Scientific direction Development of key enabling technologies
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PhD : selection by topics

Technological challenges >> Solar energy for energy transition
5 proposition(s).

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Model of energy losses due to fouling of bifacial PV modules and the reduction in induced albedo.

Département des Technologies Solaires (LITEN)

Laboratoire Systèmes PV

01-10-2020

SL-DRT-20-0303

eric.pilat@cea.fr

Solar energy for energy transition (.pdf)

The generation of energy from solar technologies becomes more and more important and consequently the serious consideration of a problem, the soiling Today, the unit of measurement is no longer the Giga Wh but the Tera Wh and, therefore, the smallest percentage of losses can generate a considerable economic deficit. In order to reduce the cost of the energy produced (LCOE), the players are looking to locate their installations in the sunniest, arid and unfortunately often very dusty regions. Finally, a promising new technology of PV cells, capable of capturing photons on both sides, has recently emerged and requires a fundamental review of the soiling approach, taking particular account of variations in soil albedo. The context of the study is favorable, because motivated by an increasing number of patents and articles, strong pressure on the cost of cleaning and water consumption, new applications such as agro-PV particularly sensitive. The main objective of the doctoral student is to develop algorithms for calculating the impact of soiling from the characteristics of the PV fields, data measured on the systems and taking into account the influencing environmental parameters. He identifies the best measurement methods and instruments to quantify the level of soiling. The scientific difficulty lies in the diversity of the materials concerned and the challenge consists in apprehending and reproducing multiple physico-chemical phenomena involved in the process of accumulation of soiling.

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Dynamic simulation and control of Continious solar fuel gazeification process

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire des Systèmes Solaires et Thermodynamiques

01-10-2020

SL-DRT-20-0989

nathalie.dupassieux@cea.fr

Solar energy for energy transition (.pdf)

The topic of this thesis studies deals with the valorisation of solar energy as a storable and/or transportable energy vector. For this purpose, the so-called solar thermochemical processes, combining thermal solar technologies and thermochemical conversions of renewable or waste carbonaceous materials have been selected. The reactor studied previously implements endothermic reactions. Those reactions carry out under solar thermal input, generate gaseous products in which solar energy is stored in chemical form. For the scale-up of the SOLAR-FUEL reactors studied in previous work (theses, Carnot and European projects), a major obstacle to industrial deployment remains : the variability of the solar resource does not allow continuous operation. The objective of the research project is to propose a hybrid process (carbon/solar resource) able of continuously produce a renewable solar fuel. The research work will be based both on dynamic simulation and on experimental validation, in order to ensure optimal control of the process according to the available solar resource. The energy and environmental balance will also be studied in order to compare this solar energy storage pathway with other technologies.

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Improvement and understanding of the performance of silicon cell-based solar generators in harsh environments

Département des Technologies Solaires (LITEN)

Laboratoire Photovoltaïque à Concentration

01-09-2020

SL-DRT-20-1061

philippe.voarino@cea.fr

Solar energy for energy transition (.pdf)

The thesis will be carried out at the interface of several laboratories of the Department of Solar Technologies (DTS) of the CEA located in Le Bourget du Lac on the campus of the National Institute for Solar Energy (INES). The objective of this thesis is to improve the resistance to environmental conditions (radiation, e/H+, UV, thermal cycling) of space solar generators based on silicon solar cells, and to better understand the degradation mechanisms of cells/materials associated. By finely controlling the manufacturing of cells (doping, impurity, architecture, etc.) and modules (materials, thickness, architecture, optical trapping, etc.), it is possible to improve the performance of silicon modules at the end of their lifetime while maintaining a competitive price (?/W), 1 to 3 orders of magnitude lower than space III-V modules.

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High efficiency photovoltaic modules developement for building applications

Département des Technologies Solaires (LITEN)

Laboratoire Modules Photovoltaïques Silicium

01-10-2020

SL-DRT-20-1116

bertrand.chambion@cea.fr

Solar energy for energy transition (.pdf)

Performance of photovoltaic (PV) modules has not stopped to evolve in recent years to reach higher values at 20%. This is possible by a significant effort focussed on the architecture solar cells through gains in light absorption and better collection of photo-generated charges. In contrast, the module packaging and module structure remain similar as previous module structure. On one hand, these modules have been developed in order to work in a standard outdoor PV farm configuration. On the other hand, optimization and development are carried out under standard conditions where the temperature is set at 25 ° C. For Building Integrated (BIPV) applications, it can dramatically decrease their performance. This is related to the urban environment and local microclimate conditions (temperature, surrounding diffuse radiation), orientation and the tilt of the components. In addition, non-optimized integration conditions has a direct consequence and could increase the module temperature, making the thermal dependence on yield (estimated at -0.4% per degree) much more sensitive than in standard application. In addition, BIPV poses other issues related to the architectural aspects of the building: The quality of materials and their colours must match the environment, especially for old buildings. The purpose of this thesis project is to develop integrated PV modules prototypes, optimized for BIPV application, in accordance to the following steps: - State of the art on BIPV applications, materials, light management, thermal and thermomechanical modelling tools - Multi-scale modelling (cell, module, building, town) to understand the PV system thermal behaviour and performances consequences. - PV modules prototypes definition and realization on CEA INES Lab. - Outdoor ageing test and performances monitoring, comparison to standard PV solutions

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Micro-concentration photovoltaics for space

Département des Technologies Solaires (LITEN)

Laboratoire Photovoltaïque à Concentration

01-11-2020

SL-DRT-20-1254

philippe.voarino@cea.fr

Solar energy for energy transition (.pdf)

Originally, silicon solar cells developed for space applications following their first use in 1958, with efficiency around 7-8%. Nowadays, the GaInP/GaAs/Ge triple-junctions solar cells, offering higher efficiencies and higher radiation hardness (electrons & protons), are the mainstream solution for powering space missions. However, the cost remains a significant fraction of space solar arrays based on this cell technology. On the other hand, Concentrator PhotoVoltaics (CPV) is a proven approach, developed mainly for terrestrial applications, to reduce the amount of expensive III-V cells, utilizing either reflective or refractive elements to focus the sunlight onto a much smaller solar cell area, while boosting the conversion efficiency. Thus, the use of CPV for space application appears as a promising performance/price tradeoff, which in addition can be a mission enabler for deep space low irradiation environment1. Yet, CPV for space still need to tackle the challenges of mass, reliability in harsh environment, heat dissipation and optical losses. The development of a new generation of micro-concentration photovoltaics solutions, µ-CPV2, have the potential to address many of these issues at once. µ-CPV systems are based on sub-millimeter (< 1 mm²) size solar cells, which enable both passive heat dissipation and compact optics. Recently, proof of concepts µ-CPV systems have shown efficiencies > 25% at low concentration and with large acceptance angles3. Within this context, this PhD offer will focus on an innovative & lightweight µ-CPV design addressing the key metrics of W/kg, W/m2 and W/m3, the cost. The scientific challenges associated concern the study and comprehension of degradation mechanism of materials and optical systems exposed to space environmental constraints (thermal cycling, UV, charged particles irradiations, etc.). The main objectives of this work are the following: - Definition of a smart µ-CPV cell & array design adapted for low/medium concentration in space, based on the laboratories expertise in the field & in depth literature review - Fabrication of µ-cells and development of materials and module fabrication/assembly processes - The final µ-CPV array performance will be optically/electrically characterized and its resilience to ageing tests will be studied. A loop on this iterative process will enable a fully optimized, manufactural, low cost and lightweight µ-CPV system array by the end of the PhD thesis. This work will bring scientific and technical insights on materials and optical systems behavior under space constraints, and thus will lead to communications, publications & patents. International collaboration: This PhD thesis will happen in the framework of a collaboration between CEA-LITEN (INES, Le Bourget du Lac, France) and Fraunhofer ISE (Freiburg, Germany). Strong interactions are foreseen between teams and PhD students of both institutes: joint roadmap, scientific exchange, training, etc. Expected Start: November 2020 ? 3 years duration References: 1 P.M. Stella, 34th Intersociety Energy Conversion Engineering Conference, (1999). 2 A. Ritou et., Sol. Energy 173, 789 (2018). 3 C.J. Ruud et al., Opt. Express 27, A1467 (2019).

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