Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly usingconcentrated solar power (CSP). Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Photovoltaics convert light into an electric current using the photovoltaic effect.[1]
The International Energy Agency projected in 2014 that under its "high renewables" scenario, by 2050, solar photovoltaics and concentrated solar power would contribute about 16 and 11 percent, respectively, of the worldwide electricity consumption, and solar would be the world's largest source of electricity. Most solar installations would be in China andIndia.[2]
Photovoltaics were initially solely used as a source of electricity for small and medium-sized applications, from the calculatorpowered by a single solar cell to remote homes powered by an off-grid rooftop PV system. As the cost of solar electricity has fallen, the number of grid-connected solar PV systems has grown into the millions and utility-scale solar power stations with hundreds of megawatts are being built. Solar PV is rapidly becoming an inexpensive, low-carbon technology to harnessrenewable energy from the Sun.
Commercial concentrated solar power plants were first developed in the 1980s. The 392 MW Ivanpah installation is the largest concentrating solar power plant in the world, located in the Mojave Desert of California. The 579 MW Solar Star, nearRosamond, California, is the world's largest PV power station.
Photovoltaics:
A solar cell, or photovoltaic cell (PV), is a device that converts light into electric current using the photovoltaic effect. The first solar cell was constructed by Charles Fritts in the 1880s.[4] The German industrialist Ernst Werner von Siemens was among those who recognized the importance of this discovery.[5] In 1931, the German engineer Bruno Lange developed a photo cell using silver selenide in place of copper oxide,[6] although the prototype selenium cells converted less than 1% of incident light into electricity. Following the work of Russell Ohl in the 1940s, researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the silicon solar cell in 1954.[7] These early solar cells cost 286 USD/watt and reached efficiencies of 4.5–6%.[8]
Concentrated solar power
Main article: Concentrated solar power
Concentrated solar power (CSP), also called "concentrated solar thermal", uses lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Contrary to photovoltaics – which converts light directly into electricity – CSP uses the heat of the sun's radiation to generate electricity from conventional steam-driven turbines.
A wide range of concentrating technologies exists: among the best known are the parabolic trough, the compact linear Fresnel reflector, theStirling dish and the solar power tower. Various techniques are used to track the sun and focus light. In all of these systems a working fluid is heated by the concentrated sunlight, and is then used for power generation or energy storage.[10] Thermal storage efficiently allows up to 24-hour electricity generation.[11]
A parabolic trough consists of a linear parabolic reflector that concentrates light onto a receiver positioned along the reflector's focal line. The receiver is a tube positioned right above the middle of the parabolic mirror and is filled with a working fluid. The reflector is made to follow the sun during daylight hours by tracking along a single axis. Parabolic trough systems provide the best land-use factor of any solar technology.[12] TheSEGS plants in California and Acciona's Nevada Solar One near Boulder City, Nevada are representatives of this technology.[13][14]
Compact Linear Fresnel Reflectors are CSP-plants which use many thin mirror strips instead of parabolic mirrors to concentrate sunlight onto two tubes with working fluid. This has the advantage that flat mirrors can be used which are much cheaper than parabolic mirrors, and that more reflectors can be placed in the same amount of space, allowing more of the available sunlight to be used. Concentrating linear fresnel reflectors can be used in either large or more compact plants.[15][16]
The Stirling solar dish combines a parabolic concentrating dish with a Stirling engine which normally drives an electric generator. The advantages of Stirling solar over photovoltaic cells are higher efficiency of converting sunlight into electricity and longer lifetime. Parabolic dish systems give the highest efficiency among CSP technologies.[17] The 50 kW Big Dish in Canberra, Australia is an example of this technology.[13]
A solar power tower uses an array of tracking reflectors (heliostats) to concentrate light on a central receiver atop a tower. Power towers are more cost effective, offer higher efficiency and better energy storage capability among CSP technologies.[13] The PS10 Solar Power Plant and PS20 solar power plant are examples of this technology.
possibility and necessity of solar energy in Nepal
Solar Water Heater
Copper Fin Collector- Copper Fin Collector is a modern technology that replaces the 1st generation solar water heaters that use GI pipes to heat water. Black chrome selectively coated copper absorber plates and copper riser tubes are used in this system to heat the water. The plates absorb heat from the sun and transfer it to the copper pipes containing water thus bringing a rise in the temperature of the liquid. In order to preserve the heat energy and to prevent the heat from reflecting back, low iron tempered glass with high transmittance and low reflectance are used. This type
Heat Tube Collector
Heat Tube collectors use glass tubes with copper rods to heat the water. In this heater, the solar energy heats the copper rods inside glass tubes that have low reflectance, which help to trap the heat inside. The water is made to run around the rods thus heating them. This type of solar water heaters is very efficient for freezing prone areas.
Vacuum Tube Collector
The Vacuum Tube Collector belongs to the fourth generation of Solar Water Heaters. In this system a glass tube with water is made to run inside another glass tube with a vacuum space between the two. When the inner glass tube gets heated by the sun rays, the heat is preserved as the vacuum between the two tubes prevent the transmittance. The glass tube then transmits the energy to the water thus making its temperature rise. This system is highly efficient and affordable.
Concentrated Solar Power
Concentrated solar power (CSP) systems use lenses or mirrors to focus a large area of sunlight onto a small area. Electrical power is produced when the concentrated light is directed onto photovoltaic surfaces or used to produce steam for a conventional power plant. CSP is the latest development in Solar power solutions and is highly efficient for commercial, industrial and mass consumption purposes.
Solar Pool Heating
Pool heating is a very good solar application. The systems are simple and relatively inexpensive. Pool systems usually use simple, inexpensive, unglazed polypropylene collectors. The pool itself is the thermal storage for the system, and the pump you already use for filtering pool water will also circulate water through the solar collectors.
Solar Distillation
Solar distillation is the method of distilling water with the use of heat energy from the Sun. A solar collector is placed at the bottom of a box that is selectively coated black from inside. A glass cover is used to cover the mouth of the box and is placed in a slanting position so that when the water gets collected on the glass, it flows towards a collecting vessel. When the sun rays enter the box, it heats the collector that immediately transmits it to the water and turns it into vapor. When the vapor comes in contact with the glass cover, the vapor condenses because of the cool temperature on the outside and turns into water droplets. The droplets on the slanted glass slowly move down and get collected in a collecting vessel.
Solar Pasteurizer
Solar Pasteurizer is an environment friendly technology to purify water. Water can be pasteurized by making it remain in 71 degree centigrade for a minute, solar pasteurizer does this by using the heat energy from the Sun. When water is heated through a solar water heater it is collected in a tank that is connected to a thermo sensitive valve that only opens when the water is 71 degree centigrade. When the water passes through the valve after travelling for one minute through an insulated pipe, it is then made to cool through a heat convertor thus making the water ready to drink.
Solar Dryer
Solar dryers are used for food and crop drying, for industrial drying process, dryers have proved to be most useful device from the energy conservation point of view. It not only saves energy but also saves lot of time, occupying less area, improves quality of the product, make the process more efficient and helps protect environment also. Solar dryers circumvent some of the major disadvantages of classical drying. Solar drying can be used for the entire drying process or for supplementing artificial drying systems, thus reducing the total amount of fuel energy required.
Solar Cooker
A solar cooker is a device which uses sunlight as its energy source. They are made of shiny panels of aluminum which collect the heat energy from the sun and direct it to a cooking pot. Solar cookers are a form of outdoor cooking, and are often used in situations where minimum fuel consumption or fire risks are considered highly important. Because they use no fuel and they cost nothing to run, humanitarian organizations are promoting their use worldwide to help slow deforestation and desertification, caused by using wood as fuel for cooking.
No comments:
Post a Comment