Crystalline Silicon Solar Cell - Essay Example

Name: Professor: Date of Submission: Crystalline Silicon Solar Cell Introduction Every year the global energy consumption is increasing every year at a very high rate. This according to the predictions is alarming since it has led to higher energy prices. A lot of money is annually being spent in order to have the public enlightened on the upcoming danger of higher energy prices. Eventually, this is what has opened the door to the market of the solar cells (Ferrazza.P 52). Silicon is a principal raw material in making the solar cells. Experts say that in order to come up with better PV technology materials, and then manufacturers would take at least a decade. There is a slight growth in the PV industry. Though the solar cells have been around for quite a long time, most of this has been dedicated to a lot of research and development by experts. The theory of the solar cells is; when some light reaches them, they generate power and produce a photovoltaic effect. The amount of electricity that will be will give out, will be determined by the cell material, cell size and the quality and intensity of the source of light. The sun is always considered to be the best source of light, and even better, it is affordable because it costs nothing. The manufacture of the Silicon devices requires very toxic chemicals, a lot of water, and also uses up a lot of energies. The Integrated Circuit industry has eventually come up with programs that aim at promoting this process in the last two years. The manufacturing tactics aim at recovering, recycling and reusing the environmentally available materials with a reduced intake of energy. According to module shipment that was carried out recently, the Solar Silicon Photovoltaic, accounted for at least 89%. This industry stands very high chances to implement environmental Beign manufacturing approaches (Yamamoto K et al.P 576.). These techniques have been proven to be substantial in cutting the cost of purchasing new chemicals, and also reduce the energy use. This report will review the growth of the crystalline Solar Silicon cell, and the new processes that have been implemented in the manufacture of several groups of these cells. What is crystalline silicon solar cell? These cells are also known as the photovoltaic cell. They convert the energy of sun-light, directly into electricity through the effect of photovoltaic (Ferrazza.P 52). These cells are known as the photovoltaic cells, and they have a voltage, resistance and current that vary enormously when exposed to light. Solar panel, are also considered to be the building blocks of the photovoltaic modules. They are successfully used to detect light or even other electromagnetic radiations. (Fig 1)Operating principle of the photovoltaic Si-cells (Ferrazza.P 52) The photovoltaic crystalline silicon cells (PV) are utilized in different types of solar cells that are found in the market. According to L.C (P 45), there were about 93% of the total world PV productions. These silicon crystalline cells have a significant primary role in the PV market in future. With the recent technologies and research, crystalline silicon solar cell, has the highest percent in terms of energy conservation efficiency. Most of the PV cells can perform well compared to other cells, but their production is quite low. The low production, limitation is partly connected to their complex structures and tedious manufacturing processes that are fabricated. To bring the processing cost low and achieve a high energy conversion rate, it can successfully be attained by coming up with advanced ways of manufacture that includes new production technologies and new tools (L.C. p34). With the advancement done, then there would be great efficiency of more than 25% of the production cost and commercial viability. The growth of the crystal cells The photovoltaic solar energy market has been expanding rapidly, and that has led to a situation of demanding surpassing supply. Most of the new evolutions and expansion capacities are classified as Polycrystalline silicon by casting or the growth of the single-Crystal silicon by Czochralski. Based on best-known practices (BKPs), there are an increasing number of suppliers, aiming at developing the production of equipments. The processing of the solar electricity module generation is quite vast in its application. PV industry will end up using more silicon compared to the integrated circuits (IC). There are four branches of the solar cells of crystalline silicon. The Ribbon cells, polycrystalline, silicon film that is deposited on a substrate and the single-crystal. According to data that was collected ,the market shares for the PV cells and module shipment for these cells were3.5% for ribbon,48.3% for the single crystal,34.0% for the polycrystalline and finally 0.4% for silicon film (L.C. P 67). Analysts show that the growth of the crystal, generating from the melt of silicon will generate a few by-products. There is a tremendous amount of energy used to release the argon that is used up in the crystal growth. The Argon and electricity used up for the Cz growth are said to be highest among the rest of the four silicon materials. The Siemens solar industries have been declared to have an alliance project with the Northern Energy Efficiency. This is important in order to reduce the amount of energy used in the process of crystal growth. This has led to a positive yield saving of about 40% to 50%. Following reports from the recent initiatives by the Semiconductor industry, there is the aim of producing similar results that will be of benefit to the PV industry. The first initiative was to have the semiconductor and National Science Research Corporations foundations that jointly came up with NSF-SRC. The organizations would become an Engineering Research Centre for Environmental Benign. Secondly, SRC that was a consortium of 65 government agencies and corporations, would fund, direct and plan the semi-conductor industry for its long-term, competitive research (Yamamoto K et al.P 576.) The Semiconductor Equipment and Material International (SEMI), was later created to explore the worldwide environmental goals and priorities for the industry. SEMATECH Corporation and the Electric Power Research Institute (EPRI), established a Centre that was mandated to handle environmental issues, energy, and production problems, which face the electronic industry. This was reported by Yamamoto k et al, (P 580). According to the U.S semiconductor manufacturers, the SEMATECH is a non-profit organization. Likewise, the NSF-SRC centers as a semiconductor industry was set to handle research in six areas. These would include; the wet chemicals, the conservation of water, plasma processes, the mechanical-chemical polishing, blood plasma processes, the emissions of organics and the assessment of risk studies (Lunt & Bulovic.P 1). Recently held, was the weekly teleconference seminars series by four participating universities to analyze these results. The (ES&H) goals of the semiconductor industry became a reliable source of information on the environmental safety and health. The goals were targeting the industry of the semiconductor section, in the United States National Roadmap for Semiconductors. On related issues, the feedstock material that is used up in crystal growth from the IC industry, is not wasted but the Silicon PV industry uses it up. These rejected material comprised of about 2,100 metric tons, which amounted to approximately 13% of the polysilicon semiconductor level that is utilized by the IC industry (Ferrazza.P 52). The process of recycling these waste products was carried out for some time until there was a report on a declining feedstock of Polysilicon .Recycling eventually made the cost shoot up which limited the Silicon Industry from growing. The growth rate of this industry in the current years has been tremendously higher than that of the IC industry. The PV industry has continually become dominant because of the growth of the Silicon Crystalline. With this trend, there is a need to develop new sources of solar-grade polysilicon. (Fig 2) Layers in a polysilicon cell (Rolf B.P 85) One way to effectively achieve this is by building new factories that are dedicated at production to low- cost solar grade polysilicon (US$10/kg).Secondly, it would be significant to invent ways of using the waste silicon that have not been exploited yet. Purifying about 30% of the silicon that is a by-product from the water cutting operations of the polysilicon solar-grade and the semiconductors is one example (Yamamoto K et al.P 575).The polysilicon is preferred because it has no compensation with either P or B doping, which is according to the Silicon Stakeholders Group. The resistivity of the polysilicon at room temperature (25%) is expected to exceed one ohm-cm while carbon and oxygen should not go beyond the saturation limits.The overall saturation rates for the non- dopant impurity concentration should fall less than 1ppma (Lunt & Bulovic.P 1). Types of Crystalline Silicon Solar Cell The crystalline Silicon solar cells(c-Si) have currently been discovered to be the most common solar cell that is in use. This is mainly because they are stable, and they deliver efficiently in ranges of 15% to 25%.The cells rely on already established process technologies with an enormous database. This shows why they are preferred, because they are reliable. On the other hand, the shortcoming of the silicon cells is that they are poor absorbers of light, and this requires it to be thick and rigid to counteract this problem. A crystalline silicon solar cell will consist of seven layers as shown in (fig 2), above. The transparent adhesive holds a protective cover glass over the coating that is anti-reflective. This is to ensure that all the light that filters through the silicon crystalline layers is trapped through. Just like the semiconductor technology, an N layer sandwiches against the P layer and the whole package is then held together by the negative side below and the positive side above electrical contacts. There are four categories of the crystalline solar cells as mentioned earlier (Rolf B.P 87). The single crystal, ribbon cells, silicon film and the polycrystalline cells. The crystalline silicon solar panels are commonly used in power harvest systems and also the general utility designs. The single-crystalline.; Unlike most of the other silicon solar cells that are fabricated from silicon wafers, the single crystalline has better material parameters which counts as its major advantage, but its short coming is that it is the most expensive type of silicon to install. The structure of the crystalline silicon has each of its atoms lying in a pre-determined position. It has a predictable and uniform behavior, but very slow in its manufacturing processes. The single crystalline silicon material is a particular crystal plane that is noted using parenthesis. It has a cubic structure that is symmetric. The crystal wafers always have a flat that denotes their orientation and the doping. The polycrystalline silicon; they are also known as the multi-crystalline (multi-Si) cells. They have square cast that are made from ingots. These are massive blocks of molten silicon that are methodically cooled and solidified. They have minute crystals that are made of the metal flake material effect. The commonly used cells are the polysilicon that are used in photovoltaic (Rolf B.P 86). This is because of their greatest advantage that they can be acquired at a lower price, but, on the other hand, they are not as efficient as those that are made from monocrystalline silicon. Ribbon crystalline cells; they are also a group of the polycrystalline silicon that is made by draining, slim thin films from silicon that is in a molten form. This in turn results in a polycrystalline structure. The main disadvantage of these cells is that they have very low efficiency, and they are also very expensive. The high price is in relation to their ability to greatly reduce the silicon by-products. This approach did not require any sawing from the ingots. It is the ultimate advantage of using the ribbon cells (L.C. p45). Silicon Thin film; just like the name suggests one would think that this crystal would be thinner and lighter than all the other cell technologies. It is not very different from the c-Si solar cells, since it consists of about six layers as shown in (fig 1) above. However, they are identical in structure and also in the way they function. This means that they have a similar operation principle (photovoltaic) the thin film however has a flexible pair of layers, unlike the c-Si solar cells. One advantage of dealing with a thin film cell is that they minimize the amount of an active part of the a cell. In most of the other structures, the active material is sandwiched between the two glass panes. The silicon solar panel mostly uses only one glass pane, and the thin panels are heavier than the silicon crystalline panel. The main disadvantage though is that they have a smaller ecological impact. This is so because their conversion efficiencies are lower than that of the crystalline silicon by about 2-3%.They are also lower due to the reduced carrier of the incident photons. They are considered to be potentially cheaper compared to the traditional panels (Yamamoto K ET al.P 575). Conclusion The crystalline silicon devices have recently been reported to have dominated the commercial marketplace for photovoltaic. However, there is still room for more considerations and improvements that can be made to have a better performance and cost of these cells. In particular, there is the need for an energy technology that can be recycled, and that will address the environmental impact and bring it down. This would create alternative approaches that are more reliable and environmentally benign (Rolf B .P 88). c Work Cited Ferrazza F, ‘Growth and post-growth processes of multi-crystalline silicon for Photovoltaic use’, in Polycrystalline Semiconductors IV—Physics, Chemistry and Technology, (2012), 2 rd edition.Vol. 51–52, Solid State Phenomena SciTech Publ., Zug, Switzerland. L.C. Rogers, ‘Handbook of Semiconductor Silicon Technology’, (2010), Noyes Publications, New Jersey, USA, Lunt, R. R.; Bulovic, V. (2011). "Transparent, near-infrared organic photovoltaic solar cells for window and energy-scavenging applications." Applied Physics Letters 98 (11): 113305. doi: 10.1063/1.3567516. Edit Rolf Brendel. Thin-Film Crystalline Silicon Solar Cells: Physics and Technology. (2011). Wiley Publishers. Yamamoto K., Yoshimi M., Suzuki T., Okamoto Y., Tawada Y. and Nakajima A., ‘Thin film poly-Si solar cell with “Star Structure” on glass substrate fabricated at low temperature’, (2010) Conf. Record 26th. IEEE Photovoltaic Specialists Conf., Anaheim, IEEE Press, Piscataway, 575–580. Read More

(Fig 1)Operating principle of the photovoltaic Si-cells (Ferrazza.P 52) The photovoltaic crystalline silicon cells (PV) are utilized in different types of solar cells that are found in the market. According to L.C (P 45), there were about 93% of the total world PV productions. These silicon crystalline cells have a significant primary role in the PV market in future. With the recent technologies and research, crystalline silicon solar cell, has the highest percent in terms of energy conservation efficiency.

Most of the PV cells can perform well compared to other cells, but their production is quite low. The low production, limitation is partly connected to their complex structures and tedious manufacturing processes that are fabricated. To bring the processing cost low and achieve a high energy conversion rate, it can successfully be attained by coming up with advanced ways of manufacture that includes new production technologies and new tools (L.C. p34). With the advancement done, then there would be great efficiency of more than 25% of the production cost and commercial viability.

The growth of the crystal cells The photovoltaic solar energy market has been expanding rapidly, and that has led to a situation of demanding surpassing supply. Most of the new evolutions and expansion capacities are classified as Polycrystalline silicon by casting or the growth of the single-Crystal silicon by Czochralski. Based on best-known practices (BKPs), there are an increasing number of suppliers, aiming at developing the production of equipments. The processing of the solar electricity module generation is quite vast in its application.

PV industry will end up using more silicon compared to the integrated circuits (IC). There are four branches of the solar cells of crystalline silicon. The Ribbon cells, polycrystalline, silicon film that is deposited on a substrate and the single-crystal. According to data that was collected ,the market shares for the PV cells and module shipment for these cells were3.5% for ribbon,48.3% for the single crystal,34.0% for the polycrystalline and finally 0.4% for silicon film (L.C. P 67). Analysts show that the growth of the crystal, generating from the melt of silicon will generate a few by-products.

There is a tremendous amount of energy used to release the argon that is used up in the crystal growth. The Argon and electricity used up for the Cz growth are said to be highest among the rest of the four silicon materials. The Siemens solar industries have been declared to have an alliance project with the Northern Energy Efficiency. This is important in order to reduce the amount of energy used in the process of crystal growth. This has led to a positive yield saving of about 40% to 50%. Following reports from the recent initiatives by the Semiconductor industry, there is the aim of producing similar results that will be of benefit to the PV industry.

The first initiative was to have the semiconductor and National Science Research Corporations foundations that jointly came up with NSF-SRC. The organizations would become an Engineering Research Centre for Environmental Benign. Secondly, SRC that was a consortium of 65 government agencies and corporations, would fund, direct and plan the semi-conductor industry for its long-term, competitive research (Yamamoto K et al.P 576.) The Semiconductor Equipment and Material International (SEMI), was later created to explore the worldwide environmental goals and priorities for the industry.

SEMATECH Corporation and the Electric Power Research Institute (EPRI), established a Centre that was mandated to handle environmental issues, energy, and production problems, which face the electronic industry. This was reported by Yamamoto k et al, (P 580). According to the U.S semiconductor manufacturers, the SEMATECH is a non-profit organization. Likewise, the NSF-SRC centers as a semiconductor industry was set to handle research in six areas. These would include; the wet chemicals, the conservation of water, plasma processes, the mechanical-chemical polishing, blood plasma processes, the emissions of organics and the assessment of risk studies (Lunt & Bulovic.P 1).

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