Optimisation de stratégies de gestion des batteries au plomb utilisées dans les systèmes photovoltaïques

Batteries used in photovoltaic systems are subjected to penalizing operating conditions due to the intermittency of the solar resource. Their effects may be reduced by the optimisation of energy management strategies. This study deals with the pulse charge of lead acid batteries, the most used ones for this application. The effects of this charge mode are shown both on experimental cells and commercial batteries. The influence of the parameters, frequency, duty cycle and charge factor, on the voltage profiles is precisely studied. In a second approach, a simplified model of the lead-acid battery is developed and experimentally validated after the analysis of its sensitivity to the adjustable parameters. It shows that transport phenomena in the electrolyte may be well described by a global characteristic time depending only on the state of charge. It accounts for the voltage response of the battery after adding the terms describing the non ideal behavior of the interfacial voltages.Les batteries à usage photovoltaïque subissent des conditions opératoires pénalisantes liées à la non maîtrise de l'énergie disponible. Les effets peuvent en être minimisées par une stratégie de gestion optimisée. Cette étude concerne la recharge à courant pulsé des batteries au plomb, les plus utilisées dans ces systèmes. Les effets de cette recharge sont mis en évidence sur des cellules de laboratoire et sur des batteries commerciales. L'influence des paramètres fréquence, rapport cyclique et taux de charge sur les profils de tension est étudiée de manière précise. Dans une seconde approche, un modèle simplifié de la batterie au plomb a été développé et validé après analyse de sa sensibilité aux paramètres ajustables. Il décrit les phénomènes de transport dans l'électrolyte de manière globale par un temps caractéristique fonction de l'état de charge, et rend bien compte des réponses en tension de la batterie après introduction des termes de non idéalité dans les tensions interfaciales

Optimisation de stratégies de gestion des batteries au plomb utilisées dans les systèmes photovoltaïques

Batteries used in photovoltaic systems are subjected to penalizing operating conditions due to the intermittency of the solar resource. Their effects may be reduced by the optimisation of energy management strategies. This study deals with the pulse charge of lead acid batteries, the most used ones for this application. The effects of this charge mode are shown both on experimental cells and commercial batteries. The influence of the parameters, frequency, duty cycle and charge factor, on the voltage profiles is precisely studied. In a second approach, a simplified model of the lead-acid battery is developed and experimentally validated after the analysis of its sensitivity to the adjustable parameters. It shows that transport phenomena in the electrolyte may be well described by a global characteristic time depending only on the state of charge. It accounts for the voltage response of the battery after adding the terms describing the non ideal behavior of the interfacial voltages.Les batteries à usage photovoltaïque subissent des conditions opératoires pénalisantes liées à la non maîtrise de l'énergie disponible. Les effets peuvent en être minimisées par une stratégie de gestion optimisée. Cette étude concerne la recharge à courant pulsé des batteries au plomb, les plus utilisées dans ces systèmes. Les effets de cette recharge sont mis en évidence sur des cellules de laboratoire et sur des batteries commerciales. L'influence des paramètres fréquence, rapport cyclique et taux de charge sur les profils de tension est étudiée de manière précise. Dans une seconde approche, un modèle simplifié de la batterie au plomb a été développé et validé après analyse de sa sensibilité aux paramètres ajustables. Il décrit les phénomènes de transport dans l'électrolyte de manière globale par un temps caractéristique fonction de l'état de charge, et rend bien compte des réponses en tension de la batterie après introduction des termes de non idéalité dans les tensions interfaciales

Optimisation des stratégies de gestion des batteries au plomb utilisées dans les systèmes photovoltaïques

Les batteries à usage photovoltaïque subissent des conditions opératoires pénalisantes liées à la non maîtrise de l'énergie disponible. Les effets peuvent en être minimisées par une stratégie de gestion optimisée. Cette étude concerne la recharge à courant pulsé des batteries au plomb, les plus utilisées dans ces systèmes. Les effets de cette recharge sont mis en évidence sur des cellules de laboratoire et sur des batteries commerciales. L'influence des paramètres fréquence, rapport cyclique et taux de charge sur les profils de tension est étudiée de manière précise. Dans une seconde approche, un modèle simplifié de la batterie au plomb a été développé et validé après analyse de sa sensibilité aux paramètres ajustables. Il décrit les phénomènes de transport dans l'électrolyte de manière globale par un temps caractéristique fonction de l'état de charge, et rend bien compte des réponses en tension de la batterie après introduction des termes de non idéalité dans les tensions interfaciales.Batteries used in photovoltaic systems are subjected to penalizing operating conditions due to the intermittency of the solar resource. Their effects may be reduced by the optimisation of energy management strategies. This study deals with the pulse charge of lead acid batteries, the most used ones for this application. The effects of this charge mode are shown both on experimental cells and commercial batteries. The influence of the parameters, frequency, dut Y cycle and charge factor, on the voltage profiles is precisely studied. ln a second approach, a simplified model of the lead-acid battery is developed and experimentally validated after the analysis of its sensitivity to the adjustable parameters. It shows that transport phenomena in the electrolyte may be well described by a global characteristic time depending only on the state of charge. It accounts for the voltage response of the battery after adding the terms describing the non ideal behavior of the interfacial voltages.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Integrated photovoltaics potential for passenger car : a focus on the sensitivity to electrical architecture losses

International audienceTo reduce greenhouse emissions and improve primary energy saving, vehicle integrated pho-tovoltaics have an ongoing interest. Therefore, we developed a simulation tool of the mileage covered by VIPV. This tool considers various use profiles, different characteristics of the vehicles and of the PV system and all the losses that may decrease energy yield. Focusing on passenger car, simulations show that many parameters influence the outputs of the model, mainly: geo-graphic location, shading losses, thresholds due to extra-consumption to charge the vehicle bat-tery from PV and frequency of recharge with the grid. With projections of the technology in 2030, with 30 % shading losses, VIPV cover up to 1444 km annual mileage. This represents up to 12 % of the total distance. For the best month, it can get up to 14 km/day. For average Europe and worst-case conditions, the VIPV cover only 293 km annual mileage. Life Cycle Assessment (LCA) of solarized passenger car shows negative balance for low-carbon electricity mix. The carbon footprint is up to 489 kg CO2-equivalent avoided emissions on 13 years lifespan in fa-vorable conditions. Beyond km and LCA focus, VIPV could provide useful functions in non-interconnected zones and for resilience in case of climatic catastrophes

Shading losses measurements for integrated photovoltaics potential estimation for solar city bus and data driven simulations

International audienceIn order to improve primary energy saving and reduce greenhouse emissions, vehicle integrated photovoltaics have an ongoing interest [1]. Studies on the benefits from vehicle solar roof, which take into account all the losses and the monthly variation in different climate conditions, are required. Therefore, we developed a simulation tool of the mileage covered by VIPV. This tool takes into account various use profiles and different characteristics of the vehicles and of the PV system. Focusing on city bus, simulations show that many parameters can influence the outputs of the model, mainly: the geographic location (first order), the shading losses (second order), the electric architecture (third order) and the battery saturation (forth order). As the shading losses have a second order influence, we propose here to use in simulations shading losses measured on city bus during several months to be as close as possible to the real driving conditions.Auto generated distance, useful PV energy and carbon footprint results will be thus updated taking into account monthly real shading losses values and real bus use profiles. The relevance of our work is in coupling measurement, modeling and so data driven simulations and life cycle assessment methodology to assess the potential of VIPV on city bus in real conditions. The simulations use the experimental shading results on city bus. We used also an extrapolation method to fill the missing data and statistics analysis of city bus trips to identify the use profile. The outputs of the simulation model (used PV energy and annual mileage covered by VIPV) are inputs of the life cycle assessment, which allows calculating the carbon footprint on the whole life of the vehicle. The aim is to assess the real potential of VIPV on city bus. For this, we used three complementary approaches: simulation, experiments and life cycle assessment. The simulation approach consists in developing a dedicated modular simulation tool described in our previous work [2]. The experimental methodology consists in evaluating the irradiance received on the roof of a bus while moving in the city with GPS tracking. A correction of the irradiance values is evaluated from the measured temperature values. To perform these experiments, three silicon solar cell sensors were placed on the roof of the bus as shown in Figure 1. These experiments allow to evaluate the shading ratio. The obtained data is used to update the simulation results of PV useful energy, annual and daily mileage covered by VIPV. The life cycle assessment approach allows finally the calculation of the carbon footprint results. Our first simulations [2] take into account the shading as a model sensitivity analysis parameter. Figure 2 presents the results with projections of the technology in 2030,at midlife of the city bus, for average Europe use case, for different shading losses, with direct charge in the main battery and without battery saturation. It shows that the VIPV on city bus in this use case covers up to 6269 km and down to 4361 km annual mileage with 0 % and 30 % shading losses, respectively. Life cycle assessment of solar city bus shows neutral to high gains. For average Europe use case in term of solar irradiance and electricity mix, the avoided emissions on 20 years lifespan is up to 10 T and down to 6.5 T CO2-equivalent, with 0 % and 30 % shading losses, respectively. The work on real irradiance measurements (example in figure 3) and on data driven simulations is ongoing

ON-BOARD PHOTOVOLTAIC KIT FOR EXISTING VEHICLES

International audienceThis work is focused on the deployment of a solarization kit for electric vehicles. The interest is to be able to solarize the vehicles in after-sales and thus to self-generate km of autonomy, to gain in comfort of use by decreasing the frequency of recharging, while reducing the global CO2 impact of the vehicle at its end-of-life. A 145 Wp photovoltaic (PV) module has been designed specifically for the application, with a magnetic backside and a mechanical design allowing a good conformability on vehicles roofs (two patents pending). The associated V1 electronics consist of a MPPT charge controller, associated with a battery that is voluntarily maintained in a discharged state in order to monitor the maximum power of the module continuously, without recharging the vehicle battery (version 1). The system is intended to be non-intrusive in the vehicle so that it can be adapted to many models. The perspectives are mainly focused on the electronic part to valorize the energy produced in the battery of the vehicle with an auxiliary battery (version 2) then directly in the traction battery of the vehicle (version 3). The final version of the system will be deployed on ZOE INES vehicles fleet and will allow the measurement of the available solar energy for the VIPV application

Shading losses measurements for integrated photovoltaics potential estimation for solar city bus and data driven simulations

International audienceIn order to improve primary energy saving and reduce greenhouse emissions, vehicle integrated photovoltaics have an ongoing interest [1]. Studies on the benefits from vehicle solar roof, which take into account all the losses and the monthly variation in different climate conditions, are required. Therefore, we developed a simulation tool of the mileage covered by VIPV. This tool takes into account various use profiles and different characteristics of the vehicles and of the PV system. Focusing on city bus, simulations show that many parameters can influence the outputs of the model, mainly: the geographic location (first order), the shading losses (second order), the electric architecture (third order) and the battery saturation (forth order). As the shading losses have a second order influence, we propose here to use in simulations shading losses measured on city bus during several months to be as close as possible to the real driving conditions.Auto generated distance, useful PV energy and carbon footprint results will be thus updated taking into account monthly real shading losses values and real bus use profiles. The relevance of our work is in coupling measurement, modeling and so data driven simulations and life cycle assessment methodology to assess the potential of VIPV on city bus in real conditions. The simulations use the experimental shading results on city bus. We used also an extrapolation method to fill the missing data and statistics analysis of city bus trips to identify the use profile. The outputs of the simulation model (used PV energy and annual mileage covered by VIPV) are inputs of the life cycle assessment, which allows calculating the carbon footprint on the whole life of the vehicle. The aim is to assess the real potential of VIPV on city bus. For this, we used three complementary approaches: simulation, experiments and life cycle assessment. The simulation approach consists in developing a dedicated modular simulation tool described in our previous work [2]. The experimental methodology consists in evaluating the irradiance received on the roof of a bus while moving in the city with GPS tracking. A correction of the irradiance values is evaluated from the measured temperature values. To perform these experiments, three silicon solar cell sensors were placed on the roof of the bus as shown in Figure 1. These experiments allow to evaluate the shading ratio. The obtained data is used to update the simulation results of PV useful energy, annual and daily mileage covered by VIPV. The life cycle assessment approach allows finally the calculation of the carbon footprint results. Our first simulations [2] take into account the shading as a model sensitivity analysis parameter. Figure 2 presents the results with projections of the technology in 2030,at midlife of the city bus, for average Europe use case, for different shading losses, with direct charge in the main battery and without battery saturation. It shows that the VIPV on city bus in this use case covers up to 6269 km and down to 4361 km annual mileage with 0 % and 30 % shading losses, respectively. Life cycle assessment of solar city bus shows neutral to high gains. For average Europe use case in term of solar irradiance and electricity mix, the avoided emissions on 20 years lifespan is up to 10 T and down to 6.5 T CO2-equivalent, with 0 % and 30 % shading losses, respectively. The work on real irradiance measurements (example in figure 3) and on data driven simulations is ongoing

Estimation of integrated photovoltaics potential for solar city bus in different climate conditions in Europe

5th International Symposium on Hydrogen Energy and Energy Technologies (HEET 2022) 18/11/2022 - 19/11/2022 Osaka, JapanInternational audienceVehicle integrated photovoltaics have an ongoing interest. Studies on the benefits from vehicle solar roof which take into account all the possible losses and the monthly variation in different climate conditions, are required. Therefore, we developed a software for the simulation of useful PV energy and mileage covered by the PV in vehicles with solar roofs. This software can take into account different use profiles and different characteristics of the vehicles and of the PV system. Focusing on city bus, simulations allow seeing that many parameters can influence the outputs of the model, mainly: the geographic location (first order), the shading losses (second order), the electric architecture (third order) and the battery saturation (fourth order).At mid-life of the vehicle, with the integrated PV (projections of the technology at 2030), a city bus can collect up to 8571 kWh annual useful PV energy, thus up to 9739 km annual mileage covered by VIPV. This represents up to 24 % of the total distance. For the best month, it can get up to 47 km/day. For average Europe case, with high shading losses, a city bus can collect down to 3805 kWh per year and so only 3506 km annual mileage covered by VIPV.The upgrade of the technology from 2022 to 2030 induces an improvement of the useful PV energy and annual mileage covered by VIPV from 32 % to 56 % for city bus depending on the use case.Based on the annual distance covered by VIPV, an evaluation of the different stages of the life cycle analysis of solarized vehicle solutions is possible. The objective is to know the environmental balance of the solutions over the entire life cycle of the vehicles. The carbon footprint of the different solutions is highly variable and depends primarily on the carbon content of the electricity mix in which the vehicle is marketed, but also on the amount of solar irradiance in the considered area. Therefore, there is no simple general trend. Nevertheless, we have drawn some conclusions. With a low carbon module, for a city bus, neutral to very large gains in term of avoided CO2 are expected (up to 28 T CO$_2$ on 20 years lifetime)

ON-BOARD PHOTOVOLTAIC KIT FOR EXISTING VEHICLES

International audienceThis work is focused on the deployment of a solarization kit for electric vehicles. The interest is to be able to solarize the vehicles in after-sales and thus to self-generate km of autonomy, to gain in comfort of use by decreasing the frequency of recharging, while reducing the global CO2 impact of the vehicle at its end-of-life. A 145 Wp photovoltaic (PV) module has been designed specifically for the application, with a magnetic backside and a mechanical design allowing a good conformability on vehicles roofs (two patents pending). The associated V1 electronics consist of a MPPT charge controller, associated with a battery that is voluntarily maintained in a discharged state in order to monitor the maximum power of the module continuously, without recharging the vehicle battery (version 1). The system is intended to be non-intrusive in the vehicle so that it can be adapted to many models. The perspectives are mainly focused on the electronic part to valorize the energy produced in the battery of the vehicle with an auxiliary battery (version 2) then directly in the traction battery of the vehicle (version 3). The final version of the system will be deployed on ZOE INES vehicles fleet and will allow the measurement of the available solar energy for the VIPV application

Data-driven approach for SOH estimation and alarms generation for complex on-grid energy storage systems

International audienceOn-grid energy storage systems are used increasingly worldwide in order to optimize the use of intermittent energies such as photovoltaics. An accurate estimation of the state of health of the batteries is necessary to optimise their lifetime and reduce their Levelized Cost of Storage. The misuse of these batteries leads to frequent failures. A robust analysis of the misuse events with automatic alarms generation will also be valuable to send warnings to the system end-user before failure. This paper presents advanced analysis of some of these systems based on new approaches of data-driven diagnosis and prognosis. Several PV-Storage systems have been monitored for four years and an original diagnostic and prognostic tool is developed for the analysis of the performance and defaults of such systems. This generic approach allowed to have a feedback on the performance of grid connected PVstorage systems with two storage technologies (Li-ion and NiNaCl2). Recently, the efficiency of this kind of systems have been analysed including the performance of batteries and power conversion systems. The analysis doesn’t include the state of health evolution and the alarms generation