Tesis: "Spectrum, Solar"

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Al, Jabri Issa Khamis Mohammed. "LED based solar spectrum simulator." Thesis, Al Jabri, Issa Khamis Mohammed (2018) LED based solar spectrum simulator. Honours thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/44782/.

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The aim of the study was to design and fabricate a LED based solar simulator to match the full solar spectrum of natural light. The finding of this research can be applied in the field of solar energy as it can be utilised in testing photovoltaic technology (PV). To achieve this objective, the researcher focused on selecting appropriate LEDs to match the solar spectrum and intensity, whilst also designing the LED solar fabricator and testing the temporal drift of the simulator’s spectrum and power distribution. The key hardware requirements were LEDs and LEDs drivers which were chosen based on their sizes and dimensions in addition to the degree to which they could match the solar spectrum. In selecting the driver, avoidance of Arduino was a key consideration. The software EasyEDA was utilised in creating printed circuit boards (PCB) while wavelength was measured by employing the Ocean view spectrometer. The results of the LED solar simulator were tested against the solar simulator class A of the American Society for Testing Materials (ASTM). The overall objective of the research to design and fabricate a LED solar simulator was achieved as the solar simulator successfully simulated the full range of visible light in the solar spectrum. However, due to the limitations of the spectrometer, ultraviolet and infrared light was not able to be simulated. Another principal discovery of the research conducted was that a closer match to the solar spectrum was attained where there were sufficient LEDs to maintain a small as possible gap between the light wavelengths. A further finding was that the light concentrator designed and constructed by the researcher was crucial to achieve the required mixture of light. In conclusion, the study highlights the fact that higher efficiency of LED solar simulators can be achieved through tuning the intensity, classification, size and uniformity of the wavelengths to match the solar spectrums.

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Tatsiankou, Viktar. "Instrumentation Development for Site-Specific Prediction of Spectral Effects on Concentrated Photovoltaic System Performance." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31222.

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The description of a novel device to measure the spectral direct normal irradiance is presented. The solar spectral irradiance meter (SSIM) was designed at the University of Ottawa as a cost-effective alternative to a prohibitively expensive field spectroradiometer (FSR). The latter measures highly-varying and location-dependent solar spectrum, which is essential for accurate characterization of a concentrating photovoltaic system’s performance. The SSIM measures solar spectral irradiance in several narrow wavelength bands with a combination of photodiodes with integrated interference filters. This device performs spectral measurements at a fraction of the cost of a FSR, but additional post-processing is required to deduce the solar spectrum. The model was developed to take the SSIM’s inputs and reconstruct the solar spectrum in 280–4000 nm range. It resolves major atmospheric processes, such as air mass changes, Rayleigh scattering, aerosol extinction, ozone and water vapour absorptions. The SSIM was installed at the University of Ottawa’s CPV testing facility in September, 2013. The device gathered six months of data from October, 2013 to March, 2014. The mean difference between the SSIM and the Eppley pyrheliometer was within ±1.5% for cloudless periods in October, 2013. However, interference filter degradation and condensation negatively affected the performance of the SSIM. Future design changes will improve the longterm reliability of the next generation SSIMs.

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Kwarikunda, Nicholas. "On the characterisation of solar cells using light beam induced current measurements." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/11147.

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The presence of inhomogeneities in semiconductor materials used to fabricate solar cell devices may result in spatial non uniformities in the device properties which may affect current generation in these devices. Besides, current reducing defects such as inclusions, local shunts and optical blockages may be introduced during the various device manufacturing processes which may adversely affect the performance and overall efficiency of solar cells. Diagnostic techniques are therefore needed to identify these defects so as to improve the production technology. This thesis presents the Light Beam Induced Current (LBIC) technique for mapping spatial non uniformities in solar cell devices. The LBIC is a non destructive characterisation technique that uses a focused light beam to raster scan a solar cell surface as the photo-generated current is recorded as a function of position to generate a photo-response map. The technique was used to obtain photoresponse maps for a mc-Si, Back contact Back junction (BC-BJ) silicon solar cell and the InGaP/InGaAs/Ge concentrating triple junction (CTJ) solar cell from which various local current reducing defects were mapped. A reflection signal detector was incorporated into the LBIC measurement system to enable us distinguish between optical blockages on the cell surface and current reducing defects within the solar cell devices. By dynamically biasing the solar cell devices, the electrical activity of the identified defects was investigated and also point-by-point current-voltage (I-V) characteristics were obtained. An interval division algorithm was applied to the measured point-by-point I-V characteristics to extract device and performance parameters from which device and performance parameter uniformity of the devices were mapped. Dark and full cell solar illumination I-V characteristics were also measured to extract device parameters. Analysis of extracted parameters revealed differences between extracted dark and illuminated device parameters which was attributed to departure from the superposition principle due to non-linearity of the semiconductor device equations with respect to carrier concentration. An investigation into the effect of illumination intensity on the I-V parameters of a spot illuminated BC-BJ Si solar cell showed a linear increase and a logarithmic increase of the short circuit current and open circuit voltage respectively with intensity while the series resistance decreased with intensity, which was attributed to increase in conductivity of the active layer. The ideality factor and saturation current were observed to increase while the shunt resistance initially increased before decreasing at higher intensity levels. Under monochromatic illumination, the photo-response of the BC-BJ Si cell was higher at 785nm than at 445nm due to low absorption coefficient of Si for longer wavelength radiations, resulting in carrier generation within the bulk, where there is a higher probability of carriers being collected at the p-n junction before they recombine. Under solar illumination, as the spectral content was altered using long pass colour filters with cut off wavelengths of 610nm and 1000nm, the performance parameters were observed to decrease and this was mainly due to decrease in intensity. For the CTJ solar cell, however, blocking of radiations below 610nm resulted in current mismatch that severely degraded the short circuit current (Isc). The current mismatch affected the extracted device and performance parameters. With a 1000nm long pass filter, a dark I-V was obtained since only the bottom Ge subcell was activated.

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4

Zhang, Deming. "Holographic Spectrum-Splitting Optical Systems for Solar Photovoltaics." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301498.

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Solar energy is the most abundant source of renewable energy available. The relatively high cost prevents solar photovoltaic (PV) from replacing fossil fuel on a larger scale. In solar PV power generation the cost is reduced with more efficient PV technologies. In this dissertation, methods to improve PV conversion efficiency with holographic optical components are discussed. The tandem multiple-junction approach has achieved very high conversion efficiency. However it is impossible to manufacture tandem PV cells at a low cost due to stringent fabrication standards and limited material types that satisfy lattice compatibility. Current produced by the tandem multi-junction PV cell is limited by the lowest junction due to series connection. Spectrum-splitting is a lateral multi-junction concept that is free of lattice and current matching constraints. Each PV cell can be optimized towards full absorption of a spectral band with tailored light-trapping schemes. Holographic optical components are designed to achieve spectrum-splitting PV energy conversion. The incident solar spectrum is separated onto multiple PV cells that are matched to the corresponding spectral band. Holographic spectrum-splitting can take advantage of existing and future low-cost technologies that produces high efficiency thin-film solar cells. Spectrum-splitting optical systems are designed and analyzed with both transmission and reflection holographic optical components. Prototype holograms are fabricated and high optical efficiency is achieved. Light-trapping in PV cells increases the effective optical path-length in the semiconductor material leading to improved absorption and conversion efficiency. It has been shown that the effective optical path length can be increased by a factor of 4n2 using diffusive surfaces. Ultra-light-trapping can be achieved with optical filters that limit the escape angle of the diffused light. Holographic reflection gratings have been shown to act as angle-wavelength selective filters that can function as ultra-light-trapping filters. Results from an experimental reflection hologram are used to model the absorption enhancement factor for a silicon solar cell and light-trapping filter. The result shows a significant improvement in current generation for thin-film silicon solar cells under typical operating conditions.

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Ayala, P. Silvana, Shelby Vorndran, Yuechen Wu, Benjamin Chrysler, and Raymond K. Kostuk. "Segmented holographic spectrum splitting concentrator." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622711.

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This paper presents a segmented parabolic concentrator employing holographic spectral filters that provide focusing and spectral bandwidth separation capability to the system. Strips of low band gap silicon photovoltaic (PV) cells are formed into a parabolic surface as shown by Holman et. al. [1]. The surface of the PV segments is covered with holographic elements formed in dichromated gelatin. The holographic elements are designed to transmit longer wavelengths to silicon cells, and to reflect short wavelength light towards a secondary collector where high-bandgap PV cells are mounted. The system can be optimized for different combinations of diffuse and direct solar illumination conditions for particular geographical locations by controlling the concentration ratio and filtering properties of the holographic elements. In addition, the reflectivity of the back contact of the silicon cells is used to increase the optical path length and light trapping. This potentially allows the use of thin film silicon for the low bandgap PV cell material. The optical design combines the focusing properties of the parabolic concentrator and the holographic element to control the concentration ratio and uniformity of the spectral distribution at the high bandgap cell location. The presentation concludes with a comparison of different spectrum splitting holographic filter materials for this application.

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Bhattacharya, Yajnavalkya. "Analysis of a solar occultation experiment from the space shuttle Columbia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0030/MQ27334.pdf.

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7

Walsh, Penelope Jane, and n/a. "Modelling and spectroscopy of polypyridyl and porphyrin complexes for electroluminescence and solar cell applications." University of Otago. Department of Chemistry, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070927.151236.

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This thesis reports the spectroscopic and computational studies of two classes of compounds, which have applications in new optoelectronic materials technology. Substituted ligands of dipyrido-[3,2a:2�,3�c]phenazine (dppz), and their Cu(I), Re(I) and Ru(II) complexes have utility in organic electroluminescent devices. A series of Zn(II) tetraphenylporphyrins with conjugated functional groups at the β-position have been used with success in liquid heterojunction dye-sensitized solar cells. The vibrational spectra and optoelectronic properties of the two classes were investigated using Raman, resonance Raman and transient resonance Raman spectroscopy, in conjunction with density functional theory methods. Density functional theory frequency calculations were used to aid vibrational mode assignments for the dppz compounds, and show close agreement with the experimental non-resonance Raman spectra. The enhancement of modes which are localized on differing sections of the ligand was identified. The nature of the absorbing chromophores for the dppz ligands and complexes was established using resonance Raman spectroscopy in concert with vibrational assignments from calculations. Transient resonance Raman spectra of the ligands provided spectral signatures for the triplet ligand-centred state; these features were observed in the TR� spectra of the metal complexes, along with other features attributable to MLCT states. Electroluminescent devices were fabricated using the dppz ligands and complexes as emissive dopants, and their properties investigated. The optoelectronic behaviour of the devices was found to be influenced by the mechanism of exciton formation on the dopant. The device properties were also dependent on the dopant concentration, the concentrations of other components and the driving voltage. The electronic structure of the porphyrin compounds was investigated using time-dependent density functional theory methods. Comparison of calculated optical transitions with experimental data shows that the calculations predict trends in the optical absorption spectra with change of functional group and with increase in conjugation chain length. The calculations suggest that the electron-withdrawing substituent decreases the configuration interaction effect by breaking the degeneracy of the two lowest unoccupied MOs, and other configuration interaction effects come into play involving other frontier MOs. Interrupting the conjugation of the functional group is shown to mitigate the breakdown of the configuration interaction. The perturbation of the normal electronic structure of the porphyrin by the substituent was also investigated using resonance Raman spectroscopy. Vibrational analysis identified bands due to the substituent, implying coupling between the porphyrin and substituent chromophores. Changes in frequency of porphyrin core modes due to the differing substituents and different metal centres were reproduced by density functional theory calculations. This project has allowed the spectroscopic investigation of the active optical states in a number of polypyridyl and porphyrin compounds, and determined the efficacy of DFT and TDDFT calculations to predict the properties of these compounds.

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Bierman, David M. (David Matthew). "Full spectrum utilization for high-efficiency solar energy conversion." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113547.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017. Cataloged from PDF version of thesis. Includes bibliographical references (pages 88-97). Today, two dominant strategies for solar energy harvesting exist: solar thermal and photovoltaic. Solar thermal energy harvesting offers the distinct ability to both utilize the full solar spectrum and provide dispatchable electrical power to the grid. By contrast, the generation of power via the photovoltaic effect can reduce the complexity of a system by eliminating moving parts. Conversion strategies which use both thermal and photovoltaic principles capitalize on the advantages of each. This thesis explores the potential of these technologies through both experimental and theoretical device-level studies. First, we explored solar thermophotovoltaic devices (STPVs) which convert broadband sunlight to narrow-band thermal radiation tuned for a photovoltaic cell. We demonstrated the highest STPV efficiency to date through the suppression of 80% of sub-bandgap blackbody radiation by pairing a one-dimensional photonic-crystal selective emitter with a tandem plasma-interference optical filter. We measured a solar-to-electrical conversion rate of 6.8%, exceeding the performance of the photovoltaic cell alone. Additionally, we show experimentally that STPVs can reduce the heat generation rates in the photovoltaic cell by a factor of two for the same power density. Next, we explored the use of spectral splitting as a different strategy to use both thermal and photovoltaic technologies. A model of an ideal solar spectral-splitting converter was developed to determine the conversion efficiency limit as well as the corresponding optimum spectral bandwidth of sunlight which should illuminate the photovoltaic cell. This bandwidth was also obtained analytically through an entropy minimization scheme and matches well with our model. We show that the maximum efficiency of the system occurs when it minimizes the spectral entropy generation. Beyond solar energy harvesting, we investigated the radiation dynamics of vanadium dioxide (VO2 ), which is of interest because of the abrupt decline of emittance at the insulator-metal transition at ~340 K. Negative differential emission is exploited to demonstrate thermal runaway of this system for the first time. These results are used to validate a radiation heat transfer model which explores the limiting behavior of a VO2 material set. by David M. Bierman. Ph. D.

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Chrysler, Benjamin D., Pelaez Silvana Ayala, Yuechen Wu, Shelby D. Vorndran, and Raymond K. Kostuk. "Environmental stability study of holographic solar spectrum splitting materials." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622712.

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In this study the impact of outdoor temperature variations and solar illumination exposure on spectral filter material and holographic optical elements is examined. Although holographic components have been shown to be useful for solar spectrum splitting designs, relatively little quantitative data exist to demonstrate the extent to which these materials can withstand outdoor conditions. As researchers seek to investigate practical spectrum splitting designs, the environmental stability of holographic materials should be considered as an important factor. In the experiment presented, two holographic materials, Covestro Bayfol HX photopolymer and dichromated gelatin, and 3M reflective polymer filter materials are exposed to outdoor conditions for a period of several months. The environmental effect on absorption, spectral and angular bandwidth, peak efficiency, and Bragg matching conditions for the holograms are examined. Spectral bandwidth and transmittance of the 3M reflective filter material are also monitored. Holographic gratings are recorded, measured, and mounted on glass substrates and then sealed with a glass cover plate. The test samples are then mounted on a photovoltaic panel to simulate realistic temperature conditions and placed at an outdoor test facility in Tucson, Arizona. A duplicate set of holograms and 3M filter material is stored as a control group and periodically compared over the test period.

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Sethi, Waleed Tariq. "Optical antennas for harvesting solar radiation energy." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S129/document.

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Au cours des dernières années, la communauté scientifique s'est intéressée de plus en plus à l'acquisition de sources d'énergie renouvelables vertes et propres par rapport aux combustibles fossiles traditionnels. Le rayonnement solaire est une source particulièrement abondante d'énergie renouvelable qui a été largement utilisée dans les véhicules, les machines et les bâtiments, entre autres. Il y a généralement deux manières différentes d'utiliser l'énergie solaire: la chaleur et l'électricité. La principale motivation de ce travail de thèse est d'utiliser cette abondante source d'énergie pour produire une petite fraction de la tension et du courant continu de sortie. Puisque le spectre solaire se situe dans les longueurs d'onde à l'échelle nanométrique ou dans la bande térahertz, les antennes optiques seront utilisées comme une nouvelle technologie de nanotechnologie pour capter et récolter l'énergie solaire. Les antennes optiques ont des propriétés similaires à celles de leurs homologues micro-ondes, mais leur avantage réside dans des moyens sans précédent pour adapter les champs électromagnétiques dans tous leurs aspects et applications. Par conséquent, avec les détails mentionnés ci-dessus, l'idée principale de cette thèse est de capturer le rayonnement infrarouge solaire et l'utiliser pour produire une tension continue de sortie. La première partie de cette thèse est consacrée à la compréhension du fonctionnement de la collecte d'énergie par radiofréquence (RF) et à la présentation d'un concept de rectenna. La deuxième partie traite de l'introduction et de la simulation d'antennes optiques à base de résonateurs diélectriques (DR) car elles offrent moins de pertes à la bande THz. Deux conceptions de DR différentes sont proposées fonctionnant à la fréquence centrale de 193,5 THz (longueur d'onde 1550 nm). La troisième partie traite de la contribution principale à ce travail en termes de conception, simulation et fabrication d'une antenne optique Yagi-uda à haut gain et large bande. La technique de lithographie par faisceau d'électrons est utilisée pour réaliser la structure proposée. En dehors de la conception de l'élément unique Yagi-uda, diverses configurations de réseau ont été simulées avec la réalisation d'un réseau d'éléments 100 x 100 fabriqué sur un substrat de silicium. Pour produire une certaine quantité de tension de sortie, deux techniques ont été utilisées pour tester le réseau d'antennes optiques Yagi-uda. La première technique impliquait l'intégration du réseau Yagi-uda avec une diode fermionique du commerce qui produisait une tension de sortie de 0,15 V par excitation à partir d'une lumière visible et de 0,52 V par excitation directe à partir d'un laser à 1550 nm. La deuxième technique est basée sur la dissipation thermique entre des métaux dissemblables produisant une tension de sortie. Quatre lasers à longueurs d'onde différents (532 nm, 650 nm, 940 nm et 1550 nm) ont excité trois conceptions de nantenna réalisées. Parmi ces conceptions, la tension de sortie maximale de 0,82 V a été produite par le réseau Yagi-uda lorsqu'il est excité via un laser de 1550 nm Recent years have witnessed an increased interest by the scientific community to acquire green and clean renewable sources of energy compared to traditional fossil fuels. Solar radiation is one particular abundant source of renewable energy that has been widely applied in vehicles, machines, and buildings, among others. There are generally two different ways in which solar energy is used – heat and electricity. The main motivation of this thesis work is to utilize that abundant source of energy in producing a small fraction of output DC voltage and current. Since the solar spectrum lies in the nano scale wavelengths or terahertz band, optical antennas as a novel nano fabrication technology will be used to capture and harvest the solar energy. Optical antennas have properties similar to their microwave counterparts, but the advantage they have is in terms of unprecedented means to tailor electromagnetic fields in all its aspects and applications. Therefore, with the aforementioned details, the main idea of this thesis is to capture the solar infrared radiation and utilize it for producing output DC voltage. The first part of this thesis is dedicated to understanding the working of radio frequency (RF) energy harvesting and presenting a rectenna design. The second part deals with the introduction and simulation of optical antennas based of dielectric resonators (DR) as they offer fewer losses at the THz band. Two different DR designs are proposed working at the center frequency of 193.5 THz (1550 nm wavelength). The third part discusses the main contribution to this work in terms of design, simulation and fabrication of a high gain and wideband Yagi-uda optical antenna. E-beam lithography technique is used to realize the proposed structure. Apart for the single element Yagi-uda design, various array configurations have been simulated with realization of a 100 x 100 elements array fabricated on a silicon substrate. To produce a certain amount of output voltage, two techniques were deployed in testing the realized Yagi-uda optical antenna array. The first technique involved integration of the Yagi-uda array with a commercial fermionic diode that produced output voltage of 0.15 V via excitation from a visible light and 0.52 V with direct excitation from a 1550 nm laser. The second technique is based on thermal dissipation among dissimilar metals producing an output voltage. Four different wavelength (532 nm, 650 nm, 940 nm and 1550 nm) lasers excited three realized nantenna designs. Among these designs, the maximum output voltage of 0.82 V was produced by the Yagi-uda array when excited via 1550 nm laser

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Mambrini, Thomas. "Caractérisation de panneaux solaires photovoltaïques en conditions réelles d’implantation et en fonction des différentes technologies." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112380/document.

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Dans un contexte de fort déploiement du Photovoltaïque (PV), de plus en plus de recherches sont menées pour assurer une certaine fiabilité et prédictibilité de la production provenant du PV. Les investisseurs se plaignent d’un manque de visibilité dans cette filière et hésitent à investir dans le PV (surtout avec les baisses régulières des tarifs de rachats). Il est donc nécessaire pour le développement de la filière PV de faire des efforts pour étudier, comprendre les systèmes PV en fonctionnement et ainsi donner plus de visibilité pour l’amélioration des systèmes, leur monitoring, une plus grande fiabilité et pouvoir prédire plus précisément le productible PV en améliorant les modèles de prédiction du productible PV déjà existants.C’est dans ce cadre que s’inscrit cette thèse qui a pour but de caractériser les modules PV en conditions réelles d’utilisation en fonction des différentes technologies. Nous étudions, dans cette thèse, les facteurs extérieurs qui influent sur le comportement des modules de différentes filières, pour tenter de rendre le PV plus fiable et prédictible. C’est donc un axe de recherche qui vient en complément de la caractérisation en laboratoire qui a pour objectif l’amélioration des rendements des cellules.Pour y parvenir il est nécessaire, dans un premier temps, de connaitre les paramètres extérieurs qui influent sur le fonctionnement du module et savoir comment les étudier. Une partie de la thèse est par conséquent consacrée à l'étude des facteurs météorologiques et atmosphériques ayant un impact sur le comportement électrique du module ainsi que la mise en place d'instruments et méthodes pour les mesurer. On présente également les avantages et inconvénients de la caractérisation en extérieur.Après avoir exposé tous les paramètres à prendre en compte, on décrit l'installation de plusieurs plateformes de caractérisation de modules PV entièrement automatisées que l'on a monté au cours de cette thèse au LGEP ainsi qu'à l'École Polytechnique et qui ont toutes un objectif particulier.Ce manuscrit montre par la suite les différentes applications et utilités que peuvent avoir de telles plateformes en analysant les données enregistrées régulièrement (toutes les minutes en moyenne) sur des périodes allant de quelques jours à plusieurs mois. On compare, par la même occasion, les données constructeur prises en conditions standard de test et les performances mesurées dans de nombreuses conditions de modules PV. Les résultats obtenus peuvent servir à la fois pour la recherche, l'aide à la compréhension du comportement des modules, par conséquent aide à la prévision du productible d'installation PV et peuvent avoir un rôle pédagogique dans l'enseignement du PV.Enfin, une dernière partie est dédiée à la description et à la démonstration de faisabilité d'une carte qui permet d'obtenir les caractéristiques principales de n'importe quel module PV en les extrayant de la courbe I(V) mesurée. Cette carte, développée au LGEP, a d'autres utilités telles que la recherche du point de fonctionnement maximale du module (MPPT) Nowadays, photovoltaic (PV) keeps growing fast and an increasing number of studies is require in order to assure the reliability and predictability of the PV-produced electricity. The lack of visibility concerning this field is a continuous source of complaints from the investors who hesitate to commit to PV projects (especially after the decrease of buying prices in Europe). Therefore, to assure the successful increase of PV energy, it is necessary to provide studies aiming at better understanding PV systems in real operations conditions, that means in outdoor conditions.The goal of this doctoral work has been to characterize different PV module technologies in their real use conditions. The outdoor parameters that influence the behavior of different module technologies have been investigated. The goal was to obtain useful information which could make PV-produced electricity more reliable. Therefore, these studies can efficiently complete standard laboratory characterization tests made under a single condition, the purpose of which is usually to determine the efficiency of the different solar cells technologies.To achieve this goal, first it has been necessary to define the outdoor parameters that mainly influence the modules and the most suitable methods to be used for their investigation. For this reason, part of this doctoral work has been devoted to the study of weather and atmospheric factors affecting the electrical behavior of the modules, as well as setting up instruments and methods to measure them. Additionally, advantages and disadvantages of outdoors characterizations have been addressed.Then, after multiple fully automated PV platforms, mounted at the LGEP and at Ecole Polytechnique, thanks to a collaboration with the Laboratoire de Méteorologie Dynamique (LMD). The different applications and uses of these platforms have been highlighted by analyzing data recorded periodically (every minute on average) over periods ranging from days to several months. Manufacturer data, which are acquired in standard test conditions, and the performance measured in several conditions are compared. These results can be used for both research, understanding the behavior of the modules, help in predicting the energy yield of PV system and also to stress the educational role in teaching PV.Finally, the feasibility of an electric card that provides the main characteristics of any PV module by extracting the measured I(V) curve is described. Such electric card, developed at the LGEP, has other uses such as the determination of the maximum operating point

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Wu, Yuechen, and Raymond K. Kostuk. "Two-junction holographic spectrum-splitting microconcentrating photovoltaic system." SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS, 2017. http://hdl.handle.net/10150/623284.

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Spectrum-splitting is a multijunction photovoltaic technology that can effectively improve the conversion efficiency and reduce the cost of photovoltaic systems. Microscale PV design integrates a group of microconcentrating photovoltaic (CPV) systems into an array. It retains the benefits of CPV and obtains other benefits such as a compact form, improved heat rejection capacity, and more versatile PV cell interconnect configurations. We describe the design and performance of a two-junction holographic spectrum-splitting micro-CPV system that uses GaAs wide bandgap and silicon narrow bandgap PV cells. The performance of the system is simulated with a nonsequential raytracing model and compared to the performance of the highest efficiency PV cell used in the micro-CPVarray. The results show that the proposed system reaches the conversion efficiency of 31.98% with a quantum concentration ratio of 14.41x on the GaAs cell and 0.75x on the silicon cell when illuminated with the direct AM1.5 spectrum. This system obtains an improvement over the best bandgap PV cell of 20.05%, and has an acceptance angle of +/- 6 deg allowing for tolerant tracking. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

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13

Hashim, Hasan. "Full-spectrum solar energy harvesting using nanotechnology-enabled photovoltaic/thermoelectric hybrid system." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/87143/.

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Carbon emissions, climate change and the finite resource of fossil fuels are driving an increasing need for renewable energy, and in particular, an interest in photovoltaic (PV) cells. Most PV cells operate in temperatures above 25 oC, and the performance of PV cells reduces with increased operation temperature. This research aims to resolve some engineering issues by integrating PV cells with a thermoelectric generator (TEG). Integrating TEG with PV cells helps to transfer heat from the PV through the TEG to an actively or passively cooled heat sink. The temperature difference established across the TEG can generates additional electrical power by the Seebeck effect. The main objective of this research is to investigate the feasibility of developing a PV/TEG hybrid system that can offer better performance than that can be obtained from each individual system. The key parameters, which are crucial to the development of efficient hybrid system, were investigated. These include the temperature coefficient of PV cells, geometry of TEGs and thermal coupling between the PV and TEG. It was found that the dye sensitised solar cells (DSC) has a preferred temperature coefficient that are the most suitable for use in a PV/TEG system. In this work, a theoretical model was also developed for determination of the optimal geometry of the TEG for PV/TEG hybrid systems. A special type of DSCs was designed and fabricated which employ titanium as the counter electrode (other than conventional FTO-glass) to improve the thermal coupling between the PV and TEG. A unique DSC/TEG hybrid system was constructed using this special type of DSC and its generating performance was studied in comparison with a similar system that uses conventional FTO-glass counter electrode. The experimental results show that the power output and efficiency of the hybrid PV/TEG system with Ti counter electrode is significantly higher than the similar system with a conventional FTO-glass electrode due to an improved thermal coupling between the DSC and TEG. It is concluded that a hybrid PV/TEG system can provide improved performance beyond that of each individual system. However, the improvement can only be achieved with appropriate type of PV cells, optimised TEGs and advanced structures for integration, such as Ti counter electrode.

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Leite, Cicero Alexandre. "Utilização de malhas coloridas na produção de flores de alta, media e baixa exigencia em radiação solar." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257015.

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Orientadores: Maria Angela Fagnani Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola Made available in DSpace on 2018-08-07T22:58:20Z (GMT). No. of bitstreams: 1 Leite_CiceroAlexandre_D.pdf: 5359491 bytes, checksum: 85d9823bcfcf799676c4fee678ed8746 (MD5) Previous issue date: 2006 Doutorado Agua e Solo Doutor em Engenharia Agrícola

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Vorndran, Shelby, Benjamin Chrysler, and Raymond K. Kostuk. "Comparison of holographic lens and filter systems for lateral spectrum splitting." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622713.

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Spectrum splitting is an approach to increasing the conversion efficiency of a photovoltaic (PV) system. Several methods can be used to perform this function which requires efficient spatial separation of different spectral bands of the incident solar radiation. In this paper several of holographic methods for implementing spectrum splitting are reviewed along with the benefits and disadvantages associated with each approach. The review indicates that a volume holographic lens has many advantages for spectrum splitting in terms of both power conversion efficiency and energy yield. A specific design for a volume holographic spectrum splitting lens is discussed for use with high bandgap InGaP and low bandgap silicon PV cells. The holographic lenses are modeled using rigorous coupled wave analysis, and the optical efficiency is evaluated using non-sequential raytracing. A proof-of-concept off-axis holographic lens is also recorded in dichromated gelatin film and the spectral diffraction efficiency of the hologram is measured with multiple laser sources across the diffracted spectral band. The experimental volume holographic lens (VHL) characteristics are compared to an ideal spectrum splitting filter in terms of power conversion efficiency and energy yield in environments with high direct normal incidence (DNI) illumination and high levels of diffuse illumination. The results show that the experimental VHL can achieve 62.5% of the ideal filter power conversion efficiency, 64.8% of the ideal filter DNI environment energy yield, and 57.7% of the ideal diffuse environment energy yield performance.

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16

Alkiswani, Mutaz. "Spectrum conversion in solar cells industry : Novel model concept and steps towards commercialization." Thesis, Högskolan i Halmstad, Energivetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-28429.

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Solar photovoltaic industry is a hot research field, massive attempts are going on all over the world to increase its productivity in different ways. One of the challenges for solar cells is the light spectrum mismatch losses, which referred to the part of solar spectrum that cannot be utilized to electricity by the conventional cells. Two ways have been suggested to overcome solar spectrum mismatch losses, the first is multi layered cells (tandem cells) with a different light behavior for each layer, and the second is spectrum conversion which is this researches subject. Spectral modification or conversion in solar cells industry has been studied and different lab scale models have been introduced. According to nanoscale journal, such technology may be the base of the next generation solar cells, mentioning specifically the use of luminescence down conversion and up conversion techniques to control the light spectrum on the solar cell, these endeavors targets to produce solar cells that is not subjugated to Shockley-Queisser maximum efficiency limit of 31%. This research aims to draw a map of various ideas introduced to incorporate similar technologies in solar cell products, beside further suggestion to enhance its technical behavior and to push the commercialization of the technology forward. This is expected to reveal clear image about technology’s future development map for the upcoming studies, and to create a motivation for further studies towards a commercial production scale. The proposed commercialized model will result in enhancing the maximum theoretical efficiency limit to 48% if all spectral mismatch loses have been eliminated. Quantum energy level diagrams have been illustrated to describe each model’s performance under a theoretical light spectrum.

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17

Caga, Noloyiso. "The characterization and electrochemistry of dye-sensitized solar cells." Thesis, University of Fort Hare, 2013. http://hdl.handle.net/10353/d1016069.

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In this study a presentation of the technology behind dye-sensitized solar cells, their design as well as the role of the different parts of the cell. The characterization of the cell is divided into four sections namely: the characterization of the paste required to make the TiO2 film and its optical properties using SEM-EDX and XRD analytical techniques; Analysis of the various absorptions of three Ru-based dyes using UV-Vis spectroscopy, Photoluminescence and Fourier Transform Infra-Red spectroscopy; the characterization and the analyses of the entire cell using Electrochemical Impedance Spectroscopy. The nine cells were prepared by examining RuL2(CN)2 , RuL2(NCS)2 or N3 dye and RuL2(NCS)2 TBA+ or N719 dye. [L = 2,2'-bipyridyl-4,4'-dicarboxylic acid ;TBA = tetra-butyl ammonium] were combined with three electrolytes namely: Z–150 , AN–50 and PN–50. The Iodolyte PN–50 is an iodide based low viscosity electrolyte with 50 mM of tri-iodide dissolved in a solvent called propionitrile (PN). The Iodolyte AN–50 is an iodide based low viscosity electrolyte with 50 mM of tri-iodide dissolved in a solvent called acetonitrile (AN). The Iodolyte Z–150 is an iodide based low viscosity electrolyte with 150 mM of tri-iodide dissolved in a solvent called 3-methoxypropionitrile (MPN) and with additives such an ionic liquid, malkylbenziimidazole and guanidine thiocyanate. A solar simulator was utilized with which the standard solar irradiation can be created in laboratory conditions. The fill factors as well as overall performance efficiencies of the these cells are quite low < 1.0%,.

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18

Zhao, Jian. "Supported gold nanoparticles as photocatalysts utilising the full solar spectrum for organic synthesis." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/63703/2/Jian_Zhao_Thesis.pdf.

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This thesis is an innovative study for organic synthesis using supported gold nanoparticles as photocatalysts under visible light irradiation. It especially examines a novel green process for efficient hydroamination of alkynes with amines. The investigation of other traditional reduction and oxidation reactions also adds significantly to the knowledge of gold nanoparticles and titania nanofibres as photocatalysts for organic synthesis.

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19

Anil, Kumar R. "Measurement Of Solar Cell AC Parameters Using Impedance Spectroscopy." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/203.

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Photovoltaic (PV) conversion of solar energy appears to be one of the most promising ways of meeting the increasing future energy demand. In space, photovoltaic power source is the only alternative. The demand for higher power has necessitated the use of high speed switching charge controller and power conditioner. To design an efficient and reliable switching charge controller, the static (I-V) and dynamic (AC) characteristics of a solar cell need to be understood. The AC parameters of a solar cell can be measured either by Frequency Domain technique or by Time Domain technique. In frequency domain technique, a small signal is applied about the operating point and the AC parameters are measured. Hence, in the frequency domain technique the steady state values of AC parameters at a particular operating condition are measured. In time domain technique, a transient measurement is made where the cell voltage varies from short-circuit to open circuit or vice versa. Hence, this technique gives only the time constant of a solar cell. The impedance spectroscopy is a frequency domain technique widely used in electro chemistry to study battery characteristics. In the present investigation, the impedance spectroscopy is proposed for measuring the AC parameters of solar cells. An experimental set-up has been developed to measure the solar cell AC parameters. The AC parameters of Silicon (BSR and BSFR) solar cells and GaAs/Ge solar cells are measured using impedance spectroscopy (IS). The cell capacitance, the parallel resistance and the series resistance are measured and compared. GaAs/Ge solar cell has shown only transition Capacitance throughout its operating range while silicon (BSR and BSFR) solar cells exhibited both transition and diffusion capacitances. Theoretical and experimental values of the cell parallel resistance are compared and are in good agreement. While the diode factor in silicon solar cell varies from 2 to 1, where as in GaAs/Ge solar cell it varies from 4 to 2 to 1. Measurements conducted using open circuit voltage buildup (time domain technique) on silicon BSR solar cell shows that the collected data can be used for the restricted purpose of measuring cell transient response. The dime domain technique could not estimate the solar cell. It may be noted that the impedance spectroscopy assumes piece-wise linearity of the solar cell characteristics, lending itself for easy measurement and modeling. This assumption is valid as the signal amplitude is less than thermal voltage (VT). Since, the parameters are measured under steady state, the values are more stable and accurate. An attempt has also been made to correlate the measured AC parameters with the requirements of switching charge controllers. These correlations can be used to design the switching controllers for device rating, circuit stability and other aspects.

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20

Vorndran, Shelby D. "Diffractive Optical Element Design for Lateral Spectrum Splitting Photovoltaics." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/612878.

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In this work, two distinct types of Diffractive Optical Elements (DOEs) are designed to laterally distribute the solar spectrum across multiple photovoltaic (PV) cells. Each PV cell receives a spectral band near its bandgap energy to maximize overall solar-to-electric conversion efficiency of the system. The first DOE is an off-axis volume holographic lens. Design parameters include lateral grating period and slant angle, index modulation, film thickness, and control of swelling and index modulation attenuation in the film development process. Diffraction efficiency across the holographic lens is simulated using Rigorous Coupled Wave Analysis (RCWA). A full system model is created, and non-sequential raytracing is performed. Performance is evaluated under AM 1.5 conditions and annual insolation in Tucson, AZ, and Seattle, WA. A proof-of-concept off-axis holographic lens is fabricated and its performance is measured to confirm the optical properties of this system. The second DOE is an algorithmically-designed freeform surface relief structure. The Gerchberg-Saxton design algorithm is expanded to consider multiple wavelengths, resulting in a Broadband Gerchberg-Saxton (BGS) algorithm. All design variables are evaluated in a parametric study of the algorithm. Several DOE designs are proposed for spectrum splitting, and two of these designs are fabricated and measured. Additional considerations, such as finite sampling of the discrete Fourier transform, fabrication error, and solar divergence are addressed. The dissertation will conclude with a summary of spectrum splitting performance of all proposed DOEs, as well as a comparison to ideal spectrum splitting performance and discussion of areas for improvement and future work.

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21

Mathumba, Penny. "Aluminium and gold functionalized graphene quantum dots as electron acceptors for inverted Schottky junction type rainbow solar cells." University of Western Cape, 2020. http://hdl.handle.net/11394/7232.

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Philosophiae Doctor - PhD The main aim of this study was to prepare band gap-engineered graphene quantum dot (GQD) structures which match the different energies of the visible region in the solar spectrum. These band gap-engineered graphene quantum dot structures were used as donor materials in rainbow Schottky junction solar cells, targeting all the energies in the visible region of the solar spectrum for improved solar-to-electricity power conversion efficiency. Structural characterisation of the prepared nanomaterials under solid-state nuclear magnetic resonance spectroscopy (SS-NMR) showed appearance of bands at 40 ppm due to the presence of sp3 hybridised carbon atoms from the peripheral region of the GQD structures. Other bands were observed at 130 ppm due to the presence of polycyclic aromatic carbon atoms from the benzene rings of the GQD backbone, and around 180 ppm due to the presence of carboxylic acid carbons from oxidation due to moisture. Fourier-transform infrared resonance (FTIR) spectroscopy further confirmed the presence of aromatic carbon atoms and oxidised carbons due to the presence of C=O, C=C and -OH functional groups, concurrent with SS-NMR results. 2023-12-01

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22

Wilson, Jeanne R. "A measurement of the â¸B solar neutrino energy spectrum at the Sudbury Neutrino Observatory." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409729.

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23

Orebi, Gann Gabriel D. "An improved measurement of the B Solar Neutrino energy spectrum at the sudbury neutrino observatory." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510201.

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24

Hicks, Nathan Andrew. "Solar Power for Deployment in Populated Areas." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/141.

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The thesis presents background on solar thermal energy and addresses the structural challenges associated with the deployment of concentrating solar power fields in urban areas. Two potential structural systems and urban locales of deployment are proposed and investigated to determine whether they have the potential to be a cost-effective renewable energy solution for urban areas. The structural issues explored in the thesis include flutter, the wind loading of open frame structures, performance-based design, and the design of flexibly mounted equipment on a building.

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25

Chrysler, Benjamin D., Pelaez Silvana Ayala, Raymond K. Kostuk, and Yuechen Wu. "Design and optimization of cascaded DCG based holographic elements for spectrum-splitting PV systems." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/626491.

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In this work, the technique of designing and optimizing broadband volume transmission holograms using dichromate gelatin (DCG) is summarized for solar spectrum-splitting application. Spectrum splitting photovoltaic system uses a series of single bandgap PV cells that have different spectral conversion efficiency properties to more fully utilize the solar spectrum. In such a system, one or more high performance optical filters are usually required to split the solar spectrum and efficiently send them to the corresponding PV cells. An ideal spectral filter should have a rectangular shape with sharp transition wavelengths. DCG is a near ideal holographic material for solar applications as it can achieve high refractive index modulation, low absorption and scattering properties and long-term stability to solar exposure after sealing. In this research, a methodology of designing and modeling a transmission DCG hologram using coupled wave analysis for different PV bandgap combinations is described. To achieve a broad diffraction bandwidth and sharp cut-off wavelength, a cascaded structure of multiple thick holograms is described. A search algorithm is also developed to optimize both single and two-layer cascaded holographic spectrum splitters for the best bandgap combinations of two- and three-junction SSPV systems illuminated under the AM1.5 solar spectrum. The power conversion efficiencies of the optimized systems under the AM1.5 solar spectrum are then calculated using the detailed balance method, and shows an improvement compared with tandem structure.

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26

Bolsee, David. "Métrologie de la spectrophotométrie solaire absolue: principes, mise en oeuvre et résultats ;Instrument SOLSPEC à bord de la station spatiale internationale." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209709.

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Le Soleil est une étoile variable dont l’éclairement présente un large spectre de périodicités (de quelques minutes à plusieurs décennies). L’amplitude de ces variabilités présente une forte dépendance en longueur d’onde. La mesure précise de l’éclairement spectral hors atmosphère et de cette variabilité selon une échelle radiométrique absolue constituent une entrée fondamentale pour les domaines de recherche suivants :- En physique solaire, ces mesures permettent de valider les modèles étudiant la composition de l’atmosphère solaire, les processus physiques internes et leur variabilité.- La photochimie atmosphérique terrestre et les modèles climatiques. La composition, la structure thermique et la dynamique de l’atmosphère terrestre sont dépendantes du flux solaire incident, de sa distribution en longueur d’onde et de sa variabilité. Les mesures sont requises pour une validation des modèles de transfert radiatif et climatiques.La nécessité d’une mesure continue dans le temps et hors atmosphère s’impose car chaque cycle solaire possède ses propres caractéristiques. Ces mesures sont réalisées depuis plus de 30 ans par des spectroradiomètres adaptés à l’environnement spatial. L’instrument SOLSPEC (SOLar SPECtrum) a apporté une contribution majeure à ces mesures.Le travail présenté dans ce manuscrit est associé à la sélection de SOLSPEC pour une mission à bord de la Station Spatiale Internationale (ISS). Les objectifs ont consisté à adapter l’instrument pour une mission à long terme (2008-2016), à étendre la plage spectrale couverte par SOLSPEC et à réduire l’incertitude de mesures. Il est structuré en deux parties :- La remise à niveau de l’instrumentation et son étalonnage radiométrique.- Le traitement des données pour les premières mesures en orbite.L’instrument a été modifié pour satisfaire de nouvelles exigences de dimensions et de masse. De nouveaux sous-systèmes optiques (unité interne d’étalonnage, pointeur solaire) ont été développés pour permettre la détection et la correction de toute dérive angulaire ou de réponse absolue de manière autonome. La plage spectrale de fonctionnement a été étendue entre 166 et 3088 nm. Une caractérisation radiométrique approfondie de SOLSPEC a été effectuée. L’étalonnage absolu a été réalisé à partir de l’étalon primaire en éclairement spectral (rayonnement du corps noir) du PTB (Physikalisch-Technische Bundesanstalt). Une estimation des incertitudes standard utilisant le formalisme mathématique appliqué en métrologie a été développée. Les résultats donnent une incertitude réduite entre 2 % à 4 % pour la plage 166-370 nm, inférieure à 2 % entre 370 et 2350 nm, comprise entre 2 et 5 % pour l’intervalle 2350-2580 nm et de 5 à 10 % entre 2580 et 2920 nm. Une valeur inférieure à 1 % est atteinte entre 500 et 1900 nm. Les mesures consécutives à la mise en orbite de SOLSPEC ont confirmé le maintien des performances radiométriques. Le spectre solaire hors atmosphère a été déterminé et comparé aux résultats antérieurs et actuels des missions respectives SOLSPEC ATLAS et SORCE. Il correspond à l’activité solaire du début de la mission SOLAR (mi-2008).The Sun is a variable star. Its irradiance presents a wide range of periodicity varying from minutes to decades. The amplitude of this variability is strongly wavelength dependent. The accurate determination of the solar spectral irradiance above the atmosphere in absolute radiometric scale and the study of its variability are main issues for the following researches:- In solar physics, these measurements are required for the validation of the models studying the composition of the solar atmosphere, the internal physical processes and their variability.- For the photochemistry of the Earth’s atmosphere and the climate modeling. The composition, the thermal structure and the dynamics of the atmosphere are dependant on the incoming solar flux, its spectral distribution and variability. The measurements are required for the validation of radiative transfer and climate models.As each solar cycle presents a different behavior, there was a need for continuous measurements above the atmosphere. Such measurements were performed since more than 30 years by means of space qualified spectroradiometers. The SOLSPEC (SOLar SPECtrum) instrument brought a major contribution in this respect. The present work is devoted to the SOLSPEC instrument that was selected for a new mission on board the International Space Station (ISS). The objectives were to refurbish the instrument and to adapt it for a long term mission (2008-2016), to extend the wavelength coverage and to reduce the uncertainties on the measurements. This work is developed in two parts:- The refurbishment and the radiometric characterization of the instrument.- The data processing of the first results after the launch.The instrument was modified in order to fulfill new requirements of dimensions and mass. Different optical sub-systems (internal lamp unit, passive solar sensor) were developed in order to obtain on board capabilities for the detection and the correction of any trend in the absolute response. The spectral range was extended to 166 - 3088 nm. A full radiometric characterization of SOLSPEC has been carried out and is presented in this work. The absolute calibration was performed using the primary standard of spectral irradiance (black-body radiation) of the PTB (Physikalisch-Technische Bundesanstalt). The evaluation of the standard uncertainties is presented using the mathematical methodology applied in metrology. The results provide an uncertainty limited to 2 % - 4 % between 166 and 370 nm, below 2 % from 370 to 2350 nm, between 2 and 5 % for the spectral range 2350 - 2580 nm and 5 % to 10 % between 2580 and 2900 nm. The uncertainty is below 1 % between 500 and 1900 nm. The stability of the radiometric performances was demonstrated from the analysis of the first measurements after the launch, at the beginning of the mission. The solar spectrum above the atmosphere was determined and compared to results obtained from the previous SOLSPEC ATLAS and ongoing SORCE missions. This spectrum corresponds to the solar activity at mid-2008. Doctorat en Sciences de l'ingénieur info:eu-repo/semantics/nonPublished

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27

Deutsch, Kerry Ann. "Behavior of the atomic oxygen 5577 Ångström emission intensity at mid-latitudes : a climatological view /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/6803.

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Gouvêa, Evaldo Chagas [UNESP]. "Resposta espectral de células fotovoltaicas em condições reais de operação." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150981.

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Submitted by Evaldo Chagas Gouvêa null (gouvea.evaldo@gmail.com) on 2017-06-24T18:23:39Z No. of bitstreams: 1 Dissertação (versão FINAL 24-06-17).pdf: 2860581 bytes, checksum: 291ca83eac21bea9374f8dc5c9b080ed (MD5) Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-06-28T16:53:32Z (GMT) No. of bitstreams: 1 gouvea_ec_me_guara.pdf: 2860581 bytes, checksum: 291ca83eac21bea9374f8dc5c9b080ed (MD5) Made available in DSpace on 2017-06-28T16:53:32Z (GMT). No. of bitstreams: 1 gouvea_ec_me_guara.pdf: 2860581 bytes, checksum: 291ca83eac21bea9374f8dc5c9b080ed (MD5) Previous issue date: 2017-04-22 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Uma das alternativas à utilização de combustíveis fósseis é a energia solar, obtida pelo uso de painéis fotovoltaicos. A existência de diferenças diárias, sazonais e regionais na distribuição espectral da luz do sol pode produzir variações na capacidade de produção de energia dos painéis. O objetivo deste trabalho é verificar como a geração de energia de células fotovoltaicas varia em função dos diferentes comprimentos de onda do espectro da luz solar, quando as células estão submetidas a condições reais de operação. Este trabalho possui caráter experimental. Dois painéis fotovoltaicos policristalinos idênticos foram montados lado a lado. Oito diferentes filtros de cor, com curvas conhecidas de distribuição espectral, foram instalados sobre um dos painéis e foi registrada a quantidade de energia gerada por cada painel ao longo do dia. Cada filtro permite apenas a passagem de uma determinada faixa de comprimentos de onda da luz solar. Foi calculada a eficiência relativa de cada filtro, dada pela relação entre a quantidade de energia gerada pelo painel com filtro e a gerada pelo painel sem filtro, de referência. Os resultados indicam que os painéis produzem mais energia na faixa do vermelho, com eficiência relativa de 23,83%, sendo, portanto, mais sensíveis à radiação nesta faixa de comprimentos de onda. Por outro lado, ocorre uma redução da resposta do painel na faixa do verde e azul, apresentando eficiências de 19,15% e 21,58% respectivamente. Isso mostra que painéis fotovoltaicos não respondem de maneira uniforme à luz solar. A radiação infravermelha, além de produzir um aumento de temperatura, exerce um importante papel na produção total de energia, com eficiência de 13,56%. Conclui-se que painéis de silício cristalino não respondem de maneira uniforme à luz solar. Os painéis produzem energia nas faixas não-visíveis do espectro; sendo o infravermelho um importante componente do espectro. As respostas espectrais em condições reais de operação apresentam diferenças significativas em relação àquelas obtidas nas condições padrão de ensaio. Solar energy is an alternative to fossil fuels. It can be obtained through the use of photovoltaic panels. There are daily, seasonal and regional differences in the spectral energy distribution of sunlight that can result in variations in the energy production capacity of the panels. The objective of this study is the verification of the photovoltaic cell’s response to different wavelengths of the sunlight’s spectrum, under real operating conditions. This is an experimental study. Two identical polycrystalline photovoltaic modules were mounted side-by-side. Eight different color filters, each one with a specific spectral distribution curve, were installed above one of the panels and the daily generated energy of each panel was registered. Each color filter allows just a specific wavelength range of solar spectrum to pass through it. The relative efficiency of each filter was calculated; it is given by the relation between the energy generated by the solar panel with filter and the solar panel without filter. The results indicate that the panels produce more power in the red range (with a relative efficiency of 23.83%) and therefore they are more sensitive to radiation at this wavelength range. Also, the panel’s response is reduced in the color ranges of green and blue, with efficiency of 19.15% and 21.58%, respectively. This shows that photovoltaic panels do not respond uniformly to sunlight. Infrared radiation, which leads to an increased temperature, plays an important role in the total energy production. The relative efficiency of infrared filter is 13.56%. It can be concluded that crystalline silicon photovoltaic modules do not respond uniformly to sunlight. Photovoltaic panels are able to produce energy not only with visible light but also with non-visible wavelengths, being infrared an important component of solar spectrum. The spectral responses under real operating conditions are significantly different from the responses obtained at the standard test conditions. CNPq: 134367/2015-4

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Chrysler, Benjamin D., Yuechen Wu, Raymond K. Kostuk, and Zhengshan Yu. "Volume holographic lens spectrum-splitting photovoltaic system for high energy yield with direct and diffuse solar illumination." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/627188.

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In this paper a prototype spectrum-splitting photovoltaic system based on volume holographic lenses (VHL) is designed, fabricated and tested. In spectrum-splitting systems, incident sunlight is divided in spectral bands for optimal conversion by a set of single-junction PV cells that are laterally separated. The VHL spectrum-splitting system in this paper has a form factor similar to conventional silicon PV modules but with higher efficiencies (>30%). Unlike many other spectrum-splitting systems that have been proposed in the past, the system in this work converts both direct and diffuse sunlight while using inexpensive 1-axis tracking systems. The VHL system uses holographic lenses that focus light at a transition wavelength to the boundary between two PV cells. Longer wavelength light is dispersed to the narrow bandgap cell and shorter wavelength light to the wide bandgap cell. A prototype system is designed with silicon and GaAs PV cells. The holographic lenses are fabricated in Covestro Bayfol HX photopolymer by 'stitching' together lens segments through sequential masked exposures. The PV cells and holographic lenses were characterized and the data was used in a raytrace simulation and predicts an improvement in total power output of 15.2% compared to a non-spectrum-splitting reference. A laboratory measurement yielded an improvement in power output of 8.5%.

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30

Shanmugha, Sundaram G. A. "Imaging and Spectral Studies of Solar type I Noise Storms at Metric Wavelengths." Thesis, Indian Institute of Science, 2004. http://etd.iisc.ernet.in/handle/2005/46.

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Type I noise storms constitute a sizeable fraction of the active-Sun component of solar radiation at meter wavelengths. The storms occur over a prolonged duration as intense, narrow-band spikes, superposed on a low-intensity broadband continuum, in the 30-400 MHz frequency range. Either component of the noise storm radiation has a very high degree of ordinary-mode circular polarization (~ 100 %), and is widely believed to be generated by the plasma emission mechanism. Existence of large sunspot groups or active region complexes, with a high degree of complexity and strength in the associated magnetic topology, have a remarkable spatio-temporal correlation to the occurance of noise storms. Hence type I noise storm events were employed as tracers in estimating the solar cycle activity, with specific relevance to resolving the mimimum-phase occuring between solar cycles 22 and 23, to a precise yet unique epoch of 1998 October,in consonance with the monthly average sunspot count and the 10.7 cm solar radio flux data. The latter have a proven close link with associated sunspot activity. Spatio-temporal correlation of energetic eruptive event termed Coronal Mass Ejection ( CME ), with the type I noise storm events has been convincingly established, from the point of view of ``Space Weather'' prediction. A particular aspect of this study has been the choice of limb-event CMEs as against the halo ones; this criterion has aided in an unambiguous position-angle determination for the eruption- site of the CMEs. Noise storms are found to be the precursors, temporally succeeded by the CME events over a time-scale of 1 to 14 hours. Large scale reconfiguration of the photospheric magnetic field topology, by way of reconnection, merging, cancellation or submergence, in the ambience of pre-existing lines of magnetic flux, triggered by the shearing and twisting motion of the footpoints, and leading to the sigmoid-to-arcade evolution of coronal magnetic loops, traces the event-specific linkage involving the type I noise storms and CMEs. Phenomena that occur at metric wavelengths in the solar corona, and vary on short time scales, are investigated, with the aid of a prototype, custom-built antenna-receiver system to the Gauribidanur RadioHeliograph ( GRH ). The GRH is a transit-mode instrument, while the time-delay control implemented on the prototype enables a radio source to be followed, as it traverses the sky at the sidereal rate. The delay-tracking scheme has been implemented on the front-end electronics, as this would eliminate the otherwise cumbersome task of mechanical-steering of the log-periodic dipole array, while also permitting radio observations over a significantly wider frequency band. The performance of the Gauribidanur Prototype Tracking System ( GPTS ) has been validated on the basis of exhaustive tests, in order to characterise its attenuation, phase, and pointing-accuracy, and optimised for solar observations at 77.5 MHz. Continuous Sun observation was performed with the GPTS, over a period from 24th of June, 2002 to 20th of August, 2002. The daily schedule involved solar observations at seven beam-positions on either side of the local meridian,spaced apart by ~ 9 deg., for about four hours each day. Absolute radio flux calibration was performed by following an identical observing schedule for the intense, unresolvable radio source Cygnus A. Periods of enhanced radio emission, corresponding to global rise in the solar radio radiation, were detected on several days. On each of those days of enhanced activity, the absolute deviation from the mean-flux, corresponding to the various beam-positions for that day, was determined. From this, the intra-day quasi-periodicity in solar radio flux was found to be 110 minutes, with the fluctuation in flux being 3 (+/- 1.5) sfu. Positional information from the Nancay (sic) Radioheliograph data, and features of the causative Active Regions of the underlying photospheric disk from the full-disk H-alpha images of the Big Bear Solar Observatory, along with the radio-spectral data published in the Solar Geophysical Data Reports led to conclusion that, heightened flux emission had been the result of the type I noise storms, known for their sharply defined directivity characteristics. The continuum component of type I noise storms is studied for variation in the frequency-dependent flux characteristics. Swept-frequency data from the Gauribidanur Radio Spectrograph, on 26th and 27th September 2000, in the 30-80 MHz band, were analyzed. The quiet-sun and burst components in the acquired data were excised-out. Absolute flux calibration was performed from spectral observations of Cygnus A in the same band. The spectral-index of the continuum was found to be ~ +3.7 . From a knowledge of the continuum source-size at various other spot frequency imaging observations, the source-size of the particular event was estimated, from interpolation and curve-fitting, to be 13.2 +/- 1.2 arcmin. From a knowledge of the continuum radio flux and its source-size, the brightness-temperature was found to vary from 1.07 x 1e7 to 1.96 x 1e7 K, in the 50 - 80 MHz band. Plasma emission is widely believed to bethe radiation mechanism for the continuum. The excitation of plasma waves by trapped, energetic electron beams moving along the coronal magnetic loops, and their coalescence with the low-frequency ion-acoustic waves or upper-hybrid waves excited due to shock-waves generated by magnetic reconnections above the active region complexes, at sites of coronal density inhomogeneities, are the cause for the noise storm radiation. From knowing the brightness-temperature in the source-region, the supra-thermal density in the electron-beam is estimated. Corroborative evidence, in the form of complementary observations for source-size, extent of the active region complexes, and the associated variations in strength and polarity of magnetic flux on the photosphere, the density enhancement over that of the tenuous coronal density, as per the Newkirk's model, above such active regions, the emission-measure, density, and brightness-temperature in the large-scale coronal loops interconnecting the trans-equatorial active regions in this case, in extreme uv and soft X Ray wavelengths, is applied to validate the assumptions, and estimations on various parameters involved in this plasma emission phenomenon. The burst component of type I noise storms is studied with the newly commissioned high temporal and spectral resolution spectrograph at the Gauribidanur Radio Observatory. The bursts reveal themselves as narrow-band, spiked events on the dynamic spectral records, and their occurance is of a stochastic nature. Isolated Type I bursts were chosen based on their bandwidth (2-2.5 MHz ), fractional-bandwidth ( 1.5 ), lifetime ( 1.5 seconds ), and their radio flux (~ 20-40 sfu ) distribution. The dynamic~- spectrum was calibrated from galactic background observations towards the direction of the North and the South Galactic poles. The flux calibration scheme is ideally suited for those radio telescopes capable of a low spatial resolution, wherein the predominant contribution to the system temperature arrives from the galactic background radiation. The frequency and time profiles of the bursts were analyzed on a case-by-case basis. The results of the study reveal that, a majority of the frequency profiles show a remarkable gaussian symmetrical distribution as compared to the less significant assymmetry in either the ascending or the descending limb ( which appear as enhanced tail-like features ) of the corresponding gaussians. This, in consonance with their narrow emission bandwidth, endorses the view that, the source region for Type I bursts are in a state of extreme homogeneity, as regards their plasma density and temperature. The time profiles on the other hand show a greater level of asymmetry on either their ascending or descending segments; deviations from the gaussian fit, to each of the bursts' time profiles, reveal a higher incidence in abrupt rise or fall on either of the limbs, to cases where the profiles conform to a symmetric gaussian. Since the rise and decay in the time profiles correspond to growth of plasma instabilities and damping of the plasma waves, respectively, they portray a region of the turbulent corona that is replete with magnetic reconnections contributing to the energetics of plasma waves.

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31

Menang, Kaah Promise. "A high-resolution extraterrestrial solar spectrum and water vapour continuum at near infrared wavelengths from ground-based spectrometer measurements." Thesis, University of Reading, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.654492.

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32

Rodrigues, Sonia Luiz. "Comparação da atenuação da radiação solar e dos fatores que determinam o clima de radiação solar subaquática em lagos e reservatórios do Brasil." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-23092003-112001/.

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O estudo da penetração da radiação solar no meio aquático foi desenvolvido em quatro partes. Na primeira delas, voltada para a atenuação da radiação solar na coluna dágua, foram discutidos fatores de interferência e suas inter-relações. Neste sentido, foi feita uma comparação da penetração da radiação solar em ecossistemas continentais naturais e artificiais, analisando as diferenças e similaridades. O estudo comparativo da atenuação da radiação solar subaquática em toda extensão de reservatórios constituiu a segunda parte deste trabalho. A comparação foi feita entre reservatórios que apresentam proximidades de localização, mas com diferenças marcantes nos usos e ocupações nas regiões em que os mesmos estão inseridos. Na terceira parte foram apresentados dois recursos de grande utilização na obtenção das respostas imediatas do ambiente aquático, do ponto de vista óptico, diante dos impactos sofridos. O primeiro recurso foi a determinação do espectrograma da radiação solar, indicando a atenuação da radiação solar subaquática na faixa fotossinteticamente ativa (400 nm - 700 nm). O outro recurso foi a obtenção do espectro de absorção da água superficial, que permitiu o estabelecimento do Índice de Absorção Espectral da Água, I.A.E.A., que facilmente possibilita a detecção de fontes pontuais de poluição e contaminação. Como quarta e última parte foi proposto o desenvolvimento de um aparelho a partir da reconstrução do hidrofotômetro (Modelo Nº 268 WA 310 GM MFG & Instrument Corp. Bronx. N.Y. 10 451), onde foi introduzido e adaptado o detector fotocondutivo (PIN - 250DP) em substituição às fotocélulas anteriormente danificadas. Durante o trabalho de campo, este aparelho foi testado e foi feita a comparação com os obtidos do Quanta-meter LI-COR (LI - 185A) também utilizado neste trabalho. The study of solar radiation penetration in aquatic environment was developed in four parts. The first one, directed to solar radiation attenuation in the water column, interference factors and their inter-relations were discussed. In this sense, a penetration comparison of the solar radiation in natural and artificial continental ecosystems was carried out, analyzing differences and similarities. The second part of this work consisted of a comparative study of underwater solar radiation in the entire reservoir. The comparison was done between reservoirs that are near to one another, but with marked differences in use and occupation within the regions where they are located. In the third part, two resources of great utilization in obtaining immediate response from the aquatic environment, from an optical point of view of the impacts experienced, were presented. The first resort was the spectrogram determination of solar radiation, which indicated the underwater solar radiation attenuation in the active photosynthetic range (400 nm - 700 nm). The other resort was the superficial water absorption spectrum, which allowed establishing the Water Spectral Absorption Index, I.A.E.A. that easily makes possible detection of accurate sources of pollution and contamination. The fourth and last part proposed to develop an apparatus from the construction of an underwater hydrophotometer (Model 268 WA 310 GM MFG & Instrument Corp. Bronx N.Y. 10451), where the photoconductor detector was adapted and introduced (PIN - 250DP) substituting the previously damaged photocells. During field work, this apparatus was tested and comparison was performed with data obtained from Quanta-meter LI-COR (LI - 185A), also used in this work.

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33

Mohammed, Jafaru. "Impact of Solar Resource and Atmospheric Constituents on Energy Yield Models for Concentrated Photovoltaic Systems." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24342.

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Global economic trends suggest that there is a need to generate sustainable renewable energy to meet growing global energy demands. Solar energy harnessed by concentrated photovoltaic (CPV) systems has a potential for strong contributions to future energy supplies. However, as a relatively new technology, there is still a need for considerable research into the relationship between the technology and the solar resource. Research into CPV systems was carried out at the University of Ottawa’s Solar Cells and Nanostructured Device Laboratory (SUNLAB), focusing on the acquisition and assessment of meteorological and local solar resource datasets as inputs to more complex system (cell) models for energy yield assessment. An algorithm aimed at estimating the spectral profile of direct normal irradiance (DNI) was created. The algorithm was designed to use easily sourced low resolution meteorological datasets, temporal band pass filter measurement and an atmospheric radiative transfer model to determine a location specific solar spectrum. Its core design involved the use of an optical depth parameterization algorithm based on a published objective regression algorithm. Initial results showed a spectral agreement that corresponds to 0.56% photo-current difference in a modeled CPV cell when compared to measured spectrum. The common procedures and datasets used for long term CPV energy yield assessment was investigated. The aim was to quantitatively de-convolute various factors, especially meteorological factors responsible for error bias in CPV energy yield evaluation. Over the time period from June 2011 to August 2012, the analysis found that neglecting spectral variations resulted in a ~2% overestimation of energy yields. It was shown that clouds have the dominant impact on CPV energy yields, at the 60% level.

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34

Browne, Courtney 1982. "Development of a light detection system for bidirectional measurements over the solar spectrum and sun course simulations with scale models." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35660.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. Includes bibliographical references (leaves 89-93). The use of natural light in building structures can increase energy efficiency and lead to more sustainable architecture. To encourage such use of natural light, a dual experimental device is being developed at MIT to help evaluate the effectiveness of various daylighting approaches, to be used as a goniophotometer for materials and coatings analysis and as a heliodon for studying scale models. The goniophotometer will be used to conduct detailed assessments of the bidirectional transmission or reflecting distribution function ("BT(R)DF") properties of building materials, using a CCD camera to produce a luminance map of the emerging light distribution. The heliodon mode will be used to as an educational tool to perform qualitative evaluations of shadow patterns by simulating sunlight illumination on scale models. This thesis focuses on several aspects of this larger project. This thesis first describes the design of an illumination system appropriate for both functions of the joint goniophotometer/heliodon. (cont.) This thesis then describes the design and manufacture of a light collection system for the goniophotometer mode, specifically the design and fabrication of an acrylic semi-ellipsoid with a half-mirrored coating that focuses the collected light at the CCD camera used for collection and analysis. Finally, this thesis describes the calibration of the light detection system (the color CCD camera) to make its spectral sensitivity match that of the human eye. With this calibration, the CCD camera will be useful not only as a component of the goniophotometer/heliodon system, but may also be adapted to serve as a freestanding multi-point luminance meter for the characterization of BT(R)DFs for various materials of interest. by Courtney A. Browne. S.M.

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35

Phillipps, Nathan. "Design and Construction of a Tunable Light Source with Light Emitting Diodes for Photosynthetic Organisms." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1399.

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This thesis describes and documents the design and construction of a light source which is tunable and has the ability to mimic the spectral output of the sun in the photosynthetic active radiation range (400 - 700 nm). To adjust the spectral output at different wavelengths different types of LEDs were chosen and combined. This thesis describes the design, construction, testing, and suggestions for further improvements to this light source. The light source is comprised of 900 LEDs with 26 different peak wavelengths within the photosynthetically active radiation range. The light source is made tunable through the use of a control system utilizing pulse width modulation. This unique light source will allow studies to be performed to understand spectral influences on microalgae and lipid production as well as other photosynthetic organisms.

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36

Aroca, Silvia Calbo. "Ensino de física solar em um espaço não formal de educação." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-13032009-100501/.

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Planetários e observatórios oferecem a possibilidade de desenvolver um ensino contextualizado de Astronomia, permitindo a realização de atividades educativas que proporcionam acesso a uma ciência escolar mais autêntica. Com isso em vista, esta pesquisa consistiu no desenvolvimento, aplicação e análise de minicursos sobre o Sol, para o ensino fundamental e física solar, para o ensino médio em um espaço não formal de educação, o Observatório Astronômico do CDCC/USP. Tópicos como a composição química, temperatura e evolução estelar foram ensinados a partir de experimentos clássicos em uma sala totalmente dedicada ao Sol, a Sala Solar com equipamentos de baixo custo. Os cursos enfatizaram atividades práticas, observacionais e questionadoras, como discussões sobre a natureza do Sol, manchas solares e proeminências, estimativas da temperatura da fotosfera, observaçã do espectro solar na região do visível e identicação das linhas de absorção entendendo como são produzidas e que tipo de informações podem ser extraídas a partir delas. O objetivo do curso do ensino fundamental foi mostrar que o Sol e um astro dinâmico e que influencia a Terra de diversas maneiras, além de contextualizar o conteúudo ensinado com atividades práticas. O objetivo do curso do ensino médio foi compreender o papel chave desempenhado pela espectroscopia na astrofísica e permitir abordagens interdisciplinares incluíndo física moderna e química no ensino de Astronomia. A metodologia de pesquisa consistiu de uma abordagem qualitativa com a realização de questionários escritos, entrevistas semi-estruturadas e lmagens. Antes dos cursos, muitos alunos concebiam o Sol como sendo uma esfera quente de fogo, as manchas solares como sendo buracos no Sol e as proeminências como magma expelido por vulcões. Após a realizaçã dos cursos os alunos apresentaram ideias sobre o Sol e aspectos de física solar mais próximas das aceitas hoje em dia pela comunidade cientca. Esta pesquisa não ficou restrita aos ganhos cognitivos dos alunos após a realização dos minicursos, pois considerou a interação de diferentes contextos responsáveis pela aprendizagem em museus de ciências. Isso foi possível pelo referencial teórico adotado: o Modelo Contextual de Aprendizagem de Falk e Dierking. Trabalhar conteudos astronômicos de forma interdisciplinar e ao mesmo tempo de maneira ativa e questionadora traz alguns desafios para as equipes de instituições como o Observatório. As atividades elaboradas nos centros de ciências devem ter como principal objetivo despertar o interesse do aprendiz pela ciência, mas também destacamos a necessidade da oferta de minicursos para voluntários, pois a linguagem, conteúdos e metodologias em atividades mais longas podem facilitar abordagens interdisciplinares e integradoras da Astronomia com outras áreas do conhecimento científico pouco exploradas nas salas de aula. Isso pode ocorrer quando o projeto pedagógico da escola é construído coletivamente, envolvendo museus de ciências, professores, escola e alunos buscando conciliar propostas de um ensino de ciências que considere o contexto fora da escola e que ao mesmo tempo tenha relação com o que o aluno está estudando em sala de aula. Observatories and planetariums offer the possibility of developing contextualized astronomy teaching by fostering educational activities that provide access to a more authentic school science. Thus, this research consisted in developing, applying and evaluating courses about the Sun for middle, junior high school students and solar physics for high school students in an informal educational space, the CDCC/USP Astronomical Observatory. Topics of chemical composition, temperature and stellar evolution were taught in a room totally dedicated to the study of the Sun, a Solar Room, designed with simple and inexpensive equipment. The course strongly emphasized practical, observational and inquirybased activities, such as estimation of the solar surface temperature, observation of the visible solar spectrum, identication of solar absorption lines, understanding how they are produced, and what kind of information can be extracted from the observed spectral lines. Some of the course goals were to foster the comprehension of the key role played by spectroscopy in astrophysics, to contextualize contents with practical activities, and to allow interdisciplinary approaches including modern physics and chemistry in physics teaching. The research methodology consisted of a qualitative approach by fillming the whole course and performing written questionnaires and semi-structured interviews. Before the courses were applied most students conceived the Sun as a hot sphere composed of fire, sunspots as holes in the Sun and solar prominences as magma expelled by volcanoes. After the courses students presented ideas about the Sun and solar physics more closely related to the ones accepted by contemporary science. This research was not restricted to students\' cognitive gains after concluding the courses, since it considered the interaction of different contexts responsible for learning in science museums. This was possible due to the theoretical framework adopted: The Contextual Model of Learning of Falk and Dierking. Some challenges have to be faced by institutions such as the Astronomical Observatory in order to teach astronomy in an interdisciplinary form and with inquiry-based activities The activities developed at science centers must have as their main objective to motivate the public towards science, but it is also important to offer courses for volunteers, since language, contents and methodologies in longer activities can facilitate interdisciplinary approaches of Astronomy with other areas of scientic knowledge seldom explored in classrooms. This can happen when the school\'s educational project is collectively constructed including science museums, teachers, school and students by seeking to enhance teaching proposals that consider the out of school context and is related to contents taught in the classroom.

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37

Fernández, Ortega Carlos. "A differential spectroscopic study of a faint solar twin in the open cluster M67." Thesis, Uppsala universitet, Observationell astrofysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-302601.

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A solar twin is a star with characteristics very similar to those of the Sun. This is, a Sun-like star. Earlier studies show that M67-1194 is one of the best solar twins found to date. But this star is not exactly like the Sun. There exist differences between them, in terms of chemical composition, that were defined as well. The goal of this study is to apply a new method to study the similarities of the mentioned star with the Sun. Hopefully a method that provides more precise results. The method uses difference spectra, result of subtracting the spectrum of the star from the solar spectrum, instead of the regular spectra. Then the question is: can this method cast more precise results than those obtained by Önehag et al. in 2011? The answer is that it does. The earlier study gave an uncertainty of ±0.02 dex and ours gave uncertainties between ±0.01 dex and ±0.02 dex. Nevertheless, this conclusion must be taken with caution as the study is not as conclusive as the one out carried by Önehag et al.. En soltvilling är en stjärna som liknar solen väldigt mycket. Tidigare studier visar att M67-1194 är en av de bästa upptäckta soltvillingarna hittills. Men stjärnan är inte exakt som solen. Det finns skillnader mellan dem angående deras kemiska sammansättningar vilket har också visats i tidigare studier. Den här studiens syfte är att tillämpa en ny metod för att granska likheterna mellan den nämnda stjärnan och solen. En metod som förhoppningsvis ger noggrannare resultat. Metoden använder differensspektra som erhålls genom att subtrahera stjärnans spektrum från solens spektrum, i stället för att använda de vanliga spektra. Frågan är om den här nya metoden kan ge noggrannare resultat än dem som Önehag et al. fick 2011. Svaret är ja. Den tidigare studien visade en osäkerhet på ±0,02 dex medan vår gav osäkerheter mellan ±0,01 dex och ±0,02 dex. Icke desto mindre måste våra slutsatser tas försiktigt ty vår studie är inte lika säker som Önehags et al..

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38

Pinatti, Adriana Amadeu. "Indicações sobre a utilização de filme eletrocrômicos Nb2O5 como proteção solar em edifícios." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-14092016-162031/.

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A importância da compreensão da questão energética nos edifícios, com enfoque nos fenômenos energéticos pelos quais o vidro participa e o delineamento de uma aproximação de desempenho em energia e conforto de vidros recobertos com filme eletrocrômico de Nb2O5, formam a finalidade deste trabalho. Os invisíveis fenômenos energéticos em superfícies envidraçadas promovem descontrole de ambos iluminação e climatização de ambientes, associando janelas a impacto energético, cujas consequências tem causado desenvolvimento de especificações, normatização e legislação. A origem deste desequilíbrio nasce da desatenção dos projetistas (e da maioria dos homens), que deixam de observar o céu. O sol envia a Terra diariamente dez mil vezes mais energia que o consumo mundial. Tamanha intensidade disponível no meio ambiente, deparando-se com superfícies que permitem sua entrada em ambientes internos. Este trabalho integra conceitos básicos de energia,sol, conforto e comportamento térmico e óptico de parte dos materiais vítreos de mercados atual e futuro, com a pretensão de apresentar-se como orientação primária aos profissionais do ramo. Paralelamente obteve-se a curva de transmissão solar de filme eletrocrômico de Nb2O5 obtido via sol-gel sonocatalítico. Este processo foi desenvolvido por grupo de pesquisa desta universidade. Busca-se então associar os resultados obtidos com os conceitos apresentados, indicando efeitos a respeito de sua aplicação na arquitetura como vidro e protetor solar. The aim of this work proposes an understanding about the energy impact promoted by buildings, focalizing the energetic phenomenon involving glazing bulks and indicating an energetic and comfort behavior of glasses recovered with Nb2O5 film. The energetic transfer through glasses promotes decontrol of environment illumination and temperature, associating windows to energetic impact, whose consequences have caused the development of specifications, standardization and legislation. The source of this energetic instability arises from designers inattention (also majority men), who forget to observe the sky. The Sun sends to Earth daily ten thousand times more energy than world consume. When such energy reaches surfaces that permit its entrance and hinder its exit, indoors illumination and heating are caused. This work groups basic concepts of energy, sun, comfort and thermal-optical behavior of glass materiaIs in nowadays and future markets, pretending offer a primary orientation to professional in this field. Allied to this, were obtained the solar transmission curves of the electrochromic film of Nb2O5, produced by Sol-Gel sonocatalytic process. Such process was developed by research group from this university. The results were associated with the concepts presented, indicating effects about its application as glass and solar protector in architecture.

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39

Davis, Jimmy Allen. "FREQUENCY DISTRIBUTION OF PYROXENE TYPES AND A METHOD TO SEPARATE THE COMPOSITION OF MULTIPLE PYROXENES IN A SAMPLE." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3145.

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Determining mafic mineral composition of asteroid bodies is a topic reviewed by M.J. Gaffey et al. (2002). The iterative procedure discussed can be implemented as an algorithm, and such efforts revealed weaknesses that are examined in this work. We seek to illustrate the limits of this method and graphically determine its predictions. There are boundaries in the formulae given where the equations break down. In ranges where mafic mixtures are predicted, a method is illustrated that allows a decoupling of these mixtures into the constituents. M.S. Department of Physics Sciences Physics MS

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40

Yandt, Mark. "Characterization Techniques and Optimization Principles for Multi-Junction Solar Cells and Maximum Long Term Performance of CPV Systems." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35870.

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Two related bodies of work are presented, both of which aim to further the rapid development of next generation concentrating photovoltaic systems using high efficiency multi junction solar cells. They are complementary since the characterization of commercial devices and the systematic application of design principles for future designs must progress in parallel in order to accelerate iterative improvements. First addressed, is the field characterization of state of the art concentrating photovoltaic systems. Performance modeling and root cause analysis of deviations from the modeling results are critical for bringing reliable high value products to the market. Two complementary tools are presented that facilitate acceleration of the development cycle. The “Dynamic real-time I V Curve Measurement System…” provides a live picture of the current-voltage characteristics of a CPV module. This provides the user with an intuitive understanding of how module performance responds under perturbation. The “Shutter technique for noninvasive individual cell characterization in sealed concentrating photovoltaic modules,” allows the user to probe individual cell characteristics within a sealed module. This facilitates non-invasive characterization of modules that are in situ. Together, these tools were used to diagnose the wide spread failure of epoxy connections between the carrier and the emitter of bypass diodes installed in sealed commercial modules. Next, the optimization principals that are used to choose energy yield maximizing bandgap combinations for multi-junction solar cells are investigated. It is well understood that, due to differences in the solar resource in different geographical locations, this is fundamentally a local optimization problem. However, until now, a robust methodology for determining the influences of geography and atmospheric content on the ideal design point has not been developed. This analysis is presented and the influence of changing environment on the representative spectra that are used to optimize bandgap combinations is demonstrated. Calculations are confirmed with ground measurements in Ottawa, Canada and the global trends are refined for this particular location. Further, as cell designers begin to take advantage of more flexible manufacturing processes, it is critical to know if and how optimization criteria must change for solar cells with more junctions. This analysis is expanded to account for the differences between cells with up to 8 subcell bandgaps. A number of software tools were also developed for the Sunlab during this work. A multi-junction solar cell model calibration tool was developed to determine the parameters that describe each subcell. The tool fits a two diode model to temperature dependent measurements of each subcell and provides the fitting parameters so that the performance of multi-junction solar cells composed of those subcells can be modeled for real world conditions before they are put on-sun. A multi-junction bandgap optimization tool was developed to more quickly and robustly determine the ideal bandgap combinations for a set of input spectra. The optimization process outputs the current results during iteration so that they may be visualized. Finally, software tools that compute annual energy yield for input multi-junction cell parameters were developed. Both a brute force tool that computes energy harvested at each time step, and an accelerated tool that first bins time steps into discrete bins were developed. These tools will continue to be used by members of the Sunlab.

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41

Wu, Yuechen, Shelby Vorndran, Pelaez Silvana Ayala, and Raymond K. Kostuk. "Three junction holographic micro-scale PV system." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622714.

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In this work a spectrum splitting micro-scale concentrating PV system is evaluated to increase the conversion efficiency of flat panel PV systems. In this approach, the dispersed spectrum splitting concentration systems is scaled down to a small size and structured in an array. The spectrum splitting configuration allows the use of separate single bandgap PV cells that increase spectral overlap with the incident solar spectrum. This results in an overall increase in the spectral conversion efficiency of the resulting system. In addition other benefits of the micro-scale PV system are retained such reduced PV cell material requirements, more versatile interconnect configurations, and lower heat rejection requirements that can lead to a lower cost system. The system proposed in this work consists of two cascaded off-axis holograms in combination with a micro lens array, and three types of PV cells. An aspherical lens design is made to minimize the dispersion so that higher concentration ratios can be achieved for a three-junction system. An analysis methodology is also developed to determine the optical efficiency of the resulting system, the characteristics of the dispersed spectrum, and the overall system conversion efficiency for a combination of three types of PV cells.

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42

Xu, Chenzhi. "Optical Spectrocopy on Nanostructrured Materials." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174866.

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Solar cells are designed to transform the optical energy into electrical energy. Using solar energy is the best way for humans to solve the energy shortage problem. Dye sensitized solar cell(DSSC) has a low cost and helps people to obtain the solar energy expediently. The DSSC is based on nano structured TiO2 ; and dye molecules help the particles of TiO2 to absorb more photons. Hence DSSC has higher efficiency than SC(solar cell without dye). This thesis elaborates and analyzes the dye which is sensitized to TiO2. The absorption spectrum of the dye was achieved. Two kinds of dye sample were made on the basis of their places in structure of TiO2. One dye sample is solution, nanopowder of the dye in aceton. The other dye sample is film, thin film on a quartz plate. The absorption spectrums of the samples have been measured in laboratory. The measurement suggests that the dye works improves the absorption of solar energy in DSSC. This thesis mainly contains the following sections: Chapter I reviews the solar energy technology development, the research purposes, and the principles of DSSC. Chapter II introduces the theory of optical spectroscopy. Chapter III and Chapter IV describe the apparatus employed in this experimental system, the experimental method, and the testing results. Chapter V gives the conclusions drawn from the experiments.

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43

Aronson, Erik. "Modelling reﬂected polarized light from exoplanetary atmospheres". Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173451.

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I present numerical simulations of intensity and degree of polarization of light reﬂected by Earth-like exoplanets. The results are presented as a function of wavelength, and for a few diﬀerent phase angles and a few diﬀerent points on the planet. At this stage the aim is to show the working code and test a few diﬀerent set ups of the star-planet system in order to ﬁnd preferable conﬁgurations for observations. Not surprisingly, phase angle 90◦ shows the largest degree of polarization. For beneﬁcial wavelength regions, visual light shows a larger overall degree of polarization, while NIR shows very clear absorption patterns in the degree of polarization, making detection of the atmospheric composition possible.

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44

Vlček, Josef. "Automatické vyhodnocování spektra slunečního záření." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221098.

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This master’s thesis deals with properties of a solar radiation, measurement of a solar spectrum and standard IEC 60904-9, which defines the requirements for a solar simulator. Solar simulators are classified as A, B or C for each of the three categories based on criteria of spectral distribution match, irradiance non-uniformity on the test plane and temporal instability. The goal of this thesis was creation software for automatic evaluation of a solar spectrum. Software was created in Matlab application and its function is to determine class of solar spectral match with spectrum AM1.5. The last part contains a measurement of various solar sources and using the created software was determined its spectral match with spectrum AM1.5.

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45

Huaman, Denis Pavel Cabezas. "Estudo em múltiplas frequências da baixa atmosfera solar durante explosões." Universidade Presbiteriana Mackenzie, 2015. http://tede.mackenzie.br/jspui/handle/tede/1303.

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Made available in DSpace on 2016-03-15T19:35:52Z (GMT). No. of bitstreams: 1 DENIS PAVEL CABEZAS HUAMAN.pdf: 1718725 bytes, checksum: b98f52c6b4dac9b37a33cc5bc62d871e (MD5) Previous issue date: 2015-03-26 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior The project aims to study the disturbances (responses) of the low solar atmosphere caused by solar flares, using Hα, 30 THz (10 μm), UV/EUV, soft and hard X-rays observations, and a wide range of radio waves emissions (microwaves, millimeter, sub-millimeter). This set of multispectral data enabled us to (i) examine in detail various aspects of the phenomena, (ii) determine the origin of the radio emission during the gradual phase, and therefore (iii) understand the mechanism of the particles acceleration. The data we used for the completion of this study are based on Hα and 30 THz (10 μm) observations, made by the high cadence flare imaging system installed at OSM4 and CASLEO5 observatories, additionally data from HASTA (H-Alpha Solar Telescope for Argentina) telescope installed at OAFA6 observatory. In the sub-millimeter and millimeter domain at 212, 405 GHz and 45, 90 GHz, were from SST (Solar Sub-millimeter Telescope) and from POEMAS (POlarization Emission of Millimeter Activity at the Sun) solar radio telescopes, respectively. Complementary radio observations in the microwave range (0.2-15 GHz) from RSTN (Radio Solar Telescope Network) were considered. In addition, solar observations obtained by RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager), Fermi and GOES (Geostationary Operational Environmental Satellite) satellites in X-ray channels, and from AIA (Atmospheric Imaging Assembly) and HMI (Helioseismic and Magnetic Imager) instruments, onboard the SDO (Solar Dynamics Observatory) satellite, respectively. O trabalho tem como objetivo estudar as perturbações da baixa atmosfera solar produzidas pelas explosões solares, usando observações em Hα, 30 THz (10 μm), UV/EUV, raios X e uma ampla faixa de emissões em ondas de rádio (microondas, milimétrica, submilimétrica); com o propósito de determinar a natureza dos processos físicos envolvidos. Este conjunto de dados multiespectrais nos permitiu (i) analisar os diferentes aspectos das explosões tanto na fase impulsiva como gradual, (ii) determinar a origem da emissão em rádio durante a fase gradual, e consequentemente (iii) entender melhor os mecanismos de aceleração das partículas. Os dados em Hα e 30 THz foram fornecidos pelo sistema de aquisição de dados com alta resolução temporal, instalado nos observatórios OSM1 e CASLEO2, adicionalmente dados do telescópio HASTA (H-Alpha Solar Telescope for Argentina) instalado no observatório OAFA3. Enquanto as observações em rádio, os dados foram do rádio polarímetro POEMAS (POlarization Emission of Millimeter Activity at the Sun) nas frequências de 45 e 90 GHz, do telescópio SST (Sub-millimeter Solar Telescope) nas frequências 212 e 405 GHz, ambos instalados no CASLEO. Dados na faixa de microondas (0,2-15 GHz) obtidos pela rede RSTN (Radio Solar Telescope Network). Além disso, foram considerados observações do Sol obtidas pelos satélites RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager), Fermi e GOES (Geostationary Operational Environmental Satellite) para raios X, e dos instrumentos AIA (Atmospheric Imaging Assembly), HMI (Helioseismic and Magnetic Imager), a bordo do satélite SDO (Solar Dynamics Observatory), respectivamente.

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46

Olds, William James. "Elucidating the links between UV radiation and vitamin D synthesis : using an in vitro model." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/32073/1/William_Olds_Thesis.pdf.

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Ultraviolet radiation (UV) is the carcinogen that causes the most common malignancy in humans – skin cancer. However, moderate UV exposure is essential for producing vitaminDin our skin. VitaminDincreases the absorption of calcium from the diet, and adequate calcium is necessary for the building and maintenance of bones. Thus, low levels of vitamin D can cause osteomalacia and rickets and contribute to osteoporosis. Emerging evidence also suggests vitamin D may protect against falls, internal cancers, psychiatric conditions, autoimmune diseases and cardiovascular diseases. Since the dominant source of vitamin D is sunlight exposure, there is a need to understand what is a “balanced” level of sun exposure to maintain an adequate level of vitamin D but minimise the risks of eye damage, skin damage and skin cancer resulting from excessive UV exposure. There are many steps in the pathway from incoming solar UV to the eventual vitamin D status of humans (measured as 25-hydroxyvitamin D in the blood), and our knowledge about many of these steps is currently incomplete. This project begins by investigating the levels of UV available for synthesising vitamin D, and how these levels vary across seasons, latitudes and times of the day. The thesis then covers experiments conducted with an in vitro model, which was developed to study several aspects of vitamin D synthesis. Results from the model suggest the relationship between UV dose and vitamin D is not linear. This is an important input into public health messages regarding ‘safe’ UV exposure: larger doses of UV, beyond a certain limit, may not continue to produce vitamin D; however, they will increase the risk of skin cancers and eye damage. The model also showed that, when given identical doses of UV, the amount of vitamin D produced was impacted by temperature. In humans, a temperature-dependent reaction must occur in the top layers of human skin, prior to vitamin D entering the bloodstream. The hypothesis will be raised that cooler temperatures (occurring in winter and at high latitudes) may reduce vitamin D production in humans. Finally, the model has also been used to study the wavelengths of UV thought to be responsible for producing vitamin D. It appears that vitamin D production is limited to a small range of UV wavelengths, which may be narrower than previously thought. Together, these results suggest that further research is needed into the ability of humans to synthesise vitamin D from sunlight. In particular, more information is needed about the dose-response relationship in humans and to investigate the proposed impact of temperature. Having an accurate action spectrum will also be essential for measuring the available levels of vitamin D-effective UV. As this research continues, it will contribute to the scientific evidence-base needed for devising a public health message that will balance the risks of excessive UV exposure with maintaining adequate vitamin D.

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47

Palla, Martin. "Simulátory solárního záření pro testování solárních článků." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220120.

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The first part deals with an introduction to the basic fundamentals and presentation of theory from the assignment. The fundamentals are presented and described in detail. This part is followed by chapter describing possibilities of using solar energy. The paper presents possibilities of using both direct and diffuse solar radiation. The last chapter of the theoretical part is devoted to the basic description of the IEC 60904 and IEC 60904-9 standards. The practical part presents selected solar simulators and their measurement. Classification class according to IEC 60904-9 is determined from this measurement. The last part of the work is devoted to the construction of a solar simulator composed of LEDs. The simulator is then measured and its class is determined by emitted spectrum.

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48

DI, FELICE VALERIA. "Low energy electron and positron measurements in space with the PAMELA experiment." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1245.

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Questa tesi descrive lo studio di elettroni e positroni nella radiazione cosmica. Nuove misure della frazione di positroni al top dell’atmosfera tra 200 MeV e 3.0 GeV, nonché lo spettro di elettroni fino a 20 GeV, sono presentati. La misura è stata effettuata con l’esperimento PAMELA da Luglio 2006 a Dicembre 2008, periodo di minima attività solare e polarità negativa. PAMELA fornisce le prime osservazioni a lungo termine della frazione di positroni di bassa energia durante questo particolare stato della eliosfera. La grande statistica collezionata permette di studiare la variazione del flusso di particelle a Terra in funzione dell’energia e del tempo, e di investigare effetti dipendenti dal segno della carica. Durante circa 860 giorni di raccolta dati circa 16000 positroni e 178000 elettroni sono stati identificati. Le maggiore fonte di fondo, costituite da protoni e pioni localmente prodotti, sono state studiate. Lo spettro di elettroni derivato mostra chiaramente l’effetto della modulazione solare sotto qualche GeV. La frazione di positroni è risultata in accordo con le predizioni di modelli teorici che descrivono il trasporto di particelle nell’eliosfera che tengono conto di effetti di drift. This thesis describes the study of electrons and positrons in the cosmic radiation. New measurements of the positron fraction at the top of the atmosphere between 200 MeV and 3.0 GeV are presented, together with the electron spectrum up to 20 GeV. The measurement was conducted with the space borne PAMELA experiment from July 2006 to December 2008, that is a period of minimum solar activity and negative solar magnetic field polarity. PAMELA provides the first long term observation of the low energy positron abundance during this particular solar and heliospheric state. The great amount of collected statistics allows to study the variation of the particle intensity at Earth with energy and time, and to investigate effects depending on the particles sign of charge. During approximately 860 days of data collection about 16300 positrons and 178000 electrons were identified. The major sources of background, constituted by cosmic protons and locally produced pions, have been studied. The derived electron spectrum clearly shows the effect of the solar modulation below few GeV. The detected positron fraction has been found to be in accordance with predictions from theoretical models that describe the transport of particles in the heliosphere taking drift effects into account.

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49

Pan, Lei. "Development of perovskite for X-ray detection and gamma-ray spectroscopy." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu161886103349645.

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50

Greer, Caroline J. "Spectral emission from high temperature plasmas." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337035.

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