This article presents different combinations of input parameters based on an intelligent techniqu... more This article presents different combinations of input parameters based on an intelligent technique, using neural networks to predict daily global solar radiation (GSR) for twentyfive Moroccan cities. The collected measured data are available for 365 days and 25 stations around Morocco. Different input parameters are used, such as clearness index K T , day number, the length of the day, minimal temperature T min , maximal temperature T max , average temperature T average , difference temperature ĪT, ratio temperature T-Ratio, average relative humidity RH, solar radiation at the top outside atmosphere TOA, average wind speed Ws, altitude, longitude, latitude, and solar declination. A different combination was employed to predict daily GSR for the considered locations in order to find the most adequate input parameter that can be used in the prediction procedure. Several statistical metrics are applied to evaluate the performance of the obtained results, such as coefficients of determination (R 2), mean absolute percentage error (MAPE), root mean square error (RMSE), normalized root mean square error (NRMSE), mean bias error (MBE), test statistic (TS), linear regression coefficients (the slope "a" and the constant "b"), and standard deviation (Ļ). It is found that the usage of input parameters gives highly accurate results in the artificial neural network (FFNN-BP) model, obtaining the lowest value of the statistical metrics. The results showed the best input of 25 locations, 12 inputs
2020 5th International Conference on Smart and Sustainable Technologies (SpliTech), Sep 23, 2020
One way to increase the energy amount obtained from renewable sources is to improve their efficie... more One way to increase the energy amount obtained from renewable sources is to improve their efficiency. This study analyses the influence of hybridization upon the monocrystalline silicon and Maxeon photovoltaic cells temperature distribution and its variation in days with clear and cloudy sky. Three photovoltaic cells for each type mentioned before are measured. Two of them, connected in series, are part of photovoltaic/thermoelectric generators/solar collector hybrid system, which are cooled, and the third is uncooled and mounted on the same plane with the other two. The maximum power and the efficiency gain for both types of photovoltaic cells are performed and analyzed in different conditions using a fixed system and a sun tracker system as support for the hybrid system. The advantages of the temperature decrease are also discussed.
Increased reflectance (higher albedo) of solar radiation by the wheat canopy can contribute to re... more Increased reflectance (higher albedo) of solar radiation by the wheat canopy can contribute to reducing canopy temperature and transpiration, and therefore to improved performance under drought and heat, and to mitigating the effects of climate changes. The measurements of albedo were made on twenty four Romanian winter wheat cultivars and one Russian cultivar as historical check, using an albedometer based on solar cells, and found significant differences among cultivars, both between and within earliness groups. These differences can be used in a breeding program aimed at increasing crop albedo, for improving wheat performance under water and high temperature stress.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The performance of the hybrid structures PV/TEG/STC which consist of photovoltaic cells PV, therm... more The performance of the hybrid structures PV/TEG/STC which consist of photovoltaic cells PV, thermoelectric elements TEG and solar collector STC is studied in this paper function of different levels of illumination from 30 suns to 130 suns (1 sun = 1000 W/m2). The concentrated light is obtained using a solar simulator with four parabolic xenon lamps and an optical mixer to ensure the quasi homogenous illumination of the hybrid system. The important parameters of the photovoltaic cells and of the thermoelectric generators are determined using the current-voltage characteristics. The measurements and control are realized using the NI-cRIO platform and the software is developed in LabVIEW.
The quick progress in solar energy technology has made it one of the most promising alternatives ... more The quick progress in solar energy technology has made it one of the most promising alternatives to conventional energy systems in recent years. In this work, in order to make efficient use of the solar energy, a hybrid system composed of the concentrated photovoltaic cell and thermoelectric generator (CPV-TEG) is studied using both experimental and numerical approaches. The experimental study is carried out under concentrated radiation of a solar simulator, and the numerical simulation is accomplished using finite volume method. The results are presented for various solar concentration (SC) values ranging from 8 suns to 37 suns. The variation of the temperatures, open circuit voltage, and short circuit current are discussed. I-V-P curves for both CPV and TEG are obtained and evaluated experimentally and numerically. The results show that contribution of the TEG in the total electrical power produced by the hybrid system enhances with increasing the solar radiation. Furthermore, the experimental results indicate that the maximum and minimum efficiency of the CPV is reached to 35.33% and 23.02%, while these values for the TEG are 1.20% and 0.63%, respectively.
2020 5th International Conference on Smart and Sustainable Technologies (SpliTech), Sep 23, 2020
During field operation, photovoltaic cells (PVs) are often subject to rapid variations in inciden... more During field operation, photovoltaic cells (PVs) are often subject to rapid variations in incident light, due to fast moving clouds. This causes variations in the operating temperature of the PVs as well. In this work we study the effect of rapid concentrated light variation over the PVs as an ageing method. The irradiance and thermal cycles were performed using a self-developed system with a controlled shutter that modulates the highly concentrated light incident on the PVs. Through the load we developed based on the impedance variation of a capacitor and a coil during the charge/discharge process, the main DC and AC parameters of the PVs are monitored in-situ through the I-V characteristics and RLC method measurements. Preliminary results show a degradation of 0.6% of the PVs caused by the light and temperature stress.
This paper describes a model and its PSPICE simulation for a hybrid electric generator that is co... more This paper describes a model and its PSPICE simulation for a hybrid electric generator that is composed of a photovoltaic cell and a thermoelectric generator. The focus is to combine both models to obtain a hybrid system model. The electrothermal models of the photovoltaic cell and thermoelectric generator are described. The simulations are done using the NI Multisim electronic circuit simulators. The comparison between the results obtained through simulation and through real measurements on commercial PV and thermoelectric generators is also presented.
LabVIEW - Virtual Instrumentation in Education and Industry [Working Title]
The demand of energy increases once with the growth of population, and therefore, the finding of ... more The demand of energy increases once with the growth of population, and therefore, the finding of or improvement in the efficiency of renewable energy sources becomes very important for researchers and industry. The conversion of solar energy into electrical energy can be done based on photovoltaic or Seebeck effects. In the first case, photovoltaic panels are used, while in the second case, thermoelectric generators are used. The two can be combined to obtain the so-called hybrid systems, which have the goal to improve the overall conversion efficiency of the system. This chapter is focused on showing how the graphical programing language, called NI LabVIEW, together with a SPICE simulator, called NI Multisim, can be used for studying and understanding the behavior of the photovoltaic and thermoelectric generators as parts of the renewable energy sources. Different simulations developed in LabVIEW or Multisim are presented, and some monitoring and characterization applications are a...
Editorial on the Research Topic Forecasting solar radiation, photovoltaic power and thermal energ... more Editorial on the Research Topic Forecasting solar radiation, photovoltaic power and thermal energy production aplications." Forecasting energy production of photovoltaic systems is a hot Research Topic nowadays, when energy prices are one of the highest in history. The forecast of the photovoltaic power production can be on the long term from 1 month to 1 year, on medium-term from 1 week to 1 month, on short-term from 6 h to 72 h, and on very shortterm from 15 min to 6 h. It is crucial to forecast solar radiation and photovoltaic power production so as to control and manage the electrical stand-alone systems, smartgrids and grids, to ensure power demand can be met (Kumar et al., 2020). The forecast can be made using the following methods: numerical weather prediction models (NWP), physical techniques, linear statistical models, and machine learning techniques (Ramirez-Vergara et al., 2021). The Research Topic aims to cover some of the forecast problems. It has eight accepted papers, that cover the following Research Topic: methods to maximize the output power of the photovoltaic system, solar radiation forecast, and power generation prediction. There are several methods to maximize the energy output of the photovoltaic systems. Guo et al. use artificial intelligence to find the maximum power point (MPP) under partial shading conditions. They designed a fuzzy adaptive PSO-based MPP tracker. The solar radiation is forecasted using several methods. Mohanty et al. used an adaptive neuro-fuzzy inference system, for different locations, which has three input parameters, such as: the duration of the sunshine, temperature, and humidity, and clearness index as the output parameter. Silva et al. used linear modeling ARX and ARMAX to forecast solar radiation with very good accuracy for the Brazilian locations. Belmahdi et al. predicted the daily global solar radiation for 25 different Moroccan cities by using feedforward neural backpropagation network method, FFNN-BP. The input parameters are solar radiation at the top outside atmosphere, clearness index, solar declination, latitude, longitude, altitude, day number, the length of the day, minimum and maximum temperature, mean temperature, temperature
Journal of Optoelectronics and Advanced Materials, 2008
The article includes a review of some methods to determine series and shunt resistances. It also ... more The article includes a review of some methods to determine series and shunt resistances. It also presents a new method to determine series and shunt resistances and a comparison of results to previous literature methods. The new method is based on the one diode model for solar cells and is applied on a c-Si cell. The dependence of the series resistance on the irradiance levels is also presented. The complex programme developed to determine the cell characterization and implicitly for the determination of series resistance is included. The programme was created in the graphical programming language LabVIEW.
2021 International Aegean Conference on Electrical Machines and Power Electronics (ACEMP) & 2021 International Conference on Optimization of Electrical and Electronic Equipment (OPTIM), 2021
With the growth of Industry 4.0, cyber-physical systems are increasingly present in everyday life... more With the growth of Industry 4.0, cyber-physical systems are increasingly present in everyday life, thus optimizing traditional processes. This paper presents a solution for photovoltaic panel parameters monitoring application fully integrated into an IoT system. The application can record and process sensor data such as photovoltaic (PV) panel current, voltage, illuminance level, PV temperature as well as atmospheric pressure, ambient temperature, and humidity over a long-distance solution utilizing the LoRa Wide-Area Network protocol. The Internet of Things node is designed for security, accuracy and low power consumption, while also providing an established user interface through a proprietary software as a service Live Object platform. By utilizing Live Objects, complete IoT applications can be developed with the device and data management being handled by the platform. The advancements in terms of hardware and software configuration, sensor choice and operation are described. In this way, we can create a scalable and secure Internet of Things ecosystem using low-cost and power efficient devices, integrated in a secure and easy to use software as a service (SaaS) platform.
This article presents different combinations of input parameters based on an intelligent techniqu... more This article presents different combinations of input parameters based on an intelligent technique, using neural networks to predict daily global solar radiation (GSR) for twentyfive Moroccan cities. The collected measured data are available for 365 days and 25 stations around Morocco. Different input parameters are used, such as clearness index K T , day number, the length of the day, minimal temperature T min , maximal temperature T max , average temperature T average , difference temperature ĪT, ratio temperature T-Ratio, average relative humidity RH, solar radiation at the top outside atmosphere TOA, average wind speed Ws, altitude, longitude, latitude, and solar declination. A different combination was employed to predict daily GSR for the considered locations in order to find the most adequate input parameter that can be used in the prediction procedure. Several statistical metrics are applied to evaluate the performance of the obtained results, such as coefficients of determination (R 2), mean absolute percentage error (MAPE), root mean square error (RMSE), normalized root mean square error (NRMSE), mean bias error (MBE), test statistic (TS), linear regression coefficients (the slope "a" and the constant "b"), and standard deviation (Ļ). It is found that the usage of input parameters gives highly accurate results in the artificial neural network (FFNN-BP) model, obtaining the lowest value of the statistical metrics. The results showed the best input of 25 locations, 12 inputs
2020 5th International Conference on Smart and Sustainable Technologies (SpliTech), Sep 23, 2020
One way to increase the energy amount obtained from renewable sources is to improve their efficie... more One way to increase the energy amount obtained from renewable sources is to improve their efficiency. This study analyses the influence of hybridization upon the monocrystalline silicon and Maxeon photovoltaic cells temperature distribution and its variation in days with clear and cloudy sky. Three photovoltaic cells for each type mentioned before are measured. Two of them, connected in series, are part of photovoltaic/thermoelectric generators/solar collector hybrid system, which are cooled, and the third is uncooled and mounted on the same plane with the other two. The maximum power and the efficiency gain for both types of photovoltaic cells are performed and analyzed in different conditions using a fixed system and a sun tracker system as support for the hybrid system. The advantages of the temperature decrease are also discussed.
Increased reflectance (higher albedo) of solar radiation by the wheat canopy can contribute to re... more Increased reflectance (higher albedo) of solar radiation by the wheat canopy can contribute to reducing canopy temperature and transpiration, and therefore to improved performance under drought and heat, and to mitigating the effects of climate changes. The measurements of albedo were made on twenty four Romanian winter wheat cultivars and one Russian cultivar as historical check, using an albedometer based on solar cells, and found significant differences among cultivars, both between and within earliness groups. These differences can be used in a breeding program aimed at increasing crop albedo, for improving wheat performance under water and high temperature stress.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The performance of the hybrid structures PV/TEG/STC which consist of photovoltaic cells PV, therm... more The performance of the hybrid structures PV/TEG/STC which consist of photovoltaic cells PV, thermoelectric elements TEG and solar collector STC is studied in this paper function of different levels of illumination from 30 suns to 130 suns (1 sun = 1000 W/m2). The concentrated light is obtained using a solar simulator with four parabolic xenon lamps and an optical mixer to ensure the quasi homogenous illumination of the hybrid system. The important parameters of the photovoltaic cells and of the thermoelectric generators are determined using the current-voltage characteristics. The measurements and control are realized using the NI-cRIO platform and the software is developed in LabVIEW.
The quick progress in solar energy technology has made it one of the most promising alternatives ... more The quick progress in solar energy technology has made it one of the most promising alternatives to conventional energy systems in recent years. In this work, in order to make efficient use of the solar energy, a hybrid system composed of the concentrated photovoltaic cell and thermoelectric generator (CPV-TEG) is studied using both experimental and numerical approaches. The experimental study is carried out under concentrated radiation of a solar simulator, and the numerical simulation is accomplished using finite volume method. The results are presented for various solar concentration (SC) values ranging from 8 suns to 37 suns. The variation of the temperatures, open circuit voltage, and short circuit current are discussed. I-V-P curves for both CPV and TEG are obtained and evaluated experimentally and numerically. The results show that contribution of the TEG in the total electrical power produced by the hybrid system enhances with increasing the solar radiation. Furthermore, the experimental results indicate that the maximum and minimum efficiency of the CPV is reached to 35.33% and 23.02%, while these values for the TEG are 1.20% and 0.63%, respectively.
2020 5th International Conference on Smart and Sustainable Technologies (SpliTech), Sep 23, 2020
During field operation, photovoltaic cells (PVs) are often subject to rapid variations in inciden... more During field operation, photovoltaic cells (PVs) are often subject to rapid variations in incident light, due to fast moving clouds. This causes variations in the operating temperature of the PVs as well. In this work we study the effect of rapid concentrated light variation over the PVs as an ageing method. The irradiance and thermal cycles were performed using a self-developed system with a controlled shutter that modulates the highly concentrated light incident on the PVs. Through the load we developed based on the impedance variation of a capacitor and a coil during the charge/discharge process, the main DC and AC parameters of the PVs are monitored in-situ through the I-V characteristics and RLC method measurements. Preliminary results show a degradation of 0.6% of the PVs caused by the light and temperature stress.
This paper describes a model and its PSPICE simulation for a hybrid electric generator that is co... more This paper describes a model and its PSPICE simulation for a hybrid electric generator that is composed of a photovoltaic cell and a thermoelectric generator. The focus is to combine both models to obtain a hybrid system model. The electrothermal models of the photovoltaic cell and thermoelectric generator are described. The simulations are done using the NI Multisim electronic circuit simulators. The comparison between the results obtained through simulation and through real measurements on commercial PV and thermoelectric generators is also presented.
LabVIEW - Virtual Instrumentation in Education and Industry [Working Title]
The demand of energy increases once with the growth of population, and therefore, the finding of ... more The demand of energy increases once with the growth of population, and therefore, the finding of or improvement in the efficiency of renewable energy sources becomes very important for researchers and industry. The conversion of solar energy into electrical energy can be done based on photovoltaic or Seebeck effects. In the first case, photovoltaic panels are used, while in the second case, thermoelectric generators are used. The two can be combined to obtain the so-called hybrid systems, which have the goal to improve the overall conversion efficiency of the system. This chapter is focused on showing how the graphical programing language, called NI LabVIEW, together with a SPICE simulator, called NI Multisim, can be used for studying and understanding the behavior of the photovoltaic and thermoelectric generators as parts of the renewable energy sources. Different simulations developed in LabVIEW or Multisim are presented, and some monitoring and characterization applications are a...
Editorial on the Research Topic Forecasting solar radiation, photovoltaic power and thermal energ... more Editorial on the Research Topic Forecasting solar radiation, photovoltaic power and thermal energy production aplications." Forecasting energy production of photovoltaic systems is a hot Research Topic nowadays, when energy prices are one of the highest in history. The forecast of the photovoltaic power production can be on the long term from 1 month to 1 year, on medium-term from 1 week to 1 month, on short-term from 6 h to 72 h, and on very shortterm from 15 min to 6 h. It is crucial to forecast solar radiation and photovoltaic power production so as to control and manage the electrical stand-alone systems, smartgrids and grids, to ensure power demand can be met (Kumar et al., 2020). The forecast can be made using the following methods: numerical weather prediction models (NWP), physical techniques, linear statistical models, and machine learning techniques (Ramirez-Vergara et al., 2021). The Research Topic aims to cover some of the forecast problems. It has eight accepted papers, that cover the following Research Topic: methods to maximize the output power of the photovoltaic system, solar radiation forecast, and power generation prediction. There are several methods to maximize the energy output of the photovoltaic systems. Guo et al. use artificial intelligence to find the maximum power point (MPP) under partial shading conditions. They designed a fuzzy adaptive PSO-based MPP tracker. The solar radiation is forecasted using several methods. Mohanty et al. used an adaptive neuro-fuzzy inference system, for different locations, which has three input parameters, such as: the duration of the sunshine, temperature, and humidity, and clearness index as the output parameter. Silva et al. used linear modeling ARX and ARMAX to forecast solar radiation with very good accuracy for the Brazilian locations. Belmahdi et al. predicted the daily global solar radiation for 25 different Moroccan cities by using feedforward neural backpropagation network method, FFNN-BP. The input parameters are solar radiation at the top outside atmosphere, clearness index, solar declination, latitude, longitude, altitude, day number, the length of the day, minimum and maximum temperature, mean temperature, temperature
Journal of Optoelectronics and Advanced Materials, 2008
The article includes a review of some methods to determine series and shunt resistances. It also ... more The article includes a review of some methods to determine series and shunt resistances. It also presents a new method to determine series and shunt resistances and a comparison of results to previous literature methods. The new method is based on the one diode model for solar cells and is applied on a c-Si cell. The dependence of the series resistance on the irradiance levels is also presented. The complex programme developed to determine the cell characterization and implicitly for the determination of series resistance is included. The programme was created in the graphical programming language LabVIEW.
2021 International Aegean Conference on Electrical Machines and Power Electronics (ACEMP) & 2021 International Conference on Optimization of Electrical and Electronic Equipment (OPTIM), 2021
With the growth of Industry 4.0, cyber-physical systems are increasingly present in everyday life... more With the growth of Industry 4.0, cyber-physical systems are increasingly present in everyday life, thus optimizing traditional processes. This paper presents a solution for photovoltaic panel parameters monitoring application fully integrated into an IoT system. The application can record and process sensor data such as photovoltaic (PV) panel current, voltage, illuminance level, PV temperature as well as atmospheric pressure, ambient temperature, and humidity over a long-distance solution utilizing the LoRa Wide-Area Network protocol. The Internet of Things node is designed for security, accuracy and low power consumption, while also providing an established user interface through a proprietary software as a service Live Object platform. By utilizing Live Objects, complete IoT applications can be developed with the device and data management being handled by the platform. The advancements in terms of hardware and software configuration, sensor choice and operation are described. In this way, we can create a scalable and secure Internet of Things ecosystem using low-cost and power efficient devices, integrated in a secure and easy to use software as a service (SaaS) platform.
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