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working principle of solar cell

The core of these devices is the electron-releasable semiconductor. While light ray strikes on any materials some portion of the light is reflected, some portion is transmitted through the materials and rest is absorbed by the materials. The solar cell converts solar energy to the electrical energy which is stored in the battery. A solar cell works in three steps: Photons in the sunlight hit the solar cell and are absorbed by the semiconductor material. When light reaches the p-n junction, the light photons can easily enter in the junction, through very thin p-type layer. As the covalent bonds are broken, there will be a number of holes created in the n-type material near the contact surface. The energy knocks electrons loose so they can flow freely and produce a difference in electric potential energy, or voltage. This is as such equivalent to the migration of holes from p-type to the n-type semiconductor. Similarly, holes will no more migrate to n-type semiconductor from p-type. Inverter Price. These light generated electrons and holes cannot produce electricity in the silicon crystal alone. In this way, one hole appears to disappear another neighbour hole. Advertising. (Supervisory Control and Data Acquisition), Programmable Logic Controllers (PLCs): Basics, Types & Applications, Diode: Definition, Symbol, and Types of Diodes, Thermistor: Definition, Uses & How They Work, Half Wave Rectifier Circuit Diagram & Working Principle, Lenz’s Law of Electromagnetic Induction: Definition & Formula. As such holes are having relative motion inside the semiconductor crystal. They convert sunlight into direct current (DC) electricity. Not only free electrons, but valence electrons of n-type material near the contact surface also come out from the covalent bond and recombine with more nearby holes in the p-type semiconductor. Hence free electrons in n-type semiconductor near to its contact surface jump to the adjacent holes of p-type material to recombine. The pentavalent dopants which donate their fifth free electron to the semiconductor crystal are known as donors. As soon as the solar cell is exposed to sunlight, the solar energy which is present in the form of light photons is absorbed by semi conductor materials. Even at room temperature, the thermal energy available in the crystal is large enough to disassociate these relatively loose fifth electrons from their parent phosphorus atom. Full disclaimer here. The sun’s photons strike the cell on the microthin p-side and penetrate to the junction to generate the electron-hole pairs. When one bond is broken one hole is created in it. The solar lamp draws the current from this battery and it requires no other wiring. In this way, silicon crystal gets a tetrahedral lattice structure. Negatively-charged electrons are knocked off from their atoms and start flowing in the same direction to produce electric current. The same thing happens when light falls on a silicon crystal. At the same time, the light-generated holes cross the depletion region due to the attraction of electric field of depletion layer where they recombine with electrons, and then the lack of electrons here is compensated by valence electrons of p-region, and this makes as many numbers of holes in the p-region. Why Solar. Cloudflare Ray ID: 6129981b2db80d7e While n-type semiconductor and p-type semiconductor contact each other, the free electrons near to the contact surface of n-type semiconductor get plenty of adjacent holes of p-type material. Due to their special structure and the materials in solar cells, the electrons are only allowed to move in … Silicon is the most widely used semiconductor material for constructing the photovoltaic cell. Premier Data. These excited electrons then get sufficient energy to migrate from valence band to conduction band. Thus, its maximum power is 3 W. These free electrons come from pentavalent impurity are always ready to conduct current in the semiconductor. Price Download. When semiconductor materials are exposed to light, the some of the photons of light ray are absorbed by the semiconductor crystal which causes a significant number of free electrons in the crystal. In this video we will learn solar cell.Also we will see how this solar cells are made. Your IP: 34.236.218.29 • All the aspects presented in this chapter will be discussed in greater detail in the following chapters. For this configuration, there will be a silicon atom for each boron atom, fourth valence electron of which will not find any neighbour valance electrons to complete its fourth covalent bond. Please enable Cookies and reload the page. These free electrons and holes have a vital role in creating electricity in photovoltaic cell. Protons are positively charged and electrons are negatively charged. This fifth electron then relatively loosely bounded with its parent atom. After some instant, there will be a layer of negative charge (excess electrons) in the p-type semiconductor adjacent to the contact along the contact surface. If you are at an office or shared network, you can ask the network administrator to run a scan across the network looking for misconfigured or infected devices. These electrons and holes are hence called light-generated electrons and holes respectively. According to estimates, 10,000 times more energy than our annual energy need from fossil fuels reaches the world from the sun. So as soon as one n-type semiconductor and one p-type semiconductor come into contact the electrons from n-type will transfer to p-type and holes from p-type will transfer to n-type. In n-type semiconductor mainly the free electrons carry negative charge and in p-type semiconductor mainly the holes in turn carry positive charge therefore free electrons in n-type semiconductor and free holes in p-type semiconductor are called majority carrier in n-type semiconductor and p-type semiconductor respectively. You may need to download version 2.0 now from the Chrome Web Store. Now let us come to the silicon crystal. These holes serve as the positive charge carriers while the electrons serve as negative charge carriers. As sunlight falls over a solar cells, a large number of photons strike the p-type region of silicon. The silicon atom has four valence electrons. A solar cell, or photovoltaic cell, is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon. Monthly Insights. The working of PSCs are based on the photoelectrochemical reaction/process where as in conventional PN junction solar cells physics plays a complete role as described by Dr. Phil Denby. Do not get confused, the electrons or holes do not constitut… If light strikes on n-type semiconductor the electrons from such light-generated electron-hole pairs are unable to migrate to the p-region since they are not able to cross the potential barrier due to the repulsion of an electric field across depletion layer. In addition to producing energy, they can be used as a photodetector (for example infrared detectors), detecting light or other electromagnetic radiation near the visible range, or measuring light intensity. Let us understand solar cell working principle. When instead pentavalent phosphorous atoms, trivalent impurity atoms like boron are added to a semiconductor crystal opposite type of semiconductor will be created. The free electrons in the depletion region can quickly come to the n-type side of the junction. Solar cells are described as being photovoltaic, irrespective of whether the source is sunlight or an artificial light. Photovoltaic cell is the basic unit of the system where the photovoltaic effect is utilised to produce electricity from light energy. When a pentavalent impurity such as phosphorus is added to silicon, the four valence electrons of each pentavalent phosphorous atom are shared through covalent bonds with four neighbour silicon atoms, and fifth valence electron does not get any chance to create a covalent bond. The light energy, in the form of photons, supplies sufficient energy to the junction to create a number of electron-hole pairs. Silicon is the most widely used semiconductor material for constructing the photovoltaic cell. While this fifth relatively loose electron is disassociated from parent phosphorus atom, the phosphorous atom immobile positive ions. Performance & security by Cloudflare, Please complete the security check to access. In this lecture I will try and explain the working principles of a polymer solar cell. Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, CAS These are called free electrons move randomly inside the crystal structure of the silicon. Many notions presented in this chapter will be new but nonetheless the general idea of how a solar cell works should be clear. In a solid crystal, each silicon atom shares each of its four valence electrons with another nearest silicon atom hence creating covalent bonds between them. Similarly, the holes in the depletion can quickly come to the p-type side of the junction. When light ray strikes on the crystal, some portion of the light is absorbed by the crystal, and consequently, some of the valence electrons are excited and come out from the covalent bond resulting free electron-hole pairs. PV Cell Working Principle to Generate Electricity Solar cells convert the energy in sunlight to electrical energy. When sunlight falls on a solar panel this plate absorbs it and this light reaches the pn junction. Chapters 6-8cover the designs of systems constructed from individual cells-includingpossible constructions for putting cells together and the equipment needed for a practioal producer of electrical energy. Working of Solar Street Lights. The semiconductors doped by donor impurities are known as n-type or negative type semiconductor as there are plenty of free electrons which are negatively charged by nature. As the energy level of these electrons is in the conduction band, they leave from the covalent bond leaving a hole in the bond behind each removed electron. 3 weeks ago. Figure 2 | Working principle of solar cell based in semiconductor bulk and nanocrystals (image). A typical silicon solar cell can produce up to 0.5 V and current up to 6 A. 2006). So there will be lack of one electron in the incomplete bond, and hence an incomplete bond always attracts electron to fulfil this lack. However, these prin-ciples are not as obvious for photovolt- This sunlight photon can then easily enter the junction through a very thin P-type layer. 8 2 minutes read. The direction of the current (I) is in the opposite direction of the electrons. The readeris told why PV cells work, and how theyare made. The process is very fast but does not continue forever. In a solid crystal, each silicon atom shares each of its four valence electrons with another nearest silicon atom hence … The DC current is converted into 240-volt AC current using an inverter for different applications. As each of the holes can accept an electron, the trivalent impurities are known as acceptor dopants and the semiconductors doped with acceptor dopants are known as p-type or positive type semiconductor. 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