Light itself is energy in the form of electromagnetic radiation and thus everywhere you see light, you perceive pure natural energy as well. A fact which is unknown to many is that even light rays put pressure on whatever it touches on its way, but the pressure is so light that it cannot be felt by us physically. To determine the exact amount of pressure that photons exert on objects, you would need to divide the energy present in the light waves by its speed (300,000 km/s). The energy in light can be measured via two techniques, namely radiometry and photometry. Photometry involves reading the brightness in light while keeping the normal ability of the human eye’s tolerance to bright light in perspective. Both photometry as well as radiometry measure light energy in wavelengths but the difference is that in radiometry, light energy from all possible wavelengths are measured. Photometric devices are designed to measure light and detect if it is adequate enough for the purpose for which the lights are going to be used in the first place. A match official uses a photometric device to check the light during certain sporting events if he thinks that the light is inadequate or if the players complain regarding visibility. Radiometry is used to measure the intensity of the light energy while photometry is basically used to determine the brightness of a source of light. The primary source of all light on planet earth is the sun, be it any kind of light energy, rest assured that it had once been a part of the sun and therefore light energy is sometimes considered synonymous with solar energy. When we refer to solar energy, we usually associate it with PV cells or thermal receptors that convert the energy in sunlight to electrical and thermal energy. In fact, the energy which is present in the sunlight that reaches the earth is enough to meet all the needs of the earth many times over and this has fascinated scientists for decades. This is the reason why light energy is viewed as the main source of alternative energy. The concept of interstellar journeys is still a concept at this point of time, but even that concept is based on the light energy that is present in the outer space. It has been found that the reason why the revolutions of an asteroid gains pace is because light energy present in the outer space works on them. This phenomenon is the main idea that is meant to control the interstellar journeys with the help of “solar sails” (another concept till date) if and when they are possible. These are however far from practical application yet and the useful utilization of light energy today is done either through a CSP solar system or a PV cell panel.
Solar energy is converted with the help of photo voltaic cells. The photovoltaic (PV) cells have the ability to convert the electromagnetic radiation which is light, into electricity and with the help of modern PV systems, it is possible to not only capture the energy in light and convert it into electricity, but also to store and use that energy to meet our electrical needs. In order to understand how this works, one must first be aware of the fact that the rays of light contain energy and that is exactly the reason why most things exposed to direct sunlight for a significant amount of time turns hot. Just like we begin to heat up as the photons from the sunlight touches our body and turns into heat energy, in case of certain materials, the photons turn into electrical energy on coming into contact. Among such materials, silicon was chosen to serve the function and most traditional solar panels consist of silicon based PV cells.
The PV cells are different from objects that use sun as a thermal source of energy as the cells in this case, use the sun as an electrical source of energy. Most solar panels consist of a series of interlinked PV cells that work together and sometimes, two or more solar panels are interlinked as well to greatly improve the total electricity output. Now, as the photons hit the panels, the electrons in the semiconductor, be it silicon or CIGS, are put into motion in the form of direct current (DC). Had it not been a conductor, then the electrons would not have been able to move through the crystals and therein lays the difference. Although this is the basic process that goes on while harvesting light energy, the DC current is not the final product of this process. To convert the DC into usable electricity, the charged electrons now go through the connected inverter where the direct current turns to alternating current (AC). After the transformation process is also complete, the usable energy is now stored to be used as per demand. Depending on the type and quality of the solar apparatus that you have installed, the total energy lost during the AC to DC conversion will vary.
Although we tend to think that conversion to electricity is the only place where we can use the electromagnetic radiation energy in light, it is not true. We often neglect to see that even the heating capacity of light can also be used directly without converting it into electricity. Solar cookers, furnaces and pool heaters are examples of such appliances that make use of the sun’s potential as a source of thermal energy. The cells used for solar heat collection are different from PV cells both in function and design. Even these types of thermal receptors can be used to produce indirect electricity though. Often, the thermal receptors (CSP) heat up the water to produce steam which in turn is used to turn a special steam turbine to produce electricity. In this way, the thermal energy from the sun is used to manufacture usable electricity from steam. Both of these sources are theoretically infinite and does not put stress on the environment; thus with the help of one renewable source of energy, another renewable source of energy is utilized to manufacture a different kind of power than the original source.
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