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Concept

Hors réseau

Le hors réseau (en anglais off-the-grid) est un système et un mode de vie conçus pour aider les gens à fonctionner sans le soutien d'une infrastructure à distance. Les maisons hors réseau visent à atteindre l'autonomie ou l'autosuffisance ; elles ne dépendent pas d'un ou de plusieurs services publics d'approvisionnement en eau, d'égout, de gaz, d'électricité ou de services publics similaires. Les personnes qui adoptent ce mode de vie, sont appelés « off-gridders ». L'alimentation électrique Lorsqu'on parle de hors réseau, on fait souvent référence au réseau électrique. Le « hors réseau » peut être rendu possible par un système d'alimentation autonome ou des mini-réseaux généralement destinés à fournir de l'électricité à une petite collectivité. L'alimentation électrique peut être produite sur site, avec des sources d'énergie renouvelable telles que le solaire (en particulier le photovoltaïque), l'éolien, la micro hydraulique, la géothermie ; avec un générateur ou une mic

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Ce cours décrit les composants d'un réseau électrique. Il explique le fonctionnement des réseaux électriques et leurs limites d'utilisation. Il introduit les outils de base permettant de les piloter.

The objective of this lecture is to give an in-depth understanding of the physics and manufacturing processes of photovoltaic solar cells and related devices (photodetectors, photoconductors). The principle and techniques addressed in this lecture will be useful in a wide range of related fields.

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A comparative performance analysis of stand-alone, off-grid solar-powered sodium hypochlorite generators

Enrico Chinello, Laurent Coulot, Antonin Faes, Miguel Antonio Modestino, Demetri Psaltis

Sodium hypochlorite (NaClO) is a chemical commodity widely employed as a disinfection agent in water treatment applications. Its production commonly follows electrochemical routes in an undivided reactor. Powering the process with photovoltaic (PV) electricity holds the potential to install stand-alone, independent generators and reduce the NaClO production cost. This study reports the comparative assessment of autonomous, solar-powered sodium hypochlorite generators employing different photovoltaic (PV) technologies: silicon hetero-junction (SHJ) and multi-junction (MJ) solar cells. For Si hetero-junctions, the series connection of either four or five SHJ (4SHJ and 5SHJ, respectively) cells was implemented to obtain the reaction potential required. MJ cells were illuminated by a novel planar solar concentrator that guarantees solar tracking with minimal linear displacements. The three solar-hypochlorite generators were tested under real atmospheric conditions, demonstrating solar-to-chemical conversion efficiencies (SCE) of 9.8% for 4SHJ, 14.2% for 5SHJ and 25.1% for MJ solar cells, respectively. Simulations based on weather databases allowed us to assess efficiencies throughout the entire model year and resulted in specific sodium hypochlorite yearly production rates between 7.2-28 g(NaClO) cm(-2) (referred to the PV surface), depending on the considered PV technology, location, and deployment of electronics converters. The economic viability and competitiveness of solar hypochlorite generators have been investigated and compared with an analog disinfection system deploying ultraviolet lamps. Our study demonstrates the feasibility of off-grid, solar-hypochlorite generators, and points towards the implementation of SHJ solar cells as a reliable technology for stand-alone solar-chemical devices.

ROYAL SOC CHEMISTRY2019

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Computational Modeling of Thin-Film Silicon Solar Cells and Modules

Thomas Andreas Lanz

Solar photovoltaic energy production relies on the direct conversion of sunlight into electricity. Silicon thin-film solar cells represent a reliable and environmentally friendly technology to make photovoltaics economically viable. As these solar cells do not contain any rare or toxic materials they are an ideal candidate for the large scale deployment of solar energy. At the same time photovoltaic energy production is ideal for off-grid, stand-alone installations. This thesis presents new methods and results on computational engineering of thin-film silicon solar cells and modules. Computational engineering employs numerical methods and simulation techniques to address engineering challenges. Predictive numerical simulations allow for device optimizations that otherwise require substantial experimental effort and they may lead to new insights into the device physics which is the basis for further improvements in terms of cell efficiency and lifetime. We discuss the development of two new simulation methods and present several case studies that illustrate their use in solar cell characterization and optimization. The first presented method addresses optical simulations, i.e. the interaction of the solar cell with sunlight. Our optical model is based on the net-radiation method that considers incoherent, ray-like propagation of light. We extend the net-radiation method with thin-film optics to allow for arbitrary sequences of thick and thin layers. Experimentally, advanced techniques such as optimized surface textures have been developed to increase the absorption in the solar cell and thereby to increase the produced current. We illustrate how our optical model takes into account these textures by means of azimuth integrated light scattering properties to formulate a computationally efficient model of light propagation within the solar cell. Our optical model thus integrates coherent and incoherent propagation of light as well as a non-iterative treatment of ligth scattering. It bridges the gap between wave and ray optics that alternative approaches are most often facing. We first apply the method to study a recently proposed rear electrode architecture based on lithium fluoride and aluminum in amorphous silicon solar cells. Our model-based optical analysis identifies the increased reflectivity of this back electrode as its main advantage. Secondly, we then explore the potential performance gains in microcrystalline silicon solar cells that can be reached by eliminating absorption in layers that do not contribute to the photogeneration of solar cell current. Finally, our optical model is also suited for other solar cell technologies and we illustrate its extension and application to light extraction calculations in light emitting diodes (LEDs). Our optical model has been incorporated into the software package setfos, commercialized by Fluxim Inc. It is thus available to the research community. We then turn to address large area solar modules. A new method based on the finite element method (FEM) is presented to calculate the electrical charge and heat transport in these devices and how it is influenced by defects as well as partial shading. We identify such defects with surface temperature measurements by means of lock-in thermography and demonstrate how our model accounts for the thermal signature of localized defects. Taking into account the large aspect ratio of thin-film solar modules we show how geometrical projections can be used to reduce the model complexity, leading to a numerically efficient approach based on the finite element method. We demonstrate this by presenting full current-voltage curves of solar modules under partial shading.

EPFL2013

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The sliding Frank-Wolfe algorithm and its application to super-resolution microscopy

Quentin Alain Denoyelle, Gabriel Peyré, Emmanuel Emilien Louis Soubies

This paper showcases the theoretical and numerical performance of the Sliding Frank-Wolfe, which is a novel optimization algorithm to solve the BLASSO sparse spikes super-resolution problem. The BLASSO is a continuous (i.e. off-the-grid or grid-less) counterpart to the well-knownsparse regularisation method (also known as LASSO or basis pursuit). Our algorithm is a variation on the classical Frank-Wolfe (also known as conditional gradient) which follows a recent trend of interleaving convex optimization updates (corresponding to adding new spikes) with non-convex optimization steps (corresponding to moving the spikes). Our main theoretical result is that this algorithm terminates in a finite number of steps under a mild non-degeneracy hypothesis. We then target applications of this method to several instances of single molecule fluorescence imaging modalities, among which certain approaches rely heavily on the inversion of a Laplace transform. Our second theoretical contribution is the proof of the exact support recovery property of the BLASSO to invert the 1D Laplace transform in the case of positive spikes. On the numerical side, we conclude this paper with an extensive study of the practical performance of the Sliding Frank-Wolfe on different instantiations of single molecule fluorescence imaging, including convolutive and non-convolutive (Laplace-like) operators. This shows the versatility and superiority of this method with respect to alternative sparse recovery technics.

IOP PUBLISHING LTD2020

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Production décentralisée (énergie)

Aussi appelé production distribuée (calque de l'anglais), la production décentralisée est la production d'énergie électrique à l'aide d'installations de petite capacité raccordées au réseau électriqu

Solar power

Solar power is the conversion of energy from sunlight into electricity, either directly using photovoltaics (PV) or indirectly using concentrated solar power. Photovoltaic cells convert light into an

Bâtiment à énergie zéro

vignette|Bâtiment d'essai zéro énergie à Tallinn , Estonie . Université de Technologie de Tallinn Un bâtiment à énergie zéro (en anglais zero-energy building (ZEB), zero net energy (ZNE) ou net-zero