BUSCADOR RECOLECTA

In this paper a dynamic model for the simulation of pressurized alkaline water electrolyzers is presented. The model has been developed following a multiphysics approach, integrating electrochemical, thermodynamic, heat transfer and gas evolution processes in order to faithfully reproduce the complete dynamical behavior of these systems. The model has been implemented on MATLAB/Simulink and validated through experimental data from a 1 Nm3/h commercial alkaline water electrolyzer. Validations have been performed under real scenarios where the electrolyzer is working with power profiles characteristic from renewable sources, wind and photovoltaic. The simulated results have been found to be consistent with the real measured values. This model has a great potential to predict the behavior of alkaline water electrolyzers coupled with renewable energy sources, making it a very useful tool for designing efficient green hydrogen production systems., This work has been supported by the Spanish State Research Agency (MCIN/AEI/10.13039/501100011033) under grants PID2019-111262RBI00, PID2019-110956RB-I00 and TED2021-132457B-I00 (also funded by the European Union NextGenerationEU/PRTR), by Ingeteam R&D Europe and by Ingeteam Power Technology.

The thermal runaway (TR) is one of the most dangerous phenomena related to lithium-ion batteries. For this reason, there are different proposals in the literature for its modelling. Most of these proposed models take into account the decomposition reactions between the internal components of the cell, and base the adjustment of the parameters on numerous abuse tests that lead to the appearance of TR. However, these tests are destructive, require specific equipment, present a high economic cost and are very time consuming. This paper proposes a modelling method which enables the development of TR models with the use of fewer resources. This method is based on chemical kinetics, which allow a simplification of the general modelling process published in the literature. At the same time it maintains good accuracy and makes it possible to define the TR behavior of any type of cell, regardless of its chemistry, shape or size. Furthermore, the proposed method allows the use of the experimental results most commonly presented in the specialized literature, which significantly reduces the need for destructive testing. The presented modelling method achieves a good compromise between accuracy and applicability in the validations shown in the paper., This work has been supported by the Spanish State Research Agency (AEI) under grant PID2019-111262RB-I00 /AEI/ 10.13039/501100011033, the European Union under the H2020 project STARDUST (774094), and the Public University of Navarra under project ReBMS PJUPNA1904.

Lithium-ion batteries are energy storage systems used in an increasing number of applications. Due to their flammable materials, their use entails risks of fire and explosion. The study of the abuse operation of these batteries before reaching the thermal runaway is a relevant research topic to prevent safety issues. There are various studies in the bibliography providing exhaustive thermal studies of the safe operating area, as well as concerning the thermal runaway. However, the onset irreversible reactions, that take place at a SOC around 110%, have not been properly analyzed. We present in this contribution an experimental study of this onset reaction measured in pouch Li-ion cells under various conditions of charge current and temperature. We also propose a lumped-parameter thermal model for the cell, which allows a detailed characterization of this exothermic reaction. The results achieved in this contributions can be a key tool to prevent overcharge accidents that may arise due to malfunctioning of the battery charger or battery management system., This work is part of the projects PID2019-111262RB-I00, funded
by MCIN/AEI/10.13039/501100011033/, TED2021-132457B-I00, funded by
MCIN/AEI/10.13039/501100011033/ and by the European Union NextGenerationEU/PRTR, STARDUST (774094), funded by European Union's Horizon
2020 research and innovation programme, HYBPLANT (0011-1411-2022-
000039), funded by Government of Navarre, and has also been supported by
MCIN/AEI/10.13039/501100011033/ and by European Social Fund under a
PhD scholarship (grant PRE2020-095314).

Nowadays, the economic viability of second-life (SL) Li-ion batteries from electric vehicles is still uncertain. Degradation assessment optimization is key to reduce costs in SL market not only at the repurposing stage, but also during SL lifetime. As an indicator of the ageing condition of the batteries, state of health (SOH) is currently a major research topic, and its estimation has emerged as an alternative to traditional characterization tests. In an initial stage, all SOH estimation methods require the extraction of health indicators (HIs), which influence algorithm complexity and on-board implementation. Nevertheless, a literature gap has been identified in the assessment of HIs for reused Li-ion batteries. This contribution targets this issue by analysing 58 HIs obtained from incremental capacity analysis, partial charging, constant current and constant voltage stage, and internal resistance. Six Nissan Leaf SL modules were aged under extended cycling testing, covering a SOH range from 71.2 % to 24.4 %. Results show that the best HI at the repurposing stage was obtained through incremental capacity analysis, with 0.2 % of RMSE. During all SL use, partial charge is found to be the best method, with less than 2.0 % of RMSE. SOH is also estimated using the best HI and different algorithms. Linear regression is found to overcome more complex options with similar estimation accuracy and significantly lower computation times. Hence, the importance of analysing and selecting a good SL HI is highlighted, given that this made it possible to obtain accurate SOH estimation results with a simple algorithm., This work is part of the projects PID2019-111262RB-I00, funded by MCIN/AEI/10.13039/501100011033/, STARDUST (774094), funded by European Union's Horizon 2020 research and innovation programme, HYBPLANT (0011-1411-2022-000039), funded by Government of Navarre, and a Ph.D. scholarship, also funded by Government of Navarre. Open access funding provided by Universidad Pública de Navarra.

Reducing carbon emissions is essential to stop
climate change. The grid-share of renewable generation plants
is increasing, being wind and photovoltaic plants the most
common ones, whereas conventional plants are the only ones
that provide the necessary services to maintain the grid stability
and keep the generation-demand balance. However, with the
aim of achieving carbon-neutral generation, conventional plants
are being dismantled. This leads to the imminent need of
providing these services with renewable plants. Due to this
challenge, this proposal analyses a hybrid plant composed by
wind and photovoltaic generation with two types of storage,
lithium-ion batteries and a thermal storage system based on
volcanic stones. In order to compare both strategies, a technoeconomic methodology is explained that allows to optimally size
the plant, using the current prices of each technology. The most
cost-competitive proposal turns to be the hybrid plant with
thermal storage, composed by 623.9 MW installed power and
21.9 GWh of storage, which could replace a 100 MW, 24/7
conventional power plant, with an LCOHS (levelized cost of
hybrid system) of 118.38 €/MWh, providing identical grid
services and an equivalent inertia in a way committed with the
environment. This is in turn a zero-carbon emissions solution
perfectly matched to a second life plan for a conventional power
plant., This work has been supported by Siemens Gamesa Renewable Energy, by the Spanish State Research Agency (AEI/ 10.13039/501100011033) under grants PID2019-111262RB-I00 and PID2019-110956RB-I00, and by the Public University of Navarra under project ReBMS PJUPNA1904.

Together with the huge growth of the traditional
crystalline silicon (Si-x) PV manufacturers, other thin-film
solar cells have also emerged such as cadmium telluride
(CdTe) manufacturers. They are characterized by the fact
that they were created to reduce costs and by the scarcity of
silicon, from which the rest of the modules are made. Despite
they need more space to generate the same amount of energy
as crystalline modules, their price is supposed to be much
lower, and argue that they have a better performance at high
temperatures. However, real comparisons between the
outdoor performance of CdTe and Si-x modules have been
scarcely addressed in the literature. This paper provides a
comparison under real operating conditions of a CdTe
photovoltaic generator versus a conventional silicon
generator during 5 years of operation in a mid-latitude area,
identifying the causes of the differences observed., This work was supported in part by the Spanish State Research Agency (AEI) under grants PID2019-111262RBI00/AEI/10.13039/501100011033 and PID2019-110816RB-C21-I00/AEI/10.13039/501100011033

Lithium-ion batteries are the leading technology for energy storage systems due to their attractive advantages. However, the safety of lithium-ion batteries is a major concern, as their operating conditions are limited in terms of temperature, voltage and state of charge. Therefore, it is important to monitor the conditions of lithium-ion batteries to guarantee safe operation. To this end, in the present work, we analyze electrochemical impedance spectroscopy (EIS) as a tool to estimate the temperature of batteries. Overtemperature abuse tests from 25 °C to 140 °C are performed at various states of charge, and EIS measurements are obtained during the tests. The influence of temperature on cell impedance at different frequencies is analyzed and new findings are revealed. The real part of the impedance is identified to be the best indicator for cell temperature estimation by EIS. In addition, the best frequency to achieve accurate temperature monitoring, avoiding disturbances produced by state of charge variations, is proposed based on experimental results. Finally, EIS is proven to be a reliable technique for overtemperature and thermal runaway detection., This work is part of the projects PID2019-111262RB-I00, funded
by MCIN/AEI/10.13039/501100011033/, TED2021-132457B-I00, funded by
MCIN/AEI/10.13039/501100011033/ and by the European Union NextGenerationEU/PRTR, STARDUST (774094), funded by European Union’s Horizon
2020 research and innovation programme, HYBPLANT (0011-1411-2022-
000039), funded by Government of Navarre, and has also been supported by
MCIN/AEI/10.13039/501100011033/ and by European Social Fund under a
PhD scholarship (grant PRE2020-095314).

A battery model predicts the battery performance, which can be a useful tool for optimizing battery design and preventing unsafe operation. This becomes especially significant in second-life batteries where the cells have already endured degradation and predicting the lifetime becomes challenging. The assessment of physical phenomena is often performed individually, but the overall battery behavior depends on their interaction. For this purpose, an integrated battery model is developed. Equivalent electric circuits are interconnected to represent the electrochemical reactions, thermodynamic phenomena, and heat transfer mechanisms of the battery. To consider cell degradation, calendar and cycling aging were represented using a semi-empirical model. A battery management system is included to oversee and remain within the safe limits of battery voltage, temperature, and current. Additionally, a passive cell balancing distributes charge evenly. The integrated model is applied to a second-life battery prototype with a nominal capacity and power of 45 Ah and 4 kW, respectively. Its performance is validated with constant current and power cycles, as well as in a microgrid with photovoltaic generation under a self-consumption profile. The model accurately reproduces experimental results of battery power, voltage, temperature, and state of charge., This work is part of the projects PID2019-111262RB-I00, funded by MCIN/AEI/10.13039/501100011033/, TED2021-132457B-I00, funded by MCIN/AEI/10.13039/501100011033/ and by the European Union NextGenerationEU/PRTR, STARDUST (774094), funded by European HYBPLANT (0011-1411-2022-000039), funded by Government of Navarre.

This study analyses and presents a new ramp-rate control algorithm for smoothing PV power fluctuations, designed to address three fundamental objectives: to reduce battery cycling, to meet minimum storage requirements and to be able to operate, without ramp-rate violations, with real publicly-available forecasting. The algorithm was compared to three benchmark methods and, as a performance limit, also to a hypothetical perfect prediction. Different performance variables were analyzed for all the strategies within a restricted ramp-rate constraint (2%/min): minimum storage requirement, battery power distributions, throughput energy, state of charge (SOC) distributions, degradation (calendar and cycling), expected battery lifespan and levelized cost of energy (LCOE). The proposal proves to be the most cost-effective smoothing technique and the simulation results show that its performance is comparable to the obtained with the use of an assumed perfect prediction., Support of the Spanish State Research Agency (AEI) under grants PID2019111262RB-I00 and
PID2019-110816RB-C21. Open access funding provided by Universidad Pública de Navarra.

This paper proposes an energy management strategy for a residential microgrid comprising photovoltaic (PV)
panels, a small wind turbine and solar thermal collectors. The microgrid can control the power exchanged with
the grid thanks to a battery and a controllable electric water heater, which provide two degrees of freedom to the
control strategy. As input data, the proposed control strategy uses the battery state of charge (SOC), the temperature
of the hot water tank, the power of each microgrid element as well as the demand and renewable
generation forecasts. By using forecasted data and by controlling the electric water heater, the strategy is able to
achieve a better grid power profile while using a smaller battery than previous works, hence reducing the overall
cost of the system. The strategy is tested by means of simulation with real data for one year and it is also
experimentally validated in the microgrid built at the Renewable Energy Laboratory at the UPNA., The authors would like to acknowledge that this work has been
partially funded under grants PID2019-110816RB-C21 and
PID2019–111262RB–I00 by the Spanish State Research Agency (AEI/
10.13039/501100011033). And also by VLIR-UOS and the Belgian
Development Cooperation (DGD) under the project EC2020SIN322A101
(2020-EXT-007).

The reuse of Li-ion batteries from electric vehicles
is a promising alternative to recycling nowadays. However, the
technical and economic viability of these second-life (SL) batteries
is not yet clear. Degradation assessment plays a key role not only
to analyse the impact of ageing factors in reused batteries, but
also to quantify their durability. In this context, this contribution
aims to analyse calendar ageing behaviour in SL cells. 16 reused
Nissan Leaf modules are aged during 750 days under three
temperatures and four State of Charge (SOC), covering a State of
Health range from 72.2 % to 13 %. The impact of temperature
and SOC as stress factors is firstly analysed, concluding that
their increase accelerates ageing. Temperature rise is found to
have a major impact, accelerating up to 27 times capacity fade
and almost 6 times resistance increase when compared to light
ageing conditions, while increasing SOC nearly doubles ageing
rates. The worst ageing case is found to be the combination of
60 ◦C and 66 % of SOC. Regarding degradation trends, they
are proven to be constant during all SL lifetime. This work also
proposes and validates a calendar ageing model for SL cells.
Accuracy of validation results show a fitting Rsq of 0.9941 in
capacity fade and 0.9557 in resistance increase, thereby tracking
the heterogeneous degradation of the SL cells under calendar
ageing., We would like to acknowledge the support of the Spanish State Research Agency (AEI) grant PID2019-111262RB-I00/AEI/10.13039/501100011033, the European Union H2020 Project STARDUST (74094) and the Government of Navarre Ph.D. scholarship.

Experimental aging studies are commonly conducted on lithium-ion batteries by full charge and discharge cycles. However, such profiles may differ from the actual operation of batteries in electric vehicles and stationary applications, where they are subjected to different partial charges and discharges. These partial cycles, which take place during a main charge or discharge process, are called micro-cycles if their depth of discharge is <2 %. A number of authors have pointed out the relevance of the time resolution to estimate the energy throughput of a battery due to these micro-cycles in applications such as renewable microgrids. However, to the best of our knowledge, there are no experimental studies in the literature that assess the impact of these micro-cycles on battery degradation. In this article, the impact of micro-cycles on the loss of performance of a lithium-ion battery is experimentally studied. The results show that micro-cycles have a negligible, or even positive effect on the aging of lithium-ion cells compared to the aging caused by full cycles. In fact, if charge throughput or equivalent full cycles are used to measure the use of a battery, then cells subjected to micro-cycles exhibit a 50 % extended lifetime compared to cells only subjected to full cycles. More precisely, cells including micro-cycles with depth of discharge of 0.5 % lasted for nearly 3000 equivalent full cycles, whereas cells aged under standard deep cycles lasted for no >1500. Nevertheless, if the number of deep cycles, disregarding micro-cycles, is the unit to measure battery use, then the degradation of cells with and without micro-cycles is similar. Based on this result, the number of cycles can be identified as a more accurate variable to measure the use of a cell, in comparison to charge throughput., This work is part of the projects PID2019-111262RB-I00, funded by MCIN/AEI/10.13039/501100011033/, STARDUST (774094), funded by European Union¿s Horizon 2020 research and innovation programme, HYBPLANT (0011-1411-2022-000039), funded by Government of Navarre, and a Ph.D. scholarship, funded by Public University of Navarre. Open access funding provided by Universidad Pública de Navarra.

This work deals with the design of a Fuzzy Logic Control (FLC) based Energy Management
System (EMS) for smoothing the grid power prole of a grid-connected electro-thermal microgrid. The
case study aims to design an Energy Management System (EMS) to reduce the impact on the grid power
when renewable energy sources are incorporated to pre-existing grid-connected household appliances. The
scenario considers a residential microgrid comprising photovoltaic and wind generators, at-plate collectors,
electric and thermal loads and electrical and thermal energy storage systems and assumes that neither
renewable generation nor the electrical and thermal load demands are controllable. The EMS is built through
two low-complexity FLC blocks of only 25 rules each. The first one is in charge of smoothing the power
prfile exchanged with the grid, whereas the second FLC block drives the power of the Electrical Water
Heater (EWH). The EMS uses the forecast of the electrical and thermal power balance between generation
and consumption to predict the microgrid behavior, for each 15-minute interval, over the next 12 hours.
Simulations results, using real one-year measured data show that the proposed EMS design achieves 11.4%
reduction of the maximum power absorbed from the grid and an outstanding reduction of the grid power
profile ramp-rates when compared with other state-of-the-art studies., This work was supported in part by the projects 2019-PIC-003-CTE and 2020-EXT-007 from the Research Group of Propagation,
Electronic Control, and Networking (PROCONET) of Universidad de las Fuerzas Armadas ESPE, in part by the Belgian Development
Cooperation (DGD) and the VLIR-UOS under the project EC2020SIN322A101, in part by the Spanish Ministry of Industry and
Competitiveness under Grant DPI2017-85404 and Grant PID2019-111443RB-100, and in part by the Spanish State Research Agency
(AEI/10.13039/501100011033) under Grant PID2019-110816RB-C21 and Grant PID2019-111262RB-I00.

The potential of batteries from electric vehicles to be given a second life in stationary applications could be starting to become a reality in few years. However, the technical and economic feasibility of such second-life batteries (SLBs) is still uncertain. In this context, this paper analyses the real operation of a SLB in three scenarios: two of residential microgrids with photovoltaic generation under different strategies, and a fast charging station for electric mobility. To this end, three energy management strategies are developed, the first of which seeks to maximise the self-consumption of a typical household with photovoltaic generation; the second, in addition to maximising self-consumption, presents a night-time charge and peak shaving of the contract power from the grid; and the last refers to an urban bus charging station in which the aim is to reduce the contract power from the grid. Experimental validation of SLB during more than three weeks of operation in each of the scenarios have proved the technical viability of these batteries in the applications analysed., Spanish State Research Agency (AEI) grant PID2019-111262RB-I00/AEI/10.13039/501100011033; European Union H2020 Project STARDUST (74094). E. Braco was supported by a Predoctoral Contract of the Government of Navarra.

Upgraded metallurgical grade silicon (UMG-Si) PV modules have failed to make their space in the PV market, which was partly to the uncertainty on their in-field performance that brings the wide disparity of results published over the years. The most-recently developed UMG-Si PV modules have demonstrated similar initial degradation and efficiencies under standard test conditions (STC) to those obtained with conventional solar grade silicon (SoG-Si). Nevertheless, their performance under operating conditions other than STC and its impact on the energy production are key aspects that have not yet been properly characterized in the literature. This article analyzes the in-field performance of a PV generator comprised of recently developed UMG-Si modules. This performance was compared to that of another PV generator comprising standard polysilicon modules. The cells and modules of both types of generators were made by the same manufacturer in the same period and on the same production lines, which guarantees that performance differences encountered are exclusively due to the silicon employed. Contrary to the previous experience, this article reveals that UMG-Si modules do not necessarily present a better temperature performance than today's conventional modules. The analyzed UMG-Si modules presented 1.6% less efficiency under low irradiance conditions, but this different irradiance performance led to an insignificant difference (less than 0.5%) in their energy production. No significant degradation was measured in both UMG-Si and SoG-Si modules during the two-year analyzed period, being the final energy performance of both types of modules essentially the same. These results can be considered as highly representative of the current state-of-the-art of UMG-Si technology., This work was supported by the Spanish State Research Agency and the ERDFEU under Grant PID2019-110816RB-C21 and Grant PID2019-111262RB-I00.

The worldwide growth of the PV market has been
almost exponential during the last years. Together with
conventional crystalline (c-Si) PV modules, “new” commercially
available PV technologies such as copper indium selenide (CIS)
based solar cells have appeared achieving a similar efficiency
comparable to c-Si at similar production cost. In addition to the
use of cheaper materials, CIS solar cells manufacturers claim
some enhancements such as lower temperature coefficient or
higher absorption of diffuse light that achieve to reduce the cost
of electrical energy. Although several papers deal with this
topic, little is known about real comparisons between CIS
technology and conventional crystalline at a PV generator level
with real test conditions. This paper analyses the in-field
performance and degradation of a commercially available CIS
solar based PV generator compared to a conventional c-Si one
during four years of operation attributing the differences
observed to the possible factors that can influence in both
technologies., This work was supported in part by the Spanish State Research Agency (AEI) under grants PID2019-111262RB-I00/AEI/10.13039/501100011033 and PID2019-110816RB-C21-I00/AEI/10.13039/501100011033

This work presents a novel control method for multi-megawatt photovoltaic (PV) plants that is able to regulate each plant inverter and the battery system to mitigate PV power fluctuations. The proposed control method makes it possible to implement different PV ramp-rate control strategies based on the use of batteries and the limitation of inverters during positive fluctuations, which have been conceptually proposed in the specialized bibliography, but have omitted how to perform the coordination between PV generators. The dynamic model and the tuning of the control parameters are presented and the method is used to correctly implement different inverter-limitation strategies using 5-second data from a real 45 MWp PV plant. Furthermore, a new control strategy is proposed. This strategy reduces curtailment losses to negligible values and takes into account and addresses the intrinsic asymmetry in the battery charging and discharging capability, an issue that has been overlooked in the specialized bibliography. The results show that the proposed control method can effectively control each of the multiple inverters in order to obtain the desired PV plant operation to regulate the battery charging power, even during highly fluctuating scenarios., The authors to acknowledge the support of the Spanish State Research Agency (AEI) under grants PID2019111262RB-I00 and PID2019-110816RB-C21. Alejandro González-Moreno would like to thank the Universidad Pública de Navarra (UPNA) for its financial support. Open access funding provided by Universidad Pública de Navarra.

The increasing wind power penetration in electrical power systems results in a reduction of operative conventional power plants. These plants include synchronous generators directly connected to the grid. Facing a change in grid frequency, these generators inherently respond by varying their stored kinetic energy and their output power, which contributes to grid stability. Such a response is known as inertial response. Wind turbines (WTs) are mostly based on Doubly-Fed Induction Generator (DFIG) or Permanent Magnet Synchronous Generator (PMSG) machines. Their power electronics interface decouples the electromechanical behaviour of the generator from the power grid, making their inertial response null or insignificant. Therefore, in order not to weaken the frequency response of the power system, WTs must be able to react to frequency variations by changing their output power, i.e., emulating an inertial response. Common techniques for inertia emulation in WTs rely on pitch control and stored kinetic energy variation. This contribution proposes a strategy (applicable for both DFIG and PMSG) which uses the energy stored in a supercapacitor connected to the back-to-back converter DC link to emulate the inertial response. Its performance is compared by simulation with aforementioned common techniques, showing ability to remove certain limitations., This work has been supported by Siemens Gamesa Renewable Energy, by the Spanish State Research Agency (AEI/ 10.13039/501100011033) under grants PID2019-111262RB-I00 and PID2019-110956RB-I00, and by the Public University of Navarra under project ReBMS PJUPNA1904

In the last few years, the growing demand for electric vehicles (EVs) in the transportation sector has contributed to the increased use of electric rechargeable batteries. At present, lithium-ion (Li-ion) batteries are the most commonly used in electric vehicles. Although once their storage capacity has dropped to below 80¿70% it is no longer possible to use these batteries in EVs, it is feasible to use them in second-life applications as stationary energy storage systems. The purpose of this study is to present an embedded system that allows a Nissan® LEAF Li-ion battery to communicate with an Ingecon® Sun Storage 1Play inverter, for control and monitoring purposes. The prototype was developed using an Arduino® microcontroller and a graphical user interface (GUI) on LabVIEW®. The experimental tests have allowed us to determine the feasibility of using Li-ion battery packs (BPs) coming from the automotive sector with an inverter with no need for a prior disassembly and rebuilding process. Furthermore, this research presents a programming and hardware methodology for the development of the embedded systems focused on second-life electric vehicle Li-ion batteries. One second-life battery pack coming from a Nissan® Leaf and aged under real driving conditions was integrated into a residential microgrid serving as an energy storage system (ESS)., This work was supported by: 1. Spanish State Research Agency: PID2019-111262RBI00/AEI/10.13039/501100011033; 2. Government of Navarra under Research Project: 0011-1411-2022-000039 HYBPLANT; 3. European Union's Horizon 2020 Research and Innovation Programme (Stardust-Holistic and Integrated Urban Model for Smart Cities) under Grant 774094.; 4. To the Autonomous University of Tamaulipas (México) for APC support.

Nowadays, the reuse of electric vehicle batteries is considered to be a feasible alternative to recycling, as it allows them to benefit from their remaining energy capacity and to enlarge their lifetime. Stationary applications, such as self-consumption or off-grid systems support, are examples of second-life (SL) uses for retired batteries. However, reused modules that compose these batteries have heterogeneous properties, which limit their performance. This article aims to assess the influence of degradation in modules from electric vehicles, covering three main aspects: performance, capacity dispersion, and extended SL behavior. First, a complete characterization of new and reused modules is carried out, considering three temperatures and three discharge rates. In the second stage, intra- and intermodule capacity dispersions are evaluated with new and reused samples. Finally, the behavior during SL is also analyzed, through an accelerated cycling test so that the evolution of capacity and dispersion are assessed. Experimental results show that the performance of reused modules is especially undermined at low temperatures and high current rates, as well as in advanced stages of aging. The intramodule dispersion is found to be similar in reused and new samples, while the intermodule differences are nearly four times greater in SL., This work was supported in part by the Spanish State Research Agency (AEI) under Grant PID2019-111262RB-I00/AEI/10.13039/501100011033 and Grant DPI2016-80641-R, in part by the European Union under the H2020 Project STARDUST under Grant 774094, in part by the Government of Navarra under Research Project 0011-1411-2018-000029 GERA, and in part by the Public University of Navarre under Project ReBMS PJUPNA1904.

This work studies the importance of the correct
selection of control parameters in order to avoid unnecessary
cycling in batteries when they perform PV smoothing. The
classic ramp-rate control method (CRRC) is studied as smoothing
technique and the key role of the state of charge (SOC) control
is analyzed for a real 38.5 MW PV plant, particularly the
influence of proportional gain (K). Depending on K, battery
cycling degradation (CyD), power requirements, SOC limits and
throughout energy performance were discussed. According to
the results, the correct tuning could prolong battery lifespan
by reducing cycling degradation up to 80% (depending on the
fluctuation restrictions and K) and avoiding unnecessary energy
losses, power requirements and undesirable SOC operation levels.
Finally, a simple general rule is proposed to set K value when
CRRC is used and its applicability is tested by simulating two
additional PV plants with rated power of 1.1 and 75.6 MW., This work was supported in part by the Spanish State Research Agency (AEI) under grants PID2019-111262RBI00 and PID2019-110816RB-C21-I00 as well as the Doctoral
Scholarships funded by Public University of Navarra (UPNA).

La necesidad de un cambio en el modelo energético actual hacia un futuro en el que se abogue por la sostenibilidad como pilar indispensable del progreso ha suscitado un cambio en el paradigma energético. Las fuentes de generación
basadas en la nociva quema de combustibles fósiles han de ser erradicadas con la mayor celeridad posible. Es en este contexto, en el que las baterías de iones de litio emergen como una solución viable y amigable con el medio ambiente.
Las baterías de iones de litio, dada su alta densidad energética, pueden ser empleadas en el sector del transporte como sustitutas a los combustibles fósiles. No obstante, la electricación del sistema automovilístico no conlleva
asociada una mejora sustancial si la generación eléctrica sigue proviniendo de sistemas basados en la quema de combustibles fósiles o de la energía nuclear. La principal alternativa estriba en remplazar estas fuentes convencionales por fuentes de origen renovables. No obstante, un sistema basado únicamente en los incontrolables recursos renovables no sería más que una utopía sin un sistema de almacenamiento que los acompañe, como son las baterías de iones de litio.
Esta tesis analiza en detalle esta tecnología, y en especial, su aplicación en entornos de generación renovables. Las principales líneas de trabajo son:
Análisis del estado actual de la tecnología de baterías de iones de litio; Estudio de las principales técnicas de caracterización no invasivas como herramienta para cuantificar e identificar los mecanismos de degradación en baterías de iones de litio; Modelizado eléctrico de baterías de iones de litio y validación en sistemas reales; Estudio e identificación de aspectos clave en baterías de iones de litio para la integración de energías renovables en la red eléctrica., Gaur egungo energia-eredua aldatzeko beharra dago, jasangarritasuna oinarria izan behar du, horrek energia-paradigma aldatzea ekarri du. Erregai fosilen erreketa kaltegarrian oinarritutako sorkuntza-iturriak ahalik eta azkarren murriztu behar dira. Testuinguru honetan, litiozko ioien bateriak ingurumenarekiko irtenbide bideragarri eta lagunkoi gisa azaleratzen dira. Litioiozko bateriak, energia-dentsitate handia dutenez, garraio-sektorean erabil daitezke erregai fosilen ordez. Hala ere, automobil-sistemaren elektrifikazioak ez dakar berekin funtsezko hobekuntzarik, baldin eta elektrizitatea erregai fosilen erretzean edo energia nuklearrean oinarritutako ohiko sistemetatik badator.
Aukera nagusia iturri horiek energia berriztagarriekin ordezkatzea da. Hala eta guztiz ere, iturri berriztagarriak kontrolagaitzak direnez, sistema energetikoa energia berrizagarrietan bakarrik oinarritutakoa utopia bat baino ez litzateke, haiekin batera doan biltegiratze-sistemarik gabe, litio-ioizko bateriekin, adibidez.
Tesi honek zehazkiro aztertzen du teknologia hori, eta bereziki, sorkuntza berriztagarriko inguruneetan duen aplikazioa. Hauek dira ikerketa-lerro nagusiak:
Litio-ioizko baterien teknologiaren egoeraren azterketa; Karakterizazio ez-inbaditzaileko teknika nagusiak aztertzea, litio-ioizko baterien degradazio-mekanismoak kuantikatzeko eta identikatzeko tresnagisa; Litio-ioizko baterien modelatze elektrikoa eta balidazioa sistema errealetan; Litio-ioizko baterien funtsezko alderdiak aztertu eta identi katzea, energia berriztagarriak sare elektrikoan integratzeko., The need for a change in the current energy model towards a future in which sustainability is advocated as an indispensable pillar of progress has led to a change in the energy paradigm. The hitherto used power sources based on the harmful burning of fossil fuels must be eradicated as quickly as possible.
In this context, lithium-ion batteries emerge as a viable and environmentally friendly solution. Lithium-ion batteries, given their high energy density, can be used in the transport sector as substitutes for fossil fuels. However, the electrication of the automotive system does not entail a substantial improvement if the power generation continues to come from conventional systems based on the burning of fossil fuels or nuclear energy. The main alternative is to replace these sources with renewable sources. However, a system based solely on uncontrollable renewable resources would be nothing more than a utopia without a storage system to accompany them, such as lithium-ion batteries.
This thesis analyses in detail this technology, and in particular, its application in renewable generation environments. The main lines of work are: Analysis of the current state of lithium-ion battery technology; Study of the main non-invasive characterisation techniques as a tool to quantify and identify the degradation mechanisms on lithium-ion batteries; Electrical modelling of lithium-ion batteries and validation in real systems; Study and identication of key aspects of lithium-ion batteries for the integration of renewable energies into the power grid., This thesis has been subsidised by a Ph.D. Scholarship from the Public University of Navarre. Moreover, it has been partly supported by the Spanish State Research Agency (AEI) and FEDER-UE under grants PID2019-111262RB-I00/AEI/10.13039/501100011033, DPI2016-80641-R and DPI2016-80642-R, by the European Union under the H2020 Project STARDUST under Grant 774094, by the Government of Navarre under the research and development projects PI020 RENEWABLE-STORAGE and 'Integration of renewable energy in the electricity grid by means of advanced energy storage systems','GERA' and by the Public University of Navarre through the research project ReBMS PJUPNA1904., Programa de Doctorado en Tecnologías de las Comunicaciones, Bioingeniería y de las Energías Renovables (RD 99/2011), Bioingeniaritzako eta Komunikazioen eta Energia Berriztagarrien Teknologietako Doktoretza Programa (ED 99/2011)

In this paper a dynamic model for the simulation of pressurized alkaline water electrolyzers is presented. The model has been developed following a multiphysics approach, integrating electrochemical, thermodynamic, heat transfer and gas evolution processes in order to faithfully reproduce the complete dynamical behavior of these systems. The model has been implemented on MATLAB/Simulink and validated through experimental data from a 1 Nm3h-1 commercial alkaline water electrolyzer, and the simulated results have been found to be consistent with the real measured values. This model has a great potential to predict the behavior of alkaline water electrolyzers coupled with renewable energy sources, making it a very useful tool for designing efficient green hydrogen production systems., This work has been supported by the Spanish State Research Agency. (AEI/10.13039/501100011033) under grants PID2019-111262RB-I00 and PID2019-110956RB-I00, and by Ingeteam R&D Europe.

The economic viability of second-life (SL) Li-ion batteries from electric vehicles (EVs) is still uncertain nowadays. Assessing the internal state of reused cells is key not only at the repurposing stage but also during their SL operation. As an alternative of the traditional capacity tests used to this end, the estimation of State of Health (SOH) allows to reduce the testing time and the need of equipment, thereby reinforcing the economic success of SL batteries. However, the estimation of SOH in real SL operation has been rarely analysed in literature. This contribution aims thus to cover this gap, by focusing on the experimental assessment of SOH estimation in reused modules from Nissan Leaf EVs under two SL scenarios: a residential household with self-consumption and a fast charge station for EVs. By means of partial charge and experimental data from cycling and calendar ageing tests, accuracy and robustness of health indicators is firstly assessed. Then, SOH estimation is carried out using real profiles, covering a SOH range from 91.3 to 31%. Offline assessment led to RMSE values of 0.6% in the residential profile and 0.8% in the fast charge station, with a reduction in testing times of 85% compared to a full capacity test. In order to avoid the interruption of battery operation, online assessment in profiles was also analysed, obtaining RMSE values below 1.3% and 3.6% in the residential and charging station scenarios, respectively. Therefore, the feasibility of SOH estimation in SL profiles is highlighted, as it allows to get accurate results reducing testing times or even without interrupting normal operation., This work is part of the projects PID2019-111262RB-I00, funded by MCIN/AEI, Spain/ 10.13039/501100011033/, STARDUST (774094), funded by European Union’s Horizon 2020 research and innovation programme, HYBPLANT (0011-1411-2022-000039), funded by Government of Navarre, Spain, and a Ph.D. scholarship, also funded by Government of Navarre. Open access funding provided by Universidad Pública de Navarra, Spain .

The success of second-life (SL) Li-ion batteries from electric vehicles is still conditioned by their technical and economic viability. The knowledge of the internal parameters of retired batteries at the repurposing stage is key to ensure their adequate operation and to enlarge SL lifetime. However, traditional characterization methods require long testing times and specific equipment, which result in high costs that may jeopardize the economic viability of SL. In the seek of optimizing the repurposing stage, this contribution proposes a novel fast characterization method that allows to estimate capacity and internal resistance at various state of charge for reused cells, modules and battery packs. Three estimation models are proposed. The first of them is based on measurements of AC resistance, the second on DC resistance and the third combines both resistance types. These models are validated in 506 cells, 203 modules and 3 battery packs from different Nissan Leaf vehicles. The results achieved are satisfactory, with mean absolute percentage errors (MAPE) below 2.5% at cell and module level in capacity prediction and lower than 2.4% in resistance estimation. Considering battery pack level, MAPE is below 4.2% and 1.8% in capacity and resistance estimation respectively. With the proposed method, testing times are reduced from more than one day to 2 min per cell, while energy consumption is lowered from 1.4 kWh to 1 Wh. In short, this study contributes to the reduction of repurposing procedures and costs, and ultimately to the success of SL batteries business model., This work is part of the projects PID2019-111262RB-I00, funded by MCIN/AEI, Spain/10.13039/501100011033/, STARDUST (774094), funded by European Union’s Horizon 2020 research and innovation programme, HYBPLANT, Spain (0011-1411-2022-000039), funded by Government of Navarre, Spain, and a Ph.D. scholarship, also funded by Government of Navarre, Spain . Open access funding provided by Universidad Pública de Navarra, Spain .

This work analyzes the reduction of power
generation in strategies that regulate the PV ramp-rate
by using inverter limitation. Although the operating
principle implies some energy production losses, not
all these losses are necessary. Three different strategies
were simulated using experimental 5-second data collected throughout a year at a 38.6 MW PV plant, and
their energy losses were obtained for different ramprate levels. An improvement in one of these strategies
is proposed and evaluated. The main findings suggest
that the proposed modification has the potential to
drastically reduce annual production losses to insignificant levels. Regardless of the ramp-rate constrain,
simulation results evidenced energy losses bellow 1%., This work was supported in part by the Spanish State Research Agency (AEI) under grants PID2019-111262RBI00/AEI/10.13039/501100011033 and PID2019-110816RBC21-I00/AEI/10.13039/501100011033 as well as the Doctoral Scholarships funded by Public University of Navarre (UPNA).

The energy transition towards renewables must be accelerated to achieve climate targets. To do so, renewable power plants, such as wind power plants (WPPs) must replace conventional power plants (CPPs). Transmission System Operators require this replacement to be made without weakening the frequency response of power systems, so it must be ensured that WPPs match the response of CPPs to grid frequency variations. CPPs consist of grid-tied synchronous generators that inherently react to frequency variations by modifying their stored kinetic energy and their output power, thereby contributing to grid stability. Such response is known as inertial response. By contrast, wind turbines (WTs) are mostly based on either doubly-fed induction generators (DFIG) or permanent magnet synchronous generators (PMSG). Their power electronics interface decouples the electromechanical behavior of the generator from the power grid, leading to a negligible inertial response. Therefore, in order to replace CPPs with WPPs, WTs must be able to react to frequency variations by changing their output power, i.e., emulating an inertial response. Currently implemented inertia emulation strategies in WTs rely on pitch control and stored kinetic energy variation. This paper proposes an alternative strategy, using the energy stored in a supercapacitor directly connected to the back-to-back converter DC link to emulate inertia. Its performance is validated by means of simulation for both DFIG and PMSG. Compared to state-of-the-art techniques, it allows a more accurate emulation of grid-tied synchronous generators, favoring the replacement of these generators by WTs., This work was supported in part by Siemens Gamesa Renewable Energy, in part by the Spanish
State Research Agency, AEI/10.13039/501100011033 under Grants PID2019-
111262RB-I00 and PID2019-110956RB-I00, and in part by the Government
of Navarre under Grant 0011-1411-2022-000049 through EnVeNA Project.

This contribution presents a methodology for the integration of Li-ion batteries discarded from electric vehicle into a collective self-consumption installation, showing the technical feasibility of such battery second use. In this regard, the state of charge (SOC) estimation is a relevant issue for the energy management of the second-life battery. Therefore, a SOC estimator is proposed in this contribution and tested in field. Moreover, the revealed costs analysis allows an economic comparison between the integration of a discarded battery pack in a second-life application or a remanufacture of these packs, thereby selecting the most suitable cells to build second-life batteries. This is a crucial issue for companies focused on the development of second-life batteries. The results obtained after testing the second-life battery pack in a real installation make it possible to extol the benefits of including this type of batteries in a self-consumption system, reaching a self-consumption ratio of 69 % and reducing by 36 % the maximum power peak demanded from the grid., This work has been supported by the Spanish State Research Agency (AEI) under grants PID2019-111262RB-I00 /AEI/ 10.13039/501100011033 and DPI2016–80641-R, the European Union under the H2020 project STARDUST (774094), the Government of Navarra through research project 0011–1411–2018–000029 GERA and the Public University of Navarra under project ReBMS PJUPNA1904. Also noteworthy is the support received from the Mexican Program for Strengthening Educational Quality (PFCE) (2017-2021) for the Postgraduate Program Master of Science and -UAT.

Although lithium-ion batteries have gained considerable popularity in renewable energy and electric vehicle applications, their safety still remains a concern under certain voltage, temperature, or state of charge conditions. This can lead to degradation and potential thermal runaway. In order to improve the safety assessment of LIBs based on their operating conditions, it is therefore essential to analyze not only their safe operating area but also their abuse region. This study focuses on the characterization of the abuse region of lithium-ion batteries by proposing a new methodology in which four areas of abuse are identified and experimentally validated using a commercial 3.6 Ah pouch cell. The cell is subjected to overtemperature and overcharge conditions, exploring various states of charge (0 to 200%) and ambient temperatures (25 to 100 °C). The influence of temperature and state of charge on the battery's behavior is thoroughly analyzed to fully characterize the abuse region. Results reveal the limiting temperatures and states of charge that define the boundaries of the abuse areas. By extending the characterization of LIBs behavior beyond the safe operation area with the determination of four areas of abuse, this article contributes to a better understanding of the phenomena and abuse mechanisms produced by overtemperature and overcharge events with an eye to improving battery safety., This work is part of the projects PID2019-111262RB-I00, funded by MCIN/AEI/10.13039/501100011033/, TED2021-132457B-I00, funded by MCIN/AEI/10.13039/501100011033/ and by the European Union “NextGenerationEU/PRTR”, STARDUST, funded by European Union’s Horizon 2020 research and innovation program, HYBPLANT, Spain (0011-1411-2022-000039), funded by Government of Navarre, Spain, and a Ph.D. scholarship (PRE2020-095314), funded by Spanish Ministry of Science and Innovation. Open access funding provided by Universidad Pública de Navarra, Spain.

El cambio en nuestro modelo de consumo y producción de energía es cada vez más urgente. Los problemas medioambientales, económicos y sociales relacionados con los combustibles fósiles han motivado la reacción gubernamental y ciudadana en búsqueda de soluciones alternativas. Así, la transición en el sector de la automoción hacia el vehículo eléctrico es ya una realidad. Las baterías de iones de litio son el corazón de los vehículos eléctricos, ya que posibilitan su autonomía y operación de forma similar a sus homólogos de combustión. No obstante, debido al uso, las características internas de estas baterías se degradadas, de tal modo que son retiradas cuando pierden en torno a un 30 % de capacidad energética. En los últimos años, la reutilización de estas baterías ha surgido como alternativa que permite aprovechar la capacidad energética remanente, alargando de este modo su vida útil. Aplicaciones estacionarias, como la integración de energías renovables o servicios de red, son consideradas como escenarios prometedores para estas baterías de segunda vida. Sin embargo, la viabilidad técnica y económica de estos sistemas de almacenamiento es hoy en día incierta.
Esta tesis se centra en la viabilidad técnica de baterías de iones de litio de segunda vida provenientes de vehículos eléctricos. El estudio tiene un gran carácter experimental, utilizando para ello baterías reales que ya han finalizado su primera vida. Las principales líneas de trabajo de la tesis son:
• Revisión del estado del arte actual de la segunda vida.
• Caracterización del estado interno y análisis de la dispersión.
• Estudio de la degradación y durabilidad en función del envejecimiento.
• Mejora de la evaluación del estado interno, tanto en la etapa de reconfiguración como durante la operación de la segunda vida.
• Estudio de la viabilidad técnica de un prototipo reconfigurado con módulosde segunda vida en distintas aplicaciones estacionarias., The transformation of our energy consumption and production model is increasingly urgent. Environmental, economic and social problems associated with fossil fuels have prompted the government and public reaction in the search for alternative solutions. Thus, the transition in the automotive sector towards an electric fleet is already a reality. Lithium-ion batteries are the core of electric vehicles, as they enable autonomy and operation in a similar way to their combustion counterparts. However, the performance features of these batteries degrade due to usage, in such a way that they are retired when their initial energy capacity fades by 30 %. The reuse of electric vehicle batteries has recently emerged as an alternative that allows benefiting from the remaining energy capacity, thus extending their lifetime. Stationary applications, such as the integration of renewable energies or the provision of grid services, are considered promising scenarios for these second-life batteries. Nevertheless, the technical and economic feasibility of these storage systems is currently uncertain.
This thesis focuses on the technical feasibility of second-life lithium-ion batteries from electric vehicles. The study has a significant experimental approach, by using real batteries that have already ended their first life. The main work lines of the thesis are:
• Revision of the existing state of the art on second-life batteries.
• Characterisation of the internal state and analysis of dispersion.
• Study of degradation and durability depending on ageing.
• Improvement of the internal state assessment, both in the repurposing stage and during the second-life operation.
• Study of the technical feasibility of a repurposed prototype with secondlife modules in different stationary applications., This thesis was awarded with public funding from a predoctoral scholarship of the Government of Navarre.; R&D national project, 'Design of optimal energy storage systems based on first and second-life lithium-ion batteries for the integration of renewable energies', DA2VIDA PID2019-111262RB-I00, Spanish Ministry of Economy, Industry and Competitiveness, 2020-2022; R&D national project, 'Hybridisation of advanced electricity storage systems in renewable-sources microgrids', HIBRITAER DPI2016-80642-R, Spanish Ministry of Economy, Industry and Competitiveness, 2016-2020; R&D Navarre Plan, 'Design and experimental validation of BMS for second-life lithium-ion batteries (ReBMS)', PJUPNA1904, Public University of Navarre (UPNA), 2020-2021.
R&D Navarre Plan, 'Integration of renewable energy in the electric grid by means of advanced energy storage systems', GERA PI020 0011-1411-2018-000029, Government of Navarre, 2018-2020., Programa de Doctorado en Tecnologías de las Comunicaciones, Bioingeniería y de las Energías Renovables (RD 99/2011), Bioingeniaritzako eta Komunikazioen eta Energia Berriztagarrien Teknologietako Doktoretza Programa (ED 99/2011)

Lithium-ion batteries (LIBs) are becoming well established as a key component in the integration of renewable energies and in the development of electric vehicles. Nevertheless, they have a narrow safe operating area with regard to the voltage and temperature conditions at which these batteries can work. Outside this area, a series of chemical reactions take place that can lead to component degradation, reduced performance and even self-destruction. The phenomenon consisting of the sudden failure of an LIB, causing an abrupt temperature increase, is known as thermal runaway (TR) and is considered to be the most dangerous event that can occur in LIBs. Therefore, the safety of LIBs is one of the obstacles that this technology must overcome in order to continue to develop and become well established for uses in all types of applications. This chapter presents a detailed study of the general issues surrounding this phenomenon. The origin of the problem is identified, the causes are detailed as well as the phases prior to TR. An analysis is made of the most relevant factors influencing this phenomenon, and details are provided of detection, prevention and mitigation measures that could either prevent the TR or reduce the consequences., This work is part of the projects PID2019-111262RB-I00, funded by MCIN/ AEI/10.13039/501100011033/, STARDUST (774094), funded by European Union´s Horizon 2020 research and innovation programme, and a FPI scholarship (PRE2020- 095314), funded by Spanish Ministry of Science and Innovation. We would also like to acknowledge the support of Ingeteam R&D Europe.

This paper presents a non-invasive technical analysis of the degra-dation of four lithium-ion batteries (LIBs) used in extreme frigid weather. In contrast to other studies in which the batteries were tested in laboratory conditions, the LIBs studied in this paper were aged in a real application, more specifically in the WindSled project. In this project, an expedition was made using a zero-emission vehicle drawn by kites, covering more than 2500 kilometers on the East Antarctic Plateau. The study performed in this paper aims to quantify the degradation of the LIBs during the expedition. The results show a 5 % capacity fade, a 30 % increase in the internal resistance and no substantial increase in the impedance of the solid electrolyte interface (SEI). Moreover, no evidence of dendrite growth at the anode is inferred by the interpretation of the distri-bution of relaxation times (DRT), incremental capacity analysis (ICA) and differential voltage analysis (DV). Based on these re-sults, it can be claimed that the LIBs used in the WindSled Project can successfully operate under 50 C. Furthermore, since non-invasive techniques were used to characterize the batteries, they can still be used in upcoming expeditions, with subsequent financial and environmental benefits., This work was supported in part by the Spanish State Research Agency (AEI) under Grant PID2019-111262RB-I00/AEI/10.13039/501100011033, in part by the European Union under the H2020 Project STARDUST under Grant 774094, and in part by the Public University of Navarre through the research project ReBMS PJUPNA1904 and a Ph.D. Scholarship.

A critical issue for a proper energy management of a lithium-ion (Li-ion) battery is the estimation of its state-of-charge (SOC). There are various methods available for the SOC estimation, being some of them robust and accurate, but requiring high computational power for its applicability, which is inconvenient for their use with the usual low-cost microcontrollers that build a typical BMS. This contribution proposes an SOC estimation algorithm based on a simplified Kalman Filter, that combines a high accuracy with reduced computational requirements. The proposed simplifications result from a careful analysis of the Li-ion battery performance and linearization of processes that entail negligible loss of accuracy. The proposed algorithm is used to estimate the SOC of a second-life Li-ion battery operating in an experimental PV self-consumption facility. Its performance, in terms of accuracy, robustness and computational requirement, is compared with an Extended Kalman Filter (EKF), a Particle Filter (PF) and other low-performance estimation algorithms, proving its tradeoff between accuracy and computational cost., This work has been supported by the Spanish State Research Agency
(AEI) under grant PID2019-111262RB-I00 /AEI/ 10.13039/501100011033,
the European Union under the H2020 project STARDUST (774094), the
Government of Navarra through research project 0011–1411–2018–000029
GERA and the Public University of Navarra under project ReBMS
PJUPNA1904.

This contribution presents a technical analysis of the Lithium-ion batteries (LIBs) used in the WindSled project. In this project, an expedition has been carried out by means of a 0-emission vehicle that have covered more than 2500 kilometers in Antarctica Eastern Plateau pulled by kites. This adventure allowed the performance of 10 scientific experiments with a minimal disturbance of the polar environment. The required electricity for the survival and the scientific experimentation was delivered by flexible PV panels installed on the sled and commercial LIBs. The study performed in this contribution aims at the quantification of the LIBs degradation after the expedition. The results show a capacity fade of 5 % and an internal resistance increase of 30 %. Based on these results, it can be claimed that the LIBs used in the WindSled Project can successfully operate under -40°C. Moreover, these batteries can be used in upcoming expeditions, entailing an improvement from an economical and environmental point of view compared to primary batteries., Spanish State Research Agency (AEI) and FEDER-UE under grants DPI2016-80641-R, DPI2016-80642-R, PID2019-111262RB-I00 and PID2019-110956RB-I00, the Government of Navarra through research project 0011-1411-2018- 000029 GERA and the Public University of Navarre under project ReBMS PJUPNA1904.