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Integrating solar cells in textiles offers a promising path toward energy-autonomous wearable electronics, but their design requires careful optimisation between energy efficiency and visual aesthetics. For this purpose, we present a systematic study of the optical properties of knitted textiles as visually concealing covers for textile-integrated solar cells. The study investigates microscopic and macroscopic factors that influence the optical performance of knitted textiles. A set of 175 samples was knitted, including 20 knit structures, 6 yarn materials, and 20 yarn colours. The knitted samples were studied using optical characterisation methods such as spectroscopy, microscopy, and photography. We developed metrics characterising solar cell performance and visual appearance, which can be used to optimise textiles based on desired performance characteristics. The strong correlation between the performance metrics demonstrates a design compromise between solar cell performance and concealment. By applying a proposed set of optimisation criteria to the knitted samples, 23 out of the 175 samples qualified as the best in solar cell performance and concealment. The developed metrics are also applicable to other textile configurations and light-sensing applications., Peer Reviewed, Postprint (published version)

Purpose Solar cells could make textile-based wearable systems energy independent without the need for battery replacement or recharging; however, their laundry resistance, which is prerequisite for the product acceptance of e-textiles, has been rarely examined. This paper aims to report a systematic study of the laundry durability of solar cells embedded in textiles. Design/methodology/approach This research included small commercial monocrystalline silicon solar cells which were encapsulated with functional synthetic textile materials using an industrially relevant textile lamination process and found them to reliably endure laundry washing (ISO 6330:2012). The energy harvesting capability of eight textile laminated solar cells was measured after 10–50 cycles of laundry at 40¿°C and compared with light transmittance spectroscopy and visual inspection. Findings Five of the eight textile solar cell samples fully maintained their efficiency over the 50 laundry cycles, whereas the other three showed a 20%–27% decrease. The cells did not cause any visual damage to the fabric. The result indicates that the textile encapsulated solar cell module provides sufficient protection for the solar cells against water, washing agents and mechanical stress to endure repetitive domestic laundry. Research limitations/implications This study used rigid monocrystalline silicon solar cells. Flexible amorphous silicon cells were excluded because of low durability in preliminary tests. Other types of solar cells were not tested. Originality/value A review of literature reveals the tendency of researchers to avoid standardized textile washing resistance testing. This study removes the most critical obstacle of textile integrated solar energy harvesting, the washing resistance., Peer Reviewed, Postprint (published version)

Climate change has been a growing cause for concern in the past decades. Major events such as floods, storms or heat waves are increasingly frequent and ring the bell for profound changes in societies. For instance, it can be initiated within companies through rethinking production methods, economic strategies and overall investments. This thesis aims to propose solutions to improve companies’ investment in the research and development of green product innovation. Developing more eco-friendly products may be perceived by companies as a competitive risk and loss of benefits. Thus, reluctance to invest in greener innovations has to be overcome. In the end, the study highlighted the importance companies can have in the development of low-carbon products, therefore contributing to the challenges raised by climate change. The main drivers, success factors and outcomes for green product innovation (GPI) investments were identified in the case of France. Two main drivers were pointed out: government funding and policy instruments. Among policy instruments, the most important are “The French recovery plan”, “The Green taxonomy” and “The general tax on polluting activities (TGAP)”. Among government funding, R&D Tax Credit is presented as the most relevant to accelerate the research in green products. Then, in terms of outcomes it is understood that being green and competitive is possible as long as top management is aware of the opportunities provided by GPI development and make it a key component of the company’s innovation strategy. Finally, the study points out the complexity for companies to implement these innovation strategies. Thus, the support of experts in financial incentives, environmental regulations and policy instruments is of paramount importance to promote green product innovation and guide companies to invest towards more sustainable practices and thus, to contribute to fight against climate change.

An unprecedented worldwide momentum is pushing forward the development of hydrogen since it is a fuel that can be synthesised using low-carbon sources. When the source is renewable energy, the hydrogen is referred to as ”green”. As such, it could have a key role in the fight against climate change and in the global reduction of greenhouse gases emissions. This paper is a literature-based review that aims to give an overview of the current situation regarding hydrogen: its current and future uses, its production routes and its related technical, environmental and economical challenges. It provides additional information about the situation in France and on the ways hydrogen can be produced from renewable electricity. Those production modes are then compared economically. From the economic analysis, it seems that it is not economically feasible to produce hydrogen only when prices are low (in periods of overproduction). Green hydrogen is also expected to become cost-competitive against the current fossilbased hydrogen by the 2030’s. The review concludes on two major comments. The first comment is the importance of remaining critical and remembering that every consumption leads to greenhouse gases emissions. Hence, hydrogen is only a very limited part of the answer to our current issues. The second comment is the importance to support the development of low-carbon hydrogen to reduce emissions in key sectors. While current production of fossil-based hydrogen represents around 2% of the global CO2 yearly emissions, this could be avoided by switching to green hydrogen. Furthermore, low-carbon hydrogen could also directly replace some fossil fuels further lowering CO2 emissions. For example, hydrogen is one of the only feasible solution to produce steel without requiring coke (currently accounting for around 7 % of CO2 emission). Therefore, the development of green hydrogen is required and it will have a major role in the energy transition of the 21st century.

Dye-sensitized solar cells (DSSCs) are an efficient photovoltaic technology for powering electronic applications such as wireless sensors with indoor light. Their low cost and abundant materials, as well as their capability to be manufactured as thin and light-weight flexible solar modules highlight their potential for economic indoor photovoltaics. However, their fabrication methods must be scaled to industrial manufacturing with high photovoltaic efficiency and performance stability under typical indoor conditions. This paper reviews the recent progress in DSSC research towards this goal through the development of new device structures, alternative redox shuttles, solid-state hole conductors, TiO2 photoelectrodes, catalyst materials, and sealing techniques. We discuss how each functional component of a DSSC has been improved with these new materials and fabrication techniques. In addition, we propose a scalable cell fabrication process that integrates these developments to a new monolithic cell design based on several features including inkjet and screen printing of the dye, a solid state hole conductor, PEDOT contact, compact TiO2, mesoporous TiO2, carbon nanotubes counter electrode, epoxy encapsulation layers and silver conductors. Finally, we discuss the need to design new stability testing protocols to assess the probable deployment of DSSCs in portable electronics and internet-of-things devices.

A semitransparent, flexible single-walled carbon nanotube (SWCNT) film was efficiently used in place of evaporated silver as the counter electrode of a poly(3,4-ethylenedioxythiophene) polymer-based solid-state dye solar cell (SSDSC): the solar-to-electrical energy conversion efficiency of the SWCNT-SSDSC was 4.8% when it was 5.2% for the Ag-SSDSC. The efficiency difference stemmed from a 0.1-V difference in the open-circuit voltage, whose reason was speculated to be related to the different recombination processes in the two types of SSDSCs.

With global environmental awareness and European environmental policy, industrial companies are looking for solutions to prove their commitment without losing money. SunMind, a French photovoltaic developer, offers self-consumption or grid injection projects with third-party investment through On-site PPAs or land leases. The profitability of these two types of projects depends on a proper design of the PV plant according to the client’s requirements. However, what are the different components of a photovoltaic power plant? What are the main steps in designing a PV power plant in the case of self-consumption or grid injection projects for industrial clients? How to choose the power to be installed in the case of both projects depending on the client? This thesis presents the self-consumption and grid injection models used by SunMind, the basics of the photovoltaic field, analyses the different components of a PV power plant, discusses the two software, SketchUp Skelion and PVSyst, used during this thesis and proposes a method for designing and sizing a photovoltaic plant according to the client, focusing on key steps such as the analysis of the client’s consumption and the solar potential of the client’s site.

As part of research work in co-innovation project Sun-Powered Textiles, this thesis studies the feasibility of powering wearable devices with textile-covered solar cells. Integrating commercial solar cells into textiles by covering them with a textile is a simple yet efficient novel solution inspired by the facades in building-integrated photovoltaics. The solution allows visually hiding or camouflaging the solar cells under the fabric or patterns in it. Thereby, the integration of solar cells can be performed in an aesthetically pleasing way, without compromising the needs of design, while still producing enough energy for powering energy autonomous wearable devices. The feasibility of the idea was analyzed in this thesis from various aspects. Methods for quantifying the suitability of a textile for use as solar cell cover were developed. Means for measuring textile transmittance, opacity and color were compared, and the power harvesting capability was estimated for combinations of different textile, solar cell and lighting condition. Furthermore, the feasibility was assessed by evaluating the solar cell area required for energy autonomous function of a few existing, commercial wearable devices, as well as through preliminary washing tests of the textile solar cell component. Ultimately, the feasibility of the demo case developed jointly by the project partners was analyzed with the methods introduced in the thesis. The energy harvesting depends on the light source and its availability, characteristics of the solar cell as well as the most essential textile property: transmittance. Devices with daily average energy consumption up to few hundred milliwatt-hours could be entirely powered by textile-covered solar cells. This includes e.g. tiny Internet of Things sensors integrated in garments, as suggested in the project demo case., Tässä diplomityössä tutkitaan tekstiilipäällysteisten aurinkokennojen soveltuvuutta puettavan elektroniikan tehonlähteeksi osana Sun-Powered Textiles --yhteisinnovaatioprojektia. Aurinkokennon peittäminen kankaalla on yksinkertainen, mutta tehokas tapa integroida energiakeruu tekstiiliin tekemättä kompromisseja tekstiilisuunnittelun estetiikan kustannuksella. Rakennuksiin integroiduista aurinkopaneeleista inspiraationsa saaneessa teknologiassa aurinkokennot voidaan piilottaa kokonaan kankaan alle tai naamioida kankaan kuvioihin niin, että kennot silti tuottavat tarpeeksi energiaa mahdollistaakseen kannettavien laitteiden energiaomavaraisen toiminnan. Teknologian soveltuvuutta kannettavien laitteiden tehonlähteeksi analysoitiin tässä diplomityössä monesta näkökulmasta. Tekstiilin soveltuvuutta aurinkokennon peitteeksi mitattiin eri tavoin: tekstiilin transmittanssin, läpinäkyvyyden ja värin mittaamisen metodeja vertailtiin keskenään, sekä arvioitiin eri aurinkokennojen tehontuottoa eri valaistusolosuhteissa ja eri kankailla päällystettynä. Lisäksi laskettiin, kuinka suuri aurinkokennopinta-ala vaadittaisiin muutamien kaupallisten laitteiden energiaomavaraisuuden mahdollistamiseen. Aurinkokennotekstiilikomponenttien ja teknologian käyttökelpoisuutta arvioitiin myös alustavien pesutestien kautta. Lopuksi työssä tarkastelluilla metodeilla analysoitiin projektissa kehitettävien esimerkkisovellusten toteutettavuutta. Kerättävissä olevan energian määrä riippuu valon lähteestä ja saatavuudesta, aurinkokennon ominaisuuksista sekä tekstiilien olennaisimmasta ominaisuudesta eli transmittanssista. Tekstiilipäällysteisillä aurinkokennoilla voidaan mahdollistaa omavarainen toiminta laitteille, jotka kuluttavat päivässä keskimäärin joitakin satoja milliwattitunteja. Tällaisia laitteita ovat mm. pienet vaatteisiin integroitavat anturit, joita myös kehitetään projektin esimerkkisovelluksissa.

Road transportation is one of the most significant CO2 emission sources, mostly done by passenger cars in cities. A few regulations have been approved by the European Union and other countries such as the United states and Japan to regulate this average emission of passenger vehicle, resulting to a push by manufacturers towards vehicle electrification. Electricity as an alternative fuel is becoming more and more common on vehicles. But some limitations are still present with the driving range being the most problematic. It can be extended by increasing the battery pack capacity but also, the efficiency of the power electronics as well as the electric motor(s). This research focuses on collecting as much information possible on the technology present in hybrid and electric vehicle to understand how it works and forecast the innovations that will be used in the future by big actors in the market. By comparing older and future model with as much characteristics as possible and analyzing the roadmap of car manufacturers and suppliers, it is possible to imagine what technology will be implemented next. Some innovations found are the use of 800 V battery instead of 400 V, the use of wide band gap semiconductor instead of silicon in power electronics, and other trends focusing the battery chemistry or the number and type of electric motor.

Climate change is a major challenge of the 21st century with potential severe consequences of global warming on all biological systems. The main reason is the CO2 emissions caused by human activities. In this context, renewable energies are one of the most promising solutions to strive against this issue. This master’s thesis aims to a better understanding of the offshore wind power, by studying the advantages, drawbacks and potential of this technology. Wind offers a large and clean resource of power, available all over the world. Wind power plants have first been developed onshore in 1980 as it is an easy and cheap technology. However, onshore wind is limited in terms of capacity suffering from volatile wind conditions and limited acceptance from the population. Conversely, offshore wind power allows very large-scale development, featuring larger turbines in areas where a stronger and more consistent wind blows. This allows to generate more power and to have better capacity factors, explaining why offshore wind power has recently emerged as an excellent asset to develop renewable energies at large-scale. Yet, offshore wind power currently suffers from one major drawback: the shallow-water requirement. Wind turbines are currently placed on fixed foundation that can reach a maximum water depth of 60 meters. This drastically limits the possible development areas and has led to large development inequalities across the world. Floating wind turbines are being developed to remove this restriction. Several approaches are under testing to tackle stability issues, all successful so far. This would be a game changing technology because it would unlock countless areas to implement offshore wind farms particularly for countries that do not have offshore shallow waters.