Photovoltaic Cells Essay

571 words - 3 pages

Photovoltaic cells convert light energy into electricity at the atomic level. Although first discovered in 1839, the process of producing electric current in a solid material with the aid of sunlight wasn't truly understood for more than a hundred years. Throughout the second half of the 20th century, the principles underlying the photovoltaic effect have been determined and the manufacturing processes have been more fully refined. As a result, the cost of these devices has put them into the mainstream of modern energy producers. This was caused in part by advances in the technology - in which PV conversion efficiencies have improved considerably - an in part by improvements in manufacturing all the other components in a complete system.The conversion efficiency of a PV cell is ...view middle of the document...

The "photovoltaic effect" is the basic physical process through which a PV cell converts sunlight into electricity. Sunlight is composed of photons, or particles of solar energy. These photons contain various amounts of energy corresponding to the different wavelengths of the solar spectrum. When photons strike a PV cell, they may be reflected or absorbed, or they may pass right through. Only the absorbed photons generate electricity. When this happens, the energy of the photon is transferred to an electron in an atom of the cell (which is actually a semiconductor). With its newfound energy, the electron is able to escape from its normal position associated with that atom to become part of the current in an electrical circuit. By leaving this position, the electron causes a "hole" to form. Special electrical properties of the PV cell--a built-in electric field--provide the voltage needed to drive the current through an external load (such as a light bulb).The most important parts of a solar cell are the semiconductor layers, because this is where the electron current is created. There are a number of different materials suitable for making these semi conducting layers, and each has benefits and drawbacks. Unfortunately, there is no one ideal material for all types of cells and applications. In addition to the semi conducting materials, solar cells consist of a top metallic grid or other electrical contact to collect electrons from the semiconductor and transfer them to the external load, and a back contact layer to complete the electrical circuit. Then, on top of the complete cell is typically a glass cover or other type of transparent encapsulate to seal the cell and keep weather out, and an antireflective coating to keep the cell from reflecting the light back away from the cell.

Other Essays On Photovoltaic Cells

Master and slave. an analysis

495 words - 2 pages Each of the characters in The Tempest finds themselves in bondage. However, by the end of the story, the same characters are set free from whatever enslaves them. A few characters one can see enslaved are Prospero, Miranda, Ariel, and Caliban.Prospero is in bondage to his magic. Since his exile by his brother from his dukedom in Milan, he has had but a few books to help pass the twelve long years. During this time, he becomes very proficient in

Methods Of Therapy Essay

2480 words - 10 pages METHODS OF THERAPY Therapy, from a psychologist's viewpoint, has many different meanings. It can be physical or psychological, or even both. In this paper, several different aspects of therapy will be discussed. First the word therapy will be defined more clearly, and then psychotherapy and how it differs from other interactions yet is also similar. Next therapy will be examined from the Psychodynamic, Cognitive and Humanistic-Existential points

Phineas And Gene A Comparitive

1538 words - 7 pages Phineas and Gene: A Comparative Study Throughout the story, Phineas and Gene, the two main characters, showed a number of contrasting traits. Phineas was a confident, non competitive, naive, irresponsible, and unintelligent person throughout the story, whereas Gene, Phineas' roommate, was insecure, competitive, mature, responsible, and intelligent throughout the story.Phineas had a confident nature in everything he did. As Phineas and Gene first

Mafia

2008 words - 9 pages Mafia. What does this word mean? The actual members of the Mafia aren't even sure where the word first originated or what it really means. One of the theories as to where the word came from is from Sicily, where people would yell " Morte alla Francia, Italia anela!" (Death to France, Italy groans!), therefore forming the acronym MAFIA. Others claim the word derived from the battle cry of rebels who slaughtered thousands of Frenchmen after a

Baseball Strike

1354 words - 6 pages GAME OVER! "I don't like it. People won't be able to come to these games anymore, and I don't like that". A sad nine - year - old fan voices his concerns on the 1994 major League Baseball strike. The '94 baseball season has come to an abrupt end. Players have ceased play because they feel they are being treated unfairly with the owner's plan to impose a salary cap. Owners are finding it difficult to come to terms with their own disagreements

Worst experience

299 words - 2 pages I wanted to lie down and cry. When I got home from the student/teacher/parent conference in fifth grade my mind was in shambles. After I had done everything possible to pass math, my fifth grade teacher was actually telling my Parents about my alleged poor effort. Poor effort? Didn't I do every homework assignment? Didn't I study every night and miss my favorite television show "Full house"? From an early age, I had been taught that grades are

Multinational Companies

2058 words - 9 pages Multinational Companies: Out for Profit Without Regard for Life                  What a company usually wants for its business is for it to be an successful establishment and to make an abundance of profit. Some businesses do not pose any concern on what they have to do to make this profit as long as it done. Multinational companies are firms with their home base in one country and operations in many other nations. (Molyeux, 133

Middle Adulthood 2

675 words - 3 pages The Dictionary of Social Work roughly defines middle adulthood as the period between forty-five and sixty-four years of age. There are four main tasks in this stage. They include meeting intimacy and family needs, satisfying achievement needs, taking care of elderly parents, and coping with end of life issues. Erikson identifies the need for achievement during midlife, which fits into his stage of generativity vs. stagnation. Success in adulthood

Political socialization

461 words - 2 pages Political Socialization There are many ways that our ideas are shaped and influenced as we grow up. This process by which we develop certain ways of thinking is called political socialization. There are three main influences which change and shape us being, the family, the mass media, and formal education.The family definitely has the greatest impact on us as we grow. This is primarily because ever since the beginning of childhood we are exposed

Procrastination and regrets

533 words - 3 pages Procrastination and Regrets It's Thursday afternoon and Jack has nothing to do except his homework. However, Jack doesn't feel like doing his homework, so he thinks to himself "I'll do my homework tomorrow night and go to a house party tonight." Ah yes, like many other young adults, Jack has resorted to procrastination. The procrastination bug, like young adults has also become abundant in parents.One thing that many young adults procrastinate

Frank o haras the day lady die

398 words - 2 pages In his poem, "The Day Lady Died", Frank O'Hara refrains from using all the conventional patterns of elegiac poetry. Instead of the common reflection of grief, utilizing tragic laments and a recount of greatness now gone, O'Hara's seemingly ordinary poem very subtly evokes a sense of loss. At first, O'Hara's poem appears to be the account of a very typical day. His classic "I do this and I do that" style, accompanied by the simplistic description

Similar Papers

Alternative Sources Of Energy: Geothermal Power And Solar Power

1377 words - 6 pages too cold.(2)This brings us to another example of a renewable energy resource. Solar power is the energy from the sun. In fact, every minute, enough energy arrives at the Earth to meet the demands of a whole year.(3) There are three main ways of using solar power. Firstly, solar cells, or as they are really called "photovoltaic" or "photoelectric" cells, directly convert light into electricity.(3,8) They were originally developed to provide energy

Architecture What Makes A Buildling Green

4150 words - 17 pages accessories.§Limit switch / key tag system for lighting control, wherever there is no occupancy§Energy efficient High Pressure Sodium Vapour (HPSV) lamps for street and outdoor lighting.§Solar photovoltaic cells for building lighting, Telephone booths, etc.,d) Air Conditioning§Energy efficient screw chiller compressor with a built-in variable frequency drive.§Non-CFC Refrigerant for refrigeration system§Variable

Persuasive Essay Gay And Lesbi

623 words - 3 pages Persuasive Essay - Gay and Lesbian Rights "If anyone says, 'I love God,' yet hates his brother, he is a liar. For anyone who does not love his brother, whom he has seen cannot love God, whom he has not seen," John 4:20. So, why do heterosexual people hate homosexuals? They are ordinary people with a different lifestyle who would simply like to be treated with respect. Many organized religions believe that a 'gay' lifestyle is wrong. But, if

Mark Mcgwire Vs Sammy Sosa Essay

1206 words - 5 pages Although a lot of people play baseball two names that come to mind are Mark McGwire and Sammy Sosa. McGwire and Sosa are very good hitters but are also so very different hitters. McGwire and Sosa are very great athletes who share apart of baseball history. McGwire and Sosa are good players but off the field they are very charitable individuals. McGwire and Sosa have many similarities and differences. IT is hard to compare Mark McGwire and