How Solar Energy Can be Used to Produce Electricity - Report Example

Explain how solar energy can be used to produce electri “Green Living” is the motto of the present day world. With the dangers of Climate Change,air pollution and ecological degradation looming large, environmental scientists and engineers are relentlessly promoting green technologies, recycling, renewable energy sources, water conservation and so on. There is enough motivation for the people to look for alternate sources of energy to replace the non-renewable sources such as fossil fuels and radioactive elements. Solar energy is the most abundant, inexhaustible, reliable and climate-friendly source of renewable energy. It can also be converted easily to electricity. Thus, solar power veritably is the holy grail of energy. According to Bradford (2006), a “solar revolution” is waiting to happen in the next couple of decades, when everyday life in the sun-powered world will be radically transformed. Solar energy is the electromagnetic radiation emitted by the sun, which is composed of visible, ultraviolet and infrared light. For the past ten billion years, the planet earth has been receiving, non-stop, incalculable amounts of energy from the sun. The energy from the sun that is received at the surface of the earth is absorbed by the land, water and atmosphere to be converted into heat. This heat energy is responsible for making the earth comfortably warm at around 15 degrees Centigrade mean temperature. Sunlight is the mainstay of life on earth, providing the three basic necessities of life on earth that is, food, water, and oxygen. The radiant energy from the sun is utilised by plants to produce food (glucose) and the by-products, oxygen and water, through the process of photosynthesis. Fossil fuel is nothing but solar energy stored millions of years ago. An important and very useful property of energy is its easy conversion from one form to another. Sunlight is an excellent source of heat and electricity, the two most important forms of energy in everyday use. Solar energy can be converted directly into electricity. The basic requirement for this is a photovoltaic (photo for light, voltaic for electricity) cell, or simply, solar cell or PV. Most photovoltaic cells are made from crystalline silicon, a common element present in the earth’s crust, and which is a semiconductor. Solar cell is the smallest semi-conductor that produces electrical energy from light energy (http://www.freesolaronline.com/). Pure silicon is a poor conductor of electricity. To make it a better conductor, silicon needs to be “doped” with an impurity such as phosphorus which imparts a negative charge (N-type). Similarly, silicon doped with boron is piositively charged (P-type). Thus, the solar cell consists partly of N-type silicon, and partly of P-type silicon (http://www.freesolaronline.com/). Solar cells in the final form, typically consist of silicon sliced into thin wafers and placing two separate wafers with the positive and negative electrical properties together, connected by wires that enable electrons to travel between layers (http://www.re-energy.ca/t_solarelectricity.shtml). A ray of sunlight consists of millions of photons which are tiny particles of light that move at a velocity of approximately 300,000 kilometres per second. When sunlight strikes the top layer of a solar panel, a part of it is absorbed by the semiconducting silicon. The energy of the absorbed light causes some electrons in the parent silicon atoms to become free. The free electrons start to flow from one layer to the other through the wire because of the different properties of the two silicon wafers thereby generating electricity. The current is drawn off, through the batteries and other appliances, for use externally. The PV array or module (Sunbook, a Guide to Solar Energy in North Carolina, 1999) is constructed to capture and convert a large amount of solar energy, a number of photovoltaic cells are connected by wires to form photovoltaic arrays. The photovoltaic arrays or solar panels can produce electricity in all kinds of conditions, even in cloudy U.K., in all seasons of the year but only during the daytime. Besides the photovoltaic array, controls, an inverter and battery storage are the other components used. Solar panels produce direct current electricity (DC). The generated DC power is stored in deep cycle lead-acid batteries for later use, that is, even when power generation is not possible. A more advanced variation of the storage device is the rechargeable battery. Modern photovoltaic systems consist of an electronic charge controller that transfers electricity from the solar panel to the battery efficiently. The inverter converts the batterys low-voltage direct current (DC) to alternating current (AC) which is the form required to run most household equipment. The size of the inverter needed depends upon the peak power loads. The rule of thumb is the total wattage of all the appliances that would be used concurrently. Lead-acid batteries are the most common storage batteries used in PV systems because they are economical and widely available. A bank of batteries would be required depending on the storage capacity required, the maximum discharge rate, the maximum charge rate, and the minimum temperature at which the batteries will be used (Ramsey and Hughes, 2007). Lead-acid batteries are significantly affected by temperature. For instance, at 40°F they will have about 75% of rated capacity, and at 0°F their capacity will go down to about 50%. The storage capacity of a battery, that is, the amount of electrical energy it can hold, is expressed in amp hours. A lead-acid battery with a slightly more storage capacity is to be preferred so as to take care of the vagaries of nature. A rechargeable battery should have enough amp hour capacity to supply needed power during the longest expected period "no sun" or extremely cloudy conditions. However, it is usual to have a source of back-up power, such as a standby generator along with a battery charger to tide over bad weather conditions. Deep cycle lead-acid batteries are to be preferred over shallow cycle batteries since they are designed to be repeatedly discharged by as much as 80 percent of their capacity. All lead-acid batteries need to be recharged completely after each cycle to prevent premature failure. Protection of the environment is our sacred duty. When fossil fuels are burnt, they release carbon dioxide which is a greenhouse gas that causes the earth to warm up. Carbon dioxide is building up in the atmosphere thanks to our current lifestyles. A significantly warmer planet will lead to many serious problems around the world. Using solar power is clean, and the supplies will never run out. In conclusion, the two most important forms of energy we consume are heat and electricity for which the sun is the ultimate source. Suns energy which is largely emitted as visible light can be easily converted into electricity using solar panels consisting of photovoltaic cell modules in which the semiconductor, crystalline silicon is the main ingredient. The power generated is stored for “no-sun” times in rechargeable lead-acid batteries, and the D.C. power is converted to A.C. using inverters to suit the power requirements of the electrical appliances. Solar power is non-polluting (“clean”) and environment-friendly (“green”). A world powered by solar electricity will definitely be brighter. References Bradford T, 2006, Solar Revolution: The Economic Transformation of the Global Energy Industry, MIT Press. Ramsey, D & Hughes D, 2007, The Complete Idiots Guide to Solar Power for your Home, 2nd Edition, Alpha, 336pp Sunbook, a Guide to Solar Energy in North Carolina, 1999, Published by the Energy Department, N.C.Department of Commerce. Read More