How to save solar energy Bashny.Net

Proven reserves of energieplus at the current pace of energy consumption growth should be enough for about 70 to 130 years. But there is the option of switching to other sources, such as solar energy. But even if the globe will open inexhaustible resources of energy, environmental woes will not be avoided. After 100 years on Earth will be so much to produce energy, what can happen ecological disaster. This will lead to the melting of the polar ice, which very much will increase the Global sea level. In this case, countries and cities that are on the ocean, solar energy is simply not needed, they will be washed away or flooded.



That is why you need to start using solar energy, which does not depend on uses or does not use it. Solar energy heats the atmosphere of the globe. In order to make maximum use of it, it must be transformed into some other form. To keep light rays absolutely no one worked. The most common and promising method of light conversion is the photovoltaic. Photons transmit their energy to electrons in semiconductors, and this makes an electric current.

As all this is happening you can read in the physics textbook. We briefly explain. Prohibited energozone in a separate semiconductors width equal to the size of energy of a quantum of light. What is the prohibited zone? In a nutshell, this so-called potential barrier, which must be passed on to the electron when jumping from one to the other atom in the crystal lattice. Once absorbed the photon, the electron becomes mobile, and hence an electric current. Electric current is the directed movement of Electrozariad.

But here's the thing, photoinduced electrons can move in both directions. EMF of different signs compensate each other. In this situation the current will not be.

If you combine 2 of the semiconductor (often use silicon) doped with different impurities (first, because of the incompatible valences, brings to primary substance of uncompensated electrons is obtained a semiconductor of type n, and the second, whose valence is a little smaller leads to the formation of holes, the carriers of "+" charges — obtained semiconductor type-R), on the border of semiconductors creates n-p junction.

More recently, fotoelectronica cost very expensive. To 1982 in our state the solar cells produced for space purposes. In our time, there is an experienced manufacturer of disk of solar cells for commercial purposes. Solar energy has decreased in price by 3-4 times. But, under any scenario, 7-10 rubles per 1 Watt is very expensive. At this time, searching for ways in which solar energy cost is a bit cheaper and was available for public use. There is one interesting development of our scholar A. Stepanova. He put forth good judgment to grow high-quality silicon in the form of large ingots, which then should be cut into a circular plate, and those are then carefully polished, while spending a large amount of energy wasted and wasting material. He offered to pull it very thin ribbons from the melt. Under this option reduced the cost of solar cells and increases the effect of solar, because you can tape to close very tightly, and between the disc elements remains unused space.

Solar energy is a stumbling block to all scientists, as the efficiency of silicon cells is very small. As only a small part of this energy in semiconductors is absorbed by the electrons, a large portion of the incident radiation goes to heating the solar cell (this reduces its photovoltaic characteristics), part of it bounces off and some punches right through him.

We will remind, in the semiconductor forbidden zone is very narrow, and thus a small "energy menu" of electrons. Also, large energy losses associated with the recombination of holes and electrons.

In the end, the efficiency of solar cells will not exceed 10%. But there are already prototypes that have been obtained in the laboratories of A. Zaitseva, M. Hagan, the efficiency of which is equal to 15-17%. And that's not the maximum limit. Experts have calculated that the limit of efficiency of solar cells with n-p junction can reach 27-30%.

Especially promising are solid-state converters with straight transitions. They are made of 2 different chemical composition of semiconductors. That is why they differ in the width of forbidden zones. In the so called region n-p transition appears due to the smoothing of the potential barriers, extension, photo-EMF. Scientists working under the guidance of academician Zhores Alferov, received by the photodiodes with heterojunction, "gallium arsenide — aluminium arsenide", the efficiency is approximately equal to 20%.

It is noteworthy that when heated, the photodiodes do not lose their photoelectric properties. They work well, even if to seal the flow of solar energy 1600 times.

It turned out that there was opportunity to do photodreamstudio device that will utilize all the light that falls on it. It has a graded gap structure, in other words forbidden zone he has a variable width. This can be achieved by introducing different zones of different semiconductor impurities. In this case, the extension of the photo-EMF is generated in a spatial area, for different points of which different prohibited areas. In such area for any quantum will be found a secluded place where he no interference will be absorbed by the electron.

Theory variating structures in Russia, developed by a team of scientists, and because of this, the solar cells will have an efficiency of 90%.

Also, in our time of high technology, the search for new and cheaper materials, which will produce solar cells. Very promising, according to many scientists, semiconductor compounds of sulfur, cadmium, and copper. Converters, which are obtained on their basis, the cheapest, well, again, same problem — efficiency is about 5%, and the materials are not very stable under the influence of the environment are destroyed. Complex and expensive sealing eliminates the previously obtained savings.

 

Source: zeleneet.com