Make silicon solar cell at home video,house solar panels for sale bc,buy a model of the solar system 5kw - For Begninners

23.04.2014
The average amount of the sun's radiation that penetrates the atmosphere and reaches the earth is 51% of the total incoming energy as illustrated above. The map above shows in maroon, red, and orange the prime regions of the world for generating solar electricity. Shown in the diagram on the left is how the energy from the sun is distributed by wavelength and photon energy.
The shape of the spectrum is almost a perfect fit for a heavenly body whose temperature is 5,800 K. Silicon (Si) is a very abundant non-metallic element which makes up about 26% of the earth's crust and is the the second most abundant element after oxygen. Large numbers of silicon atoms bond with each other by means of their valence electrons to form a crystal. Almost all of the silicon crystals grown for solar cells are produced by the Czochralski process shown at the left (invented in 1916 by the Polish chemist Jan Czochralski, pronounced Cho-crawl-ski).
The PhotoVoltaic (PV) effect is the process by which a PV cell converts sunlight into electricity. A typical solar cell consists of a glass or plastic cover, an anti-reflective layer, a front contact to allow electrons to enter a circuit, a back contact to allow them to complete the circuit, and the semiconductor layers where the electrons begin and complete their journey. Because the amount of power produced by a single solar cell is relatively small, one to two watts, designers group solar cells together to form modules (panels) that supply a more useful level of voltage, current, and power. Some newer types of solar cells are made from thin films of semiconductors chemically vapor deposited (CVD) or sputtered on glass or metal. The most significant vendor using thin film cadmium telluride technology is First Solar, the largest manufacturer of solar modules in the world, headquartered in Tempe, Arizona.
Cadmium telluride (pictured on the left) is a semiconductor which is made from cadmium and tellurium. Another type of thin film solar cell is made from Copper Indium Gallium diSelenide, CIGS for short (pronounced Sigs). Although much smaller than the normal Cadmium Telluride market, CIGS technology is breaking into new markets in what is called the Building Integrated PhotoVoltaic (BIPV) market.
Computing giant IBM announced a deal with Japanese semiconductor equipment manufacturer, Tokyo Ohka Kogyo (TOK) to make thin-film solar cells from CIGS.
There are a number of assumptions associated with the SQ Limit that restrict its general applicability to all types of solar cells.
Shown at the left are single axis "tracker" modules at Nellis Air Force Base in Nevada, USA.
Homes and businesses that have a grid tied solar system sell the excess electricity that they generate back to the utility. Solar inverters perform three major functions: as mentioned above they convert the current from DC to AC, they ensure that the solar current and voltage are synchronized with the grid, and they perform Maximum Power Point Tracking (MPPT).
MPPT - Solar inverters include MPPT (Maximum Power Point Tracking) that enables the inverter to extract an optimal amount of power from the solar string by calculating the array's Maximum Power Point (MPP).
There is some friendly controversy between large inverter companies and micro inverter companies. Higher transmission voltages are more efficient than lower voltages, have a cost advantage, and most utility electricity is already moved this way. Utility and large commercial centers are out in the open and shading (except for cloud cover) is not an issue. Utilities are already very sophisticated in the management of their sites and tracking as many as 50,000 thousand individual micro inverters on a 10 MW site is not practical. The large commercial and utility markets are forecast to grow faster than the residential market. Micro inverters perform the same basic electrical functions as their big brothers, but do it for each panel rather than the whole solar array. Micro inverters output AC current directly from each panel, so there is no need for DC wiring, etc. Voltages are only 240 volts AC which are much safer for technicians than 600 volts DC, plus the whole system can be shut down for repairs.
Micro inverters are much more flexible when it comes to roofs with shading, east and west slopes, odd shapes, etc. Large micro inverter systems do not require a huge enclosure with a concrete pad, large cooling fans, and isolation for safety's sake. Data collection systems down to the panel level are very advantageous from a maintenance point of view to medium size commercial customers. So we can see that each type of converter has significant advantages depending on the customer. There are some interesting things happening in universities around the world that may eventually find their way into solar cell production.
The sketch at the left shows long wavelengths of light striking small silver metal nanoparticles on the surface of thin film silicon only several microns (1 micron = one millionth of a meter) thick. The NREL in Boulder, Colorado is using Quantum Dots (QDs) to generate more than one electron-hole pair for every photon absorbed. Researchers from the NREL have demonstrated quantum efficiencies of 114 percent in solar cells “excited” from photons from the high-energy region of the solar spectrum. This process, which creates more than one electron-hole pair from a single photon, is called "multiple exciton generation" (MEG) by NREL. Harry Atwater and fellow researchers at Caltech have developed arrays of minute silicon micro wires - 1 micron in diameter and up to 100 microns high - that are embedded in a thin transparent rubbery polymer that absorbs enough sunlight to have a potential efficiency of 15 to 20%, as good as the best crystalline cells of today. While these arrays have the thickness of a conventional crystalline solar cell, their semiconductor volume is equivalent to that of a two micron thick film. A conventional thermionic converter (used on satellites) is driven solely by intense heat (1,500°C) and converts thermal energy into electricity.
Solar power has two major issues that have been holding back wide spread acceptance of the technology: 1) the initial capital equipment cost is expensive relative to other alternatives, and 2) solar power is a daytime phenomenon.
Dan Nocera's vision for the future is that each residential house will have a PV solar panel system on the roof. There is competition, Nanoptek Corporation, also in the Boston suburbs, is pursuing its own catalytic, water-splitting process, and has raised $4.7 million in financing. Only about 50% of the sun's energy reaches the earth and then only 15% to 25% of that reaches the grid.
As we come to the later part of the 21st century and with the availability of fossil fuels declining resulting in extremely high fuel prices, many scientists believe SBSP will be seen as the ultimate answer. Ohio University has initiated a "SunSat Design Competition" which is "an international competition intended to accelerate the design, manufacture, launch and operation of the next generation satellites that will collect energy in space and deliver it to earth as electricity. The Mission of the SunSat Design Initiative is to move space solar power out of the research labs and onto the public agenda. High quality silicon polycrystalline solar cell features solder plating on connection bars to make it easier to solder your flexible leads onto the cell.
Factory perfect cells come packaged in a foam cushion inside a small box containing 24 pieces. Some amorphous solar panels also come with shade-resistant technology or multiple circuits within the cells, so that if an entire row of cells is subject to complete shading, the circuit won't be completely broken and some output can still be gained. Photovoltaic (PV) devices generate electricity directly from sunlight via an electronic process that occurs naturally in certain types of material, called semiconductors. PV devices can be used to power anything from small electronics such as calculators and road signs up to homes and large commercial businesses. Photons strike and ionize semiconductor material on the solar panel, causing outer electrons to break free of their atomic bonds.
The PV effect was observed as early as 1839 by Alexandre Edmund Becquerel, and was the subject of scientific inquiry through the early twentieth century. The energy crisis of the 1970s saw the beginning of major interest in using solar cells to produce electricity in homes and businesses, but prohibitive prices (nearly 30 times higher than the current price) made large-scale applications impractical. Industry developments and research in the following years made PV devices more feasible and a cycle of increasing production and decreasing costs began which continues even today.
The cost of PV has dropped dramatically as the industry has scaled up manufacturing and incrementally improved the technology with new materials. Most modern solar cells are made from either crystalline silicon or thin-film semiconductor material.
Learn more about how SEIA's research team calculates how many homes are powered by solar energy.


Of the 49% that does not reach the earth, 30% is reflected back into space and 19% is absorbed by the atmosphere and clouds. There are enough strong solar regions to one day provide all the energy that is needed by mankind. Very high purity, 99.9999% pure, semiconductor grade silicon (a few parts per million of impurities) is required for solar applications. When light shines on a PV cell, the radiation may be reflected, absorbed, or passed right through. The voltage causes electrons to move towards the negative surface, where they become available to the external electrical circuit. This is where electrons are freed and the electric current is created - it's the active layer. First Solar has come on very strong since 2006 due to its low module manufacturing cost per watt ($.73 as of Q4 2011). This is noteworthy because the semiconductor material can be deposited on a flexible base or substrate. Unlike conventional PV products such as solar panels, which are an add-on to say a roof, BIPV is manufactured directly into building materials, such as roof shingles, and installed during the building's construction stage.
Neither IBM nor TOK plan to manufacture the solar cells themselves, rather, they are developing technology that will be licensed to solar manufacturing companies.
A solar cell's energy conversion efficiency is the percentage of power converted from sunlight to electrical energy under "standard test conditions" (STC). Although there are numerous programs underway to find ways around the SQ Limit, it is still applicable to 99.9% of the solar cells on the market today. Field layouts must consider shading from one panel to the one behind it and to the ones adjacent to it.
Inverters take the DC power from the solar string (typically 300 to 600 volts DC) and invert it to AC power so it can be fed into the grid.
If however, there are circuits in the electrical system that happen to resonate at the frequency of the grid, the inverter may be fooled into thinking that the grid is still active even though it has been shut down. Some people use the analogy that the micro inverter entrance is akin to the PC revolution in the computer industry. Installer electricians and their companies like AC which they are very familiar with in most of their normal applications.
The long wavelengths are then absorbed by the silicon below as opposed to passing through the silicon as is the case for normal thin film silicon. However, it should be emphasized that the research into Quantum Dots is at a very basic stage of demonstrating scientific principles. Scientists have known for for a long time how to use electricity to split water into hydrogen and oxygen, which is called electrolysis. At a later time, the oxygen and hydrogen gases can then be fed into a fuel cell, creating carbon-free electricity.
During the day the sun will generate electricity and the excess, that is not currently used for heat, air conditioning, etc., will be converted to hydrogen and oxygen gas using only ordinary water and stored in local tanks.
Still it is important for scientists to have a road map to the future to guide them in their day to day activities along the way. As shown in the sketch at the far left, there are energy losses as the sun's rays are reflected from the atmosphere, clouds, dust, the day-night cycle and seasonal changes.
As shown on the right hand side of the sketch, a Space Based Solar Power (SBSP) system would collect solar energy by a satellite 24 hours a day, convert it to microwaves, transmit the microwave radiation to earth where it would be captured by a very large ground antenna and converted into usable electricity on the grid.
The real question is "Will we by then be ready to exploit this endless source of cheap electrical power?" For a more detailed discussion of SBSP see the Solar High Brochure by Dr. We connected one of these to a motor and the shaft started spinning as soon as the cell was exposed to the sun. The low efficiency rate is partly due to the Staebler-Wronski effect, which manifests itself in the first hours when the panels are exposed to sunlight, and results in a decrease in the energy yield of an amorphous silicon panel from 10 percent to around 7 percent.A German researcher from Delft University of Technology has demonstrated how to raise the energy output of amorphous silicon solar panels from around 7 percent to 9 percent.
Electrons in these materials are freed by solar energy and can be induced to travel through an electrical circuit, powering electrical devices or sending electricity to the grid. Due to the semiconductor structure, the electrons are forced in one direction creating a flow of electrical current. To make this type of cell, wafers of high-purity silicon are “doped” with various impurities and fused together. They use lenses and mirrors to reflect concentrated solar energy onto high-efficiency cells.
The average price of a completed PV system has dropped by 33 percent since the beginning of 2011.
Silicon cells are more efficient at converting sunlight to electricity, but generally have higher manufacturing costs. The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 3,850,000 exajoules (EJ) per year.
Radiation in the ultraviolet region (5%), which is not visible, causes the skin to tan and has more energy than that in the visible region. Other stars have enormous sources of energy in the form of high energy X-rays, but lucky for us, our sun releases almost half of its energy as visible light. At the same time, the holes move in the opposite direction, toward the positive surface, where they await incoming electrons. This is done by connecting the positive terminal of one cell to the negative terminal of the next cell. First Solar had about 7% of world market share as measured by watts installed during 2011. IBM's CIGS technology came out of its Research Division and they believe that it can achieve 15% efficiency in production. The STC conditions approximate solar noon at the spring and autumn equinoxes in the continental United States with the surface of the solar cell perpendicular to the sun.
The spacing has to be optimized considering the amount and cost of land versus any shading losses. The entity that owns the solar equipment receives compensation from the utility for the outflow of power.
This is a dynamic situation as the string voltage can vary over time, such as when a cloud obstructs the sun's radiance. For an inverter to output its rated amount of power, it will need to have power input that exceeds the rated output. The transparent polymer contains reflective nanoparticles of aluminum that shuttle light back and forth in the cell until it is finally absorbed by a tiny wire of silicon.
When the cathode is heated to a high temperature, electrons become excited, jump across the thin vacuum to the relatively cold anode, and drive a current through an external circuit back to the cathode. In the second case, storage of solar power in batteries is very expensive and not enough capacity exists, the same as other alternatives. The new discovery is a way of doing what existing electrolyzers do, but much more simply and efficiently.
When needed, the hydrogen and oxygen gas will be fed into a fuel cell to generate electricity at night or on cloudy days.
The energy efficiency from the space station to the grid would be about 50%, roughly the same as fossil fuel electrical plants. There have been enormous improvements in solar panel efficiency reducing the size of the panel array in space. The resulting structure creates a pathway for electrical current within and between the solar cells. Thin-film materials typically have lower efficiencies, but can be simpler and less costly to manufacture. Radiation in the infrared region (49%), which we feel as heat, has slightly more total energy than the radiation in the visible region. Radiation is usually short for electromagnetic radiation and radiance is an instantaneous measurement at a distinct point in time.
Because of the opposite charges of the layers, the electrons want to flow from the n-type layer to the p-type layer, but the electric field at the P-N junction prevents this from happening. IBM's manufacturing process calls for the chemicals to be dissolved in a liquid and then dried. The modern SQ Limit calculation is a maximum efficiency of 33% for any type of single junction solar cell.


There are two types of inverters: those that are tied to the grid and those that are stand alone inverters.
For example if during a month, a solar power system feeds 500 kilowatt-hours into the grid and uses 950 kilowatt-hours (approximately the national average) from the grid. For example, a 5,000W rated inverter operating at 95% efficiency will need to consume 5,263 watts (rated power of 5,000 divided by 95%) from the string.
Some of the micro inverter advantages in smaller installations do not hold true in utility size operations.
No solar cells produced prior to December, 2011 have quantum efficiencies greater than 100 percent. Production solar cells using Quantum Dots are thought to be about 10 years into the future. The Stanford Photon Enhanced Thermionic Emission (PETE) prototype uses concentrated sunlight as its source of energy and in a two step process uses both the sun's photon energy and its heat to excite the cathode electrons to jump across the vacuum to the collector anode. Daniel Nocera, Professor of Chemistry and Energy at MIT, and assistant, Matthew Kanan Postdoctoral Fellow, have made a scientific discovery that may lead to a cheap way to store solar energy in the future. The key component in the process is a new catalyst which consists of cobalt metal, phosphate and an electrode. This system imitates the water splitting reaction that occurs in nature that is called photosynthesis (carbon dioxide + water + light => stored sugar + waste oxygen). The electricity could be used for home appliances or to charge an electric car or anything else. Nocera has founded a new start up company in the Boston area, Sun Catalytix Corporation, thanks to a $700,000 seed investment led by Polaris Ventures. A specialized category of solar cells - called multi-junction or tandem cells - are used in applications requiring very low weight and very high efficiencies, such as satellites and military applications.
With their newfound energy, these electrons escape from their normal positions in the atoms of the semiconductor material and become part of the electrical flow, or current, in an electrical circuit.
The presence of an external circuit provides the escape path for electrons in the n-type layer to travel to the p-type layer. This is done by connecting the positive terminal of the first cell to the positive terminal of the next cell, and the negative terminal of the first cell to the negative terminal of the second cell. This kind of solar cell is called a crystalline silicon cell. CdTe has an optimum absorption profile (band gap) for the light spectrum of sunshine which allows it to obtain better performance in dim lighting. It will inject small pulses that are slightly out of phase into the AC system in order to cancel any stray resonances that may be present after the grid has shut down. With a centralized inverter controlling a whole string of modules (typically 17 or so), if one module or several modules are performing significantly below the the others (strings are performance matched during installation), the power output of the whole string is reduced. Quantum efficiency (not to be confused with solar cell efficiency) per the NREL is the “ratio of collected charge carriers (electrons or electron holes) to incident photons”. The extra electrons come from the extra energy left over after the initial photon-electron collision. To be commercially viable, these cells have to be scaled up by a factor of a 100 times or more. That might sound like a small sum, but Nocera has been an epic center of buzz ever since he first published the research behind Sun Catalytix. Satellite transportation costs remain the biggest obsticle to this technology being implemented. Putting this in another way, the earth absorbs more energy in one hour than the world uses in one year according to physicist Steven Chu, US Energy Secretary and former Director of Lawrence Berkeley National Laboratory. Electrons that are further from the nucleus have more energy than electrons closer to the nucleus. Extremely thin wires running along the top of the n-type layer provide the external circuit and the electrons flowing through this circuit provide the current. They are the dominant technology in the solar marketplace, accounting for about 90% of the installed market at the end of 2011. In layman terms - its the ratio of the number of electrons produced in a solar cell to the number of the sun's photons hitting the cell. Light photons with wavelengths below 0.7 micrometers do not have enough energy to dislodge more than one electron. One feature of this technology is that the final solar cell is very flexible which opens up new solar BIPV markets as shown above in the CIGS section. First the sunlight's photons partially excite the electrons in the cathode semiconductor (similar to a silicon PV cell) so that in step two the remaining heat energy necessary for emission is lower than that for a standard thermionic converter (but not as low as a regular solar cell). In total, the sun emits about 2.2 billion times the amount of radiation that is received by the earth. The four electrons that orbit the nucleus in the outermost energy levels, valence electrons, are the ones that interact with neighboring atoms to form solids. Efficiency of crystalline solar cells range from about 15% to a high of 23% which is very, very good. The best modern production silicon cell efficiency is 23% at the cell level and 20% at the module level as presented by SunPower in May, 2010. In essence when excess solar power is generated, the inverter feeds the grid through the meter, which runs backwards selling the power back to the utility at the same price as it is purchased. The inverter has an on board computer which will sense the grid's AC current waveform, and output a voltage to correspond exactly to the grid's.
The nanoparticles on the surface do not affect the workings of the solar cell below, they just increase the absorption. In silicon solids, each silicon atom shares one of its four valence electrons with each of four neighboring atoms. Under certain conditions silicon conducts electricity and under other circumstances it doesn't.
In the laboratory, the record solar cell efficiency for monocrystalline silicon is held by the University Of New South Wales in Sydney, Australia at 25%. Sun Catalytix recently received a contract for over $4 million in federal funding from the US Department of Energy (DOE). Only the outermost four electrons can be given to, accepted from, or shared with other atoms. Efficiency is defined as the electrical energy converted by the cell compared to the energy of the sunlight striking the surface of the cell. They found that the concept had several major problems - the huge expense of putting the solar satellite in orbit requiring hundreds of space trips and the lack of experience in space for projects of this scale. The ingot can be one to two meters in length depending on the amount of silicon in the crucible.
For safety reasons if the grid has lost utility power, the inverter will automatically shut down to prevent the current it produces from harming workers who are sent to restore power. Micro inverter companies say the increased cost is more than worth it and have made significant inroads into small to medium sized systems. However, not all the heat is consumed, the surplus heat can be used to feed an auxiliary heat engine.
This process is normally performed in an inert atmosphere, such as argon, and in an inert chamber.
Coupling a PETE device with a thermal heat engine such as a parabolic solar trough system, which already has a steam turbine engine (see Parabolic Trough Systems), the total energy efficiency could be in the 50% to 60% range - a major improvement over current solar technologies.
Since each module has an inverter which contains communication electronics, it is possible for maintenance purposes to see exactly how each panel is performing on a remote customer computer. This device is especially important in the silicon solar cell industry in order to cut the ingots into very thin wafers 200 microns (millionths of a meter) or so thick, and some as thin as 160 microns. For more information on micro-inverters, see the Enphase Energy Section on the Companies Page. A lot of work needs to be done to get from today's laboratory set up to a production product in the field.



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