Solar Cells

SOLAR CELLLS-THE FOUNDTION OF SOLAR ENERGY full report
| |ABSTRACT | |
| |A solar cell is a semiconductor device | |
| |that converts solar energy into | |
| |electricity by the photovoltaic effect, | |
| |representing the fundamental power | |
| |conversion unit of a photovoltaic system| |
| |,works under the principle of a P-N | |
| |junction that absorbs light , releases | |
| |electrons and holes , creating a voltage| |
| |in the cell , which is then applied to | |
| |load; being environmentally aware, and | |
| |with the price of living rising at an | |
| |alarming rate, solar power, generating | |
| |energy from the natural resources of the| |
| |sun, has in recent times become quite a | |
| |viable alternative to the normal | |
| |resources for generating electricity, | |
| |with a great advantage that solar energy| |
| |is free; it needs no fuel and produces | |
| |no waste or pollution, environmentally | |
| |friendly, so particularly useful in | |
| |situations where electrical power from | |
| |the grid is unavailable such as in | |
| |remote area power systems, | |
| |Earth-orbiting satellites and space | |
| |probes, remote radiotelephones and water| |
| |pumping applications, where its | |
| |applications stands alone, and exploit | |
| |with their special advantages ,giving | |
| |rebirth to the mankind. | |
| |INTRODUCTION | |
| |Solar cells represent the fundamental | |
| |power conversion unit of a photovoltaic | |
| |system. They are made from | |
| |semiconductors, and have much in common | |
| |with other solid-state electronic | |
| |devices, such as diodes, transistors and| |
| |integrated circuits. For practical | |
| |operation, solar cells are usually | |
| |assembled into modules. | |
| |Many different solar cells are now | |
| |available on the market, and yet more | |
| |are under development. The range of | |
| |solar cells spans different materials | |
| |and different structures in the quest to| |
| |extract maximum the device while keeping| |
| |the cost to a minimum. | |
| |Cheaper (but also less efficient) types | |
| |of silicon cells, made in the form of | |
| |amorphous thin films, are used to power | |
| |a variety of consumer products. We were | |
| |familiar with the solar-powered watches | |
| |and calculators, but larger amorphous | |
| |silicon solar modules are also | |
| |available. | |
| |A particular class of high-efficiency | |
| |solar cells from single crystal silicon | |
| |or compound semiconductors (for example,| |
| |gallium arsenide or indium phosphide) | |
| |are used in specialized applications, | |
| |for example, to power satellites or in | |
| |systems which operate under | |
| |high-intensity concentrated sunlight. | |
| |WHAT IS A SOLAR CELL | |
| |A solar cell or photovoltaic cell is a | |
| |semiconductor device that converts solar| |
| |energy into electricity by the | |
| |photovoltaic effect.. Photovoltaicâ„¢s | |
| |is the field of technology and research | |
| |related to the application of solar | |
| |cells as energy. Sometimes the term | |
| |solar cell is reserved for devices | |
| |intended specifically to capture energy | |
| |from sunlight, while the term | |
| |photovoltaic cell is used when the | |
| |source is unspecified. | |
| |SOLAR CELL | |
| |WHAT IS THE PRINCIPLE OF A SOLAR CELL | |
| |It is based on the ability of a | |
| |semiconductor to directly convert | |
| |sunlight into electricity. Basically, a | |
| |solar cell is a P-N junction that | |
| |absorbs light, releases electrons and | |
| |holes, reating a voltage in the cell, | |
| |which is then applied to the load. | |
| |HOW A SOLAR CELL DOES WORKS | |
| |In order to produce energy to work a | |
| |load, e.g., light a light bulb, the | |
| |solar cell needs an outside source (the | |
| |Sun) to produce electricity to power it.| |
| |When light strikes a photovoltaic | |
| |(solar) cell, atoms are bombarded with | |
| |photons, and produce electrons. When the| |
| |atom loses the electron, it leaves | |
| |behind a Ëœholeâ„¢, which has an equal | |
| |and opposite charge. Both the electron, | |
| |with its negative charge, and the hole, | |
| |with its positive charge, begin are | |
| |carried down the gradient. A proportion | |
| |of carriers which cross this junction | |
| |can be harvested by completing a circuit| |
| |from a grid on the cell 's surface to a | |
| |collector on the backplane. In the cell,| |
| |the light "pumps" electrons out one side| |
| |of the cell, through the circuit, and | |
| |back to the other side, energizing any | |
| |electrical devices. | |
| |In the conversion process, the incident | |
| |energy of light creates mobile charged | |
| |particles in the semiconductor which are| |
| |then separated by the device structure | |
| |and produce electrical current. | |
| |WHAT ARE THE ADVANTAGES OF SOLAR -CELLS | |
| |Recently, more people are becoming | |
| |environmentally aware, and, with the | |
| |price of living rising at an alarming | |
| |rate, we are all looking for ways to | |
| |save some money. So why not try to save | |
| |the environment at the same time Solar | |
| |power, generating energy from the | |
| |natural resources of the sun, has in | |
| |recent times become quite a viable | |
| |alternative to the normal resources for | |
| |generating electricity. | |
| |1. SOLAR ENERGY IS A RENEWABLE RESOURCE | |
| |You will never run out of solar energy. | |
| |Sure, the sun sets at night, and on | |
| |those dark and gloomy days it may not | |
| |always be visible, but you can be sure | |
| |that it will return. Oil, on the other | |
| |hand, is limited, and once you run out, | |
| |it is gone forever. Although the amount | |
| |of power the sun can generate is limited| |
| |to the amount of sunlight you get, it is| |
| |possible to generate electricity even on| |
| |cloudy days. | |
| |2. SOLAR POWER IS NON-POLLUTING | |
| |Unlike oil, solar power does not emit | |
| |any sort of toxic gases into the | |
| |environment. It is a completely | |
| |environmentally friendly approach to | |
| |generating electricity. There is even | |
| |work being done to make the recycling of| |
| |solar panels more effective. | |
| |3. LIGHT FROM THE SUN IS FREE | |
| |After the initial costs involved in | |
| |setting up the solar panels and solar | |
| |lights etc, you will never have to pay | |
| |to run them. | |
| |4. SOLAR POWER IS QUITE FLEXIBLE | |
| |You can have an array of solar panels on| |
| |your roof to generate power from your | |
| |home. You can also have smaller solar | |
| |cells on garden lights or anything else | |
| |outside that only needs a small amount | |
| |of electricity. Not having to run a wire| |
| |can be a huge time saver. | |
| |5. SOLAR CELLS REQUIRE MINIMAL | |
| |MAINTENANCE | |
| |Once the solar cells are set up, they | |
| |require very little maintenance, mainly | |
| |because there are no moving parts that | |
| |have to be maintained. Solar cells can | |
| |last a lifetime and is very easy to | |
| |install. | |
| |6. SOLAR POWER IS SILENT | |
| |The methods that are used to find and | |
| |extract oil are very noisy. Even wind | |
| |power can create a lot of noise. Solar | |
| |power is completely silent. | |
| |7. SOLAR ENERGY CAN SAVE MONEY IN THE | |
| |LONG RUN | |
| |Solar energy has many advantages, some | |
| |of them not as common as others. The | |
| |main reason for this perhaps is that the| |
| |initial cost is quite high. However, you| |
| |can save a significant amount of money | |
| |using solar power, which compares | |
| |favorably to paying an electricity bill | |
| |at the end of the month. There is a lot | |
| |of work that has been done to make solar| |
| |power more accessible to the common man,| |
| |with researchers finding ways and means | |
| |to make this resource a common practice.| |
| |Solar power is indeed an amazing, | |
| |natural energy resource with so much | |
| |potential to be tapped into. It is just | |
| |a matter of time before solar power | |
| |becomes a global hit. | |
| |WHAT ARE THE APPLICATIONS OF SOLAR CELL | |
| |Along side a variety of consumer | |
| |products - electronic watches, | |
| |calculators, power for leisure equipment| |
| |and tourism - there is an extensive | |
| |range of applications where solar cells | |
| |are already viewed as the best option | |
| |for electricity supply. These | |
| |applications are usually stand-alone, | |
| |and exploit the following advantages of | |
| |photovoltaic electricity: | |
| |¢ There are no fuel costs or fuel | |
| |supply problems | |
| |¢ The equipment can usually operate | |
| |unattended | |
| |¢ Solar cells are very reliable and | |
| |require little maintenance | |
| |THE APPLICATIONS ARE AS FOLLOWS | |
| |RURAL ELECTRIFICATION | |
| |The provision of electricity to rural | |
| |areas derives important social and | |
| |economic benefits to remote communities | |
| |throughout the world. Power supply to | |
| |remote houses or villages, | |
| |electrification of the health care | |
| |facilities, irrigation and water supply | |
| |and treatment are just few examples of | |
| |such applications. | |
| |1. WATER PUMPING: Solar pumps are used | |
| |principally for two applications: | |
| |village water supply (including | |
| |livestock watering), and irrigation. | |
| |Since villages need a steady supply of | |
| |water, provision has to be made for | |
| |water storage for periods of low | |
| |insolation. In contrast, crops have | |
| |variable water requirements during the | |
| |year which can often be met by supplying| |
| |water directly to produce without the | |
| |need for a storage tank. | |
| |2. LIGHTENING: In terms of the number of| |
| |installations, lighting is presently the| |
| |biggest application of photo-voltaic, | |
| |with tens of thousands of units | |
| |installed world-wide. They are mainly | |
| |used to provide lighting for domestic or| |
| |community buildings, such as schools or | |
| |health centers. PV is also being | |
| |increasingly used for lighting streets | |
| |and tunnels, and for security lighting. | |
| |PROFESSIONAL APPLICATIONS | |
| |For some time, photovoltaic modules have| |
| |proved to be a good source of power for | |
| |high-reliability remote industrial use | |
| |in inaccessible locations, or where the | |
| |small amount of power required is more | |
| |economically met from a stand-alone PV | |
| |system than from mains electricity. | |
| |Examples of these applications include: | |
| |1. OCEAN NAVIGATION AIDS: Many | |
| |lighthouses and most buoys are now | |
| |powered by solar cells. | |
| |2. TELECOMMUNICATION SYSTEMS: radio | |
| |transceivers on mountain tops or | |
| |telephone boxes in the country can often| |
| |be solar powered. | |
| |3. REMOTE MONITORING AND CONTROL: | |
| |scientific research stations, seismic | |
| |recording, weather stations, etc. use | |
| |very little power which, in combination | |
| |with a dependable battery, is provided | |
| |reliably by a small PV module. | |
| |4. CATHODIC PROTECTION: this is a method| |
| |for shielding metalwork from corrosion, | |
| |for example, pipelines and other metal | |
| |structures. A PV system is well suited | |
| |to this application since a DC source of| |
| |power is required in remote locations | |
| |along the path of a pipeline. | |
| |GRID CONNECTED SYSTEMS | |
| |Two types of grid-connected | |
| |installations are usually distinguished,| |
| |centralized PV power stations, and | |
| |distributed generation in units located | |
| |directly at the customer 's premises(PV | |
| |in buildings). | |
| |1. PV POWER Stations: A PV power station| |
| |feeds the generated power | |
| |instantaneously into the utility | |
| |distribution network (the 'grid ') by | |
| |means of one or more inverters and | |
| |transformers. PV power stations may be | |
| |approaching economic viability in | |
| |locations where they assist the local | |
| |grid during periods of peak demand, and | |
| |obviate the need to construct a new | |
| |power station. This is known as peak | |
| |shaving. It can also be cheaper to place| |
| |small PV plants within the transmission | |
| |system rather than to upgrade it | |
| |( 'embedded ' generation). | |
| |2. PV In Buildings: PV arrays mounted on| |
| |roof tops or facades offer the | |
| |possibility of large-scale power | |
| |generation in decentralized medium-sized| |
| |grid-connected units. | |
| |The main advantages of these distributed| |
| |systems over large PV plants are as | |
| |follows: | |
| |¢ There are no costs in buying the land| |
| |and preparing the site. | |
| |¢ The transmission losses are much | |
| |lower because the load is on the same | |
| |site as the supply. | |
| |¢ The value of the PV electricity is | |
| |also higher because it is equal to the | |
| |selling price of the grid electricity | |
| |which has been replaced, rather that to | |
| |the cost of generating it. | |
| |ELECTRIC POWER GENERATION IN SPACE | |
| |Photovoltaic solar generators have been | |
| |and will remain the best choice for | |
| |providing electrical power to satellites| |
| |in an orbit around the Earth. Indeed, | |
| |the use of solar cells on the U.S. | |
| |satellite Vanguard I in 1958 | |
| |demonstrated beyond doubt the first | |
| |practical application of photovoltaics. | |
| |Since then, the satellite power | |
| |requirements have evolved from few Watts| |
| |to several kilowatts, with arrays | |
| |approaching 100 kW being planned for a | |
| |future space station. | |
| |A space solar array must be extremely | |
| |reliable in the adverse conditions of | |
| |space environment. Since it is very | |
| |expensive to lift every kilogram of | |
| |weight into the orbit, the space array | |
| |should also have a high power-to-weight | |
| |ratio. | |
| |RESULTS | |
| |1. We can have pollution“less world. | |
| |2. Avoid the scarcity of fossil fuels. | |
| |3. Abundant electricity for all | |
| |purposes. | |
| |4. Supply power in deserts, oceans, and | |
| |to remote areas. | |
| |5. Supply of sufficient power to earth | |
| |orbiting satellites and space probes. | |
| |CONCLUSION | |
| |Solar cells are long lasting sources of | |
| |energy which can be used almost anywhere| |
| |particularly useful where there is no | |
| |national grid and also where there are | |
| |no people such as remote site water | |
| |pumping or in space, provide cost | |
| |effective solutions to energy problems | |
| |in places where there is no mains | |
| |electricity. Moreover they are totally | |
| |silent and non-polluting. They have no | |
| |moving parts they require little | |
| |maintenance and have a long lifetime | |
| |when compared to other renewable sources| |
| |they also possess many advantages; wind | |
| |and water power rely on turbines which | |
| |are noisy, expensive and liable to | |
| |breaking down. We are living in a | |
| |society where there is a tremendous | |
| |pollution ,with the scarcity of fossil | |
| |fuels and resources .To overcome those | |
| |problems we need to change our life | |
| |styles. Since the solar energy is | |
| |abundant and is free of cost, we can | |
| |utilize the solar power to give a | |
| |rebirth to mankind. | |
| |BIBLIOGRAPHY | |
| |1. http://www.wikipedia.org | |
| |2. Google.com | |
| |3. Principles of electronics by Sze | |
| |4. http://www.greenblog.com | |
| | | |

Attached File(s)
[pic] SOLAR CELLLS-THE FOUNDTION OF SOLAR ENERGY.doc (Size: 1.02 MB / Downloads: 351)

Reference: http://seminarprojects.com/Thread-solar-cellls-the-foundtion-of-solar-energy-full-report#ixzz2E5u2yAzs

http://seminarprojects.com/Thread-solar-cellls-the-foundtion-of-solar-energy-full-report

Bibliography: | | | |1. http://www.wikipedia.org | | | |2. Google.com | | | |3. Principles of electronics by Sze | | | |4. http://www.greenblog.com | | | | | | Attached File(s) [pic]  SOLAR CELLLS-THE FOUNDTION OF SOLAR ENERGY.doc (Size: 1.02 MB / Downloads: 351) Reference: http://seminarprojects.com/Thread-solar-cellls-the-foundtion-of-solar-energy-full-report#ixzz2E5u2yAzs http://seminarprojects.com/Thread-solar-cellls-the-foundtion-of-solar-energy-full-report