Solar Energy?

Can someone explain how solar energy works?

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  • Anonymous
    1 decade ago
    Favorite Answer

    This is a actual explanation of how it works.

    Photovoltaic Cells: Converting Photons to Electrons

    The solar cells that you see on calculators and satellites are photovoltaic cells or modules (modules are simply a group of cells electrically connected and packaged in one frame). Photovoltaics, as the word implies (photo = light, voltaic = electricity), convert sunlight directly into electricity. Once used almost exclusively in space, photovoltaics are used more and more in less exotic ways. They could even power your house. How do these devices work?

    Photovoltaic (PV) cells are made of special materials called semiconductors such as silicon, which is currently the most commonly used. Basically, when light strikes the cell, a certain portion of it is absorbed within the semiconductor material. This means that the energy of the absorbed light is transferred to the semiconductor. The energy knocks electrons loose, allowing them to flow freely. PV cells also all have one or more electric fields that act to force electrons freed by light absorption to flow in a certain direction. This flow of electrons is a current, and by placing metal contacts on the top and bottom of the PV cell, we can draw that current off to use externally. For example, the current can power a calculator. This current, together with the cell's voltage (which is a result of its built-in electric field or fields), defines the power (or wattage) that the solar cell can produce.

    That's the basic process, but there's really much more to it. Let's take a deeper look into one example of a PV cell: the single-crystal silicon cell.

    How Silicon Makes a Solar Cell

    Silicon has some special chemical properties, especially in its crystalline form. An atom of silicon has 14 electrons, arranged in three different shells. The first two shells, those closest to the center, are completely full. The outer shell, however, is only half full, having only four electrons. A silicon atom will always look for ways to fill up its last shell (which would like to have eight electrons). To do this, it will share electrons with four of its neighbor silicon atoms. It's like every atom holds hands with its neighbors, except that in this case, each atom has four hands joined to four neighbors. That's what forms the crystalline structure, and that structure turns out to be important to this type of PV cell.

    We've now described pure, crystalline silicon. Pure silicon is a poor conductor of electricity because none of its electrons are free to move about, as electrons are in good conductors such as copper. Instead, the electrons are all locked in the crystalline structure. The silicon in a solar cell is modified slightly so that it will work as a solar cell.

    A solar cell has silicon with impurities -- other atoms mixed in with the silicon atoms, changing the way things work a bit. We usually think of impurities as something undesirable, but in our case, our cell wouldn't work without them. These impurities are actually put there on purpose. Consider silicon with an atom of phosphorous here and there, maybe one for every million silicon atoms. Phosphorous has five electrons in its outer shell, not four. It still bonds with its silicon neighbor atoms, but in a sense, the phosphorous has one electron that doesn't have anyone to hold hands with. It doesn't form part of a bond, but there is a positive proton in the phosphorous nucleus holding it in place.

    When energy is added to pure silicon, for example in the form of heat, it can cause a few electrons to break free of their bonds and leave their atoms. A hole is left behind in each case. These electrons then wander randomly around the crystalline lattice looking for another hole to fall into. These electrons are called free carriers, and can carry electrical current. There are so few of them in pure silicon, however, that they aren't very useful. Our impure silicon with phosphorous atoms mixed in is a different story. It turns out that it takes a lot less energy to knock loose one of our "extra" phosphorous electrons because they aren't tied up in a bond -- their neighbors aren't holding them back. As a result, most of these electrons do break free, and we have a lot more free carriers than we would have in pure silicon. The process of adding impurities on purpose is called doping, and when doped with phosphorous, the resulting silicon is called N-type ("n" for negative) because of the prevalence of free electrons. N-type doped silicon is a much better conductor than pure silicon is.

    Actually, only part of our solar cell is N-type. The other part is doped with boron, which has only three electrons in its outer shell instead of four, to become P-type silicon. Instead of having free electrons, P-type silicon ("p" for positive) has free holes. Holes really are just the absence of electrons, so they carry the opposite (positive) charge. They move around just like electrons do.

    The interesting part starts when you put N-type silicon together with P-type silicon. Remember that every PV cell has at least one electric field. Without an electric field, the cell wouldn't work, and this field forms when the N-type and P-type silicon are in contact. Suddenly, the free electrons in the N side, which have been looking all over for holes to fall into, see all the free holes on the P side, and there's a mad rush to fill them in.

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  • 6 years ago

    Solar energy is a free source of sunlight. For use of solar energy we use solar panel which converts to heat energy into powerful energy. When sunlight hits in any object it produces heat at this object. Our use of crystals made out of silicon in very large amount which convert heat into electricity.

    Now a day we use cheap copper-indium-gallium-selenide crystals. When sun light entered into crystals, bonds gets excited and the electrons move around. Mean flow of electrons starting and produce electricity.

    Source(s): For solar products, can go there: Luminous Renewable Energy Solutions
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  • 6 years ago

    sun energy

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  • Anonymous
    1 decade ago

    Solar Energy, in general terms, come from the sun which actually is a giant fire ball continuously exploding. This explosion throw energy under different forms ( heat, light, gas, etc) We, has human, found out how to change the "light" energy in electricity while plant use it has food (photosynthesis). "Heat" energy can also be used to heat houses among other thing. If you need something more specific, ask a different question. This subject is quite vast.

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  • 4 years ago

    Solar energy is free and inexhaustible natural energy.There are many solar solutions and products that utilize solar energy to save energy and protect environment. For example,solar evacuated tube, absorber tube, parabolic trough receivers ,solar PV panel, solar water heater solar light,solar cooker, solar tent/yurt,solar greenhouse and so on for solar power and industrial application.

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  • 4 years ago

    Solar energy can be converted into heat energy and elecricity through some physic and chemical effect with the help of special instrument.

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  • 4 years ago

    In a crystal, the bonds [between silicon atoms] are made of electrons that are shared between all of the atoms of the crystal. The light gets absorbed, and one of the electrons that's in one of the bonds gets excited up to a higher energy level and can move around more freely than when it was bound. That electron can then move around the crystal freely, and we can get a current.

    Imagine that you have a ledge, like a shelf on the wall, and you take a ball and you throw it up on that ledge. That's like promoting an electron to a higher energy level, and it can't fall down. A photon [packet of light energy] comes in, and it bumps up the electron onto the ledge [representing the higher energy level] and it stays there until we can come and collect the energy [by using the electricity].

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  • Anonymous
    1 decade ago

    Solar panels take the energy from the sun and convert it into electrical energy. Often on cloudy days it doesn't work, but on sunny days it does.

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  • 1 decade ago

    You can use photoelectric cells, which are semiconductors like computer chips only simpler, to make electricity from light; or you can use mirrors to concentrate a lot of sunlight on a boiler and run a steam engine; or you can just run water through pipes attached to a black metal panel exposed to direct sunlight to warm up the water to make a solar water heater.

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  • 4 years ago

    solar energy can be used by many many ways, the direct way is solar thermal and PV, one is get the heat energy from sunlight like solar water heater, the other is get power from sunlight like solar power station, solar light,solar charger etc. you can refference www.himinsun.com

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  • 1 decade ago

    there are actually several types of solar energy and they all work differently.

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