Rachid Malek - Academia.edu (original) (raw)
Papers by Rachid Malek
IntechOpen eBooks, Mar 31, 2023
In this chapter, we propose the analysis of the maximum power point (MPP) of photovoltaic panels ... more In this chapter, we propose the analysis of the maximum power point (MPP) of photovoltaic panels (PV) in a renewable energy application. From the current–voltage characteristics, we deduced the MPP of a PV panel and specified the use of a power block (DC/DC converter) controlled by an MPPT control. In the case of an MPPT control of type perturb and observe, we realized the photovoltaic system that heats a photovoltaic solar cooker, taking into account this MPPT command. The experimentation of this application, during a sunny day, shows that the MPPT control carries out its role correctly, such as optimal operation of the PV panels and heating of the cooker by the maximum power supplied by the PV panels. The analysis of all the results shows an excellent agreement between the experiment and the simulation of the operation of the photovoltaic system which made it possible to operate the photovoltaic panels around their MPP, over the course of the sun. Under these conditions, the efficiency of the proposed DC/DC converter, with a power of 500 Wp, is of the order of 97%.
Key Engineering Materials, Jul 29, 2022
Improving the conversion efficiency of solar cells is a key way to make solar cells cost-competit... more Improving the conversion efficiency of solar cells is a key way to make solar cells cost-competitive with conventional sources of energy because the cost of electricity produced from solar cells depends on their efficiency. According to Shockley-Queisser limit, all single junctions cells have a theoretical efficiency limit of 33.7%. Efficiency losses are associated with light that either is not energetic enough or too energetic for the generation of an electron-hole pair. In other words, the two most important loss mechanisms in single bandgap solar cells are the inability to convert photons with energies below the bandgap energy (Eg) into electricity and the thermalization of photon energies exceeding Eg. These two mechanisms alone represent the loss of about half of the incident solar energy during the conversion. Intermediate band (IB) located inside the forbidden band of the host semiconductor, making it possible to increase the absorption of photons with energy lower than the band gap energy Eg, can be a solution for the first problem. The effect of IB on the efficiency of solar cells was discussed. Our aim is to show how IB can improve the efficiency of solar cells based on Quantum Dots (QDs), i.e, the efficiency of a solar cell can be greatly increased through additional optical absorption. In this paper, two cases were discussed applying a numerical model. Our model, used to calculate solar cells efficiency and to plot the current-voltage (I-V) characteristics and the power-voltage (P-V) characteristics curves, is mainly based on the principles of the detailed balance between absorption and emission of solar light and well separated quasi-Fermi levels. The first case is an idealized case where the recombinations are assumed to be entirely radiative. In the second case, the model takes into account the non-radiative recombinations introduced by the increase in the density of defects caused by the increase in the size of the QDs. It has been shown that Consideration of size leading to the reduction of the defects is one of important key solution to increase the efficiency of intermediate band solar cells (IBSC).
Materials Today: Proceedings, 2023
Materials Today: Proceedings
Scientific African, Sep 1, 2022
Research Developments in Science and Technology Vol. 10
Materials Today: Proceedings
Materials Today: Proceedings, 2021
† Yazar isimleri alfabetik olarak sıralanmıştır. Yazarlar makaleye eşit katkıda bulunmuştur.
The purpose of this study is to analyze the energy behavior of a solar oven box-type with four re... more The purpose of this study is to analyze the energy behavior of a solar oven box-type with four reflectors inside and outside and with thermal storage. To achieve this work, we have modeled the equations of heat balances transient by numerical simulation by using Matlab (the method of runge-kutta of order 4). Hence, we were able to determine the temperature profiles in different parts of the oven as well as in the material storage.
Materials Today: Proceedings, 2021
Abstract The efficiency of Quantum Dots (QDs) devices, is strongly related to their distribution,... more Abstract The efficiency of Quantum Dots (QDs) devices, is strongly related to their distribution, density and size, and shape in a QD array. The small size of the QD structure leads to a three-dimensional confinement of the electronic energies. The energy levels of electrons in QDs depends on their size – the smaller the quantum dot, the greater the amount of energy required to give electrons transitions to the next level. In this paper, we report the simulation results of pyramidal InAs/GaAs QDs coupled to Wetting Layer (WL). To investigate the effects of the InAs/GaAs QDs size on the electronic states and the transition energy. In the first part, we calculate the strain distribution to find the band edges, while the second one concerns the variation of the electronic transition energy as a function of quantum dots size by solving the stationary Schrodinger equation. This work shows clearly that the structural properties of QDs have strong effects on optoelectronic properties devices based on these nanostructures.
International Review of Electrical Engineering (IREE), 2015
The work presented in this paper concerns the conception, implementation and testing of a photovo... more The work presented in this paper concerns the conception, implementation and testing of a photovoltaic system equipped with a new concept of controller 'regulator/ MPPT'. The role of the controller is, firstly, to exploit the maximum power by Hill climbing improved algorithm that considers optimal electrical characteristics of PV panels (variation of the optimal voltage of the panels during operation around the maximum power point) regardless of the system perturbation such as sudden variation of illumination. Secondly, to manage the energy between panels and batteries and also, between panels and grid, in order to control the charge / discharge process with taking into consideration the different situations that can occur in an installation (charge cycle, discharge cycle, charge/discharge cycle). Thirdly, to inject the surplus of energy provided by panels into the grid when the batteries are fully charged and even when they are in charge phases (second and third phases of charge while regulation is enabled; a part of the power delivered by the panels is not absorbed by the batteries). And also, its role is to estimate the state of charge with precision by the combination of two methods: the OCV method and the coulomb counting method. In addition, the system ensures all of the following functions: display of parameters on LCD, acquisition and presentation of results on computer, supervision and so on. The results obtained during days of experimentation, under weather disturbances (variation of the irradiance and temperature) show the robustness of the PV system, the good control of batteries charge/discharge process under the maximum of energy provided by the PV panels and the protection against overcharging and deep discharging. The surplus of energy provided by panels and unabsorbed by the batteries is transferred into the grid. The estimation of the state of charge SoC is evaluated from the measured parameters in real time; it shows an improvement of around 5% compared to the conventional technique. It is conceived so that it can be adapted to any battery system of type lead.
2016 International Conference on Electrical and Information Technologies (ICEIT), 2016
2014 International Conference on Multimedia Computing and Systems (ICMCS), 2014
Renewable Energy and Sustainable Development, 2016
In this paper the researchers present a work concerning the conception, implementation and testin... more In this paper the researchers present a work concerning the conception, implementation and testing of a photovoltaic system that is equipped with a new concept of control and management of energy in a PV system with battery storage. The objective is to exploit the maximum of power using Hill climbing improved algorithm that considers optimal electrical characteristics of PV panels regardless of the system perturbation, to manage the energy between blocs of PV system in order to control the charge/discharge process and inject the energy surplus into the grid and also to estimate the state of charge with precision. Moreover, the system guarantees the acquisition and presentation of results on computer, supervision and so on. The results obtained show the robustness of the PV system, good control and protection of batteries under the maximum of energy provided by the PV panels. The state of charge estimation is evaluated by using measured parameters in real time; it shows an improvement of around 5% compared to the conventional technique.
2012 International Conference on Multimedia Computing and Systems, 2012
ABSTRACT In this paper, we present the results related to the design, realization and modeling of... more ABSTRACT In this paper, we present the results related to the design, realization and modeling of a photovoltaic (PV) prototype with a powerful analogical command MPPT (Maximum Power Point Tracking). The results will be validated on the ground in the case of a PV station, for lighting and pumping water. These works are realized in the framework of 'Art Gold Morocco' Program of the United Nations (UN) to improve the living conditions of the inhabitants of Douar Zragta (Rural District of Oujda-Angad Prefecture). This Douar is not connected to the electrical network of ONE and does not have access to drinking water provided by ONEP. The results obtained show that the prototype developed in our research team reduces significantly the energy losses produced by PV panels (7%). Electrical characterization and modeling results carried out at the PV station of Douar Zragta, compared to those obtained in our laboratory, allowed us to conclude that the electrical power losses of the station are about 25-30%. Therefore, the use of the prototype developed in our team is necessary to improve the energy performance and reduce the cost of the PV station.
2014 International Conference on Multimedia Computing and Systems (ICMCS), 2014
Lecture Notes in Electrical Engineering, 2016
Lecture Notes in Electrical Engineering, 2016
IntechOpen eBooks, Mar 31, 2023
In this chapter, we propose the analysis of the maximum power point (MPP) of photovoltaic panels ... more In this chapter, we propose the analysis of the maximum power point (MPP) of photovoltaic panels (PV) in a renewable energy application. From the current–voltage characteristics, we deduced the MPP of a PV panel and specified the use of a power block (DC/DC converter) controlled by an MPPT control. In the case of an MPPT control of type perturb and observe, we realized the photovoltaic system that heats a photovoltaic solar cooker, taking into account this MPPT command. The experimentation of this application, during a sunny day, shows that the MPPT control carries out its role correctly, such as optimal operation of the PV panels and heating of the cooker by the maximum power supplied by the PV panels. The analysis of all the results shows an excellent agreement between the experiment and the simulation of the operation of the photovoltaic system which made it possible to operate the photovoltaic panels around their MPP, over the course of the sun. Under these conditions, the efficiency of the proposed DC/DC converter, with a power of 500 Wp, is of the order of 97%.
Key Engineering Materials, Jul 29, 2022
Improving the conversion efficiency of solar cells is a key way to make solar cells cost-competit... more Improving the conversion efficiency of solar cells is a key way to make solar cells cost-competitive with conventional sources of energy because the cost of electricity produced from solar cells depends on their efficiency. According to Shockley-Queisser limit, all single junctions cells have a theoretical efficiency limit of 33.7%. Efficiency losses are associated with light that either is not energetic enough or too energetic for the generation of an electron-hole pair. In other words, the two most important loss mechanisms in single bandgap solar cells are the inability to convert photons with energies below the bandgap energy (Eg) into electricity and the thermalization of photon energies exceeding Eg. These two mechanisms alone represent the loss of about half of the incident solar energy during the conversion. Intermediate band (IB) located inside the forbidden band of the host semiconductor, making it possible to increase the absorption of photons with energy lower than the band gap energy Eg, can be a solution for the first problem. The effect of IB on the efficiency of solar cells was discussed. Our aim is to show how IB can improve the efficiency of solar cells based on Quantum Dots (QDs), i.e, the efficiency of a solar cell can be greatly increased through additional optical absorption. In this paper, two cases were discussed applying a numerical model. Our model, used to calculate solar cells efficiency and to plot the current-voltage (I-V) characteristics and the power-voltage (P-V) characteristics curves, is mainly based on the principles of the detailed balance between absorption and emission of solar light and well separated quasi-Fermi levels. The first case is an idealized case where the recombinations are assumed to be entirely radiative. In the second case, the model takes into account the non-radiative recombinations introduced by the increase in the density of defects caused by the increase in the size of the QDs. It has been shown that Consideration of size leading to the reduction of the defects is one of important key solution to increase the efficiency of intermediate band solar cells (IBSC).
Materials Today: Proceedings, 2023
Materials Today: Proceedings
Scientific African, Sep 1, 2022
Research Developments in Science and Technology Vol. 10
Materials Today: Proceedings
Materials Today: Proceedings, 2021
† Yazar isimleri alfabetik olarak sıralanmıştır. Yazarlar makaleye eşit katkıda bulunmuştur.
The purpose of this study is to analyze the energy behavior of a solar oven box-type with four re... more The purpose of this study is to analyze the energy behavior of a solar oven box-type with four reflectors inside and outside and with thermal storage. To achieve this work, we have modeled the equations of heat balances transient by numerical simulation by using Matlab (the method of runge-kutta of order 4). Hence, we were able to determine the temperature profiles in different parts of the oven as well as in the material storage.
Materials Today: Proceedings, 2021
Abstract The efficiency of Quantum Dots (QDs) devices, is strongly related to their distribution,... more Abstract The efficiency of Quantum Dots (QDs) devices, is strongly related to their distribution, density and size, and shape in a QD array. The small size of the QD structure leads to a three-dimensional confinement of the electronic energies. The energy levels of electrons in QDs depends on their size – the smaller the quantum dot, the greater the amount of energy required to give electrons transitions to the next level. In this paper, we report the simulation results of pyramidal InAs/GaAs QDs coupled to Wetting Layer (WL). To investigate the effects of the InAs/GaAs QDs size on the electronic states and the transition energy. In the first part, we calculate the strain distribution to find the band edges, while the second one concerns the variation of the electronic transition energy as a function of quantum dots size by solving the stationary Schrodinger equation. This work shows clearly that the structural properties of QDs have strong effects on optoelectronic properties devices based on these nanostructures.
International Review of Electrical Engineering (IREE), 2015
The work presented in this paper concerns the conception, implementation and testing of a photovo... more The work presented in this paper concerns the conception, implementation and testing of a photovoltaic system equipped with a new concept of controller 'regulator/ MPPT'. The role of the controller is, firstly, to exploit the maximum power by Hill climbing improved algorithm that considers optimal electrical characteristics of PV panels (variation of the optimal voltage of the panels during operation around the maximum power point) regardless of the system perturbation such as sudden variation of illumination. Secondly, to manage the energy between panels and batteries and also, between panels and grid, in order to control the charge / discharge process with taking into consideration the different situations that can occur in an installation (charge cycle, discharge cycle, charge/discharge cycle). Thirdly, to inject the surplus of energy provided by panels into the grid when the batteries are fully charged and even when they are in charge phases (second and third phases of charge while regulation is enabled; a part of the power delivered by the panels is not absorbed by the batteries). And also, its role is to estimate the state of charge with precision by the combination of two methods: the OCV method and the coulomb counting method. In addition, the system ensures all of the following functions: display of parameters on LCD, acquisition and presentation of results on computer, supervision and so on. The results obtained during days of experimentation, under weather disturbances (variation of the irradiance and temperature) show the robustness of the PV system, the good control of batteries charge/discharge process under the maximum of energy provided by the PV panels and the protection against overcharging and deep discharging. The surplus of energy provided by panels and unabsorbed by the batteries is transferred into the grid. The estimation of the state of charge SoC is evaluated from the measured parameters in real time; it shows an improvement of around 5% compared to the conventional technique. It is conceived so that it can be adapted to any battery system of type lead.
2016 International Conference on Electrical and Information Technologies (ICEIT), 2016
2014 International Conference on Multimedia Computing and Systems (ICMCS), 2014
Renewable Energy and Sustainable Development, 2016
In this paper the researchers present a work concerning the conception, implementation and testin... more In this paper the researchers present a work concerning the conception, implementation and testing of a photovoltaic system that is equipped with a new concept of control and management of energy in a PV system with battery storage. The objective is to exploit the maximum of power using Hill climbing improved algorithm that considers optimal electrical characteristics of PV panels regardless of the system perturbation, to manage the energy between blocs of PV system in order to control the charge/discharge process and inject the energy surplus into the grid and also to estimate the state of charge with precision. Moreover, the system guarantees the acquisition and presentation of results on computer, supervision and so on. The results obtained show the robustness of the PV system, good control and protection of batteries under the maximum of energy provided by the PV panels. The state of charge estimation is evaluated by using measured parameters in real time; it shows an improvement of around 5% compared to the conventional technique.
2012 International Conference on Multimedia Computing and Systems, 2012
ABSTRACT In this paper, we present the results related to the design, realization and modeling of... more ABSTRACT In this paper, we present the results related to the design, realization and modeling of a photovoltaic (PV) prototype with a powerful analogical command MPPT (Maximum Power Point Tracking). The results will be validated on the ground in the case of a PV station, for lighting and pumping water. These works are realized in the framework of 'Art Gold Morocco' Program of the United Nations (UN) to improve the living conditions of the inhabitants of Douar Zragta (Rural District of Oujda-Angad Prefecture). This Douar is not connected to the electrical network of ONE and does not have access to drinking water provided by ONEP. The results obtained show that the prototype developed in our research team reduces significantly the energy losses produced by PV panels (7%). Electrical characterization and modeling results carried out at the PV station of Douar Zragta, compared to those obtained in our laboratory, allowed us to conclude that the electrical power losses of the station are about 25-30%. Therefore, the use of the prototype developed in our team is necessary to improve the energy performance and reduce the cost of the PV station.
2014 International Conference on Multimedia Computing and Systems (ICMCS), 2014
Lecture Notes in Electrical Engineering, 2016
Lecture Notes in Electrical Engineering, 2016