Philippe Voarino - Academia.edu (original) (raw)

Papers by Philippe Voarino

2019 European Space Power Conference (ESPC)

Standard space solar arrays consist of solar cells protected by coverglass, glued individually on... more Standard space solar arrays consist of solar cells protected by coverglass, glued individually on rigid substrate. The solar cells / substrate bonding interface quality is crucial since trapped air bubbles at this interface can cause strong cell damages once under vacuum. In this study, we show that transient electroluminescence can be used as a fast and nondestructive characterization tool to map the solar cells rear-side gluing interface defects.

The need for low cost photovoltaic solutions is becoming more and more important with the ongoing... more The need for low cost photovoltaic solutions is becoming more and more important with the ongoing NewSpace revolution. In this study, we review, as comprehensively as possible, the radiation hardness of various photovoltaic solar cells technologies. Emphasis is placed on cells offering attractive cost reduction compared to standard III-V based triple junctions. In addition, the following benchmarking criteria were identified: performance, including begin and end of life evolution (BOL/EOL) when submitted to doses/fluences, mass, Technological Readiness Level (TRL) and reliability.

2019 IEEE 46th Photovoltaic Specialists Conference (PVSC), 2019

Nowadays spacecraft missions need more and more power supply so larger solar arrays. However, the... more Nowadays spacecraft missions need more and more power supply so larger solar arrays. However, the restricted volume between the fairing and the spacecraft sidewall limits the number and the dimension of rigid solar panels during launch. Therefore, the answer for this growing power demand lies neither in stacking more of the rigid solar arrays, nor by marginal efficiency improvements on III-V multi-junction solar cells, but rather in innovative/disruptive photovoltaic solutions. More solar cells per unit of volume are needed, and flexible solar arrays are the only answer for this high-power challenge. In this context, ALFAMA project, funded by the European commission, aims at developing a disruptive flexible space solar array technology.

2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC), 2018

Hybrid III-V/Si multi-junction solar cells, which combine efficient III-V top cells with a silico... more Hybrid III-V/Si multi-junction solar cells, which combine efficient III-V top cells with a silicon bottom cell, the most wide-spread photovoltaic material, offer great opportunities. Recent advances in this field have shown that mechanically stacked or wafer bonded III-V/Si can reach similar AM1.5g efficiencies than the standard GaInP/GaAs/Ge space triplejunction solar cells. In this study, we review the potential of this new hybrid III-V/Si cell technology for space applications. The first experimental results of wafer bonded 2-terminal GaInP/GaAs/Si solar cell electron irradiation will be presented. The BOL and EOL (1 MeV electrons) performances will be characterized under AM0 spectrum, and the radiation tolerance will be compared with single-junction silicon and standard Ge based triple-junction.

2017 IEEE 44th Photovoltaic Specialist Conference (PVSC), 2017

16TH INTERNATIONAL CONFERENCE ON CONCENTRATOR PHOTOVOLTAIC SYSTEMS (CPV-16), 2020

If the modelling of "conventional" PV modules behavior was well studied in the literature, the mo... more If the modelling of "conventional" PV modules behavior was well studied in the literature, the modelling of Concentrator PhotoVoltaic (CPV) systems is relatively unexplored. This modelling is more difficult because conversion process is more complicated and inputs more numerous: beam solar irradiance, ambient temperature and wind speed but also the spectral decomposition of the sun radiation depending on the atmosphere state and thickness. This paper presents an overview of electrical power models applied to a system installed at Ajaccio-Corsica. Results note that only DNI (Direct Normal Irradiance), Tair and AM (Air Mass) could be necessary to have a good evaluation of the power with a RMSE under 4.6 %.

AIP Conference Proceedings, 2018

The first edition of the Technical Specification (TS) on Primary Optics for Concentrator Photovol... more The first edition of the Technical Specification (TS) on Primary Optics for Concentrator Photovoltaic (CPV) Systems, IEC TS 62989:2018, has been published by the International Electrotechnical Commission (IEC), on March 8th, 2018. TS 62989 covers aspects related to the primary optics including: product identification, optical characteristics, mechanical characteristics, materials, (design) geometry, and visual appearance. This paper focuses on the key aspects of the norm, including optical performance, in order to promote the awareness and use of the standard. We describe the three methods intended to measure the key optical characteristics of the primary elements, i.e. focal spot size and optical efficiency, by using the encircled energy. The three methods are using different light sources, optical components and receiver sensors, but yielded very similar results in a round robin test. This justifies the continued use of all three methods. The use of a website (opticstests.pbworks.com) for documentation of discussions and references was novel to the standard development. The website proved to be useful for the introduction of new members of the group. The website helped to keep track of changes to the document as well as the required actions of the project team.

AIP Conference Proceedings, 2017

Existing CPV technology markets are not compliant with a standard configuration. Concentrations v... more Existing CPV technology markets are not compliant with a standard configuration. Concentrations vary from several suns to more than 1000 suns and the optical technology used could be very different. Nowadays, the market trends are moving toward more and more compact optical systems in order to exploit the Light Emitting Diode (LED) like approach. The aim is to increase the optical efficiency by using an ultra-short focal distance and to improve thermal management. Moreover the efficiency to weight ratio is increasing and the solar cell size becomes sub-millimetric. With these conditions, more stringent mechanical tolerances are essential to ensure an optimum optical alignment between cells and optics. A new process of micro-concentrator manufacturing is developed in this work. This process enables manufacturing and auto-alignment of Primary Optical Elements (POE) with Secondary Optical Elements (SOE) and solar cells with respect to certain mechanical tolerances. A 1000X micro-concentrator is manufactured with 0.6 x 0.6 mm² triple-junction cells and molded silicone optics. Mechanical alignment defects are studied by ray-tracing simulations and a prototype is characterized with respect to its mechanical behavior. An efficiency of 33.4% is measured with a Cell-to-Module ratio of 77.8%.

CPVMatch-Concentrating photovoltaic modules using advanced technologies and cells for highest eff... more CPVMatch-Concentrating photovoltaic modules using advanced technologies and cells for highest efficiencies

We evaluate mirror-based and achromatic optics at different working temperatures and cell-to-prim... more We evaluate mirror-based and achromatic optics at different working temperatures and cell-to-primary optical element (POE) distances. The magnitude and the effect of chromatic aberration and non-uniform flux profiles are assessed under controlled testing conditions. Our characterization tool is called METHOD [1]: it is capable of measuring multispectral irradiance profiles of concentrator photovoltaic optical systems along with the corresponding current (I)-voltage (V) characteristics produced on a concentrator solar cell receiver. In this study, METHOD is adapted to evaluate a mirror from the APOLLON Project [2], characterized in the framework of the European CPVMatch project.

Optics Express, 2016

A test method that measures spectrally resolved irradiance distribution for a concentrator photov... more A test method that measures spectrally resolved irradiance distribution for a concentrator photovoltaic (CPV) optical system is presented. In conjunction with electrical I-V curves, it is a means to visualize and characterize the effects of chromatic aberration and nonuniform flux profiles under controllable testing conditions. The indoor characterization test bench, METHOD (Measurement of Electrical, Thermal and Optical Devices), decouples the temperatures of the primary optical element (POE) and the cell allowing their respective effects on optical and electrical performance to be analysed. In varying the temperature of the POE, the effects on electrical efficiency, focal distance, spectral sensitivity, acceptance angle and multi-junction current matching profiles can be quantified. This work presents the calibration procedures to accurately image the spectral irradiance distribution of a CPV system and a study of system behavior over lens temperature.

AIP Conference Proceedings, 2015

Large-scale and long-term CPV power plant field results

ABSTRACT A new protocol for testing on-grid inverters accounting for the operating conditions spe... more ABSTRACT A new protocol for testing on-grid inverters accounting for the operating conditions specific to CPV arrays is introduced. First, a CPV-specific weighted average for providing the static conversion efficiency according to typical frequency distributions of CPV yield throughout the year. Then, a set of representative scenarios for analyzing the dynamic MPPT efficiency of the inverter: slow ramp (clear sky), fast cloud passage, self-shading between arrays (typical of sunrise and sunset) and a wavering current response typical of imperfect tracking. The procedures have been applied to two different string-size inverters at the CEA inverter test bench, which have revealed strong differences in their dynamic MPPT efficiency. The CPV-specific weighted average proposed was found to provide lower performance figures than the classical European and CEC efficiencies for the two studied inverters. This protocol provides important information for CPV plant dimensioning and equipment selection, as the differences in performance revealed can result in significant deviation on the final energy yield.

AIP Conference Proceedings, 2014

Optical modelling based on angle and temperature dependent EQE measurements on III-V multi-juncti... more Optical modelling based on angle and temperature dependent EQE measurements on III-V multi-junction solar cells

Concentrator photovoltaic (CPV) modules are composed of many components and interfaces, which req... more Concentrator photovoltaic (CPV) modules are composed of many components and interfaces, which require complex assembling processes, resulting in fabrication complexity and often lack of reliability. The present work addresses these issues, by proposing an innovative low concentration photovoltaic (LCPV) concept. In particular, the purpose here is to develop a module with a high level of integration by lowering the number of components and interfaces. The mirror used as the concentrator optic is multifunctional, as it combines thermal, structural and optical function. Moreover, the proposed design claims to demonstrate the applicability of reliable flat PV processes (such as lamination and cells interconnections), for the manufacturing of this LCPV module. The paper describes both thermal and optical modelling, developed to validate the concentrator design. Then, the main processes qualifications, as well as results on the characterization of the preliminary developed prototypes, are given. The potential of the LCPV concept, for space applications, is also discussed.

15th International Conference on Concentrator Photovoltaic Systems (CPV-15)

In Low Irradiation and Low Temperature (LILT) environments, the performances of silicon and III-V... more In Low Irradiation and Low Temperature (LILT) environments, the performances of silicon and III-V multijunction solar cells is degraded because of the conjugated decreases of Jsc and Voc under low irradiation although with lower temperature their Voc increases [1, 2]. Effect of shunt resistance added to the "flat spot effect" can create a drop in their fill factor, following the quality of the materials and the process of the front metallization [3]. Concentrator photovoltaics technology could be suitable for powering spatial missions in LILT environments [4, 5]. Moreover, compared to classical concentrators, micro-concentrators increase electrical performances while decreasing costs [6]. This work describes a new concept especially dedicated to space application: a linear Total Internal Reflection (TIR) module running at a low concentration of 7.6X called SLIT (Space Linear TIR) module.

15th International Conference on Concentrator Photovoltaic Systems (CPV-15)

Currently, solar simulators demand component solar cells, also named isotypes, in order to equili... more Currently, solar simulators demand component solar cells, also named isotypes, in order to equilibrate their spectrum and match the required norm. Each architecture of cell needs a specific set of isotypes and each one of them need calibration in order to assess the incident power coming from the solar simulator in its spectral range. In this article, pseudoisotypes are proposed in order to ease the spectral balance of new architectures of multijunction solar cells (MJSC). Pseudoisotypes are silicon and germanium photodiodes filtered with filters reproducing the cut-on and the cutoff of each MJSC subcell. The use of pseudo-isotypes requires the development of a simple and accurate calibration in order to obtain the constants associated with these references without sending it to a certified laboratory. An indoor calibration method is described and its accuracy is assessed. IV characteristics of 3J MJSC under a solar simulator are carried out with different sets of references: i) isotypes calibrated outdoor, ii) isotypes calibrated indoor, and iii) pseudo-isotypes calibrated indoor.

2019 European Space Power Conference (ESPC)

Standard space solar arrays consist of solar cells protected by coverglass, glued individually on... more Standard space solar arrays consist of solar cells protected by coverglass, glued individually on rigid substrate. The solar cells / substrate bonding interface quality is crucial since trapped air bubbles at this interface can cause strong cell damages once under vacuum. In this study, we show that transient electroluminescence can be used as a fast and nondestructive characterization tool to map the solar cells rear-side gluing interface defects.

The need for low cost photovoltaic solutions is becoming more and more important with the ongoing... more The need for low cost photovoltaic solutions is becoming more and more important with the ongoing NewSpace revolution. In this study, we review, as comprehensively as possible, the radiation hardness of various photovoltaic solar cells technologies. Emphasis is placed on cells offering attractive cost reduction compared to standard III-V based triple junctions. In addition, the following benchmarking criteria were identified: performance, including begin and end of life evolution (BOL/EOL) when submitted to doses/fluences, mass, Technological Readiness Level (TRL) and reliability.

2019 IEEE 46th Photovoltaic Specialists Conference (PVSC), 2019

Nowadays spacecraft missions need more and more power supply so larger solar arrays. However, the... more Nowadays spacecraft missions need more and more power supply so larger solar arrays. However, the restricted volume between the fairing and the spacecraft sidewall limits the number and the dimension of rigid solar panels during launch. Therefore, the answer for this growing power demand lies neither in stacking more of the rigid solar arrays, nor by marginal efficiency improvements on III-V multi-junction solar cells, but rather in innovative/disruptive photovoltaic solutions. More solar cells per unit of volume are needed, and flexible solar arrays are the only answer for this high-power challenge. In this context, ALFAMA project, funded by the European commission, aims at developing a disruptive flexible space solar array technology.

2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC), 2018

Hybrid III-V/Si multi-junction solar cells, which combine efficient III-V top cells with a silico... more Hybrid III-V/Si multi-junction solar cells, which combine efficient III-V top cells with a silicon bottom cell, the most wide-spread photovoltaic material, offer great opportunities. Recent advances in this field have shown that mechanically stacked or wafer bonded III-V/Si can reach similar AM1.5g efficiencies than the standard GaInP/GaAs/Ge space triplejunction solar cells. In this study, we review the potential of this new hybrid III-V/Si cell technology for space applications. The first experimental results of wafer bonded 2-terminal GaInP/GaAs/Si solar cell electron irradiation will be presented. The BOL and EOL (1 MeV electrons) performances will be characterized under AM0 spectrum, and the radiation tolerance will be compared with single-junction silicon and standard Ge based triple-junction.

2017 IEEE 44th Photovoltaic Specialist Conference (PVSC), 2017

16TH INTERNATIONAL CONFERENCE ON CONCENTRATOR PHOTOVOLTAIC SYSTEMS (CPV-16), 2020

If the modelling of "conventional" PV modules behavior was well studied in the literature, the mo... more If the modelling of "conventional" PV modules behavior was well studied in the literature, the modelling of Concentrator PhotoVoltaic (CPV) systems is relatively unexplored. This modelling is more difficult because conversion process is more complicated and inputs more numerous: beam solar irradiance, ambient temperature and wind speed but also the spectral decomposition of the sun radiation depending on the atmosphere state and thickness. This paper presents an overview of electrical power models applied to a system installed at Ajaccio-Corsica. Results note that only DNI (Direct Normal Irradiance), Tair and AM (Air Mass) could be necessary to have a good evaluation of the power with a RMSE under 4.6 %.

AIP Conference Proceedings, 2018

The first edition of the Technical Specification (TS) on Primary Optics for Concentrator Photovol... more The first edition of the Technical Specification (TS) on Primary Optics for Concentrator Photovoltaic (CPV) Systems, IEC TS 62989:2018, has been published by the International Electrotechnical Commission (IEC), on March 8th, 2018. TS 62989 covers aspects related to the primary optics including: product identification, optical characteristics, mechanical characteristics, materials, (design) geometry, and visual appearance. This paper focuses on the key aspects of the norm, including optical performance, in order to promote the awareness and use of the standard. We describe the three methods intended to measure the key optical characteristics of the primary elements, i.e. focal spot size and optical efficiency, by using the encircled energy. The three methods are using different light sources, optical components and receiver sensors, but yielded very similar results in a round robin test. This justifies the continued use of all three methods. The use of a website (opticstests.pbworks.com) for documentation of discussions and references was novel to the standard development. The website proved to be useful for the introduction of new members of the group. The website helped to keep track of changes to the document as well as the required actions of the project team.

AIP Conference Proceedings, 2017

Existing CPV technology markets are not compliant with a standard configuration. Concentrations v... more Existing CPV technology markets are not compliant with a standard configuration. Concentrations vary from several suns to more than 1000 suns and the optical technology used could be very different. Nowadays, the market trends are moving toward more and more compact optical systems in order to exploit the Light Emitting Diode (LED) like approach. The aim is to increase the optical efficiency by using an ultra-short focal distance and to improve thermal management. Moreover the efficiency to weight ratio is increasing and the solar cell size becomes sub-millimetric. With these conditions, more stringent mechanical tolerances are essential to ensure an optimum optical alignment between cells and optics. A new process of micro-concentrator manufacturing is developed in this work. This process enables manufacturing and auto-alignment of Primary Optical Elements (POE) with Secondary Optical Elements (SOE) and solar cells with respect to certain mechanical tolerances. A 1000X micro-concentrator is manufactured with 0.6 x 0.6 mm² triple-junction cells and molded silicone optics. Mechanical alignment defects are studied by ray-tracing simulations and a prototype is characterized with respect to its mechanical behavior. An efficiency of 33.4% is measured with a Cell-to-Module ratio of 77.8%.

CPVMatch-Concentrating photovoltaic modules using advanced technologies and cells for highest eff... more CPVMatch-Concentrating photovoltaic modules using advanced technologies and cells for highest efficiencies

We evaluate mirror-based and achromatic optics at different working temperatures and cell-to-prim... more We evaluate mirror-based and achromatic optics at different working temperatures and cell-to-primary optical element (POE) distances. The magnitude and the effect of chromatic aberration and non-uniform flux profiles are assessed under controlled testing conditions. Our characterization tool is called METHOD [1]: it is capable of measuring multispectral irradiance profiles of concentrator photovoltaic optical systems along with the corresponding current (I)-voltage (V) characteristics produced on a concentrator solar cell receiver. In this study, METHOD is adapted to evaluate a mirror from the APOLLON Project [2], characterized in the framework of the European CPVMatch project.

Optics Express, 2016

A test method that measures spectrally resolved irradiance distribution for a concentrator photov... more A test method that measures spectrally resolved irradiance distribution for a concentrator photovoltaic (CPV) optical system is presented. In conjunction with electrical I-V curves, it is a means to visualize and characterize the effects of chromatic aberration and nonuniform flux profiles under controllable testing conditions. The indoor characterization test bench, METHOD (Measurement of Electrical, Thermal and Optical Devices), decouples the temperatures of the primary optical element (POE) and the cell allowing their respective effects on optical and electrical performance to be analysed. In varying the temperature of the POE, the effects on electrical efficiency, focal distance, spectral sensitivity, acceptance angle and multi-junction current matching profiles can be quantified. This work presents the calibration procedures to accurately image the spectral irradiance distribution of a CPV system and a study of system behavior over lens temperature.

AIP Conference Proceedings, 2015

Large-scale and long-term CPV power plant field results

ABSTRACT A new protocol for testing on-grid inverters accounting for the operating conditions spe... more ABSTRACT A new protocol for testing on-grid inverters accounting for the operating conditions specific to CPV arrays is introduced. First, a CPV-specific weighted average for providing the static conversion efficiency according to typical frequency distributions of CPV yield throughout the year. Then, a set of representative scenarios for analyzing the dynamic MPPT efficiency of the inverter: slow ramp (clear sky), fast cloud passage, self-shading between arrays (typical of sunrise and sunset) and a wavering current response typical of imperfect tracking. The procedures have been applied to two different string-size inverters at the CEA inverter test bench, which have revealed strong differences in their dynamic MPPT efficiency. The CPV-specific weighted average proposed was found to provide lower performance figures than the classical European and CEC efficiencies for the two studied inverters. This protocol provides important information for CPV plant dimensioning and equipment selection, as the differences in performance revealed can result in significant deviation on the final energy yield.

AIP Conference Proceedings, 2014

Optical modelling based on angle and temperature dependent EQE measurements on III-V multi-juncti... more Optical modelling based on angle and temperature dependent EQE measurements on III-V multi-junction solar cells

Concentrator photovoltaic (CPV) modules are composed of many components and interfaces, which req... more Concentrator photovoltaic (CPV) modules are composed of many components and interfaces, which require complex assembling processes, resulting in fabrication complexity and often lack of reliability. The present work addresses these issues, by proposing an innovative low concentration photovoltaic (LCPV) concept. In particular, the purpose here is to develop a module with a high level of integration by lowering the number of components and interfaces. The mirror used as the concentrator optic is multifunctional, as it combines thermal, structural and optical function. Moreover, the proposed design claims to demonstrate the applicability of reliable flat PV processes (such as lamination and cells interconnections), for the manufacturing of this LCPV module. The paper describes both thermal and optical modelling, developed to validate the concentrator design. Then, the main processes qualifications, as well as results on the characterization of the preliminary developed prototypes, are given. The potential of the LCPV concept, for space applications, is also discussed.

15th International Conference on Concentrator Photovoltaic Systems (CPV-15)

In Low Irradiation and Low Temperature (LILT) environments, the performances of silicon and III-V... more In Low Irradiation and Low Temperature (LILT) environments, the performances of silicon and III-V multijunction solar cells is degraded because of the conjugated decreases of Jsc and Voc under low irradiation although with lower temperature their Voc increases [1, 2]. Effect of shunt resistance added to the "flat spot effect" can create a drop in their fill factor, following the quality of the materials and the process of the front metallization [3]. Concentrator photovoltaics technology could be suitable for powering spatial missions in LILT environments [4, 5]. Moreover, compared to classical concentrators, micro-concentrators increase electrical performances while decreasing costs [6]. This work describes a new concept especially dedicated to space application: a linear Total Internal Reflection (TIR) module running at a low concentration of 7.6X called SLIT (Space Linear TIR) module.

15th International Conference on Concentrator Photovoltaic Systems (CPV-15)

Currently, solar simulators demand component solar cells, also named isotypes, in order to equili... more Currently, solar simulators demand component solar cells, also named isotypes, in order to equilibrate their spectrum and match the required norm. Each architecture of cell needs a specific set of isotypes and each one of them need calibration in order to assess the incident power coming from the solar simulator in its spectral range. In this article, pseudoisotypes are proposed in order to ease the spectral balance of new architectures of multijunction solar cells (MJSC). Pseudoisotypes are silicon and germanium photodiodes filtered with filters reproducing the cut-on and the cutoff of each MJSC subcell. The use of pseudo-isotypes requires the development of a simple and accurate calibration in order to obtain the constants associated with these references without sending it to a certified laboratory. An indoor calibration method is described and its accuracy is assessed. IV characteristics of 3J MJSC under a solar simulator are carried out with different sets of references: i) isotypes calibrated outdoor, ii) isotypes calibrated indoor, and iii) pseudo-isotypes calibrated indoor.