Please see lecture video for example images of each type of solar technology. It acts as a diode, which can serve in electronics as a rectifier, logic gate, voltage regulator zener diode, switching or tuner varactor diode. All the aspects presented in this chapter will be discussed in greater detail in the following chapters. The working principle of a solar cell in this chapter we present a very simple model of a solar cell. The ntype material is kept thin to allow light to pass through to the pn junction. Pss htl as the ptype, can i deduce that the pn junction is present at the perovskite layer. The cell can be considered as a two terminal device which conducts like a diode in the dark and generates a photovoltage when charged by the sun. Denis ar con ljubljana, may 2011 abstract this seminar is a short overview of current photovoltaics.
Solar cell or photovoltaic cell is nothing but pn junction when the photons with energy greater than or equal to the band gap of pabsorber impenge on solar cells, the electrons excite from valence band to conduction band in the absorber. Light photon energy electric energy silicon solar photovoltaic cells a device made of semiconductor materials that produce electricity under light a pn junction is created in silicon by a doping process. It is used for many forms of rectification for current levels both large and small, as well as high and low voltage levels, and it finds many uses in all manner of electronic circuits. A detailed balance analysis of conversion efficiencies limits for nanocrystal solar cells relating the shape of the excitonic peak to conversion efficiencies j.
The ptype silicon is produced by adding atomssuch as boron or galliumthat have one less electron in their outer energy level than does silicon. Apr 05, 2019 pn junction diode is a diode which can be used as a rectifier, logic gate, voltage stabiliser, switching device, voltage dependent capacitor and in optoelectronics as a photodiode, lightemitting diode led, laser diode, photo detector, or solar cell in electronics. Therefore, asi amorphous solar cell is comparatively cheaper and widely available. Solar cells solar cells are illuminated pn junctions. Each materials pn junction will produce electric current in response to different wavelengths of light. These two emerging industries based on pn junctions make a significant contribution to the reduction in fossil fuel consumption. Traditional singlejunction cells have a maximum theoretical efficiency of 33. The semiconductor pn junction solar cell under load. What is the exact working of a pn junction in a solar panel. A solar cell is a solidstate electrical device pn junction that converts the energy of light directly into electricity dc using the photovoltaic effect. How a solar cell works a solar cell is made of two types of semiconductors, called ptype and ntype silicon. A solar cell is a semiconductor pn junction diode as shown in figure 1. Questions you should be able to answer by the end of todays lecture. Suncube mark 5 solar appliance green and gold energy of australia.
Note that the starting question of this discussion reads what are the causes of the shunt resistance formation in solar cells. How graphene is taking solar cells to the next level duration. Pdf a number of solid state organic solar cells have been prepared and tested in simulated sunlight. What is the difference between the pn junction and a. The dominant silicon solar cell technology is based on a diffused, topcontacted pn junction on a relatively thick silicon wafer for both commercial and laboratory solar cells.
Ppt on solar cell free download as powerpoint presentation. Application of pn junctions within solar cells is discussed. Modeling electrical characteristics of a pnjunction silicon. The solar energy is in the form of electromagnetic radiation, more specifically blackbody radiation, due to the fact that the sun has a temperature of 5800 k. Single junction solar cells have just one pn junction, as against multi junction solar cells, which have more than one pn junction solar cells generate electricity owing to the presence of pn junctions. A solar cell is basically a semiconductor pn junction device. If you have any doubt about the working principle of solar. Sep 29, 2015 for the love of physics walter lewin may 16, 2011 duration. Lightinduced increase of electron diffusion length in a p. In practice, pn junctions of silicon solar cells are not made in this way, but rather by diffusing an n. First solar cell was built by charles fritts, who coated the semiconductor selenium with an extremely thin layer of gold to form the junctions 1% efficient. The pn junction the pn junction is a homojunction between a ptype and an ntype semiconductor. Five junction solar cell yields module efficiency of 41.
A research team at the george washington university, us naval research laboratory, sotera defense solutions of annapolis junction, md, usa, semprius inc, durham, nc, usa and university of illinois urbanachampaign has designed and constructed a prototype solar cell that integrates multiple cells stacked into a single. Materials using to make photovoltaic cells are, for example, monocrystalline. The pn junction has the very useful property that electrons are only able to flow in one direction. As shown in the given diagram the solar cell is like an ordinary diode. A diode is an electronic component that consists of a pn junction, just like a solar cell, except that it has a much smaller surface and the. Pdf modeling electrical characteristics of a pnjunction silicon. Non pn junction solar cells using carrier selective contacts. The pn junction fabricated in the same semiconductor material such as csi is an example of the pn homojunction. Since the n type region has a high electron concentration and the p type a high hole concentration, electrons diffuse from the n type side to the p type side.
A userdefined expression is used for the photogeneration rate and the result shows typical iv and pv curves of solar cells. The solar spectrum as observed on earth is modified due to absorption in the atmosphere. What are the causes of the shunt resistance formation in. Principles of solar cells, leds and related devices wiley. A textured solar cell with 40 m depth of pn junction has the efficiency 3 times more than same nontextured solar cell.
They used a diffused silicon pn junction that reached 6% efficiency, compared to the selenium cells. It is essentially impossible for a single junction solar cell, under unconcentrated sunlight, to have more than 34% efficiency. For example, a gaas solar cell may have a ff approaching 0. And after that well go into organic solar cells where the pn junction is formed in a completely different way. They are also an essential part of metaloxidesilicon fieldeffects. For the love of physics walter lewin may 16, 2011 duration. The pn diode solar cell solar cells are typically illuminated with sunlight and are intended to convert the solar energy into electrical energy. A multi junction cell, however, can exceed that limit.
The process of conversion first requires a material which absorbs the solar energy photon, and then raises an electron to a higher energy state, and then the flow of this highenergy electron to an external circuit. V principle of solar cell v current generation v iv characteristic of an illuminated pn junction v physical process of solar cell v iv characteristic of solar cell v solar cell parameter v applications v reference v device that converts optical energy into electrical energy. What is the highest efficiency possible theoretical with single junction solar cells. This tutorial uses a simple 1d model of a silicon solar cell to illustrate the basic steps to set up and perform a device physics simulation with the semiconductor module.
A normal operating cell temperature noct is defined as the cell temperature when the ambient temperature is 20. Ch4 solar cell operational principles tu delft ocw. In addition, they can be used as solar cells, photodiodes, light emitting diodes and even laser diodes. Semiconductor solar cells are fundamentally quite simple devices. Of course, in the generalized shunt approach, the notion of a. The working principle of a solar cell tu delft ocw. The strong demand for higher efficiency photovoltaic has recently attracted considerable interest in multi junction solar cells based on iiiv semiconductors 3. Fabrication of solar cells the first practical photovoltaic cell was developed in 1954 at bell laboratories.
Aug 11, 2011 this textbook introduces the physical concepts required for a comprehensive understanding of pn junction devices, light emitting diodes and solar cells. Also, it explains the phenomenon of shockleyqueisser limit. Semiconductor devices have made a major impact on the way we work and live. A typical csi solar cell structure is shown in figure 3. The wafer was scored into 1cm x 1cm squares with a wafer saw to allow. For am1 normal incidence the power density is reduced to 925 wcm 2 whereas for am1. The use of multiple semiconducting materials allows the absorbance of a broader range of wavelengths, improving the cells sunlight to electrical energy conversion efficiency. The solar cell is the basic building block of solar photovoltaics. Solar cells are described as being photovoltaic, irrespective of whether the source is sunlight or an artificial light. Characteristics of photovoltaic solar cells analog. Sep 03, 2018 written for students in electrical engineering, physics and materials science and researchers in the electronics industry, principles of solar cells, leds and related devices is the updated second edition that offers a guide to the physical concepts of pn junction devices, light emitting diodes and solar cells. Solar cells are silicon wafers which are doped to produce a pn junction. This lecture uncovers the basic science of semiconductor devices and solar cells, including pn junction and photovoltaic effects.
Single junction solar cells the plain and simple solar. There is no difference in a pn junction and solar cell infact solar cell is a type of pn junction diode the only special character of solar cell it that one of the region p or n is made very thin so that the light reaches the depletion region and excite electrons moving them into the conduction band. Semiconductors have the capacity to absorb light and to deliver a portion of the energy of the. Many notions presented in this chapter will be new but nonetheless the general idea of how a solar cell works should be clear. The large surface area indicated in light blue is exposed to incident light energy. The pn junction is a versatile element, which can be used as a rectifier, as an isolation structure and as a voltagedependent capacitor. The pn junction is the fundamental building block of the electronic age. Single junction flatplate terrestrial solar cells are fundamentally limited to about 30% solar toelectricity conversion efficiency, but multiple junctions and concentrated light make much higher. The most commonly known solar cell is configured as a largearea pn junction made from silicon. Various types of solar cell technologies and current trends of development 2 16.
The irregularities in the spectrum are due to absorption at specific photon energies. This section reveals the operational principle of most common solar cells and also serves as a basis for further discussion. Brenner1, michael kulbak1, norbert schaefer 2, sergiu levcenco, igal levine 1, daniel abouras2, gary hodes, david cahen1 equal contribution. Efficiency is defined as the ratio of energy output from the solar cell to input energy from the sun. Pn junction diode when the junction is illuminated, a net current flow takes place in an external lead connecting the ptype and ntype. Written for students in electrical engineering, physics and materials science and researchers in the electronics industry, principles of solar cells, leds and related devices is the updated second edition that offers a guide to the physical concepts of pn junction devices, light emitting diodes and solar cells. Most common approaches to model a pn junction solar cell are detailed balance model dbm and driftdiffusion model ddm. What is a pn junction, what are single junction solar cells, and how are they different from multi junction solar cells. The above equation also demonstrates the importance of the ideality factor, also known as the nfactor of a solar cell. The amorphous word with respect to solar cell means that the comprising silicon material of the cell lacks a definite arrangement of atoms in the lattice, noncrystalline structure, or not highly structured. Modeling electrical characteristics of a pn junction silicon solar cell using pspice 5.
A novel device concept utilizing the approach of selectively extracting carriers at the respective contacts is outlined in the work. Scribd is the worlds largest social reading and publishing site. What is the difference between the pn junction and a solar cell. When electrons all move the same direction then you have electricity. Due to the pn junction, a built in electric field is always present across the solar cell. Solar to heat solar to electricity solar to heat solar to fuels electricity. Silicon nanowire radial pn junction solar cells erik c. Apr 03, 2017 the junction attracts electrons one side and repels them the other side, making electrons all move the same direction in the junction area. When photons hit the solar cell, free electrons attempt to unite with holes in the ptype layer. In the next week well talk about silicon solar cells. Iiiv multi junction solar cells, as a new technology, offer extremely high efficiencies compared with traditional solar cells made of a single layer of semiconductor material. It consist of silicon, germanium pn junction with a glass windows on the top surface layer of ptype, the ptype material is made very thin and wide so that the incident light photon may easily reach to pn junction. Feb 07, 2018 there is no difference in a pn junction and solar cell infact solar cell is a type of pn junction diode the only special character of solar cell it that one of the region p or n is made very thin so that the light reaches the depletion regi.
Solar cells have become competitive at remote locations, in navigation systems, telecomunications and as additional power in grid connected loads at peak use 12. Working principle of silicon solar pv cells photovoltaic material of device converts. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. This section reveals the operational principle of most common solar cells and also serves as. This question is part of the super big solar panel faq from solar mango, where expert answers to over 100 important questions on solar panels are provided. The pn junction diode is the basic semiconductor diode format. Non non non nontracking tracking tracking tracking. The ideality factor is a measure of the junction quality and the type of recombination in a solar cell. In addition to reflecting the performance of the solar cell itself, the efficiency depends on the spectrum and intensity of the incident sunlight and the temperature of the solar cell.
It supplies a voltage and a current to a resistive load light, battery, motor. Photovoltaics pv is the most direct way to convert so lar radiation into electricity and is based on the photo voltaic effect, which was first observed by henri bec. The functioning of a solar cell is similar to the photodiode photodetector. The generation of electric current happens inside the depletion zone of the pn junction. The shockleyqueisser limit for the efficiency of a single junction solar cell.
This is also the case of a solar cell, where a subcircuit facilitates the task of connecting several solar cells in series or in parallel. Yes, it is possible to have more than one junction in a solar cell. Photovoltaics pv is the most direct way to convert so lar radiation into electricity and is based on the photo voltaic effect, which was first observed by. The pn junction generates current and voltage due to the builtin electric field at the junction of the ptype and ntype material. One way to handle a pspice circuit is to define subcir cuits for the main blocks. Principles of solar cells, leds and related devices. Silicon a single silicon atom consists of fourteen negatively.
One type is called the ptype and the other is called the ntype. Junction solar cell an overview sciencedirect topics. A solar cell is essential a pn junction with a large surface area. The common single junction silicon solar cell can produce a maximum opencircuit voltage of approximately 0. In a typical solar cell, one side of the cell is doped with boron the ptype, and the other side ntype is doped with phosphorus. You would have likely heard about the pn junction of the solar cell, which is in fact the junction that generates the photovoltaic current. It is formed by joining ptype high concentration of hole or deficiency of electron and ntype high concentration of. Individual solar cell devices can be combined to form modules, otherwise known as solar panels. The pn junction is the fundamental building block of the. The radial pn junction design sets the direction of light absorption perpendicular to the direction of minoritycarrier transport, allowing the cell to be thick enough for e. However the electric field, a oneway downhill road superimposed across the cell, allows the electrons to flow only in one direction.
Pn junction, diode and photovoltaic cells lecture 22. Commonly used cells are produced as wafers of diameter about 8 cm and 3 mm thickness which are cut from a crystalline silicon rod. As a simplification, one can imagine bringing a layer of ntype silicon into direct contact with a layer of ptype silicon. Fivejunction solar cell yields module efficiency of 41. A photovoltaic device produces a current or a voltage at its output in the presence of light.
Whether you are looking for general insight in this green technology or your ambition is to pursue a career in solar, introduction to solar cells is an excellent starting point. The course is a tour through the fundamental disciplines including solar cell history, why we need solar energy, how solar cells produce power, and how they work. Nanocrystal in solar cells photovoltaic solar cell is a device which can convert the photon energy or light energy into electricity. Feb 01, 2014 fabrication of solarphotovoltaic cell basically a solar cell is a junction usually a pn junction with sunlight shining on it. Watch the full video first and you will get a clear idea about the working of solar cells. In practice, pn junctions of silicon solar cells are not made in this way, but rather by diffusing an ntype dopant into one.
Pdf a solar cell is an electronic device which directly converts sunlight into electricity. In this study ge and ingaas single junction solar cells which are used as the bottom cell of triple junction solar cells are investigated 4. Modeling electrical characteristics of a pnjunction silicon solar cell using pspice. This book covers the two most important applications of semiconductor diodes solar cells and leds together with quantitative coverage of the physics of the pn junction. The solar cell temperature will normally be higher than the air temperature because the panels are black and sitting in the sun. Pn junctions are formed by joining ntype and ptype semiconductor materials, as shown below.
Silicon photovoltaic cells are typically thought of as voltage supplies, but they are also useful as sensitive detectors of light and near infrared. We give the upper limit to the solar cell e ciency. Single junction solar cells the plain and simple solar cell. What weve drawn here is basically a silicon solar cell, so, like the one i have here. The highest theoretical efficiency possible with a single junction solar cells is about 34%.
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