La première partie du projet consiste à synthétiser de nouveaux chromophores de structure D-π-[M]-π-A pour des applications en cellules solaires à colorant. La synthèse de complexes symétriques contenant deux fragments métalliques [Ru(dppe)2] sera ensuite envisagée pour obtenir des architectures de type D-π-A-π-D pouvant être testées comme matériau de type n ou p en cellules solaires organiques. Enfin, comme il a été précédemment démontré que la communication électronique peut avoir lieu à travers plusieurs centres ruthénium, la longueur du complexe pourra être augmentée par addition de plusieurs unités métallo-organiques pour conduire à des structures oligomériques aux propriétés d’absorption de l’énergie lumineuse exaltées. / The first part of the research project will consist in the synthesis and study of new chromophores based on the D-π-[M]-π-A model. At that stage, easy synthesis of symmetrical complexes including two [Ru(dppe)2] metal fragments will be envisaged to afford D-π-A-π-D architectures to be tested in n-type solar cells and p-type solar cells. Later on, as it has been demonstrated that electronic communication may occur through several Ru-based metal centres,the complexes length might be incremented by addition of multiple metal-organic units to create oligomeric structures with strong light-harvesting properties.

abstract: Soiling is one of the major environmental factors causing the negative performance of photovoltaic (PV) modules. Dust particles, air pollution particles, pollen, bird droppings and other industrial airborne particles are some natural sources that cause soiling. The thickness of soiling layer has a direct impact on the performance of PV modules. This phenomenon occurs over a period of time with many unpredictable environmental variables indicated above. This situation makes it difficult to calculate or predict the soiling effect on performance. The dust particles vary from one location to the other in terms of particle size, color and chemical composition. These properties influence the extent of performance (current) loss, spectral loss and adhesion of soil particles on the surface of the PV modules. To address this uncontrolled environmental issues, research institutes around the world have started designing indoor artificial soiling stations to deposit soil layers in various controlled environments using reference soil samples and/or soil samples collected from the surface of PV modules installed in the locations of interest. This thesis is part of a twin thesis. The first thesis (this thesis) authored by Shanmukha Mantha is related to the development of soiling stations and the second thesis authored by Darshan Choudhary is associated with the characterization of the soiled samples (glass coupons, one-cell PV coupons and multi-cell PV coupons). This thesis is associated with the development of three types of indoor artificial soiling deposition techniques replicating the outside environmental conditions to achieve required soil density, uniformity and other required properties. The three types of techniques are: gravity deposition method, dew deposition method, and humid deposition method. All the three techniques were applied on glass coupons, single-cell PV laminates containing monocrystalline silicon cells and multi-cell PV laminates containing polycrystalline silicon cells. The density and uniformity for each technique on all targets are determined. In this investigation, both reference soil sample (Arizona road dust, ISO 12103-1) and the soil samples collected from the surface of installed PV modules were used. All the three techniques are compared with each other to determine the best method for uniform deposition at varying thickness levels. The advantages, limitations and improvements made in each technique are discussed. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2016

abstract: The state of the solar industry has reached a point where significant advancements in efficiency will require new materials and device concepts. The material class broadly known as the III-N's have a rich history as a commercially successful semiconductor. Since discovery in 2003 these materials have shown promise for the field of photovoltaic solar technologies. However, inherent material issues in crystal growth and the subsequent effects on device performance have hindered their development. This thesis explores new growth techniques for III-N materials in tandem with new device concepts that will either work around the previous hindrances or open pathways to device technologies with higher theoretical limits than much of current photovoltaics. These include a novel crystal growth reactor, efforts in production of better quality material at faster rates, and development of advanced photovoltaic devices: an inversion junction solar cell, material work for hot carrier solar cell, ground work for a selective carrier contact, and finally a refractory solar cell for operation at several hundred degrees Celsius. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2016

Made available in DSpace on 2014-06-11T19:24:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-11-30Bitstream added on 2014-06-13T18:21:07Z : No. of bitstreams: 1 caneppele_fl_me_botfca.pdf: 1429117 bytes, checksum: c8c896af07e13fd2373df60b74a0e4c2 (MD5) / O uso de energias alternativas e renováveis tem sido cada vez mais discutido em todos os setores da sociedade. O interesse nessas fontes de energias, alternativas e renováveis, é de fundamental importância, tanto no que se refere à escassez, quanto ao preço do petróleo, além das questões ambientais envolvidas no uso dessas energias. Sistemas de geração eólica e fotovoltaica com armazenamento de energia em baterias tem-se apresentado como uma forma de geração alternativa de energia. A variabilidade na intensidade da energia eólica e solar pode ser contornada pela complementação entre uma fonte e outra, ou pela maior estabilidade configurada à geração do sistema. O objetivo desta dissertação é criar uma metodologia fuzzy e simular seu uso no controle inteligente de um sistema híbrido de geração de energia elétrica, utilizando as energias solar-fotovoltaica e eólica. Quando utilizamos um sistema de controle baseado na lógica fuzzy, é atingido o ponto de máxima geração de energia, desta forma transferindo toda a energia gerada à partir das fontes alternativas, solar-fotovoltaica e eólica, à carga e/ou as baterias quando seu uso não imediato. O modelo utilizado adota três variáveis de entrada, que são: velocidade do vento, radiação solar e carga do banco de baterias.Serão utilizados para as simulações alguns softwares como o MATLAB e outros, que serão citados ao longo do trabalho. Nestes ambientes serão analisadas e simuladas todas as modelagens matemáticas, regras e demais variáveis descritas no sistema fuzzy. Este modelo foi utilizado para a implementação de um sistema de controle de sistemas híbridos de geração de energia, proporcionando o melhor aproveitamento das fontes de energia, sol e vento, de modo que possamos extrair o máximo de energia possível dessas fontes alternativas sem nenhum prejuízo ao meio ambiente... / The use of alternative and renewable energy has been increasingly discussed in all sectors of society. The interest in these sources of energy, alternative and renewable, it is of fundamental importance, both in terms of shortage, as the price of oil, in addition to the environmental issues involved in the use of these energies. Systems with photovoltaic and wind generation storage of energy in batteries has been presented as a form of alternative energy generation. The variability in the intensity of solar and wind energy can be circumvented by complementation between a source and another, or the more stable set to the generation of the system. The objective of this dissertation is to create a methodology fuzzy and simulate their use in intelligent control of a hybrid system of generating power, using the energy solar-photovoltaic and wind.When you use a system of control based on fuzzy logic, is reached the point of maximum generation of energy, thus transferring all the energy generated on the basis of alternative sources, solar, photovoltaic and wind, to the load and / or batteries when its use not immediately. The model takes three variables of entry, which are: wind speed, solar radiation and loading the bank of batteries. The simulations will be used for some software such as MATLAB and others, that will be cited during the work. In these environments will be analyzed and simulated all mathematical modeling, rules and other variables in the system described fuzzy. This model could be used in the implementation of a system of control of hybrid systems to generate energy, providing the best use of energy sources, sun and wind, so we can extract the maximum energy possible these alternative sources without any prejudice to the environment. The work was developed in the Laboratory of Energização Rural, of the Department of Rural Engineering of UNESP - FCA...(Complete abstract, click electronic access below)

Backup diesel generator (DG) systems continue to be a heavily polluting and costly solution for institutions with unreliable grid connections. These systems slow economic growth and accelerate climate change. Photovoltaic (PV), energy storage (ES), grid connected, DG – Hybrid Energy Systems (HESs) or, PV-HESs, can alleviate overwhelming costs and harmful emissions incurred from traditional back-up DG systems and improve the reliability of power supply. However, from project conception to end of lifetime, PV-HESs face significant barriers of uncertainty and variable operating conditions. The fit-and-forget solution previously applied to backup DG systems should not be adopted for PV-HESs. To maximize cost and emission reductions, PV-HESs must be adapted to their boundary conditions for example, irradiance, temperature, and demand. These conditions can be defined and monitored using measurement equipment. From this, an opportunity for performance optimization can be established. The method demonstrated in this study is a techno-economic and environmental approach to improving the performance of PV-HESs. The method has been applied to a case study of an existing PV-HES in Kenya. A combination of both analytical and numerical analyses has been conducted. The analytical analysis has been carried out in Microsoft Excel with the intent of being easily repeatable and practical in a business environment. Simulation analysis has been conducted in improved Hybrid Optimization by Genetic Algorithms (iHOGA), which is a commercially available software for simulating HESs. Using six months of measurement data, the method presented identifies performance inefficiencies and explores corrective interventions. The proposed interventions are evaluated, by simulation analyses, using a set of techno-economic and environment key performance indicators, namely: Net Present Cost (NPC), generator runtime, fuel consumption, total system emissions, and renewable fraction. Five corrective interventions are proposed, and predictions indicate that if these are implemented fuel consumption can be reduced by 70 % and battery lifetime can be extended by 28 %, net present cost can be reduced by 30 % and emissions fall by 42 %. This method has only been applied to a single PV-HES; however, the impact this method could have on sub-Saharan Africa as well as similar regions with unreliable grid connections is found to be significant. In the future, in sub-Saharan Africa alone, over $500 million dollars (USD) and 1.7 billion kgCO2 emissions could be saved annually if only 25 % of the fuel savings identified in this study were realized. The method proposed here could be improved with additional measurement data and refined simulation models. Furthermore, this method could potentially be fully automated, which could allow it to be implemented more frequently and at lower cost.

abstract: Current policies subsidizing or accelerating deployment of photovoltaics (PV) are typically motivated by claims of environmental benefit, such as the reduction of CO2 emissions generated by the fossil-fuel fired power plants that PV is intended to displace. Existing practice is to assess these environmental benefits on a net life-cycle basis, where CO2 benefits occurring during use of the PV panels is found to exceed emissions generated during the PV manufacturing phase including materials extraction and manufacture of the PV panels prior to installation. However, this approach neglects to recognize that the environmental costs of CO2 release during manufacture are incurred early, while environmental benefits accrue later. Thus, where specific policy targets suggest meeting CO2 reduction targets established by a certain date, rapid PV deployment may have counter-intuitive, albeit temporary, undesired consequences. Thus, on a cumulative radiative forcing (CRF) basis, the environmental improvements attributable to PV might be realized much later than is currently understood. This phenomenon is particularly acute when PV manufacture occurs in areas using CO2 intensive energy sources (e.g., coal), but deployment occurs in areas with less CO2 intensive electricity sources (e.g., hydro). This thesis builds a dynamic Cumulative Radiative Forcing (CRF) model to examine the inter-temporal warming impacts of PV deployments in three locations: California, Wyoming and Arizona. The model includes the following factors that impact CRF: PV deployment rate, choice of PV technology, pace of PV technology improvements, and CO2 intensity in the electricity mix at manufacturing and deployment locations. Wyoming and California show the highest and lowest CRF benefits as they have the most and least CO2 intensive grids, respectively. CRF payback times are longer than CO2 payback times in all cases. Thin film, CdTe PV technologies have the lowest manufacturing CO2 emissions and therefore the shortest CRF payback times. This model can inform policies intended to fulfill time-sensitive CO2 mitigation goals while minimizing short term radiative forcing. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2013

abstract: This dissertation presents a novel current source converter topology that is primarily intended for single-phase photovoltaic (PV) applications. In comparison with the existing PV inverter technology, the salient features of the proposed topology are: a) the low frequency (double of line frequency) ripple that is common to single-phase inverters is greatly reduced; b) the absence of low frequency ripple enables significantly reduced size pass components to achieve necessary DC-link stiffness and c) improved maximum power point tracking (MPPT) performance is readily achieved due to the tightened current ripple even with reduced-size passive components. The proposed topology does not utilize any electrolytic capacitors. Instead an inductor is used as the DC-link filter and reliable AC film capacitors are utilized for the filter and auxiliary capacitor. The proposed topology has a life expectancy on par with PV panels. The proposed modulation technique can be used for any current source inverter where an unbalanced three-phase operation is desires such as active filters and power controllers. The proposed topology is ready for the next phase of microgrid and power system controllers in that it accepts reactive power commands. This work presents the proposed topology and its working principle supported by with numerical verifications and hardware results. Conclusions and future work are also presented. / Dissertation/Thesis / Ph.D. Electrical Engineering 2013

Nos últimos anos, um conjunto de fatores tem colaborado para expansão da energia fotovoltaica no Brasil. No entanto, ainda não se oferecem políticas públicas ou incentivos regulatórios para que as distribuidoras contribuam com a geração fotovoltaica sem prejuízo ao equilíbrio de suas operações. Diante disso, este trabalho buscou investigar a viabilidade de novos papéis para as distribuidoras brasileiras frente aos desafios de modernização do setor elétrico. Para isso, buscou nos EUA, país que apresenta crescente participação de energia FV em sua matriz elétrica, exemplos de incentivos financeiros e regulatórios e novos modelos de negócios para operação das distribuidoras. Através da metodologia de análise SWOT, três modelos de negócio do mercado fotovoltaico norte-americano são avaliados para o setor de distribuição brasileiro. Os resultados evidenciam as forças e fraquezas das distribuidoras em relação a outros atores do mercado e as oportunidade e ameaças de cada modelo. / In recent years, a combination of events have contributed for solar photovoltaics raising adoption in Brazil. However, there are yet no available regulatory incentives or public policies to enable utilities participation without harming their financial equilibrium. As a result, the current study aims to identify new roles for Brazilian utilities that comply with smart grid emerging challenges. In an effort to identify examples of financial and regulatory incentives as well as new business models, North American solar photovoltaic experiences were evaluated. The effectiveness of three American business models for the Brazilian energy sector were discussed through SWOT analysis. The results indicate utilities main strengths and weaknesses compared to other energy market actors and also the opportunities and threats of each business model.

Organic solar cells show great potential to become a commercially available technology for renewable clean energy production due to their attractive properties. Inexpensive materials and manufacturing processes, including classical roll-to-roll fabrication, as well as the ability to produce flexible, low weight, semitransparent devices are some of the advantages organic photovoltaics provide. Addressing the most common issues in these new technologies, i.e., the low efficiencies of devices and rapid degradation of materials, could bring a realistic alternative for the photovoltaic industry. In this work, the performance of P3HT:PCBM based bulk heterojunction solar cells modified through low energy gold ion implantation in the hole transporting layer, the PEDOT:PSS, is studied. Reference solar cells without gold were also fabricated and characterized for comparison. Through field emission scanning electron microscopy (FESEM) micrographs, the formation of gold nanoparticles (AuNPs) in the PEDOT:PSS has been shown layer for the highest implantation doses used. Absorbance measurements of PEDOT:PSS films before and after gold implantation further confirmed this result. TRIDYN and SRIM simulation programs estimated shallow gold implantations of ~3 nm underneath the PEDOT:PSS films surface. Current-voltage (JxV) characteristics of reference solar cells under AM 1.5 illumination presented the uncommon S-shaped curves, an abnormal deviation from typical JxV curves. This was attributed to PEDOT:PSS degradation due to oxygen and water exposure, which reduced its work function significantly. As a result, deteriorated parallel and series resistances were obtained in reference devices, which ultimately reduced their field factors and power conversion efficiencies. This abnormal behavior was consistently eliminated with the introduction of AuNPs near the PEDOT:PSS/Active-layer interface, leading to the rectification of the illuminated JxV curves of modified solar cells and the reestablishment of cell parameters. Consequently, outstanding improvements in the field factors and power conversion efficiencies were observed in these devices. This was attributed to enhancement (and prevention from the reduction) of the PEDOT:PSS work function layer due to the presence of AuNPs, which rearranged the energy levels at the interface to a more favorable state: higher electron blocking and lower hole extraction barriers. / Células solares orgânicas têm mostrado grande potencial para se tornar uma alternativa tecnológica na produção de energia limpa e renovável. Baixo custo dos materiais e dos processos de manufatura, e a possibilidade de fabricar dispositivos com baixo peso, flexibilidade e semitransparência, inclusive pelo método clássico de roll-to-roll, são algumas das vantagens oferecidas pela fotovoltaica orgânica. Resolver os problemas mais comuns destes dispositivos, como a baixa eficiência na conversão de energia e a rápida degradação dos materiais, é necessário para sua disponibilização no mercado fotovoltaico atual. Neste trabalho, células solares de heterojunção volumétrica baseadas no polímero P3HT e modificadas através da implantação de íons de ouro de baixa energia na camada de PEDOT:PSS são estudadas. Dispositivos equivalentes sem modificação de ouro também foram fabricados e caracterizados como referência. Imagens obtidas através de um microscópio eletrônico de varredura por emissão de campo (FESEM Field Emission Scannig Electron Microscopy) mostraram a formação de nanopartículas de ouro (AuNPs) na camada de PEDOT:PSS para as doses de implantação mais elevadas. Medidas do espectro de absorbância dos filmes de PEDOT:PSS antes e depois da implantação de ouro confirmam este resultado. Simulações feitas com os softwares TRIDYN e SRIM estimaram o ouro implantado em u ma profundidade de ~3 nm abaixo da superfície do PEDOT:PSS. As curvas de corrente-tensão (JxV) características das células solares de referência sob iluminação AM 1.5 mostraram um comportamento de forma S, que corresponde a um desvio da forma típica das curvas JxV. Isto foi atribuído à degradação dos filmes de PEDOT:PSS devido à exposição ao oxigênio e à água, que reduz sua função trabalho significativamente. Como resultado, deterioraram-se as resistências em paralelo e em série destes dispositivos, o que em última instância, reduziu o Field Factor (FF) e a eficiência na conversão de energia. Este comportamento anormal foi eliminado de forma consistente após a introdução de AuNPs perto da interface PEDOT:PSS/Camada-Ativa. As curvas JxV das células solares modificadas sob iluminação foram retificadas e os valores dos seus parâmetros restabelecidos. Melhorias notáveis no FF e eficiência de conversão de energia foram obtidas para todas as células solares modificadas. Isto foi atribuído ao aumento da função trabalho da camada de PEDOT:PSS pela presença das AuNPs, que reorganizou os níveis de energia na interface para um estado mais favorável: com barreiras de potencial otimizadas para bloquear a extração de elétrons e favorecer a de buracos.

Des nanostructures basées sur des différences de cristallinité ont été insérées dans des cellules test en silicium par des techniques d’amorphisation innovantes. Un nouveau mécanisme de multiplication de porteurs a ainsi été observé. Cet effet peut provenir des niveaux d’énergie électronique introduits par de grandes densités locales de bi-lacunes. Un principe de fonctionnement impliquant des mécanismes à niveaux d’énergie multiples et un transport électronique rapide au sein de la bande d’énergie des atomes de phosphore non-ionisés a également été proposé. Cela conduit à une asymétrie favorable entre la génération et la recombinaison des porteurs libres.L’énergie nécessaire à un photon pour enclencher le procédé s’est révélée plus petite que deux fois celle de la bande interdite. L’amélioration du rendement photovoltaïque devient donc concevable et une nouvelle génération de cellules solaires à haute efficacité pourrait ainsi émerger de cet effet de multiplication à faible-énergie. / Nanostructures based on differences of crystallinity have been embedded into all-silicon test devices by innovative amorphization techniques and a new carrier multiplication mechanism was observed. This effect can indeed originate from the electron energy levels resulting from the high densities of divacancies localized at the crystalline/amorphous interfaces.An operating principle involving multiple energy level mechanisms and fast electronic transport within the unionized phosphorus energy band was also advanced. It led to a favourable asymmetry between generation and recombination of free carriers.Besides, contrary to other carrier multiplication effects, photon energy lower than twice the band gap was found sufficient to initiate the process. The enhancement of photovoltaic yields becomes therefore conceivable and propositions of prototypes are made. A new generation of high efficiency solar cells may then emerge from this Low-Energy Electron Multiplication effect.