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Photovoltaic Cells
Published in Ranjan Vepa, Electric Aircraft Dynamics, 2020
Although the photoelectric effect was discovered by Henri Becquerel in 1839, photo conductivity of selenium was established in 1873, which was followed by the first semiconductor point-contact rectifier being manufactured a year later, the first silicon solar cell appeared only in 1954, as a result of the upcoming semiconductor technology, and it had an efficiency as low as ETA = 5%. The photoelectric effect is the generation of charge following the absorption of photons by a material. Photons are first captured by a material and the charges that are generated are conducted away by the external circuit, thus resulting in a current flow. Silicon photo diodes are light sensitive “p-n” junction diodes encased in a transparent material. The junction between a “p”-type or positive doped semiconductor with an excess of holes and an “n”-type or negatively doped semiconductor with an excess of electrons, is usually reverse-biased when operating as a photoconductive cell. The reverse leakage current present when the diode is reverse-biased is sensitive to light. However, when operating as a photovoltaic cell, a similar junction is unbiased.
Historical Perspective
Published in Lynne D. Green, Fiber Optic COMMUNICATIONS, 2019
The photoelectric effect, observed by Heinrich Hertz [1857–1894] in 1887, showed that light is composed of particles or packets of energy (photons). The cause of the photoelectric effect was explained by Albert Einstein [1879–1955] in 1905, and he received the Nobel Prize in 1921 for that discovery.
Physical Phenomena Used in Sensors
Published in Bogdan M. Wilamowski, J. David Irwin, Fundamentals of Industrial Electronics, 2018
Tiantian Xie, Bogdan M. Wilamowski
The physical phenomena described above are frequently used in various sensors. For example, piezoresistive effect and piezoelectric effect can be used to measure both pressure and acceleration. Thermoelectric effect, pyroelectric effect, and temperature effect in p-n junction are usually applied in temperature sensors, bolometers, and so on. Photoelectric effect is used in light detectors such as photodiodes and thermal detectors. Hall effect is always used in measuring magnetic fields and sensing position and motion.
Learning solar energy inspired by nature: biomimetic engineering cases
Published in European Journal of Engineering Education, 2021
J. M. Delgado-Sanchez, I. Lillo-Bravo
Photovoltaic solar energy is obtained by converting sunlight into electricity based on the photoelectric effect, by which certain materials are able to absorb photons (light particles) and release electrons, generating an electrical current. Photovoltaics has been recognised as a renewable energy technology that has the potential to contribute significantly to the future energy supply, but the science and technology driving photovoltaics needs to improve the efficiency of the photovoltaics plants seeking for new materials and operation techniques. The main inputs to achieve these objectives are to consider that (a) photovoltaics modules transform the sunlight energy into electricity; so, the more irradiation they receive, greater the generation will be. For this purpose, engineers have designed the so-called Trackers Technology, to allow the continuous movement of the photovoltaic module according to the sun position; (b) furthermore, although the irradiation is intended to be maximised, the best performance of the photovoltaic module requests not to operate at high temperature.
Harness of maximum solar energy from solar PV strings using particle swarm optimisation technique
Published in International Journal of Ambient Energy, 2021
T. Nagadurga, P. V. R. L. Narasimham, V. S. Vakula
The demand for electrical energy is ever increasing in recent times; all the energy engineers investigate emerging technology called renewable energy. The naturally available renewable energy sources decrease the environmental issues and global warming effect. Among all the non-conventional sources like wind, solar, geo-thermal and bio-energy, solar energy has gained popularity in the field of electricity generation due to low expenses, maintenance free and clean energy. In spite of these advantages, there are some short comings of solar energy, i.e. the efficiency of photovoltaic (PV) cell is very less, which is in the range of 17–19% only. Now-a-days with the help of emerging technologies like usage of thin-film technology the efficiency of the solar cell may increase to 20%. According to National Renewable Energy Laboratory, NREL – US, the efficiency of solar cell is 46%. Solar energy is converted into electrical energy with the help of photo electric effect, the phenomenon of semiconductor material to convert electromagnetic radiation directly into electric current is termed as photoelectric effect. Furthermore, in solar PV module the generated output power is directly proportional to solar insolation, temperature and load. Hence, the power obtained from solar PV array varies continuously due to changes in environmental conditions.