Development of a multi-criteria comparison tool for electrochemical stationary storage systems
Use of stationary storage systems is now essential to keep pace with changes in the electricity grid and the growing integration of intermittent renewable energies such as solar and wind power. The choice of a storage solution is based on a number of criteria, including performance, lifetime, environmental impact, safety, regulatory constraints and, of course, economics.
The laboratory possesses comparative data on these different criteria, via experimental studies and feedback on existing systems. In addition, an initial software tool has been developed to assess environmental impact using LCA (Life Cycle Assessment). The aim of this thesis work is to integrate these different components into a broader comparison tool with a multi-criteria approach, targeting specific case studies and a limited number of storage technologies that have reached sufficient maturity for the available data to be reliable.
Development of a predictive power model for a photovoltaic device under spatial constraints
CEA is developing new cell and module architectures and simulation tools to assess the electrical performance of photovoltaic (PV) systems in their operating environment. One of these models, called CTMod (Cell To Module), takes into account not only the different materials making up the module, but also the different cell architectures. For space applications, the community wants to use terrestrial silicon-based technologies that can be integrated on flexible PVAs (Photovoltaic Assembly). The space environment imposes severe constraints. A relevant evaluation of performance at the start and end of a mission is therefore essential for their dimensioning.
The aim of this thesis is to correlate physical models of radiation-matter degradation in space with electrical models of photovoltaic cells. Performance degradations linked to the various electron, proton and ultraviolet (UV) irradiations of the space environment will be evaluated and validated experimentally. Linked to the CTMod Model, this new approach, never seen in the literature, will able to get a more accurate understanding of interactions between radiations and PVAs. These degradations result from non-ionizing energy deposition phenomena, quantified by the defect dose per displacement, and ionizing ones quantified by the total ionizing dose for protons and electrons. In the case of UV, the excitation of electrons in matter generates chain breaks in organic materials and colored centers in inorganic materials. Initially, the solar cell used in the model will be a Silicon cell, but the model can be extended to include other types of solar cell under development, such as perovskite-based cells.
Impact of synthesis on the modeling of sodium storage mechanisms in hard carbon
Sodium-ion (Na-ion) batteries are attracting considerable interest as a credible alternative to the lithium-ion batteries widely used today. The abundance of sodium, together with the potential use of electrode materials without critical elements in their composition, has led to intensified research into Na-ion batteries. Hard carbon (HC) has been identified as the most suitable negative electrode for this technology. However, there is no consensus on the mechanisms for storing sodium in HC, because the many precursors and synthesis methods lead to singularly different HCs, which obviously do not function in the same way. A large database provides relationships between synthesis parameters (precursor, washing, pre-treatment, pyrolysis, grinding) and HC properties (porosity, structure, morphology, surface chemistry, defects), but it does not explain them. Consequently, the approach envisaged in this thesis is a multiphysics modeling of HC performance to understand the influence of precursor and synthesis method, exploiting the large existing characterization database.
Prediction of Soiling on PV modules/systems through Real-World Environment Modeling and Data Fusion
Photovoltaic (PV) systems, particularly those installed in regions prone to soiling such as arid areas, coastal sites, and agricultural zones, can experience energy losses of up to 20–30% annually. These losses translate to financial impacts exceeding €10 billion in 2023.
This thesis aims to develop a robust and comprehensive method to predict soiling accumulation on PV modules and systems by combining real-world environmental modeling with operational PV data (electrical, thermal, optical). The research will follow a bottom-up approach in three stages:
1. Component/Module Level: Reproduction and modeling of soiling accumulation in laboratory conditions, followed by experimental validation. This stage will leverage the CEA’s expertise in degradation modeling, including accelerated testing.
2. Module/System Level: Implementation of monitoring campaigns to collect meteorological, operational, and imaging data, combined with field soiling tests on a pilot site. The data will validate and enhance CEA diagnostic tools by introducing innovative features such as AI-driven soiling propagation prediction.
3. System/Operational Level: Validation of the proposed method on commercial PV modules in utility-scale PV plants, aiming to demonstrate scalability and real-world applicability.
The outcomes of this thesis will contribute to the development of an innovative tool/method for comprehensive soiling diagnostics and prognostics in PV installations, enabling the minimization of energy losses while anticipating and optimizing cleaning strategies for PV plants.
Eco-designed materials for encapsulating new-generation flexible photovoltaic modules
The lifetime of thin-film devices such as Organic Photovoltaic (OPV) devices or new-generation lightweight and/or flexible Silicon (Si) photovoltaic modules is critical to their commercialization. In particular, it is crucial to encapsulate them with highly gas-barrier materials to avoid degradation through various water/oxygen insertion mechanisms that can be coupled to illumination. This objective is all the more complex when the device and its encapsulation need to be flexible. Moreover, the eco-design of this new generation of flexible modules raises the question of the nature of the encapsulation materials used, as well as that of the end-of-life of the materials making up the modules. For example, the current use of fluorinated polymers for encapsulation generates toxic products at end-of-life, and could be replaced by the use of eco-designed materials, potentially bio-sourced, if the performance is adapted to the photovoltaic technology employed and the use.
The aim of this thesis will be to study the physico-chemical properties (gas barriers, mechanical, thermal, etc.) of bio-sourced encapsulants developed as part of a national PEPR BioflexPV project. These studies will cover both sealing materials and flexible caps. In addition, these materials will be used to encapsulate real OPV and flexible Si devices, in order to study their degradation under different illumination, temperature and humidity conditions. These studies will help define the degradation mechanisms involved, depending on the photovoltaic technology used (OPV or Si), and thus define the desired properties for bio-sourced encapsulants.
Design and reliability of modular architecture for reconfigurable and repairable PV panels
The integration of photovoltaic modules has become a challenge for adaptation to climate change, notably with the installation of specific PV modules in urban spaces, on vehicles or on agricultural farms. These modules are required to operate in more complex situations presenting high temporal variability and changing exposure to the sun. The scientific challenges of the project are to determine the conditions needed for optimizing the performance of PV modules regarding these external disturbances by the study of reconfigurable electrical module architectures. A reliability model will be developed to integrate the impact of the system architecture, in order to guarantee an improved level of reliability. In-depth work will be carried out on the entire PV module, from cell technologies to the final electrical characteristics requested, including electrical switching technologies. In a second phase, we will develop a design methodology in conjunction with a precise state of the art of available power switching technologies. The method will be applied to a use case responding primarily to the problem of shading and/or localised failure of the PV module. Finally, the proposed architectures will be evaluated by life cycle analysis. The designs authorizing maintenance or replacement of certain elements will be detailed and compared to the performance of usual modules.