting one of the available natural resources of energy into electrical energy. We will study few of these arrangements which help to generate solar power but first we must get acquainted with a few terms related to this concept and these have been defined as follows.
Solar Cell: also known as a photovoltaic module, a solar cell is an arrangement which converts the radiation of the sun into electrical energy. It uses the principle of photovoltaic effect for this purpose (hence the name photovoltaic cell) which refers to the phenomenon of release of electrons from matter after the absorption of solar energy. And we also know that electricity is nothing but the flow of electrons hence the generation of electricity from radiation is carried out by these cells. The symbol used for solar cell is shown as first image in figure 1.
Photovoltaic Module: a collection of solar cells. A single solar cell might be sufficient to run a small device but normally they have to be combined to form a module which generates a higher level of electrical energy. A typical solar cell produces around 0.5 Volts while a Module can generate upto 12 Volts (remember your car battery)
Photovoltaic Array: a collection of photovoltaic modules also known as a solar panel as can be seen in figure1 (second image). These are the ones which you must have seen either on rooftops or on some building. These can produce varying amounts of electricity depending on requirements
Of course though a common man manly associates solar energy with these solar panels, in actual practice solar energy can also be produced without using these panels. This can be done by the use of devices such as solar trough systems and solar dish/engine systems as well. We will study about these various generation plants in detail in the next articles of this series.
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Solar Energy: Harnessing the Natural Oven (Part II)
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Figure 1: Solar Panel - Courtesy: Royal London Handyman Service