Graphic summary
  • Show / hide key
  • Information


Scientific and technological production
  •  

1 to 50 of 132 results
  • Improving the performance of PV systems by faults detection using GISTEL approach

     Tadj, Mohammed; Benmouiza, Khalil; Cheknane, Ali; Silvestre Berges, Santiago
    Energy conversion and management
    Date of publication: 2014-04-01
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    In this paper, we present a new approach for detecting the faults in the photovoltaic systems based on the satellite image approach for estimating solar radiation data and DC output power calculations for detecting the failures. At first stage, the estimation of the hourly global horizontal solar radiation data has been evaluated by using the GISTEL (Gisement solaire par teledetection: Solar Radiation by Teledectection) model improved by the fuzzy logic technique. Thus, the results were compared with the ground solar radiation measurements. On the other hand, the comparison between the simulated and measured output DC powers was reached to find the nature of the faults in the PV array.; The results showed a good accuracy and the simple implementation of the proposed approach. The estimation of the hourly solar radiation presents an NRMSE <0.22 using GISTEL model improved by fuzzy logic comparing with the estimation without fuzzy logic with an NRMSE = 0.2885 for clear sky and NRMSE = 0.2852 comparing with NRMSE = 0.3121 for cloudy sky. (C) 2014 Elsevier Ltd. All rights reserved.

  • Global MPPT scheme for photovoltaic string inverters based on restricted voltage window search algorithm

     Boztepe, Mutlu; Guinjoan Gispert, Francisco; Velasco Quesada, Guillermo; Silvestre Berges, Santiago; Chouder, Aissa; Karatepe, Engin
    IEEE transactions on industrial electronics
    Date of publication: 2014-07-01
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    String inverter photovoltaic (PV) systems with bypass diodes require improved global maximum power point tracking (GMPPT) algorithms to effectively reach the absolute maximum power operating point. Several GMPPT algorithms have been proposed to deal with this problem, but most of them require scanning wide voltage ranges of the PV array from nearly zero voltage to open-circuit voltage that increases the scanning time and, in turn, causes energy loss. This paper presents a novel GMPPT method which significantly restricts the voltage window search range and tracks the global power peak rapidly in all shading conditions. Simulation tests and experimental comparisons with another GMPPT algorithm are presented to highlight the features of the presented approach.

    String inverter photovoltaic (PV) systems with bypass diodes require improved global maximum power point tracking (GMPPT) algorithms to effectively reach the absolute maximum power operating point. Several GMPPT algorithms have been proposed to deal with this problem, but most of them require scanning wide voltage ranges of the PV array from nearly zero voltage to open-circuit voltage that increases the scanning time and, in turn, causes energy loss. This paper presents a novel GMPPT method which significantly restricts the voltage window search range and tracks the global power peak rapidly in all shading conditions. Simulation tests and experimental comparisons with another GMPPT algorithm are presented to highlight the features of the presented approach.

  • High voltage ultrathin-photovoltaic minimodules: fabrication technology and application to bioimplantable telesupplying

     Bermejo Broto, Alexandra; Silvestre Berges, Santiago; Ortega Villasclaras, Pablo Rafael
    Microelectronic engineering
    Date of publication: 2014-05-01
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    In this work we show small (0.49 cm2) and thin (<70 µm) photovoltaic mini-generators capable of providing open circuit voltages up to 99 V and short circuit currents of 43 µA, achieving a maximum density power of 4.8 mW/cm2. The fabrication process and the thinning process of the minimodules are reported as well as its potential use in high voltage wearable or implantable applications. In this work we show the potential of this technology for high voltage low power consumption applications by means of a simulation study. The minimodules have been modeled using the well known one diode model and simulation results obtained using this model have been validated experimentally. An application example based on simulation for an implantable micropump low power consuming is shown. The system simulates real consumptions of 3 mW working at voltages of 90 Vpp (±45 V) and a frequency of 1 kHz. Simulation results show that the PV system formed by two minimodules allows the micropump system working for 3 h/day showing a good energy balance of the whole system.

    In this work we show small (0.49 cm2) and thin (<70 µm) photovoltaic mini-generators capable of providing open circuit voltages up to 99 V and short circuit currents of 43 µA, achieving a maximum density power of 4.8 mW/cm2. The fabrication process and the thinning process of the minimodules are reported as well as its potential use in high voltage wearable or implantable applications. In this work we show the potential of this technology for high voltage low power consumption applications by means of a simulation study. The minimodules have been modeled using the well known one diode model and simulation results obtained using this model have been validated experimentally. An application example based on simulation for an implantable micropump low power consuming is shown. The system simulates real consumptions of 3 mW working at voltages of 90 Vpp (±45 V) and a frequency of 1 kHz. Simulation results show that the PV system formed by two minimodules allows the micropump system working for 3 h/day showing a good energy balance of the whole system.

  • New procedure for fault detection in grid connected PV systems based on the evaluation of current and voltage indicators

     Silvestre Berges, Santiago; Aires da Silva, Mario; Chouder, Aissa; Guasch Murillo, Daniel; Karatepe, Engin
    Energy Conversion and Management (ECM_4383)
    Date of publication: 2014-05-27
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    In this work we present a new procedure for automatic fault detection in grid connected photovoltaic (PV) systems. This method is based on the evaluation of new current and voltage indicators. Thresholds for these indicators are defined taking into account the PV system configuration: number of PV modules included and series and parallel interconnection to form the array. The procedure to calculate the thresholds that allow the identification of the faults is described. A simulation study was carried out to verify the evaluation of current and voltage indicators and their corresponding thresholds for a set of PV systems with different sizes and different configurations of interconnection of PV modules. The developed method was experimentally validated and has demonstrated its effectiveness in the detection of main faults present in grid connected applications. The computational analysis has been reduced and the number of monitoring sensors minimized. The fault detection procedure can be integrated into the inverter without using simulation software or additional external hardware.

    In this work we present a new procedure for automatic fault detection in grid connected photovoltaic (PV) systems. This method is based on the evaluation of new current and voltage indicators. Thresholds for these indicators are defined taking into account the PV system configuration: number of PV modules included and series and parallel interconnection to form the array. The procedure to calculate the thresholds that allow the identification of the faults is described. A simulation study was carried out to verify the evaluation of current and voltage indicators and their corresponding thresholds for a set of PV systems with different sizes and different configurations of interconnection of PV modules. The developed method was experimentally validated and has demonstrated its effectiveness in the detection of main faults present in grid connected applications. The computational analysis has been reduced and the number of monitoring sensors minimized. The fault detection procedure can be integrated into the inverter without using simulation software or additional external hardware.

  • Voltage band based global MPPT controller for photovoltaic systems

     Gokmen, Nuri; Karatepe, Engin; Ugranli, Faruk; Silvestre Berges, Santiago
    Solar energy
    Date of publication: 2013-09
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    This paper presents a new maximum power point tracking algorithm for PV systems useful in case of non-uniform irradiance conditions. This algorithm takes into account the number of bypass diodes in a PV string to calculate the voltage bands associated with the peak power points that appear in the power¿voltage characteristic of the PV system. The main contribution of this study is to state that the global maximum power point can be tracked by considering only the possible voltage bands which can be found by using the proposed analytical equation in a simple manner. The algorithm is based in the evaluation and analysis of these voltage bands and in the selection of the PV system voltage related to the maximum power point of work. The proposed algorithm has been validated by means of simulation and also in an experimental study.

    This paper presents a new maximum power point tracking algorithm for PV systems useful in case of non-uniform irradiance conditions. This algorithm takes into account the number of bypass diodes in a PV string to calculate the voltage bands associated with the peak power points that appear in the power–voltage characteristic of the PV system. The main contribution of this study is to state that the global maximum power point can be tracked by considering only the possible voltage bands which can be found by using the proposed analytical equation in a simple manner. The algorithm is based in the evaluation and analysis of these voltage bands and in the selection of the PV system voltage related to the maximum power point of work. The proposed algorithm has been validated by means of simulation and also in an experimental study.

  • Sub-Bandgap external quantum efficiency in Ti implanted Si heterojunction with intrinsic thin layer cells

     Silvestre Berges, Santiago; Boronat Moreiro, Alfredo; Colina Brito, Monica Alejandra; Castañer Muñoz, Luis Maria; Olea, Javier; Pastor, David; DelPrado, A.; Martil, Ignacio; Gonzalez Diaz, German; Luque, Antonio; Antolin, Elisa; Hernandez, Estela; Ramiro, Iñigo; Artacho, Irene; López, Esther; Martí, Antonio
    Japanese journal of applied physics
    Date of publication: 2013-11
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    In this work we present the manufacturing processes and results obtained from the characterization of heterojunction with intrinsic thin layer solar cells that include a heavily Ti ion implanted Si absorbing layer. The cells exhibit external circuit photocurrent at photon energies well below the Si bandgap. We discuss the origin of this below-bandgap photocurrent and the modifications in the hydrogenated amorphous intrinsic Si layer thickness to increase the open-circuit voltage.

    In this work we present the manufacturing processes and results obtained from the characterization of heterojunction with intrinsic thin layer solar cells that include a heavily Ti ion implanted Si absorbing layer. The cells exhibit external circuit photocurrent at photon energies well below the Si bandgap. We discuss the origin of this below-bandgap photocurrent and the modifications in the hydrogenated amorphous intrinsic Si layer thickness to increase the open-circuit voltage.

  • Ohmic contacts fabricated on moderately doped p-type GaAs by sputtering deposition and a laser-firing process

     Boronat Moreiro, Alfredo; Silvestre Berges, Santiago; Orpella Garcia, Alberto
    Journal of vacuum science and technology. B, Nanotechnology & microelectronics
    Date of publication: 2013-09-12
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    A novel approach is used to achieve ohmic contacts on moderately doped p-type GaAs substrates. A laser-firing process is used instead of the conventional annealing step. The morphology of the crater created by the laser-firing process and the electrical response of the metal¿semiconductor contact are characterized.

  • Monitoring, modelling and simulation of PV systems using LabVIEW

     Chouder, Aissa; Silvestre Berges, Santiago; Taghezouit, Bilal; Karatepe, Engin
    Solar energy
    Date of publication: 2013-05
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    This paper presents a detailed characterization of the performance and dynamic behaviour of photovoltaic systems by using LabVIEW real-time interface system. The developed software tool integrates several types of instruments into a single system which is able to offer online measurements all data sources and comparison simulation results with monitored data in real-time. Comprehensive monitoring and analyzing of PV systems play a very important role. The proposed method is a low-cost solution to provide fast, secure and reliable system by making the system database-ready for performance analysis of PV systems. The proposed method is also applied to a grid connected PV system in the Centre de Developpement des Energies Renouvelables (CDER) in Algeria. The results show that there is a good agreement between the measured and simulation results values. The integration methodology of robust simulation and monitored data in real-time can be extended to study the fault diagnosis of a PV system.

    This paper presents a detailed characterization of the performance and dynamic behaviour of photovoltaic systems by using LabVIEW real-time interface system. The developed software tool integrates several types of instruments into a single system which is able to offer online measurements all data sources and comparison simulation results with monitored data in real-time. Comprehensive monitoring and analyzing of PV systems play a very important role. The proposed method is a low-cost solution to provide fast, secure and reliable system by making the system database-ready for performance analysis of PV systems. The proposed method is also applied to a grid connected PV system in the Centre de Developpement des Energies Renouvelables (CDER) in Algeria. The results show that there is a good agreement between the measured and simulation results values. The integration methodology of robust simulation and monitored data in real-time can be extended to study the fault diagnosis of a PV system.

  • Effect of annealing atmosphere in the properties of GaAs layers deposited by sputtering techniques on Si substrates

     Galiana, Beatriz; Silvestre Berges, Santiago; Algora, C.; Rey-Stolle, I
    Journal of materials science. Materials in electronics
    Date of publication: 2013-10
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    This work reports changes in the structural properties of sputtered GaAs layers deposited on Si (100) substrates induced by thermal annealing under different arsine atmospheres. The effects of the AsH3 partial pressure (PAsH3) and of the annealing temperature in the GaAs layer properties were analyzed by means of in situ reflectance spectroscopy, in situ transient reflectance at 2.65 eV, X-ray diffraction and atomic force microscopy. The results obtained reveal a direct correlation between the AsH3 partial pressure and the evolution of the GaAs surface morphology as well as the annihilation of As clusters formed during the sputtering procedure.

  • A virtual reality study of surrounding obstacles on BIPV systems for estimation of long-term performance of partially shaded PV arrays

     Celik, Berk; Karatepe, Engin; Gokmen, Nuri; Silvestre Berges, Santiago
    Renewable energy
    Date of publication: 2013-12
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    This work presents a new analytical method to evaluate the efficiency of PV systems working in partial shading conditions by taking into account the effect of surrounding obstacles. A mathematical procedure to determine the shadowed area on PV modules, depending on the location of the PV system and obstacles nearby the array has been implemented. This methodology allows the study of the power losses present in the PV systems due to partial shading conditions as well as its effect on the evolution of the maximum power point of the array. The application of this methodology on the behavior of three PV systems located in different cities of Turkey, such as Istanbul, Izmir, and Antalya, working under the same conditions of obstacle surrounding, along a year is presented.

  • An efficient fault diagnosis method for PV systems based on operating voltage-window

     Gokmen, Nuri; Karatepe, Engin; Silvestre Berges, Santiago; Celik, Berk; Ortega Villasclaras, Pablo Rafael
    Energy conversion and management
    Date of publication: 2013-09
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    With the increasing use of photovoltaic (PV) systems, the research studies to improve the efficiency of PV systems have gained greater interest in recent years, especially under non-uniform operating conditions. However, there is a little attention on fault diagnosis of PV arrays. This paper develops and demonstrates a method that can efficiently detect the number of open and short circuit faults and discriminate between them and partial shading conditions. This method is based on only the measurement of operating voltage of PV string and ambient temperature. In that manner, the proposed method takes into consideration of the minimum number of sensors to reduce the cost of the system, as one of the main purposes of this study. The simulation and experimental results are presented to demonstrate the effectiveness of the proposed method under both uniform and non-uniform irradiance conditions.

    With the increasing use of photovoltaic (PV) systems, the research studies to improve the efficiency of PV systems have gained greater interest in recent years, especially under non-uniform operating conditions. However, there is a little attention on fault diagnosis of PV arrays. This paper develops and demonstrates a method that can efficiently detect the number of open and short circuit faults and discriminate between them and partial shading conditions. This method is based on only the measurement of operating voltage of PV string and ambient temperature. In that manner, the proposed method takes into consideration of the minimum number of sensors to reduce the cost of the system, as one of the main purposes of this study. The simulation and experimental results are presented to demonstrate the effectiveness of the proposed method under both uniform and non-uniform irradiance conditions.

  • Células solares de banda intermedia

     Martí, Antonio; Antolin, Elisa; Linares, P.G.; Ramiro, I.; López, E.; Artacho, Irene; Hernández, E.; Mellor, A.; Mendes, Manuel; Fuertes Marrón, David; Tobias, Ignacio; Tablero, C.; Cristobal, A.B.; Luque, Antonio; Martil, Ignacio; Olea, Javier; Pastor, David; Garcia Hemme, E.; Hernansanz, R.; DelPrado, A.; Gonzalez Diaz, German; Ripalda, J.M.; González, Yolanda; Briones, F.; Silvestre Berges, Santiago; Boronat Moll, Artur; Castañer Muñoz, Luis Maria
    Revista española de física
    Date of publication: 2013-05-14
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Las células solares de banda intermedia se inventaron en España. Constituyen una propuesta para aumentar la eficiencia de las células solares por encima del límite de Shockley y Queisser para células de un solo gap. El número de ideas para llevarlas a la práctica (desde la utilización de puntos cuánticos a la implantación selectiva de impurezas) se ha ido expandiendo a medida que nuestra comprensión ha ido aumentando. En este artículo repasamos el concepto de célula solar de banda intermedia y algunas de estas ideas para llevarla a la práctica.

  • Thermal response of AlN and CNx films as coatings of thin film anemometers

     Arroyo, J.; Silvestre Berges, Santiago; Coll Valenti, Arnau; Castañer Muñoz, Luis Maria
    Measurement
    Date of publication: 2013-05
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Layers of AlN and CNx were investigated as suitable films to coat thin film anemometers because they are simultaneously electrical isolators and thermal conductors. Thermal time constants were measured and thermal equivalent models are proposed in this work. AlN performed better in the experiments.

    Layers of AlN and CNx were investigated as suitable films to coat thin film anemometers because they are simultaneously electrical isolators and thermal conductors. Thermal time constants were measured and thermal equivalent models are proposed in this work. AlN performed better in the experiments.

  • Optical and compositional characterization of GaAs(Ti) thin films deposited by R.F. magnetron sputtering

     Boronat Moll, Artur; Silvestre Berges, Santiago; Castañer Muñoz, Luis Maria
    Journal of non-crystalline solids
    Date of publication: 2013-01
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    GaAs thin films with Ti incorporated, to which we refer to as GaAs(Ti), have been deposited by R.F. sputtering on fused silica and c-GaAs substrates under different process conditions. The films were characterized by EPMA, XPS and XRD to study the composition and structural dependence on the deposition conditions, paying special attention on the Ti content of the films. The optical responses of the films were analyzed by spectrofotometric, PDS and FTIR measurements. The Ti content is in all the samples above 1020 atoms/cm3, so we can consider them as GaAs films highly Ti doped. It has been observed that an evolution of the Ga/As atomic content in relation with the Ti incorporation, which together with the results obtained from XPS measurements, indicates a possible substitution of Ga by Ti atoms in the deposited films.

    GaAs thin films with Ti incorporated, to which we refer to as GaAs(Ti), have been deposited by R.F. sputtering on fused silica and c-GaAs substrates under different process conditions. The films were characterized by EPMA, XPS and XRD to study the composition and structural dependence on the deposition conditions, paying special attention on the Ti content of the films. The optical responses of the films were analyzed by spectrofotometric, PDS and FTIR measurements. The Ti content is in all the samples above 1020 atoms/cm3, so we can consider them as GaAs films highly Ti doped. It has been observed that an evolution of the Ga/As atomic content in relation with the Ti incorporation, which together with the results obtained from XPS measurements, indicates a possible substitution of Ga by Ti atoms in the deposited films.

  • Low pressure spherical thermal anemometer for space missions

     Kowalski, Lukasz; Jimenez Serres, Vicente; Dominguez Pumar, Manuel M.; Gorreta Marine, Sergio; Silvestre Berges, Santiago; Castañer Muñoz, Luis Maria
    Annual IEEE Conference on Sensors
    Presentation's date: 2013-11
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    A novel spherically shaped thermal anemometer for low pressure, Mars-like conditions, is described. The concept has been designed using finite element multyphysics simulations to find out the thermal conductance to the ambient for varying conditions of wind speed and direction and ambient pressure and temperature. A prototype 1cm diameter suitable to work under these environment in the range 0.25-10m/s speed has been build using 3D printing and tested inside a low pressure chamber. The protopype shown has two separated hemispheres, independently heated above the ambient temperature, providing angle sensitivity in one plane. Measurements of the heating power in both hemispheres required to keep an overheat of 30K are shown as a function of the wind direction showing good sensitivity at 0.5m/s. One improvement of this sensor is the means provided to also heat the core of the sphere where the circuit board is located thereby avoiding most of the conduction losses to the supports. The concept is scalable to other wind speed and pressure conditions and also to full 3D measurements.

    The novelty of this 2D thermal anemometer is the spherical compact and robust design with improved sensitivity in the range of 600-900Pa of carbon dioxide pressure and 0.25 to 10 m/s wind speed. The small size (11.2mm diameter) and unprecedented 3D printing fabrication of a low emissivity silver shell allows to place inside of the sphere the platinum heating and sensing resistors. It improves the performances of the Viking, Pathfinder and Curiosity wind sensors for the surface of Mars. The conduction losses to the support are largely suppressed by also heating the insertion point at the same temperature than the shell Overall, the convection power to the ambient is in the range of 30mW per 10K of overheat respect to the ambient, which is about the 68% of the total power. Splitting the spherical shell into two hemispheres provides angular sensitivity and the wind direction is found from the convection power differences between them. The concept can be easily extended to three-dimensional sensing by using three of these sensors in different planes. It can also be applied to aeronautical engines such as stratospheric balloons.

  • Influence of hydrogen on the optical absorption response of GaAs(Ti) films deposited by R.F. sputtering

     Boronat Moreiro, Alfredo; Silvestre Berges, Santiago; Castañer Muñoz, Luis Maria
    Spanish Conference on Electron Devices
    Presentation's date: 2013-02
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    In the present work we have investigated the optical absorption behavior of GaAs(Ti) films deposited by r.f sputtering technique under different H2 partial pressures. In previous work we have already demonstrated the feasibility to obtain GaAs films with high dose of Ti, which we refer to as GaAs(Ti). Any absorption peak, which could be related with the presence of an intermediate band, has been identified. The low Etauc parameter together with a broad Urbach tail of the films make us to suspect that the possible presence of an absorption peak could be hidden. The incorporation of H2 on sputtered GaAs films have demonstrated before a shift of the Etauc parameter to higher values and a reduction of the Urbach tail.

    In the present work we have investigated the optical absorption behavior of GaAs(Ti) films deposited by r.f sputtering technique under different H2 partial pressures. In previous work we have already demonstrated the feasibility to obtain GaAs films with high dose of Ti, which we refer to as GaAs(Ti). Any absorption peak, which could be related with the presence of an intermediate band, has been identified. The low Etauc parameter together with a broad Urbach tail of the films make us to suspect that the possible presence of an absorption peak could be hidden. The incorporation of H2 on sputtered GaAs films have demonstrated before a shift of the Etauc parameter to higher values and a reduction of the Urbach tail.

  • High voltage ultrathin-photovoltaic minimodules: fabrication technology and application to bioimplantable telesupplying

     Bermejo Broto, Alexandra; Silvestre Berges, Santiago; Ortega Villasclaras, Pablo Rafael
    International Conference on Micro and Nano Engineering
    Presentation's date: 2013-09-17
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Tecnología de fabricación de células solares con materiales candidatos a presentar banda intermedia.  Open access

     Boronat Moreiro, Alfredo
    Defense's date: 2013-10-11
    Department of Electronic Engineering, Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    El concepto de Banda Intermedia (BI) implica un nuevo reto en el desarrollo de dispositivos fotovoltaicos de alta eficiencia. Este concepto persigue superar el límite de eficiencia de conversión fotovoltaica establecido. El principio teórico básico es el aumento de la corriente fotogenerada a partir de la absorción sub-bangap de la luz sin una degradación de la tensión de circuito abierto en la respuesta del dispositivo. Esta absorción sub-bandgap se consigue gracias a la presencia de una banda (estados energéticos deslocalizados) situada entre la banda de conducción y la banda de valencia: La Banda Intermedia.La implementación de este concepto supondría una revolución dentro del campo fotovoltaico. El atractivo de las posibilidades que ofrece el concepto de BI motivó el trabajo que se recoge de forma resumida en esta Tesis.La implementación del concepto de BI supone dos estadios fundamentales desde un punto de vista tecnológico:¿El desarrollo de materiales o estructuras capaces de crear o generar la BI.¿El desarrollo de dispositivos fotovoltaicos y procesos de fabricación que permitan incorporar de una forma óptima estos materiales o estructuras.El trabajo realizado en relación al primer estadio se ha basado en la síntesis de capas, depositadas por sputtering, de Arseniuro de Galio con impurezas de Titanio GaAs(Ti). La elección de este compuesto se fundamenta en los resultados de trabajos de la literatura que, relacionados con simulaciones basadas en métodos ab initio, sugieren que estos compuestos son candidatos a presentar BI. Se ha trabajado con diferentes condiciones de depósito para analizar cómo afectan a características de la capa como: la composición elemental (en especial el contenido de Ti); la estructura cristalina; las propiedades ópticas. El trabajo desarrollado en este sentido supone la primera aproximación en la síntesis de compuestos GaAs(Ti), con la finalidad de obtener un material de BI, utilizando la técnica de sputtering.En un segundo estadio se han diseñado los procesos de fabricación y estructuras fotovoltaicas para la incorporación de los materiales de BI. Todas las estructuras desarrolladas se basan en el concepto de heterounión. Básicamente se ha trabajado con tres diseños diferentes en función del material a incorporar:¿Estructuras diseñadas para la incorporación de las capas GaAs(Ti) desarrolladas en esta Tesis.¿Estructuras diseñadas para la incorporación de sustratos (p) c-Si con altas dosis de Ti implantado. Estos materiales han presentado resultados prometedores en relación al concepto de BI.¿Estructuras diseñadas para la incorporación de puntos cuánticos y/o nano-partículas metálicas. La incorporación de puntos cuánticos ha demostrado su potencial en el desarrollo de células solares de banda intermedia (QD-IBSC).El diseño de cada una de estas estructuras ha estado acompañado de la definición de los respectivos procesos de fabricación. Cada uno de los procesos de fabricación ha prestado especial atención a aspectos como la temperatura de proceso o los procesos químicos, para evitar una alteración de las características de los materiales incorporados de cara a la posible creación de la BI.Los resultados obtenidos en este trabajo invitan al desarrollo de nuevas líneas de investigación en el marco de la implementación de células solares de banda intermedia (IBSC).

    This work has been developed in a line of research related whit the Intermediate Band (IB) concept, which explores overcoming the photovoltaic efficiency limits established for solar cells. The IB concept implies two issues: a) the determination of materials capable to generate or create an IB b) the incorporation of these materials optimally within the photovoltaic device. The first stage of this work is focused on the synthesis of GaAs layers with high doses of Titanium impurities (GaAs(Ti)) as IB candidate material. Thin layers of GaAs(Ti) have been deposited by sputtering and its optical and compositional characteristics have been characterized. In a second stage, structures and processes are designed to incorporate the GaAs(Ti) layers in photovoltaic devices. Moreover, devices with a HIT structure are fabricated using (p) c-Si substrates with high dose of implanted titanium. Other structures are developed to incorporate quantum dots and / or metallic nanoparticles.

    Este trabajo se ha desarrollado en el marco de una línea de investigación relacionada con en el concepto de la Banda Intermedia (BI), que explora la superación del límite de eficiencia fotovoltaica establecido para las células solares. Este concepto implica dos aspectos: a) la determinación de materiales capaces de manifestar o crear una BI, b) la incorporación de una forma óptima de estos materiales en el seno del dispositivo fotovoltaico. El primer estadio de este trabajo se ha centrado en la síntesis de capas de GaAs con dosis altas de impurezas de Titanio (GaAs(Ti)) como candidato a presentar BI. En un segundo estadio se han diseñado estructuras y procesos para incorporar las capas de GaAs(Ti) en dispositivos fotovoltaicos. También se han desarrollado estructuras HIT para la incorporación de sustratos de (p) c-Si con altas dosis de Titanio implantado y estructuras enfocadas a la incorporación de puntos cuánticos y/o nano-partículas metálicas.

  • Modeling and simulation of a grid connected PV system based on the evaluation of main PV module parameters

     Chouder, Aissa; Silvestre Berges, Santiago; Sadaoui, Nawel; Rahmani, Lazhar
    Simulation modelling practice and theory
    Date of publication: 2012-01
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    In this work we present a new method for the modeling and simulation study of a photovoltaic grid connected system and its experimental validation. This method has been applied in the simulation of a grid connected PV system with a rated power of 3.2 Kwp, composed by a photovoltaic generator and a single phase grid connected inverter. First, a PV module, forming part of the whole PV array is modeled by a single diode lumped circuit and main parameters of the PV module are evaluated. Results obtained for the PV module characteristics have been validated experimentally by carrying out outdoorI–Vcharacteristic measurements. To take into account the power conversion efficiency, the measured AC output power against DC input power is fitted to a second order efficiency model to derive its specific parameters.The simulation results have been performed through Matlab/Simulink environment. Results has shown good agreement with experimental data, whether for theI–Vcharacteristics or for the whole operating system. The significant error indicators are reported in order to show the effectiveness of the simulation model to predict energy generation for such PV system.

  • Optical absorption of radio frequency sputtered GaAs(Ti) films

     Boronat Moll, Artur; Silvestre Berges, Santiago; Fuertes Marrón, David; Castañer Muñoz, Luis Maria; Martí, A.; Luque, Antonio
    Journal of materials science. Materials in electronics
    Date of publication: 2012-08-14
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Composition and optical absorption of thin films of GaAs(Ti) and GaAs, deposited by sputtering on glass substrates under different process conditions, have been investigated. The thin films obtained are typically 200 nm thick. ToF–SIMS measurements show a quite constant concentration and good uniformity of Ti profiles along the GaAs(Ti) layers in all cases and EPMA results indicate that Ti content increases with the substrate temperature in the sputtering process. Measurements of the transmittance and reflectance spectra of the GaAs and GaAs(Ti) thin films have been carried out. In the optical characterization of the films it is found that optical absorption is enhanced in all samples containing Ti. The determination of the optical gap from the optical absorption, shows optical gap variations from 1.15 to 1.29 eV in the GaAs thin films, and from 0.83 to 1.13 eV in the GaAs(Ti) thin films. The differences in absorption and EgTAUC observed between samples of GaAs and GaAs(Ti) are consistent with the presence of an intermediate band.

  • Simple diagnostic approach for determining of faulted PV modules in string based PV arrays

     Gokmen, Nuri; Karatepe, Engin; Celik, Berk; Silvestre Berges, Santiago
    Solar energy
    Date of publication: 2012-11
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    This paper proposes a simple diagnostic method to determine the number of open and short circuited PV modules in a string of a PV system by taking into account the economical factor, such as minimum number of sensors. The diagnostic algorithm has as inputs the irradiance level, the PV modules temperature, the number of PV modules present in the string analyzed and its output power. So, just temperature and irradiance sensors, as well as a power meter by string are needed in the monitoring system forming part of the fault diagnostic system. The proposed fault detection method has been successfully validated experimentally.

    This paper proposes a simple diagnostic method to determine the number of open and short circuited PV modules in a string of a PV system by taking into account the economical factor, such as minimum number of sensors. The diagnostic algorithm has as inputs the irradiance level, the PV modules temperature, the number of PV modules present in the string analyzed and its output power. So, just temperature and irradiance sensors, as well as a power meter by string are needed in the monitoring system forming part of the fault diagnostic system. The proposed fault detection method has been successfully validated experimentally.

  • Light harvesting photovoltaic mini-generator

     Bermejo Broto, Alexandra; Silvestre Berges, Santiago; Ortega Villasclaras, Pablo Rafael; Herrera, Gerard
    Progress in photovoltaics
    Date of publication: 2011-08-23
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    Towards photovoltaic powered artificial retina  Open access

     Silvestre Berges, Santiago; Bermejo Broto, Alexandra; Guasch Murillo, Daniel; Ortega Villasclaras, Pablo Rafael; Castañer Muñoz, Luis Maria
    Journal of Accessibility and Design for All
    Date of publication: 2011
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    The aim of this article is to provide an overview of current and future concepts in the field of retinal prostheses, and is focused on the power supply based on solar energy conversion; we introduce the possibility of using PV minimodules as power supply for a new concept of retinal prostheses: Photovoltaic Powered Artificial Retina (PVAR). Main characteristics of these PV modules are presented showing its potential for this application.

  • Review of system design and sizing tools

     Silvestre Berges, Santiago
    Date of publication: 2011-11-01
    Book chapter

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Optical measurements of GaAs(Ti) thin films sputtered on GaAs

     Boronat Moreiro, Alfredo; Silvestre Berges, Santiago; Castañer Muñoz, Luis Maria
    Spanish Conference on Electron Devices
    Presentation's date: 2011-02
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Optical measurements on GaAs(Ti) thin films sputtered on GaAs

     Boronat Moreiro, Alfredo; Silvestre Berges, Santiago; Castañer Muñoz, Luis Maria
    Spanish Conference on Electron Devices
    Presentation's date: 2011
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Some sputtering processes of GaAs(Ti) onto c-GaAs have been carried out in order to obtain thin films as candidates to be intermediate band photovoltaic materials. This work presents the results obtained in the study of the absorptance, from transmittance and reflectance responses, in samples obtained at different conditions of temperature and power during the sputtering deposition.

  • Sensor de viento para la superficie de marte para la misión Metnet (fase inicial)

     Jimenez Serres, Vicente; Silvestre Berges, Santiago; Castañer Muñoz, Luis Maria
    Participation in a competitive project

     Share

  • Automatic supervision and fault detection of PV systems based on power losses analysis

     Chouder, Aissa; Silvestre Berges, Santiago
    Energy conversion and management
    Date of publication: 2010-10
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    Fault detection and automatic supervision methodology for PV systems  Open access

     Silvestre Berges, Santiago; Chouder, Aissa
    European Photovoltaic Solar Energy Conference and Exhibition
    Presentation's date: 2010-09
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    In this work, we show a new methodology for automatic supervision and fault detection of PV Systems, based mainly on the analysis of the power losses. This methodology includes parameter extraction techniques to calculate main PV system parameters from monitoring data [1-2], taking into account the real irradiance and module temperature, allowing simulation and evaluation of the PV system behaviour in real time.

  • Access to the full text
    Study of GaAs(Ti) thin films as candidates for IB solar cells manufacturing  Open access

     Silvestre Berges, Santiago; Boronat Moreiro, Alfredo; Castañer Muñoz, Luis Maria
    IEEE Photovoltaic Specialists Conference
    Presentation's date: 2010-06
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Thin films of GaAs(Ti) have been deposited by sputtering on glass and n_GaAs substrates under different process conditions. Optical characteristics of these samples have been analyzed to study the potential of this material in intermediate Band solar cell manufacturing.

  • Access to the full text
    Identifiying causes of power reduction in photovoltaic systems  Open access

     Silvestre Berges, Santiago; Chouder, Aissa
    IEEE Photovoltaic Specialists Conference
    Presentation's date: 2010-06-21
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    A procedure for the identification of main causes of power reduction in PV systems, based on the continuous check of the real measured losses and his comparison to simulation results obtained for the same parameter, is presented in this work.

  • Analysis, diagnosis and fault detection in photovoltaic systems

     Chouder, Aissa
    Defense's date: 2010-02-09
    Department of Electronic Engineering, Universitat Politècnica de Catalunya
    Theses

     Share Reference managers Reference managers Open in new window

  • Study of bypass diodes configuration on PV modules

     Silvestre Berges, Santiago; Boronat Moreiro, Alfredo; Chouder, Aissa
    Applied energy
    Date of publication: 2009-09
    Journal article

     Share Reference managers Reference managers Open in new window

  • Analysis Model of Mismatch Power Losses in PV Systems

     Chouder, Aissa; Silvestre Berges, Santiago
    Journal of solar energy engineering. Transactions of the ASME
    Date of publication: 2009-05
    Journal article

     Share Reference managers Reference managers Open in new window

  • Método para la fabricación de una célula solar de silicio de banda intermedia

     Puigdollers Gonzalez, Joaquin; Silvestre Berges, Santiago; Castañer Muñoz, Luis Maria; Martí, Vega A; Luque, A; Antolín, E; Olea, J; Pastor, D; Martil, Ignacio
    Date of request: 2009-02-19
    Invention patent

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Método para la fabricación de una célula solar de silicio de banda intermedia.

    Es posible crear materiales de banda intermedia en silicio mediante la implantación iónica en dosis elevadas de elementos que produzcan centros profundos en el silicio. Sin embargo, el material de banda intermedia (4) se crea en la superficie de la oblea implantada (7) planteándose una dificultad técnica ya que, para fabricar una célula solar completa, resulta necesario envolver este material de banda intermedia entre un semiconductor de tipo p (5) y otro de tipo n (6) utilizando un proceso de baja temperatura que evite la segregación y formación de clústeres del elemento implantado. En esta patente, esta dificultad se resuelve creando la estructura p n mediante la deposición de capas de silicio amorfo hidrogenado de calidad a baja temperatura.

  • IntEleCT -Internationalisation of Electronic Communications Training

     Soriano Ibáñez, Miguel; Silvestre Berges, Santiago; Bermejo Broto, Alexandra
    Participation in a competitive project

     Share

  • Mejor Proyecto Multilateral de Transferencia e Innovación

     Silvestre Berges, Santiago
    Award or recognition

     Share

  • Access to the full text
    Analysis of GaAs-Ti thin films deposited by sputtering onto c-Si and GaAs  Open access

     Silvestre Berges, Santiago; Puigdollers Gonzalez, Joaquin; Boronat Moreiro, Alfredo; Castañer Muñoz, Luis Maria
    Spanish Conference on Electron Devices
    Presentation's date: 2009-02-11
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Some sputtering processes of GaAs and Ti onto glass, c-Si and c-GaAs substrates have been carried out in order to obtain thin films as candidates to be intermediate band photovoltaic materials. This work presents first results concerning the optical and structural properties of the different deposited thin films.

  • Herramientas de simulación para sistemas fotovoltaicos en ingeniería

     Silvestre Berges, Santiago; Castañer Muñoz, Luis Maria; Guasch Murillo, Daniel
    Formación universitaria
    Date of publication: 2008-01
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Effects of shadowing on photovoltaic module performance

     Silvestre Berges, Santiago
    Progress in photovoltaics
    Date of publication: 2008-01
    Journal article

     Share Reference managers Reference managers Open in new window

  • Simulation of fuzzy-based MPP tracker and performance comparison with perturb & observe method

     Chouder, Aissa; Guinjoan Gispert, Francisco; Silvestre Berges, Santiago
    Revue des energies renouvelables
    Date of publication: 2008-12
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • ELefANTC E-Learning for Acquiring New Types of Skills - Continued.

     Silvestre Berges, Santiago; Soriano Ibáñez, Miguel; Hernández Serrano, Juan Bautista
    Participation in a competitive project

     Share

  • Manipulación de micro-nano partículas en 2D y 3D

     Castañer Muñoz, Luis Maria; Silvestre Berges, Santiago; Rodriguez Martinez, Angel; Bermejo Broto, Alexandra; Bardes Llorensi, Daniel; Lopez Gonzalez, Juan Miguel
    Participation in a competitive project

     Share

  • Analysis of power losses in pv systems

     Silvestre Berges, Santiago; Chouder, Aissa
    23rd Europeran Photovoltaic Solar Energy Conference
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Teaching PV in an Engineering environment

     Castañer Muñoz, Luis Maria; Silvestre Berges, Santiago
    4th International Workshop on Teaching in Photovoltaics
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Etude comparative de simulation entre PVsyst3 et PSpice de la centrale photovoltaïque connectée au réseau du CDER

     Chouder, Aissa; Cerfa, F; Hadj, A Arab; Silvestre Berges, Santiago
    Revue des energies renouvelables
    Date of publication: 2007-05
    Journal article

     Share Reference managers Reference managers Open in new window

  • Shading effects in characteristic parameters of PV modules

     Silvestre Berges, Santiago
    Spanish Conference on Electron Devices
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Modelisation et simulation des composants de la mini-centrale photovoltaique connectee au reseau du cder

     Cherfa, F; Chouder, Aissa; Hadjarab, A; Oussaid, R; Silvestre Berges, Santiago
    ICRESD_07 - International Conference for Renewable Energies and Sustainable Development
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Etude Comparative de Simulation entre PVSYST3 et PSpice de la Centrale Photovoltaïque Connectée au Résau du CDER

     Chouder, Aissa; Cherfa, F; Hadjarab, A; Silvestre Berges, Santiago; Oussaid, R
    CER'07 - Colloque International Sur les Énergies Renovables
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window