DIY Solar Power System
DIY Solar Panel
February
How does solar power work?
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Solar power cells convert sunlight into electricity, using the energy of speeding photons to create an electrical current within a solar panel.
Photons are created in the center of the sun by the fusion of atoms. It takes a photon about a million years to work its way to the surface of the sun, but once free it is hurled through space so fast that it reaches earth in just eight minutes – after traveling 93 million miles.
This tremendous energy from the sun is abundant, and has been powering the earth for billions of years – feeding plants, redistributing and refreshing water supplies and ultimately creating other forms of energy (such as fossil fuels) that largely power our civilization today.
Over the past several decades, scientists have been learning to harness this ancient energy source with more efficiency to do the work of non-renewable fuels – without pollution, noise or radiation, and not subject to economic whims that drive costs higher each year.
An interesting side note: Photons are also called quanta. They are literally “packets” of sunlight” . Albert Einstein got his Nobel Prize for his study of quantum mechanics.
How solar power panels work
Solar power panels are made from specially treated semiconductor materials, composed mostly of silicon atoms. The panels – also called photovoltaic modules – are constructed with two sheets of silicon manufactured to take advantage of the photons bombarding the earth.
One sheet, called the N-layer, is constructed of silicon atoms that have “extra” electrons wandering freely within the layer. The other sheet, called the P-layer, has “missing” electrons, or “holes” that attract free electrons.
The two layers are separated by an electrical field, created by the interaction of atoms from both sides.
When a photon of sunlight strikes an atom in either layer, it knocks loose an electron. In the P-layer, these free electrons easily cross through the electrical field and into the N-layer. But this movement of electrons is one-way; N-layer electrons aren’t able to cross the electrical field into the P-layer. As a result, an excess of free electrons build up in the N-layer.
A metal wire attached to the N-layer gives the excess electrons somewhere to go. This circuit ultimately leads back to the P-layer, depositing free electrons where they can begin the process again. Before returning to the P-layer, the electrons are used to power electrical appliances in homes, offices, schools and factories. The movement of electrons with energy is called an electric current. As long as the sun is shining, the electrical current in a solar-electric system continues.
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December
KTAO is the United States’ first radio station powered by solar energy. It has 140 photovoltaic panels that generate enough energy to transmit radio waves 64 km across and across the world through the Internet.
Using the sunny climate of New Mexico, KTAO’s solar panels generate an amount of 100,000 watts of green energy. To promote the use of solar energy the people from KTAO organize a music festival every year, known as the Taos Solar Music Festival.
KTAO is not a new radio station, it broadcasts music using solar energy since 1991. You can also hear the stream online from anywhere in the world, because KTAO turns the sun rays into audio streams, distributed via the Internet (you must have Media Player or Winamp installed).
Telecom operators have also taken important decisions lately regarding the usage of renewable energy as their backup or even primary source of power in some cases. In South Africa, for example they equipped the BTSes with solar panel, but they were stolen not a long time after that (if copper is being stolen from BTSes, what about solar panels?).
Anyway, it’s an interesting idea, but only such a green radio station cannot make any difference unless others join. The operators wanting to do that should take advantage of the new wave of solar panels, thin film or any organic solar cell, that is much more cheap than the classic, silicon-based one.
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December
Combining two cutting-edge nanotech breakthroughs could drive down the cost of solar power and make it even more efficient, according to Jim Zhang, an author of new research in the Journal of Physical Chemistry.
Thin-film solar technology, which uses nano-scale metal oxides “doped” with other elements, like nitrogen, to increase the conversion of sunlight to electricity, has received a lot of press lately. Another promising technique uses nanosize crystals called quantum dots that sensitize metal oxide films to visible light.
Zhang’s team combined the two techniques: a thin film doped with nitrogen and sensitized with quantum dots. The results exceeded expectations: There seemed to be unexplained gains in efficiency that could not be accounted for by just adding the benefits of the two techniques together.
“We have discovered a new strategy that could be very useful for enhancing the photo response and conversion efficiency of solar cells based on nanomaterials,” Zhang, a professor at the University of California-Santa Cruz, said in a prepared statement. “We initially thought that the best we might do is get results as good as the sum of the two, and maybe if we didn’t make this right, we’d get something worse. But surprisingly, these materials were much better.”
Here’s how UC-Santa Cruz described the research:
Zhang’s team characterized the new nanocomposite material using a broad range of tools, including atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy, and photoelectrochemistry techniques. They prepared films with thicknesses between 150 and 1100 nanometers, with titanium dioxide particles that had an average size of 100 nanometers. They doped the titanium dioxide lattice with nitrogen atoms. To this thin film, they chemically linked quantum dots made of cadmium selenide for sensitization.
The resulting hybrid material offered a combination of advantages. Nitrogen doping allowed the material to absorb a broad range of light energy, including energy from the visible region of the electromagnetic spectrum. The quantum dots also enhanced visible light absorption and boosted the photocurrent and power conversion of the material.
When compared with materials that were just doped with nitrogen or just embedded with cadmium selenide quantum dots, the nanocomposite showed higher performance, as measured by the “incident photon to current conversion efficiency” (IPCE), the team reported. The nanocomposite’s IPCE was as much as three times greater than the sum of the IPCEs for the two other materials, Zhang said.
The nanocomposite material could be used not only to enhance solar cells, but also to serve as part of other energy technologies. One of Zhang’s long-term goals is to marry a highly efficient solar cell with a state-of-the-art photoelectrochemical cell. Such a device could, in theory, use energy generated from sunlight to split water and produce hydrogen fuel The nanocomposite material could also potentially be useful in devices for converting carbon dioxide into hydrocarbon fuels, such as methane.
In essence, the team has been trying to manipulate materials so that when sunlight strikes them, the free electrons generated can easily move from one energy level to another–or jump across the different materials – and be efficiently converted to electricity.
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December
How to build homemade solar cells
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Sun is generally known as the ultimate source of energy and we humans have understood this fact clearly by realizing the benefits of the solar energy . In today’s era, when fossil fuels are being used up at a fast pace and are likely to extinct very soon, solar energy is being viewed as a boon for the human race. The solar energy provides sea of benefits to the people. The best part of using this energy is that it can tame to all the energy needs of people across the world.
On the other side, as it is a natural form of energy so it is available in abundance and can be used without any hesitation as compared to other forms of energy. Also, the gadgets being operated by the use of solar energy do not cause pollution. This factor is like icing on the cake and can help immensely in controlling pollution and global warming.
Also it cost nothing to electricity bills thus one can save a lot of money by making use of solar energy. The basic unit that helps in tapping the abundant solar energy present in the world is a solar cell. They are generally fabricated from polysilicon. Following are presented the steps using which one can manufacture homemade solar cell:
The first and foremost thing that needs to be done for manufacturing solar cell is the preparation of silicon. Silicon is extracted from silicon dioxide. Silicon dioxide is heated severely in the furnace at high temperatures so that all the purities present in it can be removed. Also, through this process of heating, oxygen dissolved in silicon dioxide gets separated and we get silicon with the purity of 99%. Thereafter, it is again undertaken from purification process so that we can obtain silicon with 99.5% purity. The fact of the matter is that this is the standard purity that is required for making solar cells.
The next step in this process is the crystallization of silicon. Under this process, first silicon is heated so that it melts and then boron is added. This particular additive provides electrical basis to the silicon and it gets charged with positive charge.
At this stage of process, silicon is in form of ingots. Then they are cut into thin sheets by using the guided machinery of computer. The depth of the thin sheets should be 200-300 microns.
Now the sheets of silicon are immersed into chemical water so that they can be electrified with the negative charge. Along with this, layer of anti-reflection is also added. This is done because it gives dark appearance to the cell that can help to tap maximum energy of the sun.
After this, aluminum or silver conductors are attached with the solar cell so that they can be used for conducting electricity.
After conducting one solar cell, it is always recommended to craft a group of solar cells or solar panel so that it can be used for multiple purposes such as in generating electricity, in geysers and in cars to name a few.
How to prepare solar panel
For preparing the solar panel , the solar cells are arranged in rows. These are well connected with each other so that there can be smooth flow of energy. Thereafter, a sheet of plastic or glass is placed upon the panel of cells so that they get well protected. After this, the edges of the solar panel are framed to add the factor of complete protection.
So, you solar panel is ready and you can use it and help in the conservation of the fossil fuels.
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December
How Solar Cells Made
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There are many different types of solar cell used in production of solar panels today, each made using a different process. The most common type is the silicon solar cel l which has been used for several decades. Silicon is first extracted from silica and formed into thin wafers, which are then converted into semiconductors by doping them with other elements, such as boron and phosphorus. Semiconductors are a group of materials whose conductivity is between that of conductors and insulators. This process is similar to how computer chips are made, but they require many more stages. The solar cells are then connected together and enclosed in a frame to make a solar panel.
Silica is the most abundant mineral on Earth and makes up a quarter of its crust, and it’s also the second most abundant element. It is found in sand and quartz, and is commonly used to make glass and concrete. Each atom of silica, also called silicon dioxide, consists of one silicon atom and two oxygen atoms. To make the extremely pure silicon used for solar cells and computer chips, the silica must undergo several stages of processing to remove the oxygen and other impurities. The first stage is to heat the silica with an electric carbon arc to remove the oxygen atoms, a process that results in silicon ingots with one percent impurity. Each ingot is then drawn many times through a heater that is almost hot enough to melt it. This floating zone technique moves the impurities towards one end, which is cut off later leaving an ingot of almost pure silicon. The ingots at this stage are made up of many small silicon crystals. While solar cells are commonly made from this polycrystalline silicon, the more efficient cells require wafers made from a single crystal, called monocrystalline silicon.
Single crystal rods of silicon can be made using the Czochralski process. A seed crystal is dipped into molten silicon and drawn out, growing as the silicon solidifies behind it. Before this happens, a precise amount of boron is added to the molten silicon. It may seem strange to add impurities after so much effort to remove them, but it is essential in converting the silicon into a semiconductor. Other impurities are left behind in the molten silicon, improving the purity of the silicon even more. Once the rod has cooled, thin wafers are cut and textured, ready to be made into solar cells.
For a wafer to function as a solar cell it needs two different semiconductor layers. The presence of boron turns the silicon into a p-type semiconductor, one with more positive charge carriers than negative ones. The wafer is heated in the presence of phosphorus gas to inject ions into the surface, creating an n-type layer, one with more negative charge carriers. There are many ways of doping semiconductors, and other elements besides boron and phosphorus are often used to create cells with different properties. The two semiconductor layers setup an electrostatic field that draws to the surface the electrons freed by the light photons. The electrons will recombine if they are not drawn off, so many thin wires are screen printed onto the front surface using solder paste, and a metal conductor is applied across the entire back surface to allow the return of electrons and complete the circuit.
There are many other methods used to makes solar cells , and the latest thin-film cells can even be printed onto a flexible surface. However, the most common type is the silicon solar cell which is made using the floating zone technique and Czochralski process to purify and crystallize the silicon, before doping it with boron and phosphorus to make a semiconductor, and screen printing thin wires onto the front surface. Even after all this effort, the cells can only convert less than one fifth of the solar energy that reaches it.
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