PHOTOVOLTAIC SOLAR CELLS Research

Document Type:Thesis

Subject Area:Engineering

Document 1

Some of the equipment used in conversion include; photovoltaic, solar thermal, solar panels among others. There are two main types of solar energy which are normally referred to as photovoltaic and thermal. The difference between the two is what they use from the sun and convert it to energy. Photovoltaic use the sunlight and directly converts it into electrical energy. The thermal, on the other hand, use the heat from the sun and converts it into electrical energy. The photovoltaic (PV) technology usually makes use of semiconductors in panels to convert the light into electricity (Lasnier, 2017, n. p). The thermal technology, however, does not convert the heat directly from the sun. First, the heat is converted into mechanical energy, and then later converted into electricity. The photovoltaic are used to provide electricity which could be used for lighting purposes and other purposes as well. The thermal devices are usually used for heating purposes most of the time. Solar energy is important to both plants and animals. In plants, through the process of photosynthesis, they get to make food and release oxygen into the air and clean the air in the process. For animals and human beings, solar energy is important because it gives them vitamin D. Human beings have been able to use the solar energy to provide electricity which is harnessed in solar plants. This solar energy is converted into electricity which can be used to light up a whole city. Solar energy is used for heating, cooking, lighting, and even to charge electronic appliances that we use every day.

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The use of solar energy has several advantages. First off, it is a renewable source of energy thus is friendly to the environment. Being renewable means that it can never be depleted. p). During cloudy and rainy days, the amount of energy stored is minimal. Finally, as much as maintenance is fairly cheap, the initial installation costs are quite high. The prices are high because for now, the solar technology has not been fully embraced yet. As time goes by and more people warm up to the idea of using solar energy, the installation costs are expected to go down. The materials that are used in the production of photovoltaic cells are toxic to the environment. The chemicals that are used in production are toxic and might have a slight effect on the environment even if not directly (Hosenuzzaman et.

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al. pp. Literature review of photovoltaic cells The solar energy is the oldest form of renewable source of energy known to man. These pockets of light energy could be used for various purposes and could be harnessed into different forms of useful energy. This discovery by Albert Einstein was followed by a realization of the electron by other scientists. The electron was used to explain the quanta of energy and more research was carried out on how it could be used. The electron gave the scientists a better comprehension of the world of photoelectricity (Nozik et. al. However, since there would be no one to change the cells when they ran out of power, the idea was clearly not wise. Dr. Hans Ziegler, who was a specialist in satellites advised them that using solar was the best because it was renewable yet the chemical cells would expire within days and the satellite would come crashing down in the process.

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The Navy was reluctant because they felt that using the silicon solar cell would be compromising their source of power. However, in the end, they decided to use both the solar cell and the chemical cell in the satellite. The solar cell actually became better than was expected. It had properties that were favorable and considering the oil crisis that was taking place at the time, the energy alternative seemed like a sweeter option. Besides, the module was not expensive to install and it required very little energy in order for it to work. Besides, there were some areas such as gas and oil fields which were far from the power lines which needed some electricity in their erosion prevention mechanism. The solar cell was able to come through during this time and provided enough electricity efficiently (Zhou & Zhu, 2016, pp.

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They are used in activities involving the space and concentrated photovoltaic systems. The materials used are quite expensive and that is why they are not common. These photovoltaic technologies include; gallium arsenide among others. Monocrystalline silicon cell Monocrystalline silicon cell was the purest form of silicon cell that was ever produced. It was the first cell to be commercially produced. The polycrystalline silicon cells were made soon after to counter this and they are thus slightly cheaper than the Monocrystalline silicon cell. Polycrystalline silicon cell Unlike the Monocrystalline cells, the polycrystalline cells have several tiny crystal grains. Their construction is simpler compared to their Monocrystalline counterparts. They are simply made by casting a cube from the molten silicon hence forming a cubical ingot. After this, the cubes are sawn together just as the case of the Monocrystalline crystals.

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They are produced by simply placing a very thin layer of silicon onto a glass substrate. These results in a thin flexible cell which has used less than 1% of the total silicon required for the crystalline cells. The amorphous silicon is much cheaper than the crystalline cells and easier to produce as well. However, since the amount of silicon is very little, the cell is less efficient as compared to the crystalline cells. These cells are suitable for use on any kind surface, both rigid and flexible. pp. High-efficiency cells These involve cells which are not made simply from silicon. They use other expensive semiconductor materials which are more efficient than silicon. One such cell is the Gallium-Arsenide cell. Gallium arsenide has a structure that looks almost like that of Monocrystalline silicon, the difference is that the crystals are of Gallium and arsenic atoms alternating.

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The thin film photovoltaic panel is not very popular due to its inefficiency. Monocrystalline panels are also quite expensive thus are not used by everyone. Some of the countries which are known for their panels include Canada, Korea, Japan, Taiwan, Germany and the United States. The company which makes the solar panel is very crucial because of the quality. The biggest brand names do not always mean that the panels are the best quality (Srinivinsan & Rajamani, 2016, pp. There are three main ways in which silicon can be purified as shown below (Youn, Park & Guo, 2015, pp. Electronic grade silicon This results in a highly pure polycrystalline silicon. This process is usually for the silicon that is used for electronic devices. The first step is known as the coke reduction. In this part, the metallurgical silicon is 98.

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Medium grade silicon The above process is the most efficient in purifying silicon. The Siemens process is very expensive and the Siemens reactor is also not readily available. The process also requires too much energy and in the process wastes a lot as well. There are a number of ways which have been realized and are used to counter the total energy and costs that are used in the Siemens process yet at the same time aim at achieving a result that is close to the required one. There are two ways which have been used though they resemble the Siemens process in a way. This process is quite cheap as compared to the other processes. Therefore, the cost of silicon in a plant that uses this purification process is cheaper.

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After the silicon is purified, the next step would be to either make crystals from them or make ribbons depending on the type of PV being manufactured. The Monocrystalline silicon cell is produced by casting a cylindrical ingot that is continuous and crystalline from molten silicon (Jones, 2018, pp 980). After this, several crystals are sawn together then placed on a glass which holds them in places and protects them. Solar planning and design A solar panel is usually installed based on different considerations. Some of the elements of the design and planning of a solar panel are considered before installing it (Jean et. al. pp. First, what is the intended purpose of the solar panel? Before a panel is installed, there must be a reason why the panel is needed. The budget one has regarding the panels.

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The three most common cells available are available at different rates. The thin film is the cheapest but least efficient. Before a person selects the kind of panel they desire, it is important that one knows the expenses to be incurred. Considering the initial installation process is also expensive on its own. Solar panel usage is not any different. The only difference is that it is true. The use of solar panels saves people a lot of money in the long-run. The most expensive part of the solar panel installation and use process is the initial purchases and installation costs incurred. Solar panels are quite expensive and this is probably why so far most people around the world are yet to install the panels on their buildings. The initial installation cost is high but it is a worthy investment.

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The productivity of the solar panels installed would depend on the direction of the sunlight and angle of the roof on which it is mounted. This will determine the amount of energy being converted into electrical power and being stored. Electricity bills consist of a major part of a household monthly expenditure (Jean et. al. Cleaning them does not really require much skill thus is not that expensive. In addition, solar panels usually have a long lifespan. This means that once installed, they are permanent. It takes a very long time before any replacement is required for any of the parts. If anything, the replacement is not usually necessary unless the efficiency is reducing due to a particular reason. It is manufactured widely due to its vast use. It is also the best since it is pure and does not require to be made into a compound for it to be efficient.

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Most of the other semiconductors used are usually made of compounds such as Gallium Arsenide, Copper Indium Gallium Arsenide, and Cadmium Telluride among others. The most commonly used PV cell today is the silicon crystalline cells (Jean et. al. It is only produced by around three companies around the world. It is flexible and can be used on almost any type of surface, but its efficiency degrades with time. It is therefore not the best if efficiency is what a client is looking for. The other cells like Gallium Arsenide cells are usually used where the efficiency required and the energy required is quite high. They have a higher resistance also which is important for the fact that they are used in space, where there are extreme conditions to deal with.

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However, the metal oxides lack effective optimization properties thus very low photovoltaic performance. This is why to date, silicon is the main photovoltaic material used around the world. Whether in polycrystalline or Monocrystalline nature, the silicon crystals are the most important part of the solar cell. They are the particles which require the sun’s energy to get excited and thus create electricity in the process. They can also be in a thin film ribbon state. This circuit is begun by a black metal contact which is in contact with the semiconductor material (Lasnier, 2017, n. p). This connection allows the electricity to flow between the semiconductor, the black metal and the rest of the circuit. At this point, electricity has already been created. A laminate film is usually placed under the black metal to ensure that there is no power leakage and that the panel is waterproof.

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al. pp. Installing a solar panel is quite expensive. Most people are usually left in debts after the installation of a panel on their building. Most of the time, the people who are advised to purchase a solar system would like to know how long a panel lasts after installation. The initial solar panels had a lifespan of 7 years. They needed to be changed after every seven years because the efficiency would be too low. However, since then, the solar panels have had a lot of improvements done on them. The technological improvements are meant to ensure that the panel lifespan is longer. The longer the lifespan offered by the solar panel, the more the people would agree to install them. Most of the time, the solar panel is in one position which makes it easier to maintain.

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The fact that it is static also ensures that the panel does not deteriorate due to friction. The solar panels, therefore, require very little maintenance over the years. There is, however, one main procedure which is easy and could be done occasionally. For the efficiency of the panel, it needs to be clean in order to allow the penetration of the sun rays to the silicon without any obstruction. The water from the automated equipment usually released water in a sprinkle motion. For instance, there is the Heliox system. This system can be programmed and made to know exactly when is needed. When it is set, it usually sprinkles the panel on the set day and time. The heliox system is very useful and helps one keep a schedule tight enough.

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pp. The people whose health is most at risk the workers in the manufacturing companies. The air they inhale is usually filled with toxins and dust. The design of the industrial process has since been improved and the monitoring of the process and thus the better models were supposed to help those workers. However, as much as the effects are being minimized, they will still be evident and the workers will still be harmed even if on a small scale. pp. Despite its minimal environmental effects, the use of PV is preferred over the use of fossil fuel as a source of energy (Kamat, 2015, n. p). Photovoltaic circuit properties The process of converting sunlight, which is more often than not taken for granted, into electrical energy is a great achievement. The process under which the conversion occurs must be very complex and must also involve a series of components which are of high quality and sophisticated.

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Other materials are used though in a smaller scale. Despite the difference in semiconductor material which could be used, the working principle of the panel is basically the same. Battery bank The electricity that is produced is not always needed when it is produced. Then at night usually when it is needed, it not produced at all. When the electricity is produced during the day, there must be a mechanism through which that energy could be saved for use later in the night. Second, the DC current produced by the silicon modules are converted into AC current. The AC current produced is the one that will allow the power to be conversant with the appliances used in a house. This conversion is made possible through the use of an Inverter. Finally, there is a charge controller.

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This controls the amount of energy that is at the output and input of the battery bank. Photovoltaic means using light to create electricity. Silicon is a semiconductor which is used in PV cells. Basically, the principle that is applied is that the light energy from the sun can be used to energize the four free electrons in the silicon atom and allow them to move freely from one atom to another thus allowing the free flow of electricity. A solar panel is made up of several photovoltaic cells put together. For the silicon to work and conduct electricity, an electric field must be created. There are some metal plates which have been strategically placed at the end of the cells. These plates are meant to transfer the electricity being produced by the silicon cells into the cable wires thus making it flow like normal electricity.

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After the flow of electricity is established, the electricity could either be used directly or stored in battery banks for future use. Bad things about solar energy Solar energy is the one way people have embraced in an attempt to use energy that does not affect the environment. The sun is renewable and there is no one who would prevent another person from using the sun because everyone has access to it. Another bad thing is that the solar panels are weather dependent. The more direct sunlight the panel receives, the more the energy that will be generated. On cloudy days, even though electricity is generated, the amount will be considerably less as compared to the other days when the sun is up. The surroundings of the building which could block the sunlight from the building during certain times of the day also affect the production of electricity considerably.

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Solar panels usually take up a considerable amount of space. As much as the panels do not require much maintenance, they usually demand expert attention once in a while. Conclusion Photovoltaic cells have a wide range of users around the world. The panels make use of the semiconductor silicon cell. The widest used silicon forms are the crystalline which forms the most efficient panels. These panels are very important because they make use of light from the sun and convert it into electrical energy which can be used for lighting, charging electronic appliances, among several other uses. pp. However, it is advantageous in that it can be put on any surface because of its flexible nature. It is environmentally friendly plus it is very cheap to maintain. However, the initial cost of installation is very high.

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the first country to produce solar electricity was the United States. However, due to its dependence on the weather, this technology works best in certain places in the world as compared to others around the world. The manufacturing plants are not very many around the world. The main manufacturing countries include the United States, Japan, South Korea and Germany. The companies in these countries have branches in other parts of the world. The main type of PV cells produced is the crystalline cells (Zeira,2007, pp. A. Pereira, L. Fortunato, E. and Martins, R. Thin film silicon photovoltaic cells on paper for flexible indoor applications. Hasanuzzaman, M. Malek, A. B. M. A. Pathways for solar photovoltaics.  Energy & Environmental Science, 8(4), pp. Lasnier, F.  Photovoltaic engineering handbook. Routledge. Solar cells versus solar fuels: two different outcomes.

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Masuko, K. Shigematsu, M. Hashiguchi, T. Fujishima, D. J. Beard, M. C. Luther, J. M. Makuta, S. Yu, Z. Tachibana, Y. Mishra, A. Bäuerle, P. B. and Heben, M. J. Pathways toward high- performance perovskite solar cells: review of recent advances in organo-metal halide perovskites for photovoltaic applications.  Journal of Photonics for Energy, 6(2), p. J. Organic photovoltaic cells: from performance improvement to manufacturing processes.  Small, 11(19), pp. Zeira, E. C.

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