Photovoltaic Solar Cells: Alternate Energy Sources for Electricity Generation - Essay Example

Photovoltaic Solar Cells: Alternate Energy Sources for Electricity Generation Abundance of free and seemingly infinite quantity of sunlight available to the earth is a resource of energy, which has remained relatively untapped. Harnessing of this energy for conversion to electricity by photovoltaic technology is of recent origin and offers considerable potential for its commercial exploitation in the years to come, amidst dwindling resources of fossilized fuels. It has emerged as a major power source, because of its proven reliability and several economic and environmental benefits. solardirect.com suggests the factors of reliability which support its cause as given below: It is free, clean and permits storage for use, when needed. Its biggest advantage is that it is virtually maintenance free and absolutely reliable, because of the absence of moving parts; it is designed for ease of assembly, use and maintenance. Its yet another significant benefit is that, it offers an option for nations to rid themselves of avoidable dependence on oil for fulfilling their gross energy needs. It is a nascent technology possessing the long term potential to create additional jobs for strengthening of economies. It does not generate hazardous waste or cause atmospheric pollution by release of gases like carbon dioxide, sulphur dioxide, nitrous oxide or mercury like many traditional forms of electrical generation do. It does not require liquid or gaseous fuel to be transported or combusted. It does not contribute to global warming, acid rain or smog. Its far reaching benefits outweigh the high initial cost of the systems. Innovations in product design in recent times have led to the feasibility of execution of maintenance of roof mounted PV systems from ground level, without taking recourse to body harnesses, ladders and cranes for accessing the roofs in compliance with the safety requirements. In colder countries where snow accumulation on roofs could pose a maintenance problem, safety and liability issues associated with jobs involving working at heights with slippery work surfaces have virtually been dispensed with. Contrarily, in hotter tropical countries, where accumulations of dust and foreign matter over the PV solar panels pose a severe maintenance problem, it has been intelligently resolved by providing them with dust-repellant coatings and by mechanisms for auto-blowing of the dust periodically. High wind velocities are known to cause problems of stability of solar arrays. Gyro-controlled hydro-electronic devices engineered with dual axis tracking systems to align the arrays in a horizontal position to allow the flow of air above and below them in cyclonic weather, has resulted in protecting them against undesirable stresses for enhanced reliability. Research and advanced technology have also made it possible for the solar arrays to align themselves with the trajectory of the Sun’s path so that the Sun’s rays are always incident upon them, leading to enhanced performance of the PV systems with the advent of similar control mechanisms. Functional and operational needs have led to the broad categorization of PV systems into two types - Stand Alone and Grid-Connected. As the name itself suggests, the former type of PV systems are ideally suited for DC and/or AC electrical loads and have established their reliability for daylight hour applications like water pumps, ventilation fans, small circulation pumps for solar thermal water heating systems and ventilation blowers etc. which are designed to operate independent of the electric utility grid; however, batteries could be used for energy storage, if deemed necessary, for specific end applications. Solardirect.com talks of the reliability of consistent AC voltage and power quality required by any utility grid is assured by the DC power generating PV arrays, which receive the energy feed from the core component of the latter type of Grid-Connected PV systems called the Inverter. Depending on whether the on-site electrical loads are required to be fed or to reverse feed the grid when the PV system output exceeds the on-site load demand, a bi-directional distribution interface on the downstream side of the inverter, performs the regulation function. Bulk of the equipment being static without any rotating parts, the bare minimum maintenance is limited to only the storage batteries. Established technologies are getting outperformed by the emerging energy storage technologies encompassing the usage of Li-ion, NiMH, flow batteries, ultra-capacitors or flywheels that are expected to provide reliable and safe energy storage at competitive cost. The method by which thermal energy of the Sun is collected during the daylight hours and stored in specially designed storage systems for eventual generation of electrical power is called the CSP technique of large scale electricity generation suggested by microthermgroup.com. It consists of directing the heat radiation from the Sun on to a parabola shaped linear collector, where the focused energy absorbed in the trough of the receptacle leads to temperatures of the order of 4000 C. The stored thermal energy redeployed for running steam turbines, which convert the thermal energy to electricity is the most common method in use. The swiveling action of the parabolic reflector troughs is achieved by well insulated ball and socket joint assemblies, which apart from interconnecting the receptacles arranged in parallel rows, also serve as a conduit for the HTF to flow to the distribution pipes for ensuring system reliability. The other important factors of reliability with maintenance orientation which merit attention among others include: Thermal insulation quality which can bring down heat losses by 30-40 % Lowering of installation cost by resorting to one layer insulation system Zero degradation to achieve the declared lifetime of the solar plant Noncombustible to render it fire accident free Environment friendly with total recyclability Free from health hazards While sunlight is the all-pervading nature’s free bounty, but countries in the proximity to the equator, lying between the tropic of Cancer and the tropic of Capricorn called tropical countries are the ones endowed with the brightest sunshine virtually all round the year. They obviously possess the brightest potential for harnessing of the abundant solar energy by virtue of the geographical advantage they enjoy, more particularly in the high noon conditions of the summer months. Solar panels facing southward with a tilt facilitating sun rays to fall at right angles to the earth assure maximal output. It is interesting to note that the world’s largest solar plant spread over 1000 acres, and which accounts for 90% of the global commercial production, is located in the Mojave Desert of North America and has a good record of reliability as per alternate-energy-sources.com; solar power produced in the desert is also for obvious reasons, estimated to cost three times lesser than in the plains or elsewhere. Other countries proactively engaged in their solar energy pursuits are North America, Germany, Italy, Spain, Brazil, Peru, Middle East countries in UAE, Israel, Saharan Africa, Korea and Japan to name a few, not to mention of China and India who have also joined this league. North America, and Germany have over the years, acquired a distinct edge over the others in respect of their focused approach at developing both captive solar installations; and Japan for grid-connected, maintenance-free, special synthetic resin- coated or polymer foil lined photo voltaic panels for residential applications, in particular for illumination and street lighting. Bibliography: 1) High Temperature Insulation in Concentrated Solar Power, Web. April 9, 2013 (http://www.microthermgroup.com/high/EXEN/site/concentrated-solar-power.aspx) 2) Complete Photovoltaic Systems, Web. April 9, 2013 (http://www.solardirect.com/pv/systems/systems.htm) 3) 30 Facts about Solar Energy, Web. April 9, 2013 (http://www.alternate-energy-sources.com/facts-about-solar-energy.html) Read More