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Zou, Elva Xin. "Sol-gel processed zinc oxide for third generation photovoltaics." Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559838.
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This thesis presents an experimental study of the incorporation and optimization of sol-gel processed aluminum doped zinc oxide (AZO) thin films in solar cell devices. I first optimized the optoelectronic properties of AZO thin films by manipulating the dopant incorporation, choice of precursor chemicals and post deposition anneal treatments. Results showed that improved performance could be attributed to several factors, including improved charge carrier concentration, mobility and conductivity. AZO thin films with transmittance of over 90% and resistivity values of the order of 10-2 Ω•cm have been achieved. I also demonstrated the successful application of these AZO thin films in organic photovoltaics (OPV), to serve as an alternative to ITO electrodes. I demonstrated greater than 2-fold improvement in device efficiency through the modification of the front contact/polymer interface using zinc oxide buffer layers. This improved the charge selectivity of the electrodes and energy level alignment at the interface while reducing the recombination of separated charges and the device's series resistance. Finally, I showed that the efficiency of inverted ZnO/PbS quantum dots solar cells can be enhanced by optimizing the p-type PbS thickness, UV treating the n-type ZnO layer and exposing the devices in the dark to nitrogen. Both ZnO and AZO systems were studied, and efficiency enhancement were demonstrated for a range of Al content from 0 to O.4at.%.
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Saliba, Michael. "Plasmonic nanostructures and film crystallization in perovskite solar cells." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:fdb36a9e-ddf5-4d27-a8dc-23fffe32a2c5.
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The aim of this thesis is to develop a deeper understanding and the technology in the nascent field of solid-state organic-inorganic perovskite solar cells. In recent years, perovskite materials have emerged as a low-cost, thin-film technology with efficiencies exceeding 16% challenging the quasi-paradigm that high efficiency photovoltaics must come at high costs. This thesis investigates perovskite solar cells in more detail with a focus on incorporating plasmonic nanostructures and perovskite film formation. Chapter 1 motivates the present work further followed by Chapter 2 which offers a brief background for solar cell fabrication and characterisation, perovskites in general, perovskite solar cells in specific, and plasmonics. Chapter 3 presents the field of plasmonics including simulation methods for various core-shell nanostructures such as gold-silica and silver-titania nanoparticles. The following Chapters 4 and 5 analyze plasmonic core-shell metal-dielectric nanoparticles embedded in perovskite solar cells. It is shown that using gold@silica or silver@titania NPs results in enhanced photocurrent and thus increased efficiency. After photoluminescence studies, this effect was attributed to an unexpected phenomenon in solar cells in which a lowered exciton binding energy generates a higher fraction of free charge. Embedding thermally unstable silver NPs required a low-temperature fabrication method which would not melt the Ag NPs. This work offers a new general direction for temperature sensitive elements. In Chapters 6 and 7, perovskite film formation is studied. Chapter 6 shows the existence of a previously unknown crystalline precursor state and an improved surface coverage by introducing a ramped annealing procedure. Based on this, Chapter 7 investigates different perovskite annealing protocols. The main finding was that an additional 130°C flash annealing step changed the film crystallinity dramatically and yielded a higher orientation of the perovskite crystals. The according solar cells showed an increased photocurrent attributed to a decrease in charge carrier recombination at the grain boundaries. Chapter 8 presents on-going work showing noteworthy first results for silica scaffolds, and layered, 2D perovskite structures for application in solar cells.
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Giraud-berbezier, Aude. "Transport quantique en formalisme des fonctions de Green et interaction électron-photon pour la modélisation de cellules photovoltaïques." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4781.
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Ce document présente notre travail sur la modélisation en formalisme des fonctions de Green (abrégé formalisme de Green) du transport quantique et de l’intéraction éléctron-photon dans une cellule photovoltaïque composée d’une boîte quantique connectée à deux nanofils semi-infinis, La simulation numérique a été réalisée sur le cluster de calculs MERLIN (IM2NP). Nous présentons le formalisme de Green en général puis appliqué à cellule. Le fonctionnement général de la cellule est déduit de son diagramme de bande qui comporte des contacts sélectifs. Ensuite, nous présentons les résultats obtenus dans l’approximation de bande plate, qui simplifie le contact aux nanofils. Ceux-ci mettent en lumière des effets intriqués du couplage tunnel (couplage entre la boîte et les nanofils) et du couplage optique (couplage avec la lumière). Nous présentons ensuite un calcul analytique effectué dans le régime de fort couplage tunnel et qui explique le fonctionnement contre-intuitif du couplage tunnel dans ce régime. Nous observons également une transition dans le processus de production du courant entre le régime de fort couplage tunnel et le régime de fort couplage optique. Ensuite, nous sortons de l’approximation de bande plate et découvrons que les effets contre-intuitifs sont toujours valides, même si le modèle analytique lui ne l’est plus. Nous présentons le nouvel effet induit par la nouvelle forme du couplage aux réservoirs hors de l’approximation de bande plate: la courbe courant-tension présente une conductance de shunt négative. Cela n’a jamais été observé dans une cellule photovoltaïque auparavant. Enfin, nous présentons une réalisation possible de notre celluleThis document present our work on the modeling of quantum transport coupled to electron-photon interaction in a solar cell composed of one quantum dot connected to two semi-infinite quantum wires. The proposed cell based on a dot in a wire, is a concept imagined in order to investigate quantum effects inside 1D structures in contact with 0D ones. The numerical simulation powered on the Merlin cluster (IM2NP) relies on Green’s function formalism. The philosophy of Green’s function formalism is introduced and then applied to the photovoltaic cell. An overview of the functioning of the cell is given. Results on the cell are presented in the wide band limit (approximation that simplifies the contact to wires). We observe an interlinked impact of the tunneling coupling (dot-wires coupling) and the optical coupling (to light) on the current. In the strong tunneling regime, an increase of the tunneling coupling decreases the current and similarly in the strong optical coupling regime, an increase of the optical coupling decreases the current. We investigate the counter-intuitive impact of the tunneling coupling in the strong tunneling regime through analytical calculations, considering only the first loop of the numerical code instead of the whole self-consistent process. We observe a transition in the current creation process while switching from the strong tunneling regime to the strong optical coupling regime. Results on the cell beyond the wide band limit approximation are presented in which the system exhibits another atypical response to illumination: I-V curve exhibits a negative shunt conductance! Finally, a realization proposal for the concept cell is described
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Wang, Caisheng. "Modeling and Control of Hybrid Wind/Photovoltaic/Fuel Cell Distributed Generation Systems." Thesis, Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/wang/WangC0806.pdf.
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Due to ever increasing energy consumption, rising public awareness of environmental protection, and steady progress in power deregulation, alternative (i.e., renewable and fuel cell based) distributed generation (DG) systems have attracted increased interest. Wind and photovoltaic (PV) power generation are two of the most promising renewable energy technologies. Fuel cell (FC) systems also show great potential in DG applications of the future due to their fast technology development and many merits they have, such as high efficiency, zero or low emission (of pollutant gases) and flexible modular structure. The modeling and control of a hybrid wind/PV/FC DG system is addressed in this dissertation. Different energy sources in the system are integrated through an AC bus. Dynamic models for the main system components, namely, wind energy conversion system (WECS), PV energy conversion system (PVECS), fuel cell, electrolyzer, power electronic interfacing circuits, battery, hydrogen storage tank, gas compressor and gas pressure regulator, are developed. Two types of fuel cells have been modeled in this dissertation: proton exchange membrane fuel cell (PEMFC) and solid oxide fuel cell (SOFC). Power control of a grid-connected FC system as well as load mitigation control of a stand-alone FC system are investigated. The pitch angle control for WECS, the maximum power point tracking (MPPT) control for PVECS, and the control for electrolyzer and power electronic devices, are also addressed in the dissertation. Based on the dynamic component models, a simulation model for the proposed hybrid energy system has been developed using MATLAB/Simulink. The overall power management strategy for coordinating the power flows among the different energy sources is presented in the dissertation. Simulation studies have been carried out to verify the system performance under different scenarios using a practical load profile and real weather data. The results show that the overall power management strategy is effective and the power flows among the different energy sources and the load demand is balanced successfully. The DG's impacts on the existing power system are also investigated in this dissertation. Analytical methods for finding optimal sites to deploy DG sources in power systems are presented and verified with simulation studies.
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Wang, Xiaoting. "Very High Efficiency Solar Cell (VHESC) sub-module measurement." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 55 p, 2008. http://proquest.umi.com/pqdweb?did=1654493881&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Shaheen, Momtaz. "Analytical model of an n+-p-p+ concentrator solar cell." Virtual Press, 1988. http://liblink.bsu.edu/uhtbin/catkey/539622.
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Concentrator solar cells operate under the conditions of non-uniform illumination and varying spectral content of incident sunlight. To predict the performance of such cells, an analytical model must account for varying carrier photogeneration rates within the cell. Further, the back surface junction fabricated to reduce recombination at the back contact must be included in the analysis.Most models of n+-p-p+ cells assume uniform generation rates within individual layers. In this study, a one-dimensional n+-p-p+ concentrator solar cell is modeled for all levels of illumination of incident sunlight. The photocarrier generation rate is considered as non-uniform in each layer of the cell. An absorption model is incorporated to permit the application for various spectral mixes of incident sunlight. The model also includes the effects of finite surface recombination velocities at the surfaces. Carrier transport equations for the three layers of the cell are developed and solved for the excess carrier concentrations under the assumptions of the model. Junction current density-voltage relationships for the two junctions of the cell are derived. The use of the current density equations in the evaluation of cell performance is discussed.Department of Physics and Astronomy
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Propp, Joshua M. "Incentives for Distributed Generation in California: The Rise of Third-Party Solar Development." Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/pomona_theses/82.
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There are a series of state and federal incentives in California to encourage the installation of distributed generation (DG) renewable energy, largely photovoltaic (PV). This thesis explores the policies behind the incentives, namely the Federal Investment Tax Credit, California Solar Initiative, and Net Energy Metering requirements. Discussion is informed by environmental policy tools, as well as business models that have acted to increase accessibility to these investment-intensive projects. Underlying this analysis is the theme of a shifting energy paradigm, with distributed generation spreading political, economic, and electric power.
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Chi, San-Hui. "Third-order nonlinear optical properties of conjugated polymers and blends." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31664.
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Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010.Committee Chair: Perry, Joseph; Committee Member: Bunz, Uwe; Committee Member: Lyon, Andrew; Committee Member: Marder, Seth; Committee Member: Trebino, Rick. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Nakayashiki, Kenta. "Understanding of defect passivation and its effect on multicrystalline silicon solar cell performance." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19854.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.Committee Chair: Dr. Ajeet Rohatgi; Committee Member: Dr. Bernard Kippelen; Committee Member: Dr. Gabriel Rincon-Mora; Committee Member: Dr. Miroslav Begovic; Committee Member: Dr. W. Brent Carter.
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Assamagan, Ketevi Adikle. "Two-dimensional analytical model of an n+-p-p+ concentrator solar cell." Virtual Press, 1989. http://liblink.bsu.edu/uhtbin/catkey/560283.
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A successful model that could accurately predict the performances of n+-p-p+ concentrator solar cells should include a model of carrier photogeneration rates consistent with the spectral content of the incident light. Furthermore, a finite back surface recombination velocity should be considered since new techniques such as 'Back Surface Field' were developed to reduce the recombination rate at the rear of the cell.In the present work, a two-dimensional concentrator solar cell is modeled for low levels of injection. The model however, assumes an incident light containing one single wavelength. The incident light is assumed to decrease linearly from the center of the illuminated area until it vanishes at the edges of the cell. Finite recombination velocities are taken into account at the front and the back surfaces. Finite-width space charge regions are also included. The transport equations are solved for the carrier concentrations in different regions of the cell. The current density expressions are derived. The generation of theoretical current voltage characteristics is outlined. However, the use of these characteristics to predict cell performances is left for further research.Department of Physics and Astronomy
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Lange, Sturla. "Study and Design of a DC-DC Converter for Third Generation Solar Cells." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254291.
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The perceived battery capacity of battery-powered devices can be increased by harvesting energy from readily available sources. Third generation solar cells are a good candidate for this purpose since they can be integrated with these battery-powered devices and harvest power from diffused light. For a single third generation solar cell to be useful in the context of charging a Lithium based battery, the voltage must be increased tenfold. To increase this perceived battery capacity as much as possible, efficiency is crucial. In this thesis, DCDC converter topologies and designs are studied from a system design perspective. The specifications of a converter suitable for interfacing Dye-Sensitised Solar Cells with Lithium batteries are described and a market research is conducted based on those specifications. A comparison of the available commercial solutions is presented, highlighting the most suitable options. However, none of the commercial solutions met the specifications to the full extent. The design process of two DC-DC converters is presented, one is a Boost converter operating in Continuous Conduction Mode and the other is a Boost converter operating in Discontinuous Conduction Mode. A comparison of the two designs highlights the advantages of operating the Boost converter in Discontinuous Conduction Mode when interfaced with a Dye-Sensitised Solar Cell. The design with a Boost converter operating in Discontinuous Conduction Mode has an efficiency of 80.3 % and is capable of tracking the Maximum Power Point of the Dye-Sensitised Solar Cell.Den uppfattade batterikapaciteten hos batteridrivna enheter kan ökas genom att skörda energi från lättillgängliga källor. Tredje generationens solceller är en bra kandidat för detta ändamål eftersom de kan integreras med dessa batteridrivna enheter och skörda ström från spritt ljus. För att en enda tredje generationens solcell ska vara användbar i samband med laddning av ett litiumbaserat batteri måste spänningen ökas tiofaldigt. För att öka denna uppfattade batterikapacitet så mycket som möjligt är effektiviteten avgörande. I denna avhandling studeras topologier och strategier för DC-DC-omvandlare från ett systemdesignperspektiv. Specifikationerna för en omvandlare som är lämplig för att ansluta Dye-sensitized solceller med litiumbatterier beskrivs och en marknadsundersökning utförs utifrån dessa specifikationer. En jämförelse av de tillgängliga kommersiella lösningarna presenteras och belyser de lämpligaste alternativen. Ingen av de kommersiella lösningarna uppfyllde emellertid specifikationerna i sin helhet. Designprocessen för två DC-DComvandlare presenteras, en Boost-omvandlare som arbetar i kontinuerligt ledande läge och en Boost-omvandlare som arbetar i diskontinuerligt ledande läge. En jämförelse av de två designerna belyser fördelarna med att driva Boost-omvandlaren i diskontinuerligt ledningsläge när den kopplats till en färgkänslig solcell. Konstruktionen med en Boostomvandlare som arbetar i diskontinuerlig ledningsläge har en effektivitet på 80.3 % och kan spåra den maximala effektpunkten för solcellen.
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Matsumoto, Seiji. "Efficacy of the third-generation bisphosphonate zoledronic acid alone and combined with anti-cancer agents against small cell lung cancer cell lines." Kyoto University, 2006. http://hdl.handle.net/2433/135878.
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Hesselsweet, Ian Brock. "Polyaniline Nanofibers as the Hole Transport Medium in an Inverse Dye-Sensitized Solar Cell." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/710.
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In order to become a viable alternative to silicon photovoltaics, dye-sensitized solar cells must overcome several issues primarily resulting from their use of a liquid electrolyte. Much research has gone into correcting these shortcomings by replacing the liquid electrolyte with solid-state hole-transport media. Using these solid-state materials brings new difficulties, such as completely filling the pores in the TiO₂nanostructure, and achieving good adhesion with the dye-coated TiO₂. A novel approach to addressing these difficulties is the inverse dye-sensitized solar cell design. In this method the devices are constructed in reverse order, with the solid-state hole-transport medium providing the nanostructure instead of the TiO₂. This allows new materials and methods to be used which may better address these issues. In this project, inverse dye-sensitized solar cells using polyaniline nanofibers as the hole transport medium were prepared and characterized. The devices were prepared on fluorine-doped tin oxide (FTO) coated glass electrodes. The first component was a dense spin-coated polyaniline blocking layer, to help prevent short circuiting of the devices. The second layer was a thin film of drop cast polyaniline nanofibers which acted as the hole transport medium and provided high surface area for the dye attachment. The dye used was 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin (TCPP), which was covalently attached to the nanofibers using a Friedel-Crafts acylation. Titania gel was then deposited into the pores of the nanofiber film by controlled hydrolysis of a titanium complex (Tyzor LA). A back electrode of TiO₂nanoparticles sintered on FTO was pressed on top to complete the devices. A typical device generated an open circuit voltage of 0.17 V and a closed circuit current of 5.7 nA/cm² while the highest open circuit voltage recorded for any variation on a device was 0.31 V and the highest short circuit current was 52 nA/cm² under AM 1.5 simulated olar spectrum at 100 mW/cm². Initially prepared devices did not generate a measureable photocurrent due to two materials flaws. The first was traced to the poorly developed conduction band of the titania gel, as deposited from Tyzor LA hydrolysis, resulting in poor electron conduction. This prevented the titania gel from efficiently functioning as the electron transport medium. A remedy was found in adding a layer of sintered anatase TiO₂nanoparticles on the back electrode to serve as the electron transport medium. However, this remedy does not address the issue of the inability of titania gel to efficiently transport electrons photogenerated deep in the nanofiber film to the back electrode. The second flaw was found to originate from fast recombination kinetics between electrons in TiO₂and holes in polyaniline. However, a positive feature was that the titania gel intended to be used as the electron transport medium was found to sufficiently insulate the interface such that the recombination rate slowed enough to allow generation of a measureable photocurrent. Electronic insulation was further enhanced by co-attaching decanoic acid onto the polyaniline nanofibers to fill in pinholes between the dye molecules. While these solutions were not ideal, they were intended to be diagnostic in nature and supplied critical information about the weak links in the device design, thus pointing the way toward improving device performance. Significant enhancements can be expected by addressing these issues in further detail.
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Surana, Kavita. "Towards silicon quantum dot solar cells : comparing morphological properties and conduction phenomena in Si quantum dot single layers and multilayers." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00647293.
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Le confinement quantique dans le silicium, sous forme de boîtes quantiques de silicium de diamètre 5 nm, permet de contrôler le bandgap et donc l'émission de lumière. Cette ingénierie du bandgap des nanocristaux de silicium est utile pour les applications photovoltaïques avancées et présente l'avantage de conserver la compatibilité avec les technologies silicium existantes. Ces boîtes quantiques peuvent aider à réduire les pertes par thermalisation dans une cellule solaire homo-jonction. Ce travail se concentre sur la fabrication à grande échelle des nanocristaux de silicium dans SiO2 en utilisant le Dépôt Chimique en Phase Vapeur assisté par Plasma (PECVD), suivi d'un recuit à haute température. Des monocouches sont comparées avec des multicouches pour les propriétés morphologiques, électriques et optiques et des dispositifs avec ces différents couches sont comparés. Dans le cas d'une structure monocouche, l'épaisseur de la couche contrôle l'organisation des nanocristaux et permet de mettre en évidence l'amélioration de la conductivité électrique, avec cependant une réponse optique faible. Les multicouches montrent un bandgap du Si augmentée et controlee, avec une meilleure absorption dans la gamme bleu-vert visible, accompagnée d'une conductivité électrique faible. L'amélioration de ces propriétés optiques est un signe prometteur pour une potentielle intégration photovoltaïque.
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Shalav, Avi School of Photovoltaic & Renewable Energy Engineering UNSW. "Rare-earth doped up-converting phosphors for an enhanced silicon solar cell response." Awarded by:University of New South Wales. School of Photovoltaic and Renewable Energy Engineering, 2006. http://handle.unsw.edu.au/1959.4/24184.
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Photovoltaic solar cells can generate electricity directly from sunlight without emitting harmful greenhouse gases. This makes them ideal candidates as large scale future energy producers for the global energy economy. Ideally, solar cells should be efficient and inexpensive to compete in the global energy market. Unfortunately, a number of fundamental limitations exist for the efficiency due to fundamental loss mechanisms of the semiconductor materials used to make solar cells. One of the dominant loss mechanisms from a conventional silicon solar cell is the transparency of sub-bandgap near-infrared photons. Up-conversion is an optical process involving the sequential absorption of lower energy photons followed by luminescence of a higher energy photon. This mechanism could be exploited to minimise photovoltaic sub-bandgap losses. Rare-earth doped materials have ideal up-conversion luminescent properties and have been utilised for many near-infrared to visible applications. This thesis investigates the near-infrared to near-infrared up-conversion processes required for the sub-bandgap photon utilisation within a silicon photovoltaic device. Various sodium yttrium fluoride phosphors doped with rare-earths were characterised theoretically and experimentally. Erbium doped phosphors were found to be ideal for single wavelength power dependent investigations for the non-linear up-conversion processes. The radiative and non-radiative rates of various erbium doped sodium yttrium fluoride phosphors have been approximated and compared with experimental photoluminescence results. These phosphors have been applied to the rear of a bi-facial silicon solar cell and an enhancement in the near-infrared region has been demonstrated. An external quantum efficiency close to 3.4% was measured at 1523nm under 6mW laser excitation. The non-linear dependence on incident pump power has been investigated along with the dominant up-conversion mechanisms involved. It can be concluded that up-conversion phosphors can enhance the near-infrared spectral response of a silicon device. These phosphors have high luminescent efficiencies once up-conversion occurs, but suffer from poor infrared absorption and low up-conversion efficiencies. The results from this study show that relatively high doping levels of selected rare-earths into low phonon energy crystals can improve the absorption and luminescent properties of the phosphor.
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Sutcu, Sinan Mahmut. "The effects of ITO surface modification on lifetime in organic photovoltaic devices and a test setup for measuring lifetime." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34685.
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Though relatively young, the field of organic electronics is a rapidly growing market and considerable research is being done in creating a whole range of devices from organic molecules from organic field effect transistors to LEDs to photovoltaic devices. The field of organic photovoltaic in particular has become important in recent years with the push for newer, renewable sources of energy to end the dependence on fossil fuels. While the efficiencies of organic photovoltaic devices continue to rise, one barrier to their commercial adoption has been the limited lifetimes of these devices. While certain degradation methods of organic photovoltaics, such as photo-oxidation, have been extensively studied and solutions to these problems, such as encapsulation, are being researched, certain other degradation mechanisms are less understood and studied. The focus of this thesis is on one such degradation mechanism, UV degradation, specific to the ITO-pentacene interface in pentacene/C60 organic photovoltaic devices. Attempts were made to increase the lifetime of the devices by using phosphonic acids or oxygen plasma to modify the surface of the ITO. While conducting these experiments, the lack of a system to test the lifetime of multiple devices for long periods of time became apparent. As such as system was a requirement for future research into the lifetimes of organic photovoltaic devices a system was designed and built. The system would operate the photovoltaic device in a way comparable to its end-use and would allow over 100 devices to be tested simultaneously for durations exceeding 10,000 hours if necessary. This system would allow for statistically significant lifetime testing to be carried out in the future.
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Basta, Marek. "Low energy photovoltaic conversion in MIND structures." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAD019/document.
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Dispositifs photovoltaïques d'aujourd'hui convertissent l'énergie solaire en électricité de manière propre, renouvelable et inépuisable et représentent un remplacement possible pour les combustibles fossiles. Toutefois, afin de rivaliser avec les sources d'énergie classiques une augmentation significative de l'efficacité de conversion est inévitable. Dans ce travail, nous nous concentrons sur des aspects pouvant propulser le rendement de conversion au-dessus des limites de cellules présentes. La première partie de l'étude est consacrée à de nouvelles idées théoriques considérés comme le photovoltaïque de 3ème génération, alors que le plus d'intérêt est maintenu à étudier les avantages possibles de la multiplication d'électrons faible seuil. Dans la deuxième partie de l'étude, nous développons un modèle qui permet un traitement précis des propriétés optiques et de transport des structures de silicium avec des interfaces enterrées. Les analyses théoriques et expérimentales approfondies des structures existantes MIND sont ensuite effectuées. En étudiant le flux exacte et la distribution d'énergie à l'intérieur de plusieurs structures dans le cadre de leur géométrie, nous estimons les rendements quantiques possibles et les comparer avec les résultats expérimentaux. Grâce aux moyens de simulations numériques couplées avec caractérisation expérimentale, nous extrayons l'efficacité de la collecte de porteur de cellules étudiées. De nouveaux effets sont observés, une telle augmentation possible de l'efficacité de la collecte au-dessus de l'unité. Une analyse plus approfondie des résultats expérimentaux couplés avec l'étude numérique suit quelques explications classiques et non classiques de l'augmentation de l'efficacité de la collecte ou l'augmentation résultante de l'efficacité quantique. Avec la plupart des explications classiques exclu, nous concluons que l'explication la plus probable, mais non définitive de cet effet peut être interprété comme le résultat d'une multiplication des porteurs faible seuilPhotovoltaic devices of today convert solar energy into electricity in a clean, renewable and inexhaustible way and represent a possible replacement for the fossil fuels. However, in order to compete with classical energy sources a significant increase in the conversion efficiency is inevitable. In this work, we concentrate on the aspects able to raise the conversion efficiency above the limitations of present cells. The first part of the study is devoted to new theoretical ideas considered as 3rd generation photovoltaics, while the most interest is kept at studying the possible benefits of electron multiplication at low-energies. In the second part of the study, we develop a model that allows a precise treatment of optical and transport properties of silicon structures with buried interfaces. Extensive theoretical and experimental analyses of existing MIND structures are then conducted. By studying the exact flux and power distribution inside several structures in conjunction with their geometry, we estimate the possible quantum efficiencies and compare them with experimental results. Through the means of numerical simulations coupled with experimental characterization, we extract the carrier collection efficiency of studied cells. New effects are being observed, such a possible increase in collection efficiency above unity. A deeper analysis of the experimental results coupled with the numerical study analyzes several classical and non-classical explanations of the increase in collection efficiency or the resulting increase in the quantum efficiency. With most of the classical explanations ruled out, we conclude that the most probable, but not definitiveexplanation of this effect can be interpreted as the result of a low-energy carrier multiplication
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Lambert, Darcy Erin. "Nanostructured Extremely Thin Absorber (ETA) Hybrid Solar Cell Fabrication, Optimization, and Characterization." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/637.
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Traditional sources of electrical energy are finite and can produce significant pollution. Solar cells produce clean energy from incident sunlight, and will be an important part of our energy future. A new nanostructured extremely thin absorber solar cell with 0.98% power conversion efficiency and maximum external quantum efficiency of 61% at 650 nm has been fabricated and characterized. This solar cell is composed of a fluorine-doped tin oxide base layer, n-type aluminum doped zinc oxide nanowires, a cadmium selenide absorber layer, poly(3-hexylthiophene) as a p-type layer, and thermally evaporated gold as a back contact. Zinc oxide nanowire electrodeposition has been investigated for different electrical environments, and the role of a zinc oxide thin film layer has been established. Cadmium selenide nanoparticles have been produced and optimized in-house and compared to commercially produced nanoparticles. Argon plasma cleaning has been investigated as a method to improve electronic behavior at cadmium selenide interfaces. The thermal anneal process for cadmium selenide nanoparticles has been studied, and a laser anneal process has been investigated. It has been found that the most efficient solar cells in this study are produced with a zinc oxide thin film, zinc oxide nanowires grown under constant -1V bias between the substrate material and the anode, cadmium selenide nanoparticles purchased commercially and annealed for 24 hours in the presence of cadmium chloride, and high molecular weight poly(3-hexylthiophene) spin-coated in a nitrogen environment.
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Meemongkolkiat, Vichai. "Development of high efficiency monocrystalline Si solar cells through improved optical and electrical confinement." Diss., online access from Digital Dissertation Consortium, 2008. http://libweb.cityu.edu.hk/cgi-bin/er/db/ddcdiss.pl?3346030.
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Zhang, Lei. "The third generation mobile phone market in China an analysis of its development and forecasts about its future : a thesis in partial fulfilment of the degree of Master of Arts (Communication Studies) at the Auckland University of Technology , 2003." Full thesis. Abstract, 2003.
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Almada, Janaina Barbosa. "Modeling, Control and Management of Microgrids Operation with Renewable Sources." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11122.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoNowadays, the distribution networks of electricity are the segment of the electrical power systems that has experienced more changes, due in particular to the presence of distributed generation and the technological advances in the areas of instrumentation, automation, measurement, information technology and comunication. This work aims to present the modelling, the control and the operation management of a group of small-scale energy resources connected to the low voltage, which coordinated form a microgrid. The microgrid energy resources are solar photovoltaic sources, wind energy based on double fed induction generator and hydrogen fuel cell, and a storage system with batteries. Two conceptions are developed: a single-phase microgrid and a three-phase microgrid, both operating in connected mode and isolated from the utility. Each energy resource is connected to a point of common coupling through power converters. For each converter was designed a set of control loops. The master-slave strategy was used to control the converters and to microgrid management. In master-slave configuration only the master converter is designed to be the voltage reference and others operate as a current source. For managing the steady state operation of microgrids different operating scenarios were considered, with variation of load and generation levels, as well as changes in tariff flags, for load supply with economy and sources operating at maximum efficiency. The proposed systems operate satisfactorily fulfill the requirements of utility for synchronization and disconnection. The injected currents are below the allowed distortion level. In stand-alone mode, the system voltage remains within the appropriate level of amplitude and frequency.
Atualmente, as redes de distribuiÃÃo de energia elÃtrica sÃo o segmento dos siste-mas elÃtricos de potÃncia que mais tem experimentado mudanÃas, devido, em es-pecial, à presenÃa da geraÃÃo distribuÃda e aos avanÃos tecnolÃgicos nas Ãreas de instrumentaÃÃo, automaÃÃo, mediÃÃo, tecnologia da informaÃÃo e comunicaÃÃo. Este trabalho tem por objetivo apresentar a modelagem, o controle e o gerenciamento da operaÃÃo de um conjunto de recursos energÃticos de pequeno porte, conectados à baixa tensÃo, que coordenados formam uma microrrede. Os recursos energÃticos da microrrede sÃo fontes solar fotovoltaica, eolielÃtrica com gerador de induÃÃo de dupla alimentaÃÃo e cÃlula combustÃvel a hidrogÃnio, e um sistema de armazenamento de energia a baterias. Duas concepÃÃes de microrredes sÃo desenvolvidas: microrrede monofÃsica e microrrede trifÃsica, ambas operando em modo conectado e isolado da rede elÃtrica principal. Cada recurso energÃtico à conectado a um ponto comum de conexÃo atravÃs de conversores de potÃncia. Para cada conversor foi projetado um conjunto de malhas de controle. A estratÃgia mestre-escravo foi usada para o controle dos conversores e gerenciamento da microrrede. Na configuraÃÃo mestre-escravo apenas o conversor mestre à designado para ser a referÃncia de tensÃo que os outros conversores necessitam para operarem como fonte de corrente. Para o gerenciamento da operaÃÃo das microrredes em regime permanente, foram considerados diferentes cenÃrios de operaÃÃo, com variaÃÃo de nÃveis de carga e de geraÃÃo, bem como variaÃÃo de bandeiras e postos tarifÃrios, visando atender a carga com economicidade e fontes operando em mÃxima eficiÃncia. Os sistemas propostos operam de forma satisfatÃria obedecendo aos requisitos da concessionÃria para a sincronizaÃÃo e desconexÃo. As harmÃnicas de corrente injetada estÃo abaixo do nÃvel de distorÃÃo permitido. No modo isolado, a tensÃo dos sistemas permanece dentro do nÃvel adequado de amplitude e frequÃncia.
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Sheoran, Manav. "Development of high-efficiency solar cells on thin silicon through design optimization and defect passivation." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/33902.
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The overall goal of this research is to improve fundamental understanding of the hydrogen passivation of defects in low-cost silicon and the fabrication of high-efficiency solar cells on thin crystalline silicon through low-cost technology development. A novel method was developed to estimate the flux of hydrogen, released from amorphous silicon nitride film, into the silicon. Rapid-firing-induced higher flux of hydrogen was found to be important for higher defect passivation. This was followed by the fabrication of solar cell efficiencies of ~ 17% on low-cost, planar cast multicrystalline silicon. Solar cell efficiencies and lifetime enhancement in the top, middle, and bottom regions of cast multicrystalline silicon ingots were explained on the basis of impurities and defects generally found in those regions. In an attempt to further reduce the cost, high-efficiency solar cells were fabricated on thin crystalline silicon wafers with full area aluminum-back surface field. In spite of loss in efficiency, wafer thinning reduced the module cost. Device modeling was performed to establish a roadmap towards high-efficiency thin cells and back surface recombination velocity and back surface reflectance were identified as critical parameters for high-efficiency thin cells. Screen-printed solar cells on float zone material, with efficiencies > 19% on 300 μm and > 18% on 140 μm were fabricated using a novel low-cost fabrication sequence that involved dielectric rear passivation along with local contacts and back surface field.
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Letty, Elénore. "Identification and neutralization of lifetime-limiting defects in Czochralski silicon for high efficiency photovoltaic applications." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI094/document.
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Les cellules photovoltaïques à base de silicium cristallin représentent plus de 90% du marché photovoltaïque mondial. Des architectures de cellules à haut rendement de conversion sont actuellement développées. Pour atteindre leurs performances maximales, ces architectures nécessitent néanmoins une amélioration des propriétés électriques des substrats de silicium cristallin. Les objectifs de cette thèse sont d’identifier les défauts limitant les propriétés électriques de ces substrats, de comprendre les mécanismes menant à leur formation et de proposer des moyens permettant leur neutralisation. Les matériaux étudiés sont des plaquettes de silicium Czochralski de type n, généralement utilisé pour les applications à haut rendement. Le four de tirage Czochralski a d’abord été modélisé afin de comprendre comment le passé thermique subi par le lingot de silicium lors de la cristallisation affecte la génération des défauts. Ces travaux ont été confirmés via des confrontations avec des données expérimentales, en utilisant une méthode originale développée dans le cadre de ce travail. Nous avons ensuite étudié l’influence du budget thermique lié aux procédés de fabrication des cellules sur la population de défauts. Nous avons ainsi pu montrer que la nature des défauts limitant les propriétés électriques du silicium était grandement modifiée selon le procédé de fabrication de cellules utilisé. Nous avons en outre mis en évidence une dégradation inattendue des propriétés électriques du silicium Czochralski de type n sous illumination, liée à la formation d’un défaut volumique inconnu. Les conditions de formation et de suppression de ce défaut ont été étudiées en profondeur. Enfin, les principaux défauts limitant les propriétés électriques du silicium ayant été identifiés et les mécanismes menant à leur formation compris, nous proposons dans un dernier chapitre des nouvelles techniques de caractérisation permettant de détecter les plaquettes défectueuses en début de ligne de production de cellules photovoltaïques, et ce à une cadence industriellePhotovoltaic solar cells based on crystalline silicon represent more than 90% of the worldwide photovoltaic market. High efficiency solar cell architectures are currently being developed. In order to allow their maximal performances to be reached, the electronic properties of their crystalline silicon substrate must however be enhanced. The goals of the present work are to identify the defects limiting the electronic properties of the substrate, to understand the mechanisms leading to their formation and to propose routes for their neutralization. The studied materials are n-type Czochralski silicon wafers, usually used as substrates for high efficiency photovoltaic applications. The Czochralski puller was first modeled in order to understand how the thermal history experienced by the silicon ingot during crystallization affects the defects generation. This study were validated through the comparison with experimental data using an original method developed in the frame of this work. We then studied the influence of the thermal budget associated to solar cell fabrication processes on the defects population. We thus showed that the nature of lifetime-limiting defects was completely changed depending on the solar cell fabrication process. Besides, we evidenced an unexpected degradation of the electronic properties of n-type Czochralski silicon under illumination, related to the formation of an unknown bulk defect. The formation and deactivation features of this defect were extensively studied. Finally, the main limiting defects being identified and the mechanisms resulting in their formation understood, we propose in a last chapter new characterization techniques for the detection of defective wafers at the beginning of production lines at an industrial throughput
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Matsumoto, Agatha 1987. "Desenvolvimento de células fotovoltaicas orgânicas e flexíveis." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266653.
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Orientadores: Rubens Maciel Filho, Fernando ElyDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: Células fotovoltaicas orgânicas (OPVs) tem sido foco de intensa pesquisa devido ao seu potencial de baixo custo de produção e pela típica característica de serem flexíveis. Apesar de tais vantagens, estes dispositivos ainda têm baixa eficiência quântica (PCE). Este trabalho explora o desenvolvimento de processos de fabricação reprodutíveis e o uso de novos materiais em estruturas de dispositivo fotovoltaico. Inicialmente foi construído dispositivo padrão seguindo a estrutura de ITO/ PEDOT VpAl/ P3HT:PCBM/ Al, que corresponde à estrutura OPV mais estudada, até hoje, e que conduz a altas eficiências de fotoconversão. Foram ajustados todos os parâmetros físico-químicos para se obter as soluções mais estáveis possíveis e camadas funcionais uniformes do dispositivo padrão. Diversas modificações, neste dispositivo padrão, foram introduzidas para incrementar a eficiência quântica originalmente obtida. Primeiramente, foi testada a aplicação de PEDOT condutor e nanoparticulas (NP) de ZnO como camada buffer em substituição ao PEDOT VpAl. Posteriormente, o composto liquido-cristalino TAPCu-52 foi introduzido como material do tipo-P na camada ativa, em substituição ao polímero P3HT. Cristais líquidos também foram estudados como aditivos funcionais na camada ativa para aumentar a mobilidade dos portadores de carga e facilitar a separação do par elétron-buraco fotogerado. Por fim, buscando tornar o dispositivo completamente flexível foi realizada a substituição do eletrodo transparente de ITO por uma camada de PEDOT condutor, obtida pelo método de spray manual e ultrasônico. As caracterizações elétricas e morfológicas das células OPV, mostraram que todas as modificações feitas levaram a resultados positivos em relação ao dispositivo padrão fabricados
Abstract: Organic photovoltaics (OPVs) have been the focus of research due its flexible characteristics and low cost of production. Despite such advantages these devices still have low quantum efficiency (PCE), which is an obstacle for commercialization. This work explores reliable fabrication processes and new materials for OPV structures. For comparison, we fabricated standard devices having the well studied structure ITO/ PEDOT VpAl/ P3HT:PCBM/ Al which can lead to high fotoconversion efficiencies. Physical and chemical parameters were modified to achieve stable solutions and uniform functional layers. Several modifications in this standard device were introduced in order to increase the original PCE obtained. Firstly, conductive PEDOT and ZnO nanoparticles layers were added in replacement of the PEDOT VpAl as buffer. Afterwards, the liquid-crystalline compound TAPCu-52 was studied as p-type material in the active layer to substitute the P3HT polymer. Liquid crystals were also investigated as functional additives to increase the charge carrier mobility and electron-hole separation. Finally, ITO was changed by a conductive PEDOT layer deposited by handheld and ultrasonic spray as transparent anode in order to have a more flexible device. In general, the electrical and morphological characterizations indicated that all studied modifications had positive effect on the PCE of the manufactured OPV devices
Mestrado
Desenvolvimento de Processos Químicos
Mestra em Engenharia Química
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Sahli, Mehdi. "Simulation and modelling of thermal and mechanical behaviour of silicon photovoltaic panels under nominal and real-time conditions." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAD036.
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Le travail présenté dans cette thèse porte sur le développement d’un modèle multi-physique numérique, destiné à étudier le comportement optique, électrique et thermique d’un module photovoltaïque. Le comportement optique a été évalué en utilisant des chaines de Markov. Le comportement électrique est obtenu pour les panneaux en Silicium à l’aide d’une méthode d’optimisation numérique. Le comportement thermique est développé en 1D sur l’épaisseur du module, et le modèle multi-physique a été faiblement couplé sous MATLAB. Le comportement sous des conditions nominales d’opération a été validé en utilisant les données déclarées par les constructeurs. Ce modèle a été utilisé pour effectuer une étude paramétrique sur l’effet des irradiances solaires en régime permanent. Le modèle a été validé pour des conditions d’utilisations réelles en comparant avec des mesures expérimentales de température et de puissance électrique. Une étude thermomécanique en 2D sous ABAQUS/CAE et se basant sur le modèle multi-physique a été effectué en conditions nominales d’opération, ainsi qu’en cycle de fatigue selon la norme 61215 pour prédire les contraintes qui sont imposées sur le panneau dans les deux cas mentionnés précédemmentThe work presented in this thesis deals with the development of a numerical multi-physics model, designed to study the optical, electrical and thermal behaviour of a photovoltaic module. The optical behaviour was evaluated using stochastic modelling based on Markov chains, whereas the electrical behaviour was drawn specifically for Silicon based photovoltaic panels using numerical optimization methods. The thermal behaviour was developed in 1D over the thickness of the module, and the multi-physics module was weakly coupled in MATLAB. The behaviour of commercial panels under nominal operation conditions was validated using data declared by the manufacturers. This model was used to perform a parametric study on the effect of solar irradiances in steady state. It was also validated for real use conditions by comparing it to experimental temperature and electrical power output. A thermomechanical study in 2D in ABAQUS/CAE based in the multi-physics model was carried out in nominal operating conditions, as well as in fatigue thermal cycling according to the IEC 61215 Standard to predict the stresses that are imposed on the panel
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Kuruc, Jiří. "Podpora kvalitativních požadavků služeb v rádiových přístupových sítích vysokorychlostních variant mobilních sítí." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-218103.
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The work deals with the developmental stages (Releases) of the third generation UMTS net-works. It explains a partial improvement from Release 99 to Release 5 and Release 6 to im-prove the quality parameters of a mobile data transmission. In the practical part, there are measured qualitative parameters of the third generation networks that are available in the Czech Republic: UMTS, HSDPA, CDMA 1xEV-DO Rev.0 and Rev.A and UMTS-TDD. The measurements give reasonably achievable data rates in both directions (downlink & uplunk), a response time, quality of VoIP calls, a dispersion, a data-loss and an ability to transmit video with different data flows. The other aspects especially an availability of coverage and end-user terminals have been assessed wihin the each network. The work is supplemeted with a laboratory, which is focused on a practical comparison of the basic parameters of data transmissions of 2G and 3G networks.
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Heideier, Raphael Bertrand. "Metodologia para avaliar o emprego de técnicas de seleção e conversão da radiação solar sobre a produção de energia elétrica de células fotovoltaicas." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-05122017-151838/.
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Esta tese propõe uma metodologia para avaliar o emprego de técnicas de seleção e conversão da radiação solar para aumentar a produção de energia elétrica de células fotovoltaicas. Foi feita uma revisão dos mecanismos fotovoltaicos para produção de energia elétrica e os entraves para aumentar sua eficiência, em especial os impactos da temperatura e da absorção do espectro solar. Uma metodologia foi criada para definir um filtro óptico ótimo a ser utilizado em uma região na presença ou não de conversão do espectro, através de simulações computacionais, que define a faixa do espectro solar que deve ser absorvida pela célula para se ter o melhor equilíbrio entre absorção e aquecimento. Um modelo matemático foi criado e implementado computacionalmente, para calcular a produção de energia de um módulo fotovoltaico, em uma dada região com ou sem a aplicação de técnicas de conversão e seleção da radiação solar. Através de um estudo de caso com dados da cidade de Petrolina, PE, Brasil, concluiu-se que o ganho esperado para utilização de um filtro óptico que reflete ondas de comprimento superiores a 1000 nm é cerca de 1% da energia gerada. Ensaios empíricos permitiram validar a metodologia proposta, comparando os dados reais com os dados teóricos obtidos pelas simulações do modelo matemático. Após a calibração do modelo matemático, verificou-se que os resultados de potência instantânea calculados com o modelo matemático variavam cerca de 5% tanto para o módulo com filtro quanto para o módulo sem filtro. Para contornar a restrição construtiva do filtro óptico e verificar outros ganhos possíveis são propostos experimentos com compostos de conversão de radiação solar associados com filtros ópticos para seleção da radiação solar. Com isto, espera-se aumentar significativamente a produção de energia elétrica de células fotovoltaicas de Silício cristalino.This thesis proposes a methodology to evaluate the use of solar radiation selection and conversion techniques to increase the production of electric energy of photovoltaic solar cells. A review of the photovoltaic mechanisms for the production of electrical energy and the obstacles to increase its efficiency, especially the impacts of temperature and the absorption of the solar spectrum was done. A methodology was developed to define an optimal optical filter to be used in a region in the presence or not of solar spectrum conversion, through computational simulations, which defines the range of the solar radiation that must be absorbed by the cell in order to have the best balance between absorption and heating. A mathematical model was created and implemented computationally to calculate the energy production of a photovoltaic module in a given region with or without the application of solar radiation conversion and selection techniques. A case study with data from the city of Petrolina, PE, Brazil, concluded that the expected gain for the use of an optical filter that reflects wavelengths above 1000 nm is about 1% of the power generated. Empirical tests allowed validating the proposed methodology comparing the actual data with the theoretical data obtained by the simulations of the mathematical model. After calibration of the mathematical model, it was verified that the instantaneous power results calculated with the mathematical model vary about 5% for both the filter module and the unfiltered module. To avoid the constructive constraint of the optical filter and to verify other possible gains are proposed experiments with solar radiation conversion compounds associated with optical filters to select the solar radiation. With this, it is expected to significantly increase the electricity production of crystalline silicon photovoltaic cells.
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Novotný, Tomáš. "Využití obnovitelných zdrojů realizací fotovoltaické elektrárny Drásov." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2009. http://www.nusl.cz/ntk/nusl-222290.
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This master’s thesis discuss the renewable energy source utilisation, to be more precise it describes the Photovoltaic Power Plants. These sources are not only capable of contributing to the regeneration of the environment and to the electricity production, but they are also capable of generating the investor’s economic profit. The individual chapters describe the external factors affecting the project, present condition of the project’s realization, the theory of photovoltaic cells and systems, CCTV camera systems, which are necessary for the power plant security.
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Albarazanchi, Abbas Kamal Hasan. "Composant diffractif numérique multispectral pour la concentration multifonctionnelle pour des dispositifs photovoltaïque de troisième génération." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAD029/document.
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La lumière du soleil est un bon candidat comme source propre et abondante d'énergie renouvelable. Cette source d'énergie écocompatible peut être exploitée pour répondre aux besoins croissants en énergie du monde. Plusieurs générations de cellules photovoltaïques ont été utilisées pour convertir directement la lumière solaire en énergie électrique. La troisième génération de type multijonction des cellules photovoltaïques est caractérisée par un niveau d'efficacité plus élevé que celui de tous les autres types de cellules photovoltaïques. Des dispositifs optiques, tels que des concentrateurs optiques, des séparateurs optiques et des dispositifs optiques réalisant simultanément la séparation du spectre et la concentration du faisceau ont été utilisés dans des systèmes de cellules solaires. Récemment, les Eléments Optiques Diffractifs (EOD) font l'objet d'un intérêt soutenu en vue de leur utilisation dans la conception de systèmes optiques appliqués aux cellules photovoltaïques. Cette thèse est consacrée à la conception d'un EOD qui peut réaliser simultanément la séparation du spectre et la concentration du faisceau pour des cellules photovoltaïques de type multijonction latéral ou similaire. Les EOD qui ont été conçus ont une structure sous-longueur d'onde et fonctionnent en espace lointain pour implanter la double fonction séparation du spectre et concentration du faisceau. Pour cette raison, des outils de simulation ont été développés pour simuler le comportement du champ magnétique à l'intérieur de l'EOD à structure sous-longueur d'onde. De plus, un propagateur hybride rigoureux a aussi été développé, il est basé sur les deux théories de la diffraction, à savoir la théorie scalaire et la théorie rigoureuse. La méthode FDTD (Finite Difference Time Domain) ou méthode de différences finies dans le domaine temporel a été utilisée pour modéliser la propagation du champ magnétique en champ proche c'est-à-dire à l'intérieur et autour de l'EOD. La méthode ASM (Angular Spectrum Method) ou méthode à spectre angulaire a été utilisée pour modéliser de façon rigoureuse la propagation libre en champ lointain. Deux EOD différents ont été développés permettant d'implanter les fonctions souhaitées (séparation du spectre et concentration du faisceau) ; il s'agit d'une part d'un composant diffractif intitulé G-Fresnel (Grating and Fresnel lens) qui combine un réseau avec une lentille de Fresnel et d'autre part d'une lentille hors-axe. Les composants proposés réalisent la séparation du spectre en deux bandes pour une plage visible-proche infrarouge du spectre solaire. Ces deux bandes peuvent être absorbées et converties en énergie électrique par deux cellules photovoltaïques différentes et disposées latéralement par rapport à l'axe du système. Ces dispositifs permettent d'obtenir un faible facteur de concentration et une efficacité de diffraction théorique d'environ 70 % pour les deux bandes séparées. Grâce à une distance de focalisation faible, ces composants peuvent être intégrés dans des systèmes compacts de cellules solaires. La validation expérimentale du prototype fabriqué montre une bonne correspondance entre les performances expérimentales et le modèle théoriqueSunlight represents a good candidate for an abundant and clean source of renewable energy. This environmentally friendly energy source can be exploited to provide an answer to the increasing requirement of energy from the world. Several generations of photovoltaic cells have been successively used to convert sunlight directly into electrical energy. Third generation multijunction PV cells are characterized by the highest level of efficiency between all types of PV cells. Optical devices have been used in solar cell systems such as optical concentrators, optical splitters, and hybrid optical devices that achieve Spectrum Splitting and Beam Concentration (SSBC) simultaneously. Recently, diffractive optical elements (DOE’s) have attracted more attention for their smart use it in the design of optical devices for PV cells applications.This thesis was allocated to design a DOE that can achieve the SSBC functions for the benefit of the lateral multijunction PV cells or similar. The desired design DOE's have a subwavelength structure and operate in the far field to implement the target functions (i.e. SSBC). Therefore, some modelling tools have been developed which can be used to simulate the electromagnetic field behavior inside a specific DOE structure, in the range of subwavelength features. Furthermore, a rigorous hybrid propagator is developed that is based on both major diffraction theories (i.e. rigorous and scalar diffraction theory). The FDTD method was used to model the propagation of the electromagnetic field in the near field, i.e. inside and around a DOE, and the ASM method was used to model rigorously propagation in the free space far field.The proposed device required to implement the intended functions is based on two different DOE’s components; a G-Fresnel (i.e. Grating and Fresnel lens), and an off-axis lens. The proposed devices achieve the spectrum splitting for a Vis-NIR range of the solar spectrum into two bands. These two bands can be absorbed and converted into electrical energy by two different PV cells, which are laterally arranged. These devices are able to implement a low concentration factor of “concentrator PV cell systems”. These devices also allow achieving theoretically around 70 % of optical diffraction efficiency for the both separated bands. The impact distance is very small for the devices proposed, which allows the possibility to integrate these devices into compact solar cell systems. The experimental validation of the fabricated prototype appears to provide a good matching of the experimental performance with the theoretical model
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Chen, Dong-Yi, and 陳東藝. "Design, Fabrication, and Application of the Third-Generation Photovoltaic Cells." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/19649768367508827977.
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博士國立臺灣大學
化學研究所
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The need to develop inexpensive renewable energy sources continues to stimulate new approaches to production of efficient, low-cost photovoltaic devices. Although inorganic semiconductors (silicon, amorphous silicon, gallium arsenide, and sulfide salts) have been the primary focus, the photosensitivity and the third generation of photovoltaic devices made with organic materials have also been explored, including conjugated polymers, organic dyes, stacked discostic liquid crystals, and self-assembling organic semiconductors. In this dissertation, we study three topics as follow about the third generation of solar cells: 1. Design and Synthesis of Trithiophene-Bound Excited-State Intramolecular Proton Transfer Dye: It’s Enhancement on the Performance of Bulk Heterojunction Solar Cells 2. Conceptual Design of Dye Sensitized Solar Cell toward Recognition; A Paradigm on Metal Ion Recognition 3. Organic Dyes with Remarkably High Absorptivity; All Solid-State Dye Sensitized Solar Cell and Role of Fluorine Substitution
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Fangsuwannarak, Thipwan Photovoltaic & Renewable Energy Engineering UNSW. "Electronic and optical characterisations of silicon quantum dots and its applications in solar cells." 2007. http://handle.unsw.edu.au/1959.4/44340.
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In this thesis, the structural, optical and electrical properties of crystalline silicon quantum dots (SiQDs) are examined for application to silicon based tandem cells. The approach has been to concentrate on all silicon devices by taking advantage of quantum confinement in low-dimensional Si. RF magnetron co-sputtering provided the capability of creating superlattice structures in conjunction with high temperature annealing, to form Si nanocrystals in an oxide matrix. Structural techniques, including Fourier transform infrared spectroscopy (FTIR), micro-Raman spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Secondary ion mass spectroscopy (SIM) were employed to gather structural information about the SiQD/SiO2 SLs. The result combine presents that the packing density of Si QDs, correlated to the oxygen content of the silicon rich oxide layer can be control independently. The effect of Si nanocrystallite density on Raman scattering is investigated. The preliminary results present that a decrease in the oxygen content (x) results in an increased sharpness of the Strokes-mode peak of nanocrystalline Si, attributed to an increase in the proportion of crystalline Si because of the increased number of SiQDs. However the influence of the surface region on the crystallite core intensity scattering becomes dominant, when SiQD size diameter is very small (less than 3 nm). The present work shows that a decrease in x-content leading to an increase of the SiQD concentration, initially results in the enhancement of the lateral conductivity in the SiQD superlattice material. In this work, the Al contacting scheme, using a prolonged heat treatment technique at elevated temperature less than the eutectic point of Al and Si (577C) has been successfully applied to making Ohmic contacts on both SiQD SLs in oxide and nitride matrices. Activation energy (Ea) of SiQDs, extracted from a linear Arrhenius plot is investigated in the present work in order to expand the understanding of engineering electrical injection in laterally active paths. It is found that a lower barrier height of dielectric matrix influences to the lateral electron transport of the SiQDs in such dielectric matrix. PL results confirm that the band gap of surface oxidized SiQDs widens due to quantum confinement. The present results reveal that the strong peak (Q-peak) due to quantum confinement is more effective in the emission with increasing SiQD concentration. The surface oxide is believed to play an important role in the reduction of SiQD luminescence due to a trapped exiciton. It is concluded that SiQDs surface oxide accompanied by a SiO2 matrix may not provide a good passivation in very small SiQD size. However the energy band gap and conductivity of the SiQDs are tunablity, in the optimum range of SiQD size and concentration. This observation may be important for future nanoelectronics applications.
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Lin, Guo-Lung, and 林國隆. "Photoreflectance Study of InN and GaAsSbN-Third-Generation Photovoltaic Materials." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/f24cbn.
Full textAbstract:
碩士國立中興大學
電機工程學系所
101
GaAsSbN and InN is the third-generation of solar cells related materials, so we study the GaAsSbN and InN of relevant characteristics to help the development of solar cells. In the last decade, low-nitrogen-containing III-V compound semiconductors have been extensively studied. Nitrogen adding into the semiconductor materials will cause significant reduction of the energy gap, because of the nitrogen atomic level and conduction band energy level interact with each other. The band will split and reduce the energy gap and at the same time reduce the lattice constant. So it’s suitable application for long-wavelength optoelectronic components. Photoreflectance (PR) spectrum has non-contact and non-destructive characteristics and a wide range of operating temperatures. It also has advantage of reducing background effects. Therefore, we use PR spectra to research the semiconductor materials GaAsSbN and use the double band anticrossing model to fit the PR results of GaAsSbN. For InN, we were using PR spectra, photoluminescence spectra, Raman spectroscopy to study the samples.We found that InN at temperatures above 100K is similar to metal conductors, andPR signals can not be measured. At temperature below 100K, InN will transform into the semiconductor-like properties, and PR signal can be measured. This results from free electrons cooling down to the trap states at such low temperatures. Then we fit the PR results at 30K to obtain the spin-orbit splitting and crystal field splitting values.The spin-orbit splitting and crystal field splitting are the basic parameters of semiconductors. So far there is no experimental values of InN in literature, but this thesis has achieved this goal.
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Smith, John-Calvin, and 史中翰. "Third Generation Photovoltaic Technology and Industrial Developemnt: A Scenario Analysis." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/86331988041468671525.
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碩士國立臺灣大學
國際企業學研究所
97
With the recent trends of tremendous energy demand growth, viable alternative renewable energy sources have received great interest. Unprecedented demand in the photovoltaic (PV) market resulted in shortages of key inputs. This led to above equilibrium prices and profit, which in turn stimulated further investment. Current economic conditions have changed the competitive landscape to one of que stionable further demand and profits, firms that produce first generation PV are likely to suffer the most. Unlike the early 1980’s when energy prices declined, PV development may have reached a sustainable level even without shortages of fossil fuels. The industry was until most recently in a period of high investment, resulting in much innovation. Due to technological advances and supply chain innovation, third generation PV should be both more efficient than current technology as well as competitive with conventional fossil fuels. Silicon Valley startups (or any other firms that have viable third generation technologies), will be able to use Asian ODM/EMS firms to move very quickly into this market without the significant cost of building capitally intensive capacity. Thus, small startups with limited capital can potentially create a paradigm shift in the energy industry.
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Kim, Sung Jin. "Nanostructured photovoltaic devices for next generation solar cell." 2008. http://proquest.umi.com/pqdweb?did=1594486561&sid=6&Fmt=2&clientId=39334&RQT=309&VName=PQD.
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Thesis (Ph.D.)--State University of New York at Buffalo, 2008.Title from PDF title page (viewed on Jan. 21, 2009) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Cartwright, Alexander N. Includes bibliographical references.
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"Advanced Hybrid Solar Cell Approaches for Future Generation Ultra-High Efficiency Photovoltaic Devices." Doctoral diss., 2014. http://hdl.handle.net/2286/R.I.25006.
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abstract: Increasing the conversion efficiencies of photovoltaic (PV) cells beyond the single junction theoretical limit is the driving force behind much of third generation solar cell research. Over the last half century, the experimental conversion efficiency of both single junction and tandem solar cells has plateaued as manufacturers and researchers have optimized various materials and structures. While existing materials and technologies have remarkably good conversion efficiencies, they are approaching their own limits. For example, tandem solar cells are currently well developed commercially but further improvements through increasing the number of junctions struggle with various issues related to material interfacial defects. Thus, there is a need for novel theoretical and experimental approaches leading to new third generation cell structures. Multiple exciton generation (MEG) and intermediate band (IB) solar cells have been proposed as third generation alternatives and theoretical modeling suggests they can surpass the detailed balance efficiency limits of single junction and tandem solar cells. MEG or IB solar cell has a variety of advantages enabling the use of low bandgap materials. Integrating MEG and IB with other cell types to make novel solar cells (such as MEG with tandem, IB with tandem or MEG with IB) potentially offers improvements by employing multi-physics effects in one device. This hybrid solar cell should improve the properties of conventional solar cells with a reduced number of junction, increased light-generated current and extended material selections. These multi-physics effects in hybrid solar cells can be achieved through the use of nanostructures taking advantage of the carrier confinement while using existing solar cell materials with excellent characteristics. This reduces the additional cost to develop novel materials and structures. In this dissertation, the author develops thermodynamic models for several novel types of solar cells and uses these models to optimize and compare their properties to those of existing PV cells. The results demonstrate multiple advantages from combining MEG and IB technology with existing solar cell structures.Dissertation/Thesis
Ph.D. Electrical Engineering 2014
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Jhin-YuLi and 李誌育. "Design and Implementation of Fuzzy Controller for Fuel Cell and Photovoltaic Generation Systems." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/73074116598547852683.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
101
The fuel cell and photovoltaic (PV) play important roles in the future of power supply because they are clean and zero-radiation energy sources. Therefore, many advanced countries have invested heavily in these technologies to reduce the dependence on fossil fuels or nuclear energy. To maximize effectiveness, the two energy sources need to be combined with DC/DC converter and digital controller. This work employs fuzzy logic control for hybrid fuel cell and PV power systems. In the hybrid fuel cell system, the fuzzy sliding surface control implemented through a digital signal processor is used to simplify the rule base and achieve stable output voltage under different load situations. Experimental results show that the output voltage of the hybrid fuel cell system is kept stable at a constant value even though the rule number is only a square root multiplied in relation to the standard fuzzy control. Because of the simpler rule base of the sliding surface fuzzy control, the gate count of logic synthesis with a field-programmable gate array (FPGA) can be reduced. Based on experimental results, fuzzy sliding surface control is successfully applied to a FPGA system to achieve stable output voltage. Subsequently, the proposed algorithm is simulated and tested on hybrid fuel cell systems in digital workstations. Simulation results based on the register transfer level (RTL) are highly consistent with our design target. In PV power systems, output efficiency is determined by the performance of maximum power point tracking (MPPT) algorithms. The perturbation and observation method (P＆O) and the incremental conductance method (INC) are commonly adopted in PV power systems. The above methods have slower speeds for tracking the optimal operating point and exhibit continuous oscillation around the optimal operating point which leads to power loss and system instability. Therefore, type-1 fuzzy control has been introduced to increase tracking speeds and reduce the steady-state oscillation of P＆O and INC algorithms. However, this fuzzy control cannot suppress the noise. Here, the interval type-2 fuzzy control algorithm is chosen for the MPPT because it provides faster tracking capability and prevents noise interference. Experimental results indicate that the efficiencies achieved by the interval type-2 fuzzy control algorithm are 98.9% under constant weather conditions and 99.2% under varying weather conditions, which are more effective compared to those of INC and type-1 fuzzy control algorithms.
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HO, YING-CHAUNG, and 何穎強. "Estimation of the hybrid electricity generation system of photovoltaic-electrolyzer and fuel cell." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/17241021159903985394.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
104
Based on the electricity generation of photovoltaic panel system, the study predicts the electricity generation of a photovoltaic-electrolyzer and fuel cell hybrid system on the days of summer solstice, autumn equinox, winter solstice, and during night. First, we choose a place located at latitude of 22.65° to collect the electricity which photovoltaic driving system generates， Furthermore, find out the optimal configuration of the photovoltaic driving system combining electrolyzer and photovoltaic panel. Once the numerical model of the photovoltaic-electrolyzer system is created, the hydrogen production volume can be used to predict the electricity generation on summer solstice, autumn equinox, winter solstice, and during night. Through the simulation，we can obtain the maximum voltage and current of fuel cell is 50.12V and 0.4A on summer solstice.
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Amoo, Akinlawon Olubukunmi. "Solar driven hydrogen generation for a fuel cell power plant." Thesis, 2011. http://hdl.handle.net/10352/114.
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Thesis. (M. Tech. (Dept. Electronic Engineering, Faculty of Engineering and Technology))--Vaal University of Technology, 2011.There are a number of ways to produce hydrogen using solar energy as the primary source. Water electrolysis, which uses solar electrical energy, is the rapidly available process. Hydrogen can be produced by using solar electric energy from photovoltaic (PV) modules for the electrolysis of water without emitting carbon dioxide or requiring fossil fuels. Solar hydrogen energy systems are considered one of the cleanest hydrogen production technologies, where the hydrogen is obtained from sunlight by directly connecting the photovoltaic modules to the hydrogen generator. This dissertation presents a designed solar photovoltaic electrolyser hydrogen production and storage system for various applications such as in the power generation and telecommunications industries. Various experiments were performed on the designed system to ensure its reliability and conformity with theoretical findings. The purity of the generated hydrogen was determined. The relationship between the amount of solar irradiance reaching the surface of the PV panel, the PV panel surface temperature, the PV panel tilt angle and the maximum power point voltage and current of the PV panel array were also considered. The effect of dust on the panel voltage and current outputs was also determined. Finally, the factors to consider when designing a solar photovoltaic electrolyser hydrogen system (based on this study) were enumerated.
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Yang, Kai-Jei, and 楊凱傑. "Cell Coverage and Maximum Available Data Rate for Third Generation Mobile Communication Systems." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/12821339474028481894.
Full textAbstract:
碩士國立清華大學
通訊工程研究所
90
Many data services are available in third-generation (3G) mobile communication systems and may have different data rates on transmission. It is important to maintain the link quality and performance when higher data rate is served. For example, real time video service is one of the services which require high data rate and high transmission quality. Unfortunately, the higher data rate we use, the lower processing gain we get, and fewer ability of anti-multiple- access-interference (MAI) we will have. Not only the processing gain, but also the carrier-to-interference ratio (CIR) will influence system performance. Simply speaking, when the CIR degrades due to either traveling away from the base-station (BS) or being shadowed by structures, the service rate must decrease to increase the processing gain for better link quality. By observing BER, we can discuss the relationship between propagation length and maximum available data rate under the forward link assumption for 3G systems. The results can be used to limit user’s data rates according to user’s positions. It is a helpful reference to resource management problems.
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Kuan-WeiHuang and 黃冠維. "Stem Cell Detection based on Convolutional Neural Network via Third Harmonic Generation Microscopy Images." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/uy4cze.
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Chen, Chien-Kuo, and 陳建國. "Video-rate Third-harmonic-generation Microscopy for in vivo Blood Cell Cytometry in Human Capillaries." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/44645326108476944617.
Full textAbstract:
碩士國立臺灣大學
醫學工程學研究所
100
Complete Blood Count (CBC) is a routine examination running in the hospital. In clinical practices, CBC plays an important role in the diagnosis of diseases. The results of inspection will be a significant indicator of evaluating individual health status. The items of checking include: erythrocytes (red blood cells, RBCs) count, leukocytes (white blood cells, WBCs) count, thrombocytes (platelets) count, Hemoglobin, Hematocrit and so on. Although CBC is a common examination in laboratory medicines, it requires a draw of blood, which is an invasive method to patients. And it cost patients’ time to wait for the results. Hence, it is highly desired to have an on-site measurement method for blood cell counts without invasive draws of blood. That can save the medical resources and the time of patients. Nowadays, laser scanning nonlinear optical microscopy, such as two-photon fluorescence microscopy (2PFM) and harmonic generation microscopy (HGM), has been widely used for in vivo biological studies with sub-micron three-dimensional (3D) spatial resolution. Owing to the nature of energy conservation of harmonic generation (HG), there is least energy deposition to tissues under observation. Compared with 2PFM, HGM is the least-invasive optical microscopic technique suitable for clinical applications. Moreover, the extra advantage of HGM is that the morphological information of tissues can be revealed without a need of extra labeling. In this thesis, we developed the video-rate third-harmonic-generation (THG) microscopy for blood cell cytometry in human skin. The excitation laser source in our research was a home-built femtosecond Cr:forsterite laser with Kerr Lens Mode-locking. With its output wavelength covering the penetration windows of most biological tissues, the Cr:forsterite laser is an indispensable excitation laser source providing deeper penetration depth and reduced on-focus photodamage. To catch up the fast motion of blood cells, the high-speed scan rate is a critical issue. Combining a 16 kHz resonant mirror and a galvanometer mirror, the 2D scan rate could achieve 30 frames per second (FPS). Taking advantage of the high-speed frame grabber, the THG signal was synchronously sampled and reconstructed to an image with 512-by-512 pixels size. With the aid of high-speed scan rate and HGM, the blood cells in human blood capillary could be clearly observed, especially for round and unstacked leukocytes. We could count the amount of white blood cells and evaluated the corresponding flux of blood volume. Thus evaluated number density agreed with the physiological range of white blood cell count. For clinical use, in the future, the technique is potential to be used to diagnose leucopenia for the patients under chemotherapy.
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Stolle, Carl Jackson. "Low cost processing of CuInSe2 nanocrystals for photovoltaic devices." Thesis, 2015. http://hdl.handle.net/2152/30473.
Full textAbstract:
Semiconductor nanocrystal-based photovoltaics are an interesting new technology with the potential to achieve high efficiencies at low cost. CuInSe2 nanocrystals have been synthesized in solution using arrested precipitation and dispersed in solvent to form a “solar ink”. The inks have been deposited under ambient conditions to fabricate photovoltaic devices with efficiency up to 3%. Despite the low cost spray coating deposition technique, device efficiencies remain too low for commercialization. Higher efficiencies up to 7% have been achieved using a high temperature selenization process, but this process is too expensive. New nanocrystal film treatment processes are necessary which can improve the device efficiency at low cost.
To this end, CuInSe2 nanocrystals were synthesized using a diphenyl phosphine:Se precursor which allows for precise control over the nanocrystal size. The size is controlled by changing the temperature of the reaction. The smallest size nanocrystals demonstrated extremely high device open circuit voltage. Ligand exchange procedures were used to replace the insulating oleylamine capping ligand used during synthesis with more conductive halide ions or inorganic chalcogenidometallate cluster (ChaM) ligands. These ligands led to improved charge transport in the nanocrystal films.
A high-intensity pulsed light processing technique known as photonic curing was used which allows for high temperature sintering of nanocrystal films on temperature-sensitive substrates. High energy pulses cause the nanocrystals to sinter into large grains, primarily through melting and resolidification. The choice of metal back contact has a dramatic effect on the final film morphology, with Au and MoSe2 back contacts providing much better adhesion with the CuInSe2 than Mo back contacts. Nanocrystal sintering without melting can be achieved by replacing the oleylamine ligands with ChaM ligands prior to photonic curing.
Low energy photonic curing pulses vaporize the oleylamine ligands without inducing sintering or grain growth. This greatly improved nanocrystal coupling and interparticle charge transport. Multiexcitons were successfully extracted from these nanocrystal films and external quantum efficiencies over 100% were observed. Transient absorption spectroscopy was used to study the multiexciton generation process in CuInSe2 nanocrystal films and colloidal suspensions. The multiexciton generation efficiency, threshold, and Auger lifetimes for CuInSe2 compare well with other nanocrystal materials.text
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Mokgosi, Itumeleng Siphiwe. "Solar cell device simulations from ab initio data and the implementation of efficiency enhancing techniques." Thesis, 2018. https://hdl.handle.net/10539/26915.
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A research report submitted in partial fulfilment to the degree of Master of Science in the School of Physics, University of the Witwatersrand, 2018With the global energy consumption at an all-time high and the demand for energy estimated to triple by 2050, renewable energy sources such as solar are pivotal in an addressing this global energy demand. Solar power generation by photovoltaic cells enjoys several advantages compared to other forms of electricity generation such as a reduced fossil fuel dependence, modularity, easy and flexible installation, and scalability. The development of novel solar cells that offer increased efficiencies is an integral component of the process of addressing the global energy needs. Solar cell device simulations offer a cost-effective means to explore the impact of different material properties on the overall efficiency of the solar cell. The use of ab initio calculated material properties that serve as an import for the device simulations offers a means to easily study and estimate the typical solar cell efficiencies of different types of solar cells. The implementation of new light harnessing features, like frequency conversion layers or plasmonic nanoparticles, and the integration of these futures into existing device simulation codes serves as a useful tool that aids solar cell development. This work explores the theoretical and numerical background for the simulation of solar cell devices. A brief explanation of how ab initio calculated parameters can be used, together with the implementation of frequency conversion techniques in existing simulation codes is given. It is shown that the solar cell performance parameters can be well approximated using ab intio parameters. Also, the positive effect of frequency conversion techniques is demonstrated with examples of how this tool can be implemented in existing solar cell device simulation codes. The approaches discussed in this work can serve as a good framework for the modeling of novel solar cell devices
MT 2019
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Srinath, R. "Digital Control Of Solar Photovoltaic Converters." Thesis, 2009. http://hdl.handle.net/2005/1060.
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A photo-voltaic system consists of solar cells, power converters, battery and the load. The power converter interfaces the solar cells, battery and the load. The battery serves to equalise the energy demand (load) and the energy supply (solar cell). Currently the solar cells and the battery cost nearly 90% of the system cost.
A typical photo-voltaic system can adopt various power bus configurations. Battery tied bus is the simplest of the power bus configurations. In this topology, the battery is always attached to the bus. This system is extremely simple in terms of power circuit configuration as well as control. Such systems weigh less and are more reliable. However, the battery tied bus suffers certain disadvantages. The first among them is the poor utilisation of solar panels. The load has to tolerate the full swing of the battery voltage variation. On account of the constraint on the solar panel voltage, the solar panels may not be loaded to the maximum power capacity. Such operating conditions lead to gross under-utilisation of the expensive solar panels. The battery tied bus configuration is designed, built and evaluated experimentally with 4 solar panels rated at 35 W each and a lead acid battery of 12 V 42 AH rating. This thesis explores alternate power architecture to overcome the above limitations. Load regulation and maximum power harvesting from the solar panels are the objectives.
In the proposed configuration, a bidirectional power converter is inserted between the bus and the battery. The bidirectional power converter operates in boost mode and charges the battery when the sunlight is available. During eclipse period, it operates in buck mode and meets the load demand. The maximum power is extracted from the panels by controlling the voltage across the solar panels. The bus voltage reference is computed by MPPT block and the bus voltage is regulated to the reference voltage through closed loop control. So the maximum power is extracted from the panels at the expense of extra bidirectional power converter. Even though there is an additional power loss due to the introduction of power converter, this power bus configuration is superior because it increases the output power from the panel itself. The entire control logic implementation is done digitally using dspic30F6010A. The simulation is done by writing script files in C language. The proposed bus configuration is designed, built and evaluated experimentally with the same setup and the results are then compared.
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Aleid, Sara. "Design and Fabrication of Multi-functional Photovoltaic-Membrane Distillation-Evaporative Crystallizer for Water Desalination, Electricity Generation, Salt Crystallization and Solar Cell Cooling." Thesis, 2019. http://hdl.handle.net/10754/660160.
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Ensuring electricity availability and acquiring access of potable water during emergencies in remote areas are becoming a global challenge around the world. Utilizing solar energy electricity generation by photovoltaics and clean water production by solar distillation have shown its great potential to meet the world’s future energy and water demands. In this work, we fabricated a photovoltaic-membrane distillation-evaporative crystallizer device (PV-MD-EC), in which high electricity generation efficiency (~15%), clean water production rate (~2.66 kg/m2 h) and salt crystallization from seawater can be achieved in such an integrated system under one sun illumination. In addition, the solar cell operates in a much lower temperature at around 48 oC, which is much lower than previous work. The advanced performance is attributed to the utilization of a highly porous and thinner hydrophobic membrane. This design provides a new strategy to address the challenge of water-energy nexus.
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Lin, Wen-Ching, and 林玟靜. "Study of Product Life Cycle of the Third Generation Cell Phone and Single Brand Product Inventory Management by Adopting EOQ Model." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/93y294.
Full textAbstract:
碩士國立東華大學
全球運籌管理研究所
95
The purpose of the study is to analyze inventory policies for a product incorporating the impact of demand variations at different stages of product life cycle. Based on the past demand data of the 3rd generation (3G) cellular phone market,we forecast the sales of 3G along its product life cycle by adopting the Bass diffusion model to estimate effect of invention, effect of imitation and market potential. To supply the demand properly, we analyze the total inventory management cost through ARENA simulation given EOQ model as a major inventory control policy. The major findings are follows. The forecasting results of 3G cell phone market, WCDMA system market and cdma 2000 system market all fit well with the original market data. The simulation results of demand supply and inventory control show that a longer forecast horizon turns out a better inventory control.
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Ciou, Jhih-Shin, and 邱志信. "A Study of Inventory Control Facing Demand Forecasted by Stochastic Bass Model Using the Third Generation Cell Phone Sales Data in Taiwan." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/d6m436.
Full textAbstract:
碩士國立東華大學
全球運籌管理研究所
96
The product life cycles of modern merchandises, such as mobile phones, have been impacted by the evolution of innovative technology. The innovation of mobile phones turns the role of the cell phone from the traditional communication products into the multi-functional action goods. Under the situation of high popularity of mobile phones, the sales forecast of its product life cycles may lead a contribution to further realize the behavior of the market. A better realization of the market will have an opportunity to coordinate the supply of the demand to achieve a better inventory management. One of the most popular product life cycle models adopted in this research is Bass Model (1969). Bass model is dedicated not only to product life cycle but also to sales volume forecast. This paper first utilizes Bass model to forecast the mean demand along the product life cycle of the third generation (3G) cell phone sales data in Taiwan. Then, the variance of the cumulative sales volume is estimated by the method based on Stochastic Bass Model in Niu (2002). In order to catch the variance of the sales volume, this research proposes a try and error method to estimate the change of the demand. Based upon the estimated mean and variance of demand in each period, (s, S) inventory policy is utilized to illustrate the behavior of inventory supply of the demand. The results show that the forecasted demand matches real trend of the data, and the requirements of the supply seems to be bounded within a fixed range.
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Karavadi, Amulya. "Power Electronics Design Implications of Novel Photovoltaic Collector Geometries and Their Application for Increased Energy Harvest." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-9897.
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The declining cost of photovoltaic (PV) modules has enabled the vision of ubiquitous photovoltaic (PV) power to become feasible. Emerging PV technologies are facilitating the creation of intentionally non-flat PV modules, which create new applications for this sustainable energy generation currently not possible with the traditional rigid, flat silicon-glass modules. However, since the photovoltaic cells are no longer coplanar, there are significant new requirements for the power electronics necessary to convert the native form of electricity into a usable form and ensure maximum energy harvest. Non-uniform insolation from cell-to-cell gives rise to non-uniform current density in the PV material, which limits the ability to create series-connected cells without bypass diode or other ways to shunt current, which is well known in the maximum power tracking literature. This thesis presents a modeling approach to determine and quantify the variations in generation of energy due to intentionally non-flat PV geometries. This will enable the power electronics circuitry to be optimized to harvest maximum energy from PV pixel elements – clusters of PV cells with similar operating characteristics.
This thesis systematically compares different geometries with identical two-dimensional projection "footprints" for energy harvest throughout the day. The results show that for the same footprint, a semi-cylindrical surface harvests more energy over a typical day than a flat plate. The modeling approach is then extended to demonstrate that by using non flat geometries for PV panel, the availability of a remotely located stand-alone power system can be increased when compared to a flat panel of same footprint. These results have broad application to a variety of energy scavenging scenarios in which either total energy harvested needs to be maximized or unusual geometries for the PV active surfaces are required, including building-integrated PV. This thesis develops the analysis of the potential energy harvest gain for advanced non-planar PV collectors as a necessary first step towards the design of the power electronics circuits and control algorithms to take advantage of the new opportunities of conformal and non-flat PV collectors.