PHOTOVOLTAIC
systems of electricity called photovoltaic systems enable the transformation of the energy content of solar radiation into electrical energy. These systems are characterized by a degree of autonomy with respect to climate, geography, and other conditions that few can achieve energy sources. Geographic locations characterized by receiving a high level of solar radiation are the most conducive to its use.
face of conventional energy, solar photovoltaic presents the characteristic of being an unlimited source of energy, renewable energy deals. Is also characterized by its "ubiquitous" and may be seized anywhere on the planet's surface (though obviously not with the same intensity in all places and at all times). This ubiquity makes possible a wide range of applications (limited only by the power required).
energy sources have environmental impacts inevitable. Increasingly, clearer purpose on the planet. Acid rain, greenhouse gases, radioactive waste, nuclear accidents ... there is greater awareness - because you know every day - with respect to these adverse effects and greater social sensitivity - which have specifically generated by the ecological movement, etc.. - Are factors that make this possible is an increasingly viable alternative and attractive compared to other energy sources. This is not a theory. A striking example is the case of the USA who has directed most of its budget for energy research to projects related to photovoltaic energy. If you continue this level of RESEARCH AND the number of projects, it is clear that photovoltaics will play a key role in power generation in the United States, especially in areas capita ; Lidasan, such as Florida (which is one of the places in America where more studies on this type of energy has been made).
Brief History of photovoltaic systems
Early research in this field focused on product development for applications space, and its first successful use in the manufacture of artificial satellites. Its main features made them ideal for supplying energy in outer space.
The cells were first marketed in 1955. But only in the early eighties, began to settle photovoltaic companies. It was also during this decade than in the U.S., the National Renewable Energy Laboratory (NREL) established standards and test methods and performance for modules photovoltaics. These activities helped companies reduce costs and improve performance, efficiency and reliability.
How are photovoltaic converters
photovoltaic cells photovoltaic panels are lined and are manufactured with Silicon. This element - the second most abundant in the crust - is what allows the process of generating electricity. The energy gap estimated by the theoretical conversion efficiency of voltaic material, determines the characteristic spectral absorption the material in the fundamental absorption region. Silicon has a cut 1.2u absorption with a strong increase in the absorption coefficient at longer wavelengths. The fundamental region is the sensitive region of the cell in Sicily.
Al doping pure silicon with impurities of certain chemicals, unique electrical properties obtained in the presence of sunlight. How doped Silicon? A diode is formed - as its name indicates - in two parts: one negative and one positive. On the positive side, the material missing electrons. On the negative side, you can spare. When the two parts come together is called semiconductor diode. It semiconductor (see the theoretical definition of this concept, which is located before ...) in the sense that the electric current can flow only in one direction. Moreover, unlike conductive materials, as the temperature increases, performance increases. Silicon has four electrons. You can only get to have "a positive and a negative Silicon" if you dope with contaminants. For example, if we introduce phosphorus to its composition, Silicon will get a negative, since an electron would get other time (if we consider that the match has 5 electrons in the last layer). However, if we introduce aluminum - three electrons in the last layer - we will have a positive silicon.
I said, only by doping the silicon, has the appropriate characteristics. This is because the chemical properties of elements are determined by the number of electrons in the top layer and electrons missing to complete. Sicily, as well as already mentioned, has four electrons and four others are missing to complete. When atoms join Sicilian other, sharing the electrons of the last layers of neighboring atoms and form covalent bonds, these combinations give rise to a crystalline structure. This is the composition of photovoltaic cells. They measure between 7 and 9 inches and are thin and rectangular or circular. Silicon is processed
- after complex processing - and it is formed with a cylinder lens and solid. This is a very pure semiconductor crystal. The cylinder is cut, in turn, into thin slices that are then chemically treated before they become photovoltaic cells. Then connect wires to the cell surface: A positively charged side and a negative side. This completes the electrical circuit. When the cell is exposed to light, electricity flows through the circuit. To improve efficiency and system capacity can be connected - including by wire - various cells in a series. This is called a module (module) and can also be connected, in turn, several modules. The more modules you add, the more electricity can be generated.
cells are powered by what is called "photovoltaic effect" (photo comes from light, voltaic electricity). When the sun hit the surface of the cell, free electrons from atoms of the material. Electrons, excited by light, moving through Sicily. Certain chemical elements added to the composition of silicon can set the path to follow the electrons. That is the phenomenon
photovoltaic and its consequence is the direct electrical current. This stream may be stored in "batteries" for, if desired, can be used outside daylight hours. Each cell (or cell) is able to generate 2 to 4 amps at a voltage of 0.46 to 0.48 V using as raw material only from solar radiation. In addition, support both direct and diffuse radiation, which means that electric energy can be even on cloudy days. Therefore, it is quite efficient. It is also relatively simple, photovoltaic cells have no moving parts, not need maintenance and have a lifespan of between 20 and 30 years - and yet, their manufacture requires a sophisticated technology that is available only in some countries like the United States , Germany, Spain Japanandthe. That is why, although the direct conversion of the visible solar spectrum is perhaps the most orderly way and aesthetics of all that exist for the use of Solar Energy unfortunately this technology has not been fully developed.
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