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Aldubyan, Mohammad Hasan. "Thermo-Economic Study of Hybrid Photovoltaic-Thermal (PVT) Solar Collectors Combined with Borehole Thermal Energy Storage Systems." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1493243575479443.
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Dupeyrat, Patrick. "Experimental development and simulation investigation of a photovoltaic-thermal hybrid solar collector." Thesis, Lyon, INSA, 2011. http://www.theses.fr/2011ISAL0049.
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L´intérêt grandissant pour les bâtiments à haute efficacité énergétique nécessite le développement de nouveaux types d´enveloppe active et multifonctionnelle pouvant couvrir une partie des besoins énergétiques du bâtiment. Les travaux présentés dans cette thèse concernent le développement de capteurs hybrides solaires photovoltaïques thermique pour la production simultanée d´eau chaude sanitaire et d´électricité au sein d´un unique capteur. L’objectif de cette thèse a été dans un premier temps d´analyser la faisabilité et la complexité du concept de capteur hybrides PV-T. Puis, à partir d’un modèle numérique développé spécifiquement pour appuyer la phase de conception du capteur PV-T les raisons expliquant la limitation des performances de tels capteurs ont été analysées, pour enfin proposer différentes solutions innovantes, tant au niveau des cellules solaires que des matériaux du modules PV et du design du capteur final afin d´en augmenter les performances. L´approche développée est par conséquent multi-échelle allant de la prise en compte des phénomènes physiques pris isolément, des propriétés locales des matériaux jusqu’à la mise en œuvre d’un composant et à l´analyse énergétique et exergétique de ses performances dans un environnement numérique dédié au bâtimentIn the context of greenhouse gas emissions and fossil and fissile resources depletion, solar energy is one of the most promising sources of power. The building sector is one of the biggest energy consumers after the transport and industrial sectors. Therefore, making use of a building’s envelope (façades and roofs) as solar collecting surfaces is a big challenge facing local building needs, specifically in regard to heat, electricity and cooling. However, available surfaces of a building with suitable orientation are always limited, and in many cases a conflict occurs between their use for either heat or electricity production. This is one of the reasons why the concept of a hybrid photovoltaic-thermal (PV-T) collector seems promising. PV-T collectors are multi-energy components that convert solar energy into both electricity and heat. In fact, PV-T collectors make possible the use of the large amount of solar radiation wasted in PV modules as usable heat in a conventional thermal system. Therefore, PV-T collectors represent in principle one of the most efficient ways to use solar energy (co-generation effect). However, such a concept still faces various barriers due to the multidisciplinary knowledge requirements (material, semi-conductors, thermal) and to the complexity of the multiple physical phenomena implied in such concepts.The objective of this PhD work is to carry out a study based on a multi-scale approach that combines both numerical and experimental investigations regarding the feasibility of the concept of hybrid solar collector. The performance of such components is estimated through an appropriate design analysis, and innovative solutions to design an efficient PV-T collector are presented. Based on improved processing methods and improved material properties, an efficient covered PV-T collector has been designed and tested. This collector was made of PV cells connected to the surface of an optimized flat heat exchanger by an improved lamination process and covered on the front side by a static air layer and AR-coated glass pane and on the back side by thermal insulation material. The results showed a significant improvement of both thermal and electrical efficiency in comparison to all previous works on PV-T concepts found in the literature. System simulations were carried out for a hot water system with the software TRNSYS in order to get a clearer statement on the performance of PV-T collectors. The results show that the integration of PV-T collectors can be more advantageous than standard solar components in regard to thermodynamic considerations (energy and exergy) and environmental considerations (CO2 and primary energy saving)
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Linde, Daniel. "Evaluation of a Flat-Plate Photovoltaic Thermal (PVT) Collector prototype." Thesis, Högskolan Dalarna, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:du-24061.
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This Master thesis, in collaboration with Morgonsol Väst AB, was completed as a part of the Solar Energy engineering program at Dalarna University. It analyses the electrical and thermal performance of a prototype PVT collector developed by Morgonsol Väst AB. By following the standards EN 12975 and EN ISO 9806 as guides, the thermal tests of the collector were completed at the facility in Borlänge. The electrical performance of the PVT collector was evaluated by comparing it to a reference PV panel fitted next to it. The result from the tests shows an improved electrical performance of the PVT collector caused by the cooling and a thermal performance described by the linear efficiency curve ηth=0.53-21.6(Tm-Ta/G). The experimental work in this thesis is an initial study of the prototype PVT collector that will supply Morgonsol Väst with important data for future development and research of the product.
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Schön, Gustav. "NUMERICAL MODELLING OF A NOVEL PVT COLLECTOR AT CELL RESOLUTION." Thesis, KTH, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-212731.
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Solar photovoltaic-thermal (PVT) modules produce heat and power via a heat exchanger attached to the rear of the PV cells. The novel PVT collector in this study is previously untested and therefore its behaviour and thermo-electric performance due to fluid channel configuration and in various climate and operating conditions are unknown. Moreover, the working fluid flowing through the heat exchanger cause a temperature gradient across the module such that a cell near the inlet and a cell near the outlet may have significant temperature differences. PV cells are sensitive to temperature; however the most common way to simulate power output from a PVT is to use the average temperature and ignore the gradient. In this study, a single diode PV model is incorporated into a commercial thermal solver to co-simulate the thermal and electrical output of a novel PVT module design with cell level resolution. The PVT system is modelled in steady state under various wind speeds, inlet temperatures, ambient temperatures, flow rates, irradiation, convection coefficients from coolant and back of the module and two different fluid channel configurations. The results show that of the controllable variables, the inlet temperature has the highest influence of the total power output and that a parallel flow of the fluid channel configuration is preferable. The difference between the cell resolution and the module resolution simulations do not motivate the use of a higher resolution numerical simulation.En kombinerad solcellspanel och solvärmefångare (PVT) producerar värme och elenergi på samma yta genom att en värmeväxlare upptar värmen från baksidan av solcellspanelen. Den PVT som berörs i denna studien är nyutvecklad och har aldrig tidigare testats, vilket medför att data för hur den beter sig samt dess termo-elektiska prestanda saknas för olika driftförhållanden samt flödeskonfigurationer. Vidare ger mediet som flödar genom värmeväxlaren upphov till en temperaturgradient, vilken kan innebära en påtaglig skillnad i temperatur mellan solcellerna i solcellspanelen vid mediets in- respektive utlopp. Trots solcellers temperaturkänslighet, så sker simulering i allmänhet med avseende på panelens medeltemperatur istället för att hänsyn tas till denna temperaturgradient. I den här studien implementeras en så kallad ”single diode”-modell i en kommersiell numerisk mjukvara termiska beräkningar för att samsimulera termiskt och elektriskt effektuttag ur den nyutvecklade PVT-designen. Designen modelleras statiskt under givna variationer av vindhastighet, inloppstemperatur, omgivande temperatur, flödeshastighet, solinstrålning och konvektionskoefficienter för mediet samt baksidan av modulen. Resultaten visar att kontrollerbara variabler som inloppstemperatur har högst inverkan på den totala effekten samt att en parallell flödeskonfiguration lämpar sig bäst. Studien visar också att skillnaden mellan simulering på cellnivå och modulnivå inte motiverar en numerisk beräkningsmetod med upplösning satt till solcellsnivå.
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Shirolikar, Jyoti. "PREPARATION AND CHARACTERIZATION OF CIGSS SOLAR CELLS AND PV MODULE DATA ANALYSIS." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4223.
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In this thesis, multiple activities have been carried out in order to improve the process of CIGSS solar cell fabrication on a 4" x 4" substrate. The process of CIGSS solar cell fabrication at FSEC's PV Materials Lab involves a series of steps that were all carried out manually in the past. A LABVIEW program has been written to carry out automated sputter deposition of Mo back contact, CuGa, In metallic precursors on a soda lime glass substrate using a stepper motor control for better uniformity. Further, selenization/ sulfurization of these precursors was carried out using rapid thermal processing (RTP). CIGS films were sulfurized using chemical bath deposition (CBD). ZnO:Al was deposited on the CIGSS films using RF sputtering. A separate LABVIEW program was written to automate the process of ZnO:Al deposition. Ni/Al contact fingers were deposited on the ZnO:Al layer using the e-beam evaporation technique. Further, in order to test these solar cells in-house, a simple current-voltage (IV) tracer was fabricated using LABVIEW. A quantum efficiency (QE) measurement setup was built with guidance from the National Renewable Energy Laboratory (NREL). Lastly, analysis of data from photovoltaic (PV) modules installed on the FSEC test site has been carried out using a LABVIEW program in order to find out their rate of degradation as time progresses. A 'C' program has also been written as an aid for keeping a daily log of errors in data and for troubleshooting of the same.M.S.E.E.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering
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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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Huang, Ming Jun. "The application of computational fluid dynamics (CFD) to predict the thermal performance of phase change materials for the control of photovoltaic cell temperatures in buildings." Thesis, Ulster University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248684.
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Gerber, Jacques Dewald. "On the thermal and electrical properties of low concentrator photovoltaic systems." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1021219.
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Low concentrator photovoltaic systems are capable of increasing the power produced by conventional silicon photovoltaic cells, thus effectively lowering the cost per kWh. However, power losses associated with resistance and temperature have limited the large scale implementation of this technology. In this study, the optical-,electrical- and thermal sub-systems of a low concentrator photovoltaic system are theoretically and experimentally evaluated with the aim of minimizing the power losses associated with series resistance and temperature. A 7-facet reflector system, with an effective concentration ratio of 4.7, is used to focus irradiance along a string of series connected poly-crystalline photovoltaic cells. I-V characteristics of 4-, 6- and 8-cell photovoltaic receivers are measured under 1-sun and 4.83-sun conditions. Under concentration, the 8-cell photovoltaic receiver produced 23 percent more power than the 4-cell photovoltaic receiver, which suggests that the effect of series resistance can be minimized if smaller, lower current photovoltaic cells are used. A thermal model, which may be used to predict operating temperatures of a low concentrator photovoltaic system, is experimentally evaluated within a thermally insulated enclosure. The temperatures predicted by the thermal model are generally within 5 percent of the experimental temperatures. The high operating temperatures associated with the low concentrator photovoltaic system are significantly reduced by the addition of aluminium heat sink. In addition, the results of a thermal stress test indicated that these high operating temperatures do not degrade the photovoltaic cells used in this study. The results of this study suggest that the power output of low concentrator photovoltaic systems can be maximized by decreasing the size of the photovoltaic cells and including an appropriate heat sink to aid convective cooling.
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Tavernier, Virgile. "Modélisation numérique de la solidification et de la ségrégation des impuretés lors de la croissance du silicium photovoltaïque à l'aide d'une méthode originale de maillage glissant." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI120/document.
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Les panneaux photovoltaïques ont pris ces dernières années une place importante dans le secteur de l’énergie. Les performances de ces panneaux dépendent notamment de la qualité et de l’homogénéité du silicium utilisé et des impuretés qu’il contient. Pour obtenir du silicium photovoltaïque, on peut utiliser un procédé de solidification dirigée afin d’obtenir un lingot de silicium de grade photovoltaïque à partir de silicium de grade métallurgique. Cette approche reste aujourd’hui difficile à simuler efficacement en raison de l’aspect multi-échelle du procédé et du suivi de l’interface mobile avec des transferts de masse et de chaleur à l’interface solide/liquide. Cette thèse présente la mise en œuvre d’une méthode originale de maillage glissant proposée pour réaliser un suivi adaptatif de l’interface mobile, afin d’améliorer l’efficacité des simulations. Dans un premier temps, la modélisation de la solidification dirigée d’un corps pur avec un tel maillage glissant est validée à l’aide d’une solution analytique dans une configuration diffusive de référence. L’impact de la méthode proposée est ensuite étudié dans une configuration de type Bridgman vertical en présence de convection naturelle dans la phase liquide. Dans un second temps, on s’intéresse à la ségrégation des impuretés dans cette même configuration. Pour cela, on propose une modélisation spécifique du rejet d’impuretés à l’interface, et on étudie l’impact sur les simulations de la méthode de maillage glissant proposée. Les résultats et les gains de performance pour les simulations sont discutés en faisant varier des paramètres de calcul et par comparaison avec des données de la littératureIn recent years, photovoltaic panels took a key role in the energy sector. The efficiency of these panels depends notably on the quality of the processed silicon ingots and on their homogeneity regarding the impurities they include. In order to process photovoltaic silicon, one can use a directional solidification process to obtain a solar grade silicon ingot from a metallurgical grade silicon feedstock. This approach is still nowadays hard to simulate with efficiency because of the multi-scales aspects of the process and because of the front tracking of the interface, where some heat and mass transfer occurs. This thesis presents the implementation of an original moving mesh method, proposed in order to perform an adaptive front tracking of the moving interface. The aim is to improve the efficiency of the numerical simulations. In a first time, the directional solidification model of a pure substance with such a moving mesh is validated against an analytical solution based on a purely diffusive reference configuration. The influence of the proposed method is then studied on a vertical Bridgman configuration with natural convection in the liquid phase. In a second time, the segregation of impurities is considered in the same configuration. For this study, a specific model for the rejection of impurities is proposed at the solid/liquid interface, and the influence of the proposed moving mesh method on the results is as well explored. Finally, the results and the performance improvements for the numerical simulations are discussed through variations of the calculation parameters and through comparisons against data from the literature
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Kubín, David. "Životní cyklus solární elektrárny, efektivita a návratnost." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220166.
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This master’s thesis named “The Life Cycle of Solar Power, Efficiency and Return” is divided into seven chapters and focuses on the utilization of solar radiation in photovoltaic power stations and solar thermal power stations. The first chapter of this thesis familiarizes the reader with issues concerning renewable resources of energy and presents an overview of the focus of each chapter. The following second chapter is occupied with a topical research of renewable resources of energy utilization in Europe. Further the author presents a brief glance back at the past of solar energy utilization and also a prediction of future solar energy utilization in the Czech Republic. The chapter named “Specification and parameterization of individual technologies” contains an overview of today’s most utilized photovoltaic cells and panels together with an overview of utilized solar collectors and solar thermal power stations. In the following chapter named “Concretization of typical applications and realizations of photovoltaic and solar thermal power stations and determination of all related parameters” the author describes further components of photovoltaic and solar thermal systems. The economical aspect of photovoltaic component production together with an overview of utilized photovoltaic technologies is presented in this chapter. The problem of recycling photovoltaic applications and the current legislative situation regarding this issue in the Czech Republic is also outlined within this chapter. In the fifth chapter of this master’s thesis the author presents mathematical models of a photovoltaic and a solar thermal power station with the focus on economic aspects of investment efficiency assessment. Within this master’s thesis a simulation program in the computational software program Mathematica was created by the author. This program allows a calculation of economic efficiency and return of photovoltaic power station investments. The results of executed simulations are presented in the sixth chapter of this thesis. The last chapter contains an appraisal and summary of results achieved by the author of this thesis.
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Motaung, David Edmond. "Structure property relationship and thermal stability of organic photovoltaic cells." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6331_1307942460.
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In this thesis, regioregularpoly( 3-hexylthiophene) (rr-P3HT) polymer was used as a light absorption and electron donating material, while the C60 fullerene and its derivative [6,6]-phenyl C61-butyric acid methyl ester (PCBM) were used as electron acceptor materials. The effect of solvent to control the degree of mixing of the polymer and fullerene components, as well as the domain size and charge transport properties of the blends were investigated in detail using P3HT:C60 films. The photo-physical, structural and electrical transport properties of the polymer blends were carried out according to their ratios. A distinctive photoluminescence (PL) quenching effect was observed indicating a photo-induced electron transfer. In this thesis, the effect of solvents on the crystallization and interchain interaction of P3HT and C60 fullerene films were studied using XRD, UV-vis, PL, Raman and FTIR spectroscopy. The polymer blends formed with non-aromatic solvents exhibited an improved crystallinity and polymer morphology than that formed with aromatic solvents. An improved ordering was demonstrated in the polymer films spin coated from non-aromatic solvents. This indicates that the limited solubility of rr P3HT in a marginal solvent such as non-aromatic solvents can offer a strategy to obtain highly ordered crystal structures and lead directly to optimal morphologies on the films.
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Dolinský, Filip. "Ostrovní systémy." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378496.
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Master thesis deals with usage issues of autonomous, self-sufficient and decentralized systems. In the first part convectional and experimental sources for autonomous systems are disclosed. Second chapter deals with accumulation of electrical and thermal energy and possibilities of applications. 3rd part is focused on pilot project realized for autonomous and smart systems, which were built in last years. In the 4th chapter electrical and thermal energy consumption curves are made on daily and monthly basis for 4 type objects. In the fifth part issue of autonomy is explained, and for type buildings solutions are made with additional return on investment. The last chapter is focused on calculation of thermal accumulator and briefly discloses small district heating.
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Thaikattil, Greeta Jose. "Thermal Analysis and Design of the Photovoltaic Investigation on Lunar Surface (PILS) Payload." Cleveland State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=csu1610669542951819.
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Subedi, Indra. "Optical Evaluation and Simulation of Photovoltaic Devices for Thermal Management." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo155448373019862.
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Jeong, Ji-Weon. "Hydrogen passivation of defects and rapid thermal processing for high-efficiency silicon ribbon solar cells." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/15615.
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Veirman, Jordi. "Effets de la compensation du dopage sur les propriétés électriques du silicium et sur les performances photovoltaïques des cellules à base de silicium solaire purifié par voie métallurgique." Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00701561.
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Ce travail a pour but de comprendre l'effet de la compensation du dopage sur les performances des cellules photovoltaïques à base de silicium de qualité solaire purifié par voie métallurgique. Après avoir développé la physique des matériaux compensés, l'influence de la compensation a été étudiée à l'échelle de la plaquette. Nous avons mis en évidence une forte réduction non prédite de la mobilité des porteurs. Au contraire, la compensation du dopage s'est avérée bénéfique à la durée de vie volumique. Nous avons précisé les propriétés recombinantes des dopants. L'étude a été transposée à l'échelle de la cellule. Des rendements de 16% ont été obtenus sur des cellules fortement dopées et compensées. La présence de nombreuses associations entre impuretés dopantes et défauts nous a conduits à l'élaboration d'un algorithme permettant de simuler la cinétique de ce type d'association. Enfin, deux techniques innovantes de mesure des teneurs en dopants et en oxygène interstitiel ont été présentées.
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Doshi, Parag Mahendra. "Fundamental understanding and integration of rapid thermal processing, PECVD, and screen printing for cost-effective, high-efficiency silicon photovoltaic devices." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/14783.
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Bruhat, Elise. "Développement de cellules photovoltaïques silicium à homojonction industrialisables à contacts passivés." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI128.
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Afin de favoriser le déploiement des énergies renouvelables, le développement de cellules solaires moins chères mais aussi plus performantes reste un enjeu pour rendre l’électricité photovoltaïque encore plus attractive. Si les technologies des cellules solaires à base de silicium à homojonction dominent le marché mondial, les performances de ces structures peuvent encore être améliorées. En effet, le contact direct entre la grille métallique et les zones fortement surdopées est source de pertes par recombinaisons des porteurs de charges. L’émergence de de nouvelles structures de cellules émergent à contacts passivés permet des solutions alternatives face à cette limitation. Ces structures visent à délocaliser la prise de contact grâce à l’introduction de couches passivantes entre le substrat de silicium cristallin et la grille de métallisation, diminuant ainsi drastiquement les phénomènes de recombinaisons au sein des dispositifs. La technologie de contacts passivés la plus connue reste celle des cellules à hétérojonction de silicium a-Si:H/c-Si. Cette technologie mature reste pour l’instant limitée car elle représente un nouveau standard industriel mais aussi car elle n’est pas compatible avec les procédés utilisant des températures excédant 250°C. De plus, l’utilisation d’indium, matériau cher et dont la ressource est limitée, dans les couches d’Oxyde Transparent Conducteur (OTC) peut représenter un frein à l’industrialisation de masse du procédé. Il est alors nécessaire de développer de nouvelles technologies de contacts passivés, compatibles avec des procédés à haute température (supérieures à 800°C), et donc intégrables dans une ligne de production existante. Des approches utilisant des OTC en combinaison avec des couches ultraminces d’oxydes, des empilements diélectriques, et des jonctions poly-silicium sur oxyde ont été investiguées afin d’améliorer les performances des cellules à homojonction. Les couches intermédiaires d’OTC développées permettent potentiellement de diminuer les pertes résistives et et celles par recombinaison au niveau des contacts. Ces travaux de thèse se sont ainsi focalisés sur le développement de couches d’oxyde de zinc dopé à l’aluminium (AZO) par pulvérisation cathodique (PC) et Atomic Layer Deposition (ALD) pour les cellules solaires à contact passivés. Ces couches, utilisées seules ou en combinaison avec des matériaux diélectriques, ont été intégrées et testées sur des dispositifs photovoltaïques fonctionnelsFor the deployment of renewable energies, the development of cheaper and more efficient solar cells remains an issue to make photovoltaic electricity even more attractive. While homojunction-based silicon solar cell technologies dominate the global market, the performances of these structures can be further improved. Indeed, the direct contact between the metal grid and the highly doped junction is a source of recombination losses. To overcome these limitations, new structures are emerging such as silicon-based passivated contacts solar cells. These structures aim at integrating of passivating layers between the crystalline silicon substrate and the metal grid, thus drastically reducing the recombination phenomena within the devices. Silicon heterojunction (a-Si:H/c-Si) cells remain the most well-known passivated contact technology. Nevertheless, this mature technology is still limited by its fabrication process which is far from the industrial standard, and is hardly compatible with temperatures exceeding 250 ° C. In addition, the use of expensive and potentially toxic indium in the Transparent Conductive Oxide (TCO) layers has restrained up to now the expansion towards mass industrialization of the process. Thus, it is necessary to develop new passivated contacts technologies compatible with high temperature (above 800°C), implementable in a standard production line. This study explores new paths for passivating contact technologies thanks to ultrathin layers of oxides or dielectrics/TCO stacks deposited on silicon homojunctions as well as poly-silicon on thin oxide junctions. In order to limit the resistive losses and potentially limit recombination losses in the contacted areas, intermediate TCO layers have been developed. In this perspective, this works aims at investigating the development of Aluminum Zinc Oxide (AZO) layers by both Magnetron Sputtering (MS) and Atomic Layer Deposition (ALD) for passivated contact solar cells. These layers, also used in combination with dielectric materials have been integrated and then tested in photovoltaic devices
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Boreland, Matt School of Electrical Engineering UNSW. "Laser Crystallisation of Silicon for Photovoltaic Applications using Copper Vapour Lasers." Awarded by:University of New South Wales. School of Electrical Engineering, 1999. http://handle.unsw.edu.au/1959.4/17190.
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Thin film silicon on low temperature glass substrates is currently seen as the best path toreduce the $/W cost of photovoltaic (PV) modules. However, producing thin film polysilicon, on glass, is an ongoing research challenge. Laser crystallisation of a-Si is one of the possible methods. Typically excimer (XMR) lasers are used for laser crystallisation. This thesis introduces the copper vapour laser (CVL) as a viable alternative for thin film photovoltaic applications. The CVL, like the XMR, is a high powered, pulsed laser. However, the CVL has higher pulse rates (4-20kHz), better beam quality and a visible wavelength output (578 & 511nm). Preliminary experiments, using 600K-heated silicon-on-quartz samples, confirmed that CVL crystallisation can produce area weighted average grain size of 0.1-0.15??m, which is comparable to results reported for XMR??? s. Importantly, the CVL results used thicker films (1??m), which is more applicable to thin photovoltaic devices that need 1-10??m of silicon to be viable. The CVL??? s longer wavelength and therefore longer penetration depth (1/alpha) are proffered as the main reason for this result. Extensive laser-thermal modelling highlighted further opportunities specific to CVL crystallisation. Through-the-glass doublesided irradiation was shown in simulations to reduce thermal gradients, which would enhance crystal growth. The simulations also produced deeper melts at lower surface temperatures, reducing the thermal stress on the sample. Subsequent experiments, using silicon-on-glass, confirmed the benefit of through-the-glass doublesided irradiation by maintaining grain sizes without the usual need for substrate heating. Furthermore, Raman analysis showed that doublesided crystallisation achieved full depth crystallisation, unlike single side irradiation which produced partial crystallisation. A new mode of crystallisation, stepwise crystallisation, was also postulated whereby a series of CVL pulses could be used to incrementally increase the crystallisation depth into the silicon. Simulations confirmed the theoretical basis of the concept, with HeNe Raman spectroscopy and analysis of surface grain sizes providing indirect experimental support. The CVL??? s ability to crystallise thicker films more directly applicable to photovoltaic devices secures its viability as an alternative laser for photovoltaic applications. The through-the-glass doublesided irradiation and the stepwise crystallisation provide additional potential for increased process flexibility over XMR???s.
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Kamanzi, Janvier. "Thermal electric solar power conversion panel development." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2527.
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Thesis (DTech (Engineering))--Cape Peninsula University of Technology, 2017.The world has been experiencing energy-related problems following pressuring energy demands which go along with the global economy growth. These problems can be phrased in three paradoxical statements: Firstly, in spite of a massive and costless solar energy, global unprecedented energy crisis has prevailed, resulting in skyrocketing costs. Secondly, though the sun releases a clean energy, yet conventional plants are mainly being run on unclean energy sources despite their part in the climate changes and global warming. Thirdly, while a negligible percentage of the solar energy is used for power generation purposes, it is not optimally exploited since more than its half is wasted in the form of heat which contributes to lowering efficiency of solar cells and causes their premature degradation and anticipated ageing. The research is geared at addressing the issue related to unsatisfactory efficiencies and anticipated ageing of solar modules. The methodology adopted to achieve the research aim consisted of a literature survey which in turn inspired the devising of a high-efficiency novel thermal electric solar power panel. Through an in-depth overview, the literature survey outlined the rationale of the research interest, factors affecting the performance of PVs as well as existing strategies towards addressing spotted shortcomings. While photovoltaic (PV) panels could be identified as the most reliable platform for sunlight-to-electricity conversion, they exhibit a shortcoming in terms of following the sun so as to maximize exposure to sunlight which negatively affects PVs’ efficiencies in one hand. On the other hand, the inability of solar cells to reflect the unusable heat energy present in the sunlight poses as a lifespan threat. Strategies and techniques in place to track the sun and keep PVs in nominal operational temperatures were therefore reviewed.
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Huuva, Ivan. "Polymer structures for photovoltaics using colloidal self-assembly, thermal nanoimprinting and electrohydrodynamic annealing." Thesis, Umeå universitet, Institutionen för fysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-57105.
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The efficiency of an organic photovoltaic cell depends mainly on its morphology where an exciton has to migrate to a p-n junction to create a photocurrent. Therefore the distance from the bulk of the cell to a junction interface should not exceed the diffusion length of the exciton. In this thesis, two novel lithographical methods, to produce specific polymer morphologies, were developed and evaluated. In the first method, called embedded annealing, self-assembled polystyrene colloids were embedded in a polydimethylsiloxane (PDMS) film and annealed under an electric field to produce a bi-polymer structure consisting of polymer columns in a thin film of PDMS. Polymer colloids were successfully assembled into two dimensional hexagonally close packed arrays. However, the annealing process was unsuccessful. The second method, imprint annealing, aimed to increase the aspect ratio (height/width) of thermally imprinted micrometer sized polystyrene features by annealing them in uniform electric fields. The results showed that the aspect ratio of imprinted features can be significantly increased, 21-fold, while maintaining the periodicity of the original imprint. This is in contrast to previous results where smooth polymer films annealed in uniform fields where the periodicity of the resulting structures cannot be independently controlled, and are highly sensitive to the electrode spacing. Feature sizes down to 1 µm and aspect ratios up to 4.5 were achieved using imprint annealing.Verkningsgraden hos en hos en solcell beror, för givna material, framförallt på dess uppbyggnad. För att bidra till fotoströmmen måste en genererad exciton vandra till en pn-övergång. På grund av detta bör det längsta avståndet till närmaste pn-övergång i solcellen inte vara längre än excitonens diffusionslängd. I detta examensarbete testas två olika litografiska metoder för att åstadkomma en specifik filmgeometri lämpad för organiska solceller. Den första metoden, kallad embedded annealing, går ut på att bädda in spontant ordnade sfäriska polystyrenkolloider i en polydimetylsiloxan (PDMS) -film för att sedan vid förhöjd temperatur applicera ett elektiskt fält över filmen. Förhoppningen var att på detta sätt töja ut kolloiderna till pelare genom PDMS-filmen. I det första steget ordnades kolloiderna sponant i tätpackade hexagonala tvådimensionella gitter på kiselsubstrat. Experimenten lyckades inte med hjälp av elektriska fält töja ut kolloiderna. Den andra metoden, imprint annealing, syftar till att öka höjd/bredd -förhållandet och minska diametern hos präglade polystyrenstrukturer. Dessa ursprungliga topografiska stukturer skapas med hjälp av en tryckpressmetod kallad nanoimprinting. Dessa strukturer värmdes upp, och ett uniformt elekrisk fält applicerades över dem. Mina resultat visar att man med elektriska fält avsevärt kan öka höjd-breddförhållandet hos polymerstrukturer och samtidigt bevara periodiciteten hos de ursprungliga strukturerna. Detta står i kontrast mot tidigare resultat på släta filmer, där periodiciteten inte kan kontrolleras oberonde av andra parametrar. Med imprint annealing ökades höjd-breddförhållandet hos enskilda strukturer upp till 21 gånger. Diametrar ner till 1 µm och höjd/breddförhållanden upp till 4,5 uppnåddes.
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Ogaili, Hamid Hawi Kadham. "Measuring the Effect of Vegetated Roofs on the Performance of Photovoltaic Panels in Combined Systems." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2299.
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Recent studies suggest that integration of photovoltaic panels with green roofs may improve the performance of both. While vegetation may provide a benefit by reducing the net radiation load on the underside of the photovoltaic (PV) panels, it may also affect convective cooling of panels, and consequently, panel efficiency. Both effects likely diminish with the height of the PV panel above the roof, although placing PV panels too close to the vegetation increases the risk of the plants growing over the edges of, and shading the PV panel. There is a gap in the literature with respect to evaluating these competing effects. The present study aims to fill this gap.
Experiments were conducted over a two-month period during summer using two identical PV panels within an array of rooftop-mounted panels. These experiments were performed at two heights (18 cm and 24 cm) using three roofing types: white, black and green (vegetated). Results showed that the mean power output of the system in which the PV panel was mounted above a green roof was 1.2% and 0.8% higher than that of the PV-black roof and the PV-white roof at the 18 cm height. At the 24 cm height, the benefit of the green roof was slightly diminished with power output for the PV panel above a green roof being 1.0% and 0.7% higher than the black and white roof experiments, respectively. These power output results were consistent with measured variations in mean panel surface temperatures; the green roof systems were generally cooler by 1.5˚C to 3˚C. The panel surface mean heat transfer coefficients for the PV-green roof were generally 10 to 23% higher than for the white and black roof configurations, suggesting a mixing benefit associated with the roughness of the plant canopy. As expected, the results indicate that the best PV panel performance is obtained by locating the PV panel above a green roof. However, the relative benefits of the roof energy balance diminish with distance between the PV panel and the roof.
Moreover, the results of this study showed that the mean power output of the PV panel above the white roof was 0.7% and 0.44% higher than that of the PV panel above the black roof at 18 cm and 24 cm heights, respectively. The results of the power output differences in all the experiments were statistically significant at the 95% confidence interval (P < 0.01).
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Dumoulin, Jérémy. "Refroidissement radiatif des cellules et modules solaires par structuration de surface." Electronic Thesis or Diss., Lyon, INSA, 2023. http://www.theses.fr/2023ISAL0005.
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Les cellules et modules photovoltaïques s’échauffent considérablement en conditions réelles de fonctionnement, ce qui est néfaste pour leur rendement de conversion et leur durée de vie. Pourtant, les aspects thermiques sont encore peu considérés, voire complètement ignorés lors de la conception des dispositifs photovoltaïques. Dans ce contexte, l'objectif de cette thèse est d'étudier une stratégie novatrice pour limiter l'échauffement : le refroidissement par échange radiatif avec le ciel. Cette approche consiste à optimiser l'échange radiatif dans les gammes spectrales où il n'y a pas de conversion photovoltaïque, notamment dans le moyen infrarouge pour profiter de la fenêtre de transparence qu'offre l’atmosphère dans la gamme 8-13 µm. Bien que prometteuse, de nombreux verrous restent à lever pour saisir les tenants et les aboutissants de cette stratégie, aussi bien du point de vue théorique que du point de vue expérimental. Grâce à un modèle électrique et thermique spécialement développé à cet effet, le bénéfice théorique que le refroidissement radiatif avec le ciel peut apporter aux dispositifs photovoltaïques est d'abord quantifié. Le profil d'émissivité idéal est également déterminé. Plus généralement, des lignes directrices et des ordres de grandeurs sont établis pour une vaste gamme de dispositifs basés sur une technologie monojonction. Les pistes expérimentales pour atteindre le profil d'émissivité idéal sont ensuite mises en lumière. A l'échelle d'un module en silicium cristallin, il apparaît que la voie la plus prometteuse concerne l'ingénierie de l'interface air-verre. A cet égard, une structure optique basée sur une multicouche diélectrique est proposée et analysée. Pour guider d'éventuelles études futures, un ensemble d'outils numériques et méthodologiques pour trouver, concevoir, et quantifier le bénéfice des structures optiques est présenté. En complément de ces résultats spécifiques au refroidissement radiatif avec le ciel, un modèle opto-électro-thermique de cellules en silicium est développé. Ce dernier a pour but de prédire les performances en conditions réelles de fonctionnement directement à partir de la connaissance des matériaux et de l'architecture de la cellule. Nous montrons notamment comment ce modèle d'un nouveau genre permet d'ouvrir de nouvelles voies pour continuer à augmenter la production d'électricité photovoltaïque via une ingénierie plus consciente des effets thermiquesPhotovoltaic solar cells and modules heat up considerably under real operating conditions, which is detrimental to their conversion efficiency and their lifetime. However, thermal aspects are still little taken into account, or even completely ignored, in the design of photovoltaic devices. In this context, the objective of this work is to study an innovative strategy to limit overheating: radiative sky cooling. This approach consists of optimising radiative heat exchange in spectral ranges where there is no photovoltaic conversion, in particular in the mid-infrared range to take advantage of the atmospheric transparency window between 8-13 µm. Although promising, many theoretical and experimental obstacles have to be adressed in order to fully grasp the opportunities and challenges of radiative sky cooling for photovoltaics. Using an in-house developped electrical and thermal model, the theoretical benefit that radiative sky cooling can bring to photovoltaic devices has been quantified. The ideal emissivity profile was also determined. More generally, guidelines and orders of magnitude were established for a wide range of devices. The experimental pathways for achieving the ideal emissivity profile have been unveiled. For crystalline silicon module, it appears that the most promising approaches relate to the engineering of the air-glass interface. In this respect, an optical structure based on a dielectric multilayer is proposed and analysed. To guide future studies, a set of numerical and methodological tools that enable to identify, design, and quantify the benefit of optical structures has been developed. In addition to these specific results for radiative sky cooling, an opto-electro-thermal model of silicon cells is presented. This model aims at predicting the performance under real operating conditions directly from the materials and the architecture of the cell. In particular, we show how this model paves the way to further increase photovoltaic electricity production through more thermally aware engineering
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Brogren, Maria. "Optical Efficiency of Low-Concentrating Solar Energy Systems with Parabolic Reflectors." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3988.
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Kulkarni, Sachin. "EFFECT OF COMPOSITION, MORPHOLOGY AND SEMICONDUCTING PROPERTIES ON THE EFFICIENCY OF CUIN1-XGAXSE2-YSY THIN-FILM SOLAR CELLS PRE." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2938.
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A rapid thermal processing (RTP) reactor for the preparation of graded CuIn1-xGaxSe2-ySy (CIGSeS) thin-film solar cells has been designed, assembled and is being used at the Photovoltaic Materials Laboratory of the Florida Solar Energy Center. CIGSeS films having the optimum composition, morphology, and semiconducting properties were prepared using RTP. Initially films having various Cu/(In+Ga) ratios were prepared. In the next step selenium incorporation in these films was optimized, followed by sulfur incorporation in the surface to increase the bandgap at the surface. The compositional gradient of sulfur was fine-tuned so as to increase the conversion efficiency. Materials properties of these films were characterized by optical microscopy, SEM, AFM, EDS, XRD, GIXRD, AES, and EPMA. The completed cells were extensively studied by electrical characterization. Current-voltage (I-V), external and internal quantum efficiency (EQE and IQE), capacitance-voltage (C-V), and light beam induced current (LBIC) analysis were carried out. Current Density (J)-Voltage (V) curves were obtained at different temperatures. The temperature dependence of the open circuit voltage and fill factor has been estimated. The bandgap value calculated from the intercept of the linear extrapolation was ~1.1-1.2 eV. Capacitance-voltage analysis gave a carrier density of ~4.0 x 1015 cm-3. Semiconductor properties analysis of CuIn1-xGaxSe2-ySy (CIGSeS) thin-film solar cells has been carried out. The values of various PV parameters determined using this analysis were as follows: shunt resistance (Rp) of ~510 Ohms-cm2 under illumination and ~1300 Ohms-cm2 in dark, series resistance (Rs) of ~0.8 Ohms-cm2 under illumination and ~1.7 Ohms-cm2 in dark, diode quality factor (A) of 1.87, and reverse saturation current density (Jo) of 1.5 x 10-7A cm-2. The efficiency of 12.78% obtained during this research is the highest efficiency obtained by any University or National Lab for copper chalcopyrite solar cells prepared by RTP. CIGS2 cells have a better match to the solar spectrum due to their comparatively higher band-gap as compared to CIGS cells. However, they are presently limited to efficiencies below 13% which is considerably lower than that of CIGS cells of 19.9%. One of the reasons for this lower efficiency is the conduction band offset between the CIGS2 absorber layer and the CdS heterojunction partner layer. The band offset value between CIGS2 and CdS was estimated by a combination of ultraviolet photoelectron spectroscopy (UPS) and Inverse Photoemission Spectroscopy (IPES) to be -0.45 eV, i.e. a cliff is present between these two layers, enhancing the recombination at the junction, this limits the efficiency of CIGS2 wide-gap chalcopyrite solar cells.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Materials Science & Engr PhD
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Kulkarni, Sachin Shashidhar. "Effect of composition, morphology and semiconducting properties on the efficiency of CuIn₁₋x̳Gax̳Se₂₋y̳Sy̳ thin-film solar cells prepared by rapid thermal processing." Orlando, Fla. : University of Central Florida, 2008. http://purl.fcla.edu/fcla/etd/CFE0002467.
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Guillo, Lohan Benoit. "Modélisation, élaboration et caractérisation de cellules photovoltaïques à base de silicium cristallin pour des applications sous concentration." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI093/document.
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Les performances électriques des cellules photovoltaïques à base de silicium sont fortement dégradées lorsque leur température augmente. Cette problématique, pourtant bien connue, n’est pas suffisamment prise en considération dans l’industrie du photovoltaïque. Pour parer à cette dégradation, deux voies d’améliorations peuvent être explorées : diminuer la température de fonctionnement des cellules ou réduire leurs coefficients de dégradation en température. Cette étude est d’autant plus importante pour les applications sous concentrations, un éclairement élevé favorisant l’échauffement des cellules. Pour les facteurs de concentration élevés, l’utilisation de systèmes de refroidissement actifs réduit drastiquement la température de fonctionnement. Pour les faibles éclairements, le refroidissement passif est préféré, bien moins coûteux en énergie. Ce travail de thèse est focalisé sur l’étude du comportement thermo-électrique des cellules sous faible concentration du rayonnement incident. Un banc de caractérisation innovant développé dans cette thèse a rendu possible la quantification des variations de la température de la cellule avec la tension de polarisation sous différents facteurs de concentration. Avec l’augmentation de la polarisation, une évolution du facteur d’émission thermique est observée du fait des variations de la concentration de porteurs de charge minoritaires. Le refroidissement radiatif est minimal au courant de court-circuit et est maximal à la tension de circuit ouvert : la température atteinte au point de court-circuit est supérieure à celle atteinte en circuit ouvert. Pour une cellule donnée, sous un éclairement de 3 soleils, un écart de température de 6.2 °C a pu être mesuré entre ces deux points. La fabrication de cellules avec des propriétés différentes nous a permis de confirmer l’importance du dopage de la base et de l’architecture sur l’augmentation du refroidissement radiatif avec la polarisation. De plus, la comparaison du comportement thermo-électrique des cellules de type de dopages différents a mis en avant de plus faibles coefficients de dégradation en température de la tension en circuit ouvert pour les cellules ayant un substrat de type n. Par exemple, pour une température de et sous un éclairement de 1 soleil, un coefficient de dégradation en température du Voc de −0.45% %·°C-1 a été mesuré sur une cellule de type n contre −0.49%·°C-1 pour une cellule de type pThe electrical performances of silicon based solar cells strongly degrade when increasing their temperature. However, such a well-known issue is too scarcely considered in the phovoltaic industry. To prevent the degradation of silicon based solar cells, two ways of improvement can be explored : one can either decrease the cells’ functionning temperature or either reduce the temperature degradation coefficient. As light intensity tends to favor cell heating, the study is even more important under concentrated sunlight. Regarding high light intensities, active cooling systems can be used to drastically reduce the cell temperature. For low light intensities, passive cooling systems, such as radiative cooling, are more energetically savy. The thesis aims at studying the electro-thermal behavior of cells under low light intensities. An innovative experimental set-up has been developped during this thesis to quantify the variation of the cell temperature with the applied bias voltage. When increasing the bias, an evolution of the cell emissivity is observed because of a variation of the minorities carrier concentration. The radiative cooling is at its lowest at the short circuit current and peaks its highest value at the open circuit voltage : as a result, the reached temperature is higher at the short circuit current than at the open circuit voltage. For a given solar cell, under 3 suns, a temperature shift of 6.2 °C was measured between these two points. The control of the fabrication process gives the opportunity to analyse the influence of the base doping and cell architecture on the evolution of the radiative cooling with the applied bias. Furthermore, the comparison between the electro-thermal behaviors of solar cells, which are related to their type of doping, has shown a lower thermal degradation coefficient of the open circuit voltage for n-type based dope solar cells. For example, at 60°C and under 1 sun, we measured a thermal degradation coefficient BVoc = −0.45% %·°C-1 for a n type solar cell whereas the p type solar cell recorded BVoc = −0.49% %·°C-1
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Dohnalová, Lenka. "Optimalizace tepelných vlastností struktur modulů fotovoltaických článků." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216637.
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The topic of presented diploma thesis is study of thermal properties structures of photovoltaic cells. The main goal of this thesis is study of ways of heat spreading from volume and planar materials (conduction, convection and radiation). Then it is needed to determine contributions of heat spread from laminated photovoltaic cell and compare them to results measured by transient pulse method, step wise method and with thermo-camera using. At the beginning of this thesis it will be needed to define heat and ways it’s spread. Heat is closely connected with temperature. That is reason why will be there spoken about temperature and methods of its measuring. Than there will be defined basic thermo-physical parameters of materials. Thermo-physical parameters of materials will be measured by transient methods that will be characterized later and by thermo-camera. This thesis deals with photovoltaic cells, so there will be described their structure, properties, utilization and way of their production. Subsequently after the definition of all needed terms the experimental part of this thesis will be introduced. It will be needed to characterize measured volume material and define its thermo-physical parameters. Using the pulse transient method, step wise method and thermo-camera there will be measured the thermal response of PMMA sample, nonlaminated photovoltaic cell and also samples of laminated photovoltaic cells. Findings of all described methods will be finally compared.
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AKA, BOKO. "Photodecomposition sensibilisee au mercure du monosilane (hg-photo-cvd) : application au depot en couches minces de silicium amorphe hydrogene (a-si : h)." Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13026.
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L'etude fondamentale des parametres mis en jeu montre que la limitation de la quantite de cilane decompose et la formation importante d'hydrogene doivent etre associees a un mecanisme chimique en phase gazeuse et a la surface plutot qu'a la diminution de la transparence de la fenetre d'entree consecutive au depot du film si. Il est ainsi mis en evidence que la quantite relative de si depose est tres importante aux basses pressions et que la vitesse de depot peut etre accrue en operant a forte intensite lumineuse. La qualite des couches depend fortement des conditions de preparation, en particulier de la temperature du support. Les couches obtenues ont des proprietes essentielles pour la fabrication de dispositifs photovoltaiques et microelectroniques de dimensions reduites et a bon marche
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Mačát, Jakub. "Vlivy ovlivňující degradaci instalovaného výkonu fotovoltaické elektrárny." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-220429.
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My diploma thesis focuses in its theoretical part on the analysis of photovoltaic cells, panels, their properties and defects . Further there are described materials from which the cells and panels are produced today but also there are mentioned materials which could affect the near future. There are also state the methods of measurement of photovoltaic cells . The practical part analyzes selected photovoltaic panels, determines the level of degradation by measurement and calculation with using the intensity of solar radiation. All results are entred into graphs and tables.
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Zaraket, Jean Gerges. "Étude de la fiabilité des structures silicium employées dans le domaine des énergies renouvelables suite à leur fonctionnement sous conditions extrêmes." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0244/document.
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Le travail de la thèse proposé consiste à étudier, caractériser et modéliser la performance et la fiabilité de composants semi-conducteurs sous conditions extrêmes c’est à dire pendant et après que ces composants ont subi un stress électrique, un stress thermique voire les deux stress en même temps. Les composants semi-conducteurs que nous avons étudiés sont des modules photovoltaïques en silicium monocristallin pour des applications dans les énergies renouvelables. Dans cette étude, ces composants ont été soumis à plusieurs types de dégradations générant des défauts localisés dans la structure des composants. Dans un premier temps, des études approfondies des caractéristiques I(V) et C(V) et des paramètres électriques des modules solaires photovoltaïques ont été réalisées en testant une série de modules sous différentes conditions environnementales afin de fournir des données pertinentes pouvant être utiles pour l'évaluation des performances, la modélisation du fonctionnement et pour la mise en œuvre correcte et complète des modules photovoltaïques. Ces caractérisations ont été complétées par l’étude des défauts créés à l’interface et dans les structures des modules photovoltaïques par les différents stress sur la base de mesures effectuées sur ces mêmes cellules par la technique Deep Level Transient Spectroscopy (DLTS). Grâce à cette technique, nous avons identifié et localisé ces défauts au sein du composant, en déterminant leur énergie d’activation et leur section efficace de capture. Les résultats de notre étude montrent ainsi l’importance des conditions de fonctionnement sur les performances instantanées et sur le long terme des systèmes photovoltaïques. Ils peuvent être exploitables directement dans la conception même des modules silicium voire transposable, en suivant la méthodologie de l’étude que nous proposons à de nouvelles technologies de modulesThe objective of this work aim to study the performance, reliability of semiconductor structures after their operation under extreme conditions, during and after electrical stress, thermal stress, and combined electro thermal stresses. The studied semiconductor structures are photovoltaic cells for applications in the field of renewable energies. These devices have been exposed to several types of degradation generating localized defects in the structures. The I (V) and C (V) characteristics and electrical parameters have been studied before and after each stress case. The Deep Level Transient Spectroscopy (DLTS) was used as advanced technique for tracking the defects created at the interface and in the bulk structures. The DLTS technique allows identifying and locating these defects within the devices, by determining their activation energy and their capture cross-Section
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Tseng, Po-Jen, and 曾柏仁. "Study on Solar Photovoltaic Cogeneration System with Solar Tracker and Thermal Efficiency Assessment for Hydrogen Fuel Cell." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/08531433857198210428.
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碩士國立東華大學
光電工程學系
104
In view of the solar power and other renewable energy sources will help reduce greenhouse gas emissions, can be considered as an alternative to dependence on imported energy from the future, but that sort of renewable energy is part of the tip load power cannot effectively fill a large number of base load electricity demand in Taiwan, so the utilization of renewable energy or the Issues of energy storage is concerned. In this thesis, the development of a new type of chase solar-type solar cell cogeneration system, in addition to the thermal efficiency of the system of assessed, but also explore the feasibility of the application of thermal energy of the hydrogen fuel cell. Research Integration 120o above flexible viewing angle of linear Fresnel lens element in the cogeneration system, the study compared the single axis and dual-axis tracking system accuracy found uniaxial tracking system with 6o higher precision, in design has scalability and modular unit. Discussion on the change of lighting in the light of the Fresnel lens curvature, after the light is incident from each angle, the lighting changes image map of the linear Fresnel lens via Digital Micrograph software quantized the image contrast can find, in the Fresnel lens curvature = 1 / 39.2, within the lateral measuring range 297 mm, have a greater focus effect than any other curvature parameters, in the season of the region will be 7 hours in focus more than 70 % area. In condenser solar cell analysis measurement study also found that although the linear Fresnel lens rendered cell performance (0.78 W/cm2) below the converging effect of the focusing point of the Fresnel lens (1.31 W/cm2), but with the deflection characteristics, although only single axis tracking the sun, can be wrapped around curved into a cylindrical shape to achieve dual-axis tracking the sun moving effect. Another study of the system in practice, focuses on the environmental characteristics of the atmosphere in Hualien area, the data show that the area within two hours of full sun in winter, the average amount is 827 W/m2, direct sunlight is about 649 W/m2, the diffusion rate is about 21.52 %, especially compared the diffusion rate with the south and the western of Taiwan, there are ideal conditions for the use of condensing. By the linear Fresnel lens focusing system to evaluate the thermal efficiency, the study found that the water temperature in the thermal insulation raised up 7.8 oC in two hours by sunshine, the system average thermal conversion efficiency is 19.3 %. We collect and store the waste heat of cogeneration system, while integrating hydrogen technology and investigate the effects of the proton exchange membrane fuel cell after preheated, when the humidity is 74 %, the proton exchange membrane fuel has maximum short circuit current density (140 mA/cm2) at operating temperature of 40 degrees, was found with increasing temperature can increase the proton exchange membrane fuel cell efficiency, but the accompanying high or low relative humidity could easily lead to mass transfer hindrance.
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Liu, Yi Yen, and 劉易彥. "Investigations of thermal annealing effect on the performance of the triple-junction InGaP-based photovoltaic solar cell." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/64223238394654061398.
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碩士長庚大學
光電工程研究所
101
Multi-junction photovoltaic devices are theoretically expected to have a highest limit of efficiency conversion as compared to other designed solar cell heterostructures. The conversion efficiency of a solar cell was a function of its band heterostructure. Furthermore, as far as the triple-junction InGaP-based photovoltaic solar cells were concerned, changing the indium composition also made a trade off between open circuit voltage and short circuit current. It was thus well-known that there was an optimum device design for the fixed sun concentration. Indeed, the promise of the multi-junction metamorphic cells providing high conversion efficiency has been realized in the top subcell structures with the indium mole fractions of about 50%. However, according to the increase of the indium composition, the device performance was essentially deteriorated. In aspect of device physics, a great loss due to the more photogenerated current flow was considered to cause the reduction of the efficiency. Nevertheless, based on the microscopic thermodynamics, an alternative perspective on the correlation between the material microstuctures and the cell characteristics is incontrovertible. In this work, we systematically characterized the optical behaviors of the subcells using photo luminescent spectroscopy. The preparation of triple-junction InGaP-based solar cells composed of top subcell with different InP mole fractions, including 50% and 65%, was carried out by a metal organic chemical vapor deposition (MOCVD) system. In order to modulate the microstates in response to the change in the nanostructures, the samples investigated were treated by post-annealing at various temperatures ranging from 100 °C to 600 °C for 30 minutes in the nitrogen atmosphere. Considering the statistical redistribution of the microstates in the InGaP-based subcell, the correlation between the photoluminescence (PL) and the continuum theory were investigated as a function of temperature. After examining the luminescent intensity, full-width at half-maximum (FWHM), and thermal activation energy closely, it was found that the In0.5Ga0.5P-based sample revealed better PL characteristics than the In0.65Ga0.35P-based one.
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Bor-TyngJou and 周柏庭. "Numerical study on thermal/electrical performance of a photovoltaic cell integrated with single/double layers of water-saturated microencapsulated phase change material." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/48825763575429814949.
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碩士國立成功大學
機械工程學系碩博士班
100
The present study via a numerical simulation aims to explore the efficacy of using a single/double layers of water-saturated microencapsulated phase change material (MEPCM) as a passive thermal management medium for a PV module under various daily operation conditions. Parametric simulations have been performed for the thermal /electrical performances of the PV module integrated with single/double layers of MEPCM under different weather conditions, focusing on the effects of varying thickness of the MEPCM layers as well as the melting point of PCM in the MEPCM. The results showed the thermal/electrical performances of PV module may be markedly improved in both winter and summer weather conditions considered by using double layers of MEPCM.
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Swathi, S. K. "Thiophene Derivative Photovoltaics : Device Fabrication, Optimization and Study of Charge Transport Characteristics." Thesis, 2013. http://etd.iisc.ernet.in/2005/3366.
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In the recent years area organic photovoltaics is generating a lot of interests because whole process of synthesis and fabrication is less energy intensive process as well as it is cost effective compared to conventional inorganic Si based photovoltaic technology. This work mainly deals with the fabrication and optimization of device fabrication conditions for organic photovoltaic materials.
In first part of the work, the solar cell fabrication conditions were optimized for the commonly used system P3HT – PCBM. The fabricated device was optimized for the solvents used for the active material, concentration of the active material solution, donor- acceptor ratio of the active material, annealing conditions of the active layer and the metal evaporation conditions for the cathode. All the optimization procedures were carried out in controlled atmosphere to minimize the environmental effect inference during fabrication of the solar cell devices. All the characterization was carried out at ambient conditions. The efficiency of the solar cell was improved from 0.009% to 6.2%. the environmental stability of the fabricated devices were carried out after encapsulating it with epoxy based resin in both ambient conditions as well as extreme conditions like 85% RH at 25°C inside the humidity chamber. It was observed that both the data matches well with each other indicating proper encapsulation required to safe guard the device for the better performance over the period of time.
Second part of this work mainly deals with understanding the structure property relationship of thiophene based donor- acceptor- donor molecule 2,5-dithienyl-3,4-(1,8-naphthylene) cyclopentadienone (DTCPA), which is highly crystalline, low band gap organic molecule which absorbs over entire visible region of the solar spectra. DTCPA crystals of various morphologies were prepared by various recrystallization routes. It was observed that macro scale morphology of these crystals differs from each other. Also depending on the method of recrystallization sizes of the crystals also varies. All the recrystallized DTCPA shows strong orientation toward (001) direction. However, it was observed that lattice parameters of these crystals slightly differ from each other owing to the recrystallization methodology. These variations in crystal parameters are more than 0.02 which is significant. It was also observed that the crystallite sizes depend on the recrystallization routes. Slow evaporation of concentrated solution (SEC) grown crystals has the larger crystallite size of 170nm. It was observed that absorption range of these crystals slightly differ from each other owing to the change in the crystallite sizes and crystal parameters.
Third part of this work deals with the fabrication and optimization of thermal evaporation process of DTCPA for photovoltaic applications. DTCPA is stable at higher temperatures as well as has sharp melting point which make it ideal candidate for thermal evaporation. In this work films of DTCPA were fabricated for various evaporation rates by thermal evaporation technique. Chemical integrity of the molecules upon evaporation is found to be intact as observed from FTIR spectroscopy. XRD shows that at lower (25 W/m2) as well as higher (40 W/m2) films are oriented to (001), (400) as well as (311) directions, at 30 W/m2 and 35 W/m2 there is a strong orientation towards (311) and (001) directions respectively. Photo luminescence studies indicate that there is strong 410 nm emission for films deposited at the power of 25 W/m2 and 40 W/m2. Microscopic studies confirm that morphology is dependent on the deposition rates as it changes with the change in deposition rate. This in turn reflects in the device characteristics of these films. It was observed that films deposited at high deposition rates show better device characteristics with high VOC and current density values. All these device fabrication and characterizations were carried out in ambient conditions.
Fourth part of this work deals with P3HT - DTCPA composites which exhibit wide range of light absorption. It was observed that DTCPA act as nucleating centers for the P3HT molecules and increases crystallinity in the composite. Furthermore, DTCPA helps in exciton separation because of donor and acceptor moieties present in the molecule. It also helps in charge transportation because of its crystalline nature and further it induces molecular ordering in the P3HT matrix. The band diagram of P3HT- DTCPA suggests that the band edges of both materials are ideal for charge separation. In addition, crystalline nature of the DTCPA molecule helps in effective charge transportation. J-V characteristics shows that there is large built in potential in the devices from these blends leading to large Voc. Composites with lower DTCPA loadings show higher efficiency than with higher loadings. These devices were prepared in ambient conditions and needs to be optimized for obtaining better device properties.
In the fifth part of the work two types of system were studied to understand the band edge matching on the photovoltaic properties, carbazole based copolymers and DTCPA based copolymers. In the case of carbazole based copolymers it was observed that by copolymerizing carbazole with thiophene based derivatives lowers the band gap and modifies the HOMO and LUMO levels for better suit for the photovoltaic device fabrication. It was observed that that is two orders of improvements in the efficiency by co polymerizing carbazole with benzothiodizole as improves the JSC and VOC. Also the copolymerization of carbazole with both benzothiodiazole and bithiophene results in better light harvesting as the optical band gap was lowered. In the case of DTCPA copolymers with DTBT and DHTBT as both are random copolymers the solubility was low as well as their HOMO band edge was mismatched with the PEDOT: PSS which is a hole transport layer. However, the alternate polymerization of DTCPA with DTBT improved the band edge matching and also the solubility. As a result there was tenfold improvement in the charge collection and hence the efficiency was improved from 0.02% to 2.4%.
Many of the conducting polymers have good material property but poor filmability. In the sixth part of this work deals with fabrication of device quality films by alternate deposition technique like pulsed laser deposition. Two types of system were studied in this work (i) polypyrrole- MWCNT nanocomposites and (ii) Poly DTCPA polymer. In both the cases it was observed that chemical integrity of the polymer retained during ablation. PolyDTCPA films were fabricated by pulsed laser deposition by both IR (Nd-YAG) and UV (KrF) laser source. Morphological studies indicate that IR laser ablated films were particulate in nature whereas UV laser ablated films were grown as continuous layers as polyDTCPA absorbs better in UV region. As a result the IV characteristics indicate that IR laser ablated films are resistive in nature and UV laser ablated films are good rectifiers indicating the suitability of the process for fabrication of device quality films.
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Tonui, Joel Kipkorir. "Hybrid photovoltaic/thermal solar energy systems." Thesis, 2006. http://nemertes.lis.upatras.gr/jspui/handle/10889/3894.
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Clemente, Miguel Rolinho. "Thermal Management of Photovoltaic Cells based on Construtal Law." Master's thesis, 2015. http://hdl.handle.net/10316/39014.
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Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraThe increase of temperature on PV cells is considered one of the most critical issues that affects their efficiency, promoting degradation and cell life reduction. Therefore, thermal management is essential and must be an integral part of PV systems. In this thesis, the constructal law is explored as a design tool to develop a thermal management system for PV cells, based on single-phase forced convection. In order to cool the PV cell rectangular area, a tree-network structure has been chosen to test the constructal theory approach. Considering this, an experimental facility has been built with 3D printing. The voltage and temperature output of a PV cell has been characterized with and without thermal management. The results evidence an improvement of 32 % on the PV cell efficiency through a decrease in the temperature coefficient (∂V/∂T) of 16.5 %. Therefore, constructal design applied to cooling technology shows great potential to improve photovoltaic thermal managements.
O aumento da temperatura em células fotovoltaicas é considerado um dos problemas mais críticos que afeta a sua eficiência, promovendo degradação e redução da vida útil da célula. Portanto, o controlo da temperatura é essencial e deve ser uma parte integrante dos sistemas fotovoltaicos. Esta tese explora a lei construtal para desenvolver uma instalação experimental para arrefecimento das células fotovoltaicas. De forma a arrefecer a área retangular da célula fotovoltaica, foi es- colhida uma estrutura em árvore para testar a abordagem da teoria con- strutal. Tendo isto em consideração, foi construída uma instalação ex- perimental com impressão 3D. A voltagem produzida e a temperatura da célula fotovoltaica foram caracterizados com e sem o sistema de gestão tér- mica. Os resultados evidenciam um melhoramento de 32 % na eficiência da célula através de uma redução no coeficiente de temperatura ((∂V/∂T) de 16.5 %. Portanto, o design construtal aplicado a tecnologia de arrefecimento demonstra grande potencial para melhorar a gestão térmica de sistemas fo- tovoltaicos.
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Chu, Hsuan-Peng, and 朱軒芃. "Improved Photovoltaic Characteristics of Silicon Nanorods Solar Cells using Thermal Oxidation and Spin-on-Dopants." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/ka9dxw.
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碩士國立虎尾科技大學
機械與機電工程研究所
100
In this thesis, the silicon nanorods (SNRs) on p-Si(100) surface were prepared by the hydrofluoric acid (HF) and silver nitrate (AgNO3) mixture solution at room temperature. The spin-on-dopants (SOD), the thermal oxide, laser firing and the screen printed processes were used to fabricate the SNR solar cells. Silicon nanorods arrays with length of 2-3 um were demonstrated. The p-n junctions were formed by the SOD dopant technique by tuning various diffusion times. Silicon dioxide was grown on the SNR surface at high temperature as the passivation layer. The dangling bounds on the surface of SNR can be reduced by the thermal oxide. In order to connect the emitter and the base, the laser firing was used under various conditions of laser. Finally, screen-printed silver and aluminum paste on the top and rear side, respectively, were achieved under various firing temperatures. Compared to currently industry pyramid and silicon nitride structure, SNRs shows excellent optical antireflection property over a wide spectral bandwidth. Photovoltaic characteristic of the conversion efficiency 8.4 % with a short circuit current density of 25.1 mA/cm2, an open circuit voltage of 560 mV, and a fill factor of 58.3% were achieved.
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Huang, Huai-Wei, and 黃懷緯. "Improved Photovoltaic Characteristics of Screen-Printed Mono-Crystalline Silicon Solar Cells by Rapid Thermal Annealing Process." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/xjjy9v.
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碩士國立虎尾科技大學
光電工程系光電與材料科技碩士在職專班
105
In this thesis, improved photovoltaic characteristics of screen-printed mono-crystalline silicon solar cells (SPMSSCs) were investigated by the rapid thermal annealing (RTA) process. First, the wet solution process for laser damage removal was demonstrated. Then, the effects of the placed way of the samples, the gas ambient, the temperature, time, the thickness of the nickel, and the wet etching of residual nickel on the quality of the seed layer for electroplated copper were presented. Finally, the copper was electroplated as the rear electrode of the SPMSSCs. The amount of the KOH solution for laser damage removal was achieved. Four placed ways, including the evaporated surface faced to top of the p-type substrate, the evaporated surface faced to top of the p-type substrate was covered by the p-type substrate, the evaporated surface up, as well as the p-type substrate faced to top of the evaporated surface, were addressed. The nitrogen and forming gas (5%H2+95%N2) were used as the process gas. The temperature of the RTA ranged from 325 to 425 oC was achieved. The time of the RTA ranged from 3 to 7 min was explored. The etching time of the SPM solution for residual metal removal was investigated. The results indicate that the increase of the KOH solution amount was help to enhance the conversion efficiency (CE) of the SPMSSCs from 15.2 to 15.8%. Compared with all placed ways, “the evaporated surface faced to top of the p-type substrate was covered by the p-type substrate” was the best condition for CE improvement. The CEs of the SPMSSCs were identical for the nitrogen and forming gas. Thus, the cheap nitrogen gas was used for CE improvement. The achievement of an CE improvement of more than 1.9% absolute from 13.9% to 15.8% in SPMSSCs with the RTA at 350 oC for 5 min was explored.
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Chien, Chin-Wei, and 簡晉緯. "Thermo-fluid Characteristics and Generation Efficiency of Photovoltaic Cells on Curved Surface." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/18975762311775772731.
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碩士國立高雄應用科技大學
模具工程系碩士班
101
When solar cell modules exposure to sunlight, only a few part of the radiation can converted into electrical energy. Most of the radiation is converted into heat energy causes temperature increase on solar cell and decrease efficiency of power generation. Presently solar cell modules can be applied extensively in all kinds of vehicles, building shape and structure art form, in order to enhance the value of design. Although solar cell module can show different appearance curvatures laying style. However, for a total generating capacity of solar cell may be affected by sunlight at different angles lead to lower power generation efficiency. In this study, we use outdoor wind tunnel measurements and numerical simulations in two ways, studies thermo-fluid characteristics and generation efficiency of photovoltaic cells on curved surface. Experimental part in three different curvature angles (curvature angle, β = 5 °, 8 °, 10 °) to the test modules and the module will be into the open-loop inhaled wind tunnel test section, adjust to different wind speed (V = 5 m/s, 8 m/s, 10 m/s). In order to simulate solar cell modules at different forced convection due to temperature affect power generation efficiency. In addition, not only study the solar cells at different curvature to obtaining the relationship between average heat convection coefficient and wind speed. Also, analysis of different curvature solar cell relationships between thermal-fluid characteristics and generation efficiency at sunlight different angles. The results show that solar cell temperature dropping as the wind speed rise. When the wind speed is larger, the heat convection coefficient also become faster. It's shows that the wind take away the better the effect of heat energy, when the heat convection coefficient is larger. According to the research when the test modules faced the sun by the curvature angle increases, the temperature rise 1℃ and it’s output power is reduced by approximately 0.06%. Also, thermo-fluid characteristics and generation efficiency photovoltaic cells on curved surface, β = 10° of heat convection coefficient is larger. At the same environmental conditions, β = 5° of the solar cell module power generation efficiency is better. When the power generation is higher, curvature solar cell does not show higher of heat convection coefficient and still need to consider the impact of solar irradiation angle.
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Hsieh, Yen-Ju, and 謝炎儒. "Photovoltaic Behavior and Thermal Stability of Bulk Heterojunction Solar Cells Based on Novel Conjugated Polymers and Fullerene Derivatives." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/83jhbc.
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博士國立臺灣大學
高分子科學與工程學研究所
105
In bulk-heterojunction (BHJ) polymer solar cells (PSCs), conjugated polymer and fullerene derivative are commonly utilized as an electron donor and an electron acceptor, respectively, to form the active layer. Searching potential polymer donor and fullerene acceptor plays an important role in advancing the power conversion efficiency (PCE) and operational lifetime of such solar devices. In the first part, a series of N-substituted fulleropyrrolidines were employed as electron acceptors blending with P3HT as electron donor to fabricate polymer solar cells. It was found that the type of substituent significantly influences the photovoltaic behavior of the solar devices. As the substituent is an alkyl group, such as N-methyl, N-hexyl, N-ethylhexyl, abnormal S-shape current-voltage (I-V) curves are resulted. The analysis of the P3HT/N-alkyl fulleropyrrolidine blends by TEM, UV-vis, and PL shows no obvious difference between these films. This abnormal I-V curve can be ascribed to the formation of a N-alkyl fulleropyrrolidine interlayer at the bottom of the photoactive film in the course of spin-dying that blocks the transport of holes to the anode. To verify this speculation, the para position of phenyl substituent in fulleropyrrolidine was functionalized with an electron-donating group. (NN-dimethyl, methoxyl), or hydrogen atom. As expected, the cell using N,N-dimethylphenyl or methoxylphenyl fulleropyrrolidine as acceptor has an S-shaped I-V curve but the one based on phenyl fulleropyrrolidine behaves a normal photovoltaic performance. Interestingly, as an inverted cell structure is adopted to reverse the transport routes of carriers inside the photoactive blend, the problem of S-shape kink associated with all fulleropyrrolidine are totally solved, suggesting these new fullerene acceptors can be applied as effective acceptor in inverted PSCs. In the second part, we investigated the effect of electron donating and withdrawing group of C60 derivatives on the open-circuit voltage (Voc) of polymer solar cell. Herein, we functionalized C60 with DPM-O, DPM-OCO or DPM-COO groups, which have various electron donating and withdrawing ability. Very interestingly, the cyclic voltamograms showed the LUMO energy levels of these three fullerene derivatives are comparable with that of PCBM, but combination of AC-2 measurements and UV-Vis absorption spectra demonstrated that the LUMO of DPM-O and DPM-OCO films is 0.04-0.08 eV higher than that of PCBM film. This is probably because the electron donated moieties and neighbor C60 cores form charge transfer complexes in the solid film. Their Voc decreased in the trend, DPM-O > DPM-OCO > DPM-COO. This result opens a new approach to develop high-Voc polymer solar cells. In the third part, we observed that thermally annealing the PTB7-Th:PC61BM blends at 100℃ for 900 minutes leads to large-scale PC61BM aggregation with PTB7-Th matrix that decreases the interface area between the donor and the accepter as well as hole mobility, significantly lowering the PCE from 6.65% to 2.83%. The multilength-scale evolution of the morphology of PTB7-Th/PC61BM film from the scattering profiles of grazing incidence small-angle and wide-angle X-ray scattering indicates the PC61BM molecules spatially confine the self-organization of polymer chains into large domains during cast drying and upon thermal activation. However, the addition of bis-PC61BM into the PTB7-Th:PC61BM blends as phase separation inhibitors effectively inhibits the formation of PC61BM clusters during high-temperature aging. As a result, the PCE of the device with bis-PC61BM retains ~90% of its initial value after 900 minutes annealing at 100 oC. In the fourth part, we explored a new class of conjugated polymers, namely NAP01, NAP02, NAP03 AND NAP04 which were synthesized by Stille polycondensation. These polymers have good solubility in common organic solvents due to the presence of 2,3-didecylthiopheneg groups. Their crystallization behavior and optical, electrochemical and electronic properties were measured and discussed. The BHJ PSCs based on the polymer with thiophene spacer show much better performance than the polymers without spacers. These findings indicate that the optoelectronical properties of polymers can be easily control by inserting thiophene spacers and fused rings into the polymer backbone. This study provides an important rout for designing new materials to obtain higher Voc, short-circuit current (Jsc), fill factors (FF) and PCE of BHJ solar devices. In last part, a novel two-dimensional (2-D) conjugated polymer with tertrthiophene-vinylene (TTV) as conjugated side chain, KBP07, containing of 2,1,3-benzothiadiazole (BTD) was synesized by Stille polymerization. The optical and electrochemical properties of KBP07 shows not only a broader absorption wavelength from 300 nm up to 800 nm (λonset~780 nm；Egopt = 1.59 eV) but low-lying HOMO energy level. In addition, as shown as the X-ray diffraction spectrum, the high crystallinity can be observed. Under AM1.5G illumination at 100 mWcm-2, the BHJ PSC fabricated from KBP07/PC71BM exhibits the best PCE of 4.90% (PCEave= 4.60%). These findings indicate that introducing an electron-withdrawing acceptor to build a D-A 2-D conjugated polymer is a simple but effective strategy to broaden the absorption and achieve high photovoltaic performances.
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Wang, Ting-Jie, and 汪廷潔. "Effects of thermal annealing on the photovoltage performance of one-step solution processed pin planar Perovskite Solar Cell." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/88902562295094810944.
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Santos, Nelson de Sousa Pedro dos. "An investigation into the thermo-fluid design and technical feasibility of a practical solar absorption refrigeration cycle." Thesis, 2010. http://hdl.handle.net/10210/3077.
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M.Eng.The need and problem was originated from the trends of the earths dwindling energy resource. As time progresses humans are becoming more aware of need to use so called “alternative energy sources” to alleviate the main energy converters i.e. power stations. The student was tasked with investigating the thermal performance of a solar powered refrigeration cycle (prototype) that could: produce enough refrigeration effect that it replaces the standard home vapour compression unit, used for cooling or freezing of foods, heats up a geyser sufficiently to have hot water for a common house hold, has excess energy to heat or cool liquid or air based environments and has the potential to lower the electrical bill of a house. The introductory step was to obtain the thermo fluid properties of aqua ammonia solutions. A setback came about when determining the aqua ammonia properties. There were too many conflicting properties being yielded by six different authors. In an attempt to gain confidence in only one author a comparison table was prepared. The table compared the six authors to each other. By looking at all the values compared it brought great clarity to the problem. When continuing the research into the fundamental law approach of solving for the cycle new findings were made. Initially very little comprehensive studies were done which explained in fundamental laws to solve for the absorption cycle. After extensive reviewing of a detailed study on how to solve for absorption refrigeration cycles, then it was able to begin improving on the thermo – fluid design of the cycle. As cycle and component design began to progress the train of thought began to steer in a direction. Each component needed to be detail designed. The advantage of having each component specifically catered for in the cycle design was that it would increase the cycle efficiency. In this way it would ensure that during the concept generation phase the functioning of each component was clear, thereby enabling a clear understanding of how components would compliment each other in a cycle. A mode of solving for the cycle was to endeavour that all parameters could be calculated unambiguously, with the aid of computerisation. Testing was carried out on a real life commercial thermal siphoning machine in order to realistically understand how absorption refrigeration works and gain experience. At the end of the study the most important result is that the dissertation research shows strong evidence that it will be possible to create a device which can fulfil the four tasks listed above. Another result is a program which is a refined cycle design of the pump absorption type refrigeration. The program solves for points along the cycle. Lastly it was found that even though EES was the simpler program to use for aqua ammonia solution properties it was the only program which catered for sub cooling and super heating.
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HUANG, YI-HSUAN, and 黃奕瑄. "Effects of Welding and Thermal Treated Molybdenum Oxide Hole-Selective Transfer Layers on Photovoltaic Characteristics of Monocrystalline Silicon Solar Cells." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/y999cc.
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碩士國立虎尾科技大學
光電工程系光電與材料科技碩士班
107
In this thesis, the effects of welding and thermal treated molybdenum oxide hole-selective transfer layers (HTLs) on photovoltaic characteristics of monocrystalline silicon solar cells were investigated. Solar cells could not be welded due to poor adhesion between MoOx and silicon substrate. In this study, the adhesion between MoOx and silicon substrate was enhanced by screen-printed silver paste and molybdenum oxide HTLs. The experimental parameters, including the numbers of screen-printing strips, line width, line length and line interval distance, were achieved. Moreover, in order to increase body defect and current conduction of molybdenum oxide HTLs, various thermal treatments, including various gas ambient, flow, time and temperature, were performed. The results show that the increase of conversion efficiency (CE) with 0.3 % was achieved by one strip of screen-printed silver paste. The increment of 0.4% for the CE can be performed by the line width of 1 mm. The increased CE of 1.2 % was demonstrated by the line length of 3 mm and line interval distance of 3 mm. The devices with a CE of 18.5 %, an open-circuit voltage (Voc) of 0.65 mV, a series resistance (Rs) of 1.81 Ω-cm2 , a fill factor (FF) of 79.2 %, a short-circuit current (Jsc) of 36.02 mA/cm2 and an adhesion of 1.52 N were presented by one strip of screen-printing silver paste, line width of 1 mm, line length of 3 mm and line interval distance of 3 mm. Although the CE can’t be improved by the rear screen-printed silver paste and MoOx/Ag stacked films, the welding cells can be demonstrated by rear screen-printed silver paste. The results indicate that the devices with a CE of 20.8 %, a Voc of 0.66 V, a Rs of 1.54 Ω-cm2 , a FF of 82.4 %, and a Jsc of 38.2 mA/cm2 , were demonstrated by thermal treated at Ar gas ambient, a flow of 15 sccm, a temperature of 75 °C, treatment of 5 min.
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GAO, SHAO-CHENG, and 高少丞. "Effects of Thermal Treated and Stacked Molybdenum Oxide Hole-Selective Transfer Layers on Photovoltaic Characteristics of Screen-Printed Monocrystalline Silicon Solar Cells." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/d3n4sv.
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碩士國立虎尾科技大學
光電工程系光電與材料科技碩士班
106
In this thesis, the effects of thermal treated and stacked molybdenum oxide hole-selective transfer layers on photovoltaic characteristics of screen-printed monocrystalline silicon solar cells (SPMSSCs) were investigated. The backside structures of passivated emitter and rear cells (PERCs) were presented by aluminium oxide (AlOx) and silicon nitride (SiNx) as passivation and diffusion layer, respectively. Since aluminium oxide and silicon nitride were insulator layer, aluminium oxide/silicon nitride stacked films were needed to form the contact holes using laser process for screen-printed Al pastes and silicon substrate contact. However, the laser damage can be formed by laser process. Thus, in this work, aluminium oxide and silicon nitride stacked films were replaced by thermal evaporated molybdenum oxide (MoOx) as the hole-selective transfer layers. The advantages of thermal evaporated MoOx were without laser process and silicon nitride formed by plasma-enhanced chemical-vapor-deposition. First, the effects of waiting time in vacuum after evaporated MoO2 on silver electrode were investigated. Next, the effects of the MoO2/MoO3 and WO3/MoO3 stacked films and sequence were investigated. Furthermore, the effects of thickness of MoO2 and MoO3 stacked films were investigated. Finally, the thermal treated MoO2 with various gas ambient, temperatures, and time were addressed. The results show that the conversion efficiency (CE) of the SPMSSCs can be slightly increased by shorter waiting time in vacuum ambient. In order to reduce the manufacturing time, the silver electrode was deposited immediately after deposition of the hole-selective transfer layers. The photovoltaic characteristics of the MoO2/MoO3 staked film was better than that of the other stacked films. The CEs of stacked films with deposition-broke vacuum-deposition-deposition in sequence were better than that of the deposition-deposition- broke vacuum-deposition in sequence ones. Finally, The CE with 18.5 % was presented by the MoO2 treated at 100 oC for 5 min in N2 ambient.
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(9787031), Ashfaque Chowdhury. "Computational assessment of building system performance: Improved energy efficiency and thermal comfortability for the future." Thesis, 2020. https://figshare.com/articles/thesis/Computational_assessment_of_building_system_performance_Improved_energy_efficiency_and_thermal_comfortability_for_the_future/16910749.
Full textAbstract:
Energy expenditure is one of the significant overheads in the lifespan of multistoreyed buildings. Reliable and proficient functions of Heating, Ventilation and Air Conditioning (HVAC) systems are further imperative as a result of the climbing price of electricity. This research recommends that the compounded energy utilisation to meet the demand from high humidity and temperature could be minimised by adopting the alternative high-performance building envelope and low emission cooling method along with the optimised control of additional operational parameters. The core purpose of this research is to computationally evaluate the performance of various alternative building envelopes and low energy cooling methods to determine the best performing envelop and cooling method to enhance the energy efficacy and human comfort in buildings in a subtropical climate in Australia.
Firstly, a detailed energy assessment of the current building systems is undertaken on a selected case study building in Rockhampton, Central Queensland. Then, a comprehensive energy simulation model is developed, employing a building energy simulation algorithm. The modelled energy and comfort data of the building systems are validated by means of on-site recorded data. The substantiated model is then expanded to evaluate the efficacy of several alternative building envelopes such as bio-phase change material (BioPCM), cavity wall, Trombe wall, building integrated photovoltaic (BIPV) and low emission cooling methods such as, cooled Beam, ground source heat pump, variable air volume, variable refrigerant flow system to secure better comfort and energy savings in both summer and winter months. Furthermore, an extensive multicriteria based optimisation is undertaken to determine combined alternative envelope and cooling method for retrofitting of the existing systems that will meet the requisite of the present and the future depending on the potential climate change scenario.
This study found that both cooled beam and ground source heat pump as low energy high-performance cooling alternatives, and BioPCM as high-performance building envelope have the higher potential for energy conservation and better thermal comfort based on the present and future weather conditions. Through multi-criteria optimisation, the study found that BioPCM and Cooled Beam as an integrated mechanism can be successfully incorporated into buildings in subtropical climate to improve the energy efficiency by 30% and human comfort which have not been evaluated in any other studies in the past. Furthermore, the use of the combined optimised approach, i.e. integration of BioPCM and Cooled Beam, produces significantly less emission (21%) per year at the same time ensures the comfortability of the occupants which is the utmost consideration in the study. Finally, the study offered a net positive energy operating method to ensure that carbon footprint is minimised considering the present and future weather conditions. Overall, a practical thermal simulation orientated optimisation framework is developed and executed that unites the objective of minimising energy consumption of building systems as well as maintaining superior comfort of the people based on the present and future weather conditions.