A solar cell made up of by different materials. The main aim of making solar cell is to keep price minimum while extracting maximum power from it. The materials used for making a solar cell is discussed below.
1) Crystalline Silicon : Nowadays solar cells present in market are usually made up off this material. Early forms of silicon photovoltaic cells were very expensive because of difficulties in the industrial preparation of high-grade silicon. very pure single-crystals of silicon need to be grown as cylindrical ingots, about 10 micrometers diameter, in order to maximum the cell exposure area. This is known as "monocrystaline silicon".
Recent development in this has been to grow silicon crystal in the form of ribbon rather than an ingot. This process generates less pure silicon than the traditional method and the efficiency is in between 10-12%.
2) Polycrystalline Silicon : It consists of a small silicon crystals oriented in a thin layer of polycrystalline material. The solar cells made up of this material is less expensive than the crystalline silicon on the cost of efficiency.
3) Amorphous Silicon : In this type of silicon there is no regular crystal structure therefore they defects in bonding and structure. Amorphous silicon can be deposited onto backing material in very thin films around 01 micrometers thickness. This reduces the amount of usage of silicon material resulting in reduction in mass production cost. Although they are cheaper but have less efficiency than the crystalline silicon.
This blog is about renewable energy sources. I am trying to cover the different types of renewable energy sources that can help in the generation of electricity.
Thursday, September 16, 2010
Tuesday, August 31, 2010
How Solar Cell Works
Bohr presented his theory of atomic model in 1913 that is more stable than that of Rutherford theory. According to his theory
Electron with mass (Mc) revolves around the nucleus in an orbit with radius (rn) and angular frequency (ωn). The centrifugal force produces is given by
F = Mc . rn. ωn^2
Electrons are held in an orbit around nucleus of an atom with a coulomb force
F = q 1 q 2 / 4 π ε r^2
These two forces are responsible for the movement of electron in an orbit.
Apart from Bohr's model, there is another theory called Plank's Theorem can be use to help an electron to remain in its orbit. According to this theory, electrons remain in an orbit, where angular momentum is an integral multiple of plank's constant.
An electron in an orbit contains energy given by En = mc * rn^2* ωn^2.
Now to move electron from its orbit to higher orbit, it is necessary to provide energy to that electron greater than that of given in the above equation from outside.
Electron with mass (Mc) revolves around the nucleus in an orbit with radius (rn) and angular frequency (ωn). The centrifugal force produces is given by
F = Mc . rn. ωn^2
Electrons are held in an orbit around nucleus of an atom with a coulomb force
F = q 1 q 2 / 4 π ε r^2
These two forces are responsible for the movement of electron in an orbit.
Apart from Bohr's model, there is another theory called Plank's Theorem can be use to help an electron to remain in its orbit. According to this theory, electrons remain in an orbit, where angular momentum is an integral multiple of plank's constant.
An electron in an orbit contains energy given by En = mc * rn^2* ωn^2.
Now to move electron from its orbit to higher orbit, it is necessary to provide energy to that electron greater than that of given in the above equation from outside.
Wednesday, July 28, 2010
Saturday, July 24, 2010
Advantages of Photovoltaic Generation
* There is no moving part so that little maintenance is required.
* They utilize an infinitely renewable and pollution free power source.
* The cells are reliable and long lasting with no harmful waste products.
* The cells are usually made of silicon which is one of earth’s most abundant and cheap materials.
* They have high power-to-weight ratio which is required in aerospace applications .
* They utilize an infinitely renewable and pollution free power source.
* The cells are reliable and long lasting with no harmful waste products.
* The cells are usually made of silicon which is one of earth’s most abundant and cheap materials.
* They have high power-to-weight ratio which is required in aerospace applications .
Energy from the Sun
Around 174 petawatts of solar radition is recieved by earth at the upper atmosphere Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth's surface is mostly spread across the visible and near-infrared ranges with a small part in the near-ultraviolet.
Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones. Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14 °C. By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived.
Genaration of Electricity through Solar Energy
Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available renewable energy on earth. Only a minuscule fraction of the available solar energy is used.
Solar powered electrical generation relies on heat engines and photovoltaics. Solar energy's uses are limited only by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes.To harvest the solar energy, the most common way is to use solar panels.
Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.
Tuesday, July 20, 2010
Renewable Energy Resources
The sources which can be reused to generate energy or electricity is commonly known as renewable energy sources. These sources include solar energy, wind energy, tidal energy, hydral power, energy from biomass and geothermal energy. Below is the chart given for the renewable energy sources in UK.
Renewable energy resources used in UK between 1990 and 1998, and the equivalent amount of oil.
Renewable energy resources used in UK between 1990 and 1998, and the equivalent amount of oil.
| Renewable energy resources | Equivalent amount in oil (thousands of tonnes) | |||
| 1990 | 1996 | 1997 | 1998 | |
| Active solar heating | 6.4 | 8.6 | 9.0 | 9.5 |
| Onshore wind | 0.8 | 41.8 | 57.2 | 76.1 |
| Hydroelectric | 447.7 | 289.0 | 354.8 | 449.3 |
| Landfill gas | 79.8 | 247.2 | 316.0 | 400.8 |
| Sewage sludge digestion | 138.2 | 190.2 | 191.5 | 184.1 |
| Wood | 174.1 | 709.7 | 710.3 | 710.3 |
| Straw | 71.7 | 71.7 | 71.7 | 71.7 |
| Municipal solid waste | 160.0 | 368.7 | 427.0 | 567.7 |
| Other biofuels | 80.6 | 175.7 | 182.1 | 185.5 |
| Total | 1,159.3 | 2,102.6 | 2,319.6 | 2,655.0 |
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