Dissertations / Theses on the topic 'Solar Mirrors'

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 42).
This thesis explores the use of binary actuators to adjust the shape of an array of mirrors. To explore this concept, an experimental system was refurbished and recalibrated. This experimental system was used to explore the range of possible configurations that could be reached by a simple binary actuated system. System models are required for accurate control of these binary actuated structures. This thesis develops and tests the accuracy of two different modeling approaches, linear and iterative. The linear model assumes that each actuator contributes a constant value to the angle of the center mirror, and that this value is not dependent on the other actuator positions. The actuator contributions are summed to find the angle of the center mirror. These contributions are found two ways: by taking a relevant single data point for each actuator, and by using a least squares fitting of a large subset of data. The iterative model assumes that each actuator adds some constant value, similar to the previous model, and that it also adds some portion of the current angle. A multiplication and shift are therefore found for each actuator, and these multiplications and shifts successively applied, starting with the initial angles, to find the final angular position. While the linear model with measured values for the actuator contributions predicted the data poorly, the linear model with the least squares fitted values performed much better. The iterative model initially produced large errors, but these errors were found to be readily correctable and once removed, the iterative model predicted the data better than the linear model.
by Teresa M. Gomez.
S.B.

The increasing availability on the market of different types of solar reflectors such as: polymeric film mirrors, aluminum mirrors and thin glass mirrors, together with: the lack of available norms in this area, and a valid methodology to compare the performances of the candidate reflectors; highlights the necessity to conduct a more detailed analysis on these new technologies. The objective of the present work is to suggest a valuable method to compare the reflectance performance of mirrors, evaluating also their performances in order to assess: - the most durable to ageing and weathering effects; - the different reflectance behavior with the variation of the solar incident angle. .For these reasons the work here proposed was carried out with an experimental apparatus composed by: - An Agilent Cary 5000 UV/Vis/NIR spectrophotometer to test the different performance of the mirrors at different characterization steps; - An integrating sphere of 150 mm in diameter (DRA ¡V Diffuse Reflectance Accessory); - A VASRA (Variable Angle Specular Reflection Accessory); - A UV chamber to accelerate the ageing process; - A £gScan SMS Scatterometer for RMS Roughness and BDSF measurement; - An outdoor bench The work was completed with two modeling tools: - An engineering equation solver (Mathcad) to dynamically evaluate the behavior; - A ray tracing software (Soltrace) to evaluate the system¡¦s optical efficiency. The analysis indicates that the candidate reflectors can be accurately characterized with five fundamental parameters: a) £lSWH, the solar-weighted hemispherical reflectance; b) £lSWS, the solar-weighted specular reflectance; c) £lSWS( á), the solar weighted specular reflectance function of the variable angle of incidence; d) BDSF, Bi Directional Scattering Function; e) RMS Roughness This evaluation will provide a valuable tool, for the companies who want to invest in concentrating solar power technology, to decide whether or not using a candidate reflectors to realize new plants, assessing their performances, their costs, and their durability.

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A possibilidade de redução na oferta de combustíveis convencionais aliada ao crescimento da demanda por energia e a crescente preocupação com o meio ambiente impulsionam a pesquisa e desenvolvimento de fontes alternativas de energia menos poluentes, renováveis e que produzam menor impacto ambiental. Dentre estas alternativas, destaca-se a energia solar, fonte disponível e passível de ser explorada a partir de todas as suas potencialidades. Atualmente, uma das vias tecnológicas de aproveitamento da fonte solar para geração de energia é a heliotermia, também conhecida como energia solar concentrada ou Concentrated Solar Power (CSP), baseada na utilização de superfícies espelhadas que refletem e concentram a radiação solar direta com o objetivo de convertê-la em energia térmica, a partir da qual se gera vapor d’água que irá acionar um ciclo termodinâmico reversível que converte calor em trabalho, conhecido como Rankine. O soiling consiste no depósito de diferentes tipos de sujeiras em uma superfície exposta em um dado ambiente. No caso de usinas CSP de torre central, o acúmulo gradativo de poeira, sujeira ou até mesmo de excremento de pássaros nas superfícies refletoras dos heliostatos causa uma redução significativa na quantidade de radiação solar que atinge o receptor posicionado no alto da torre e diminuição da eficiência de todo o sistema. Assim, faz-se necessário manter um alto fator de refletividade nas superfícies espelhadas dos heliostatos por meio de uma limpeza regular. Este trabalho apresenta a proposta de um mecanismo automatizado para efetuar a limpeza de superfícies refletoras de heliostatos. O desenvolvimento deste dispositivo, desde sua concepção, passando pelas fases de construção, instalação e funcionamento, respeita padrões de eficiência da limpeza, visa o baixo custo de produção, facilidade de instalação e minimização dos impactos ambientais pertinentes, como, por exemplo, baixo consumo de água na operação. Por meio de experimentos realizados em situações reais de aplicação, utilizando para tal um heliostato de 8 m2 localizado no Departamento de Engenharia Rural da Faculdade de Ciências Agronômicas da UNESP, campus de Botucatu, constatou-se que o dispositivo proposto é uma opção operacionalmente e economicamente viável de solução ao soiling quando aplicado na região de Botucatu, principalmente se comparado a outras propostas de métodos de limpeza de heliostatos apresentadas nos cenários internacional e nacional. Além disso, por meio de estudos sobre os impactos ambientais de usinas heliotérmicas, foi possível sugerir melhorias no processo de licenciamento ambiental de usinas CSP no Brasil.
The possibility of reduction in the supply of conventional fuels, the continuous growing demand for energy and the current concern with the environmental scenario influence the development of researches regarding alternative, renewable and less polluting energy sources, which produces less environmental impact. Among these alternatives, it is worth mentioning the solar energy, available source and that can be explored from all its potentialities. Nowadays, one of many the technological process that uses solar energy for electricity generation is the solar thermal one, also known as Concentrated Solar Power (CSP), based on the use of mirrored surfaces that reflect and concentrate the direct sunlight in order to convert it into thermal energy, from which it generates water vapor that will initiate a reversible thermodynamic cycle which converts heat into energy (Rankine cicle). The phenomenon known as soiling consists in the depositing of different types of dirt on a surface exposed in a given environment. In the case of power tower CSP plants, the gradual accumulation of dust, dirt or even bird's excrements on the reflective surfaces of heliostats causes a significant reduction in the amount of solar radiation that reaches the receiver located at the top of the tower and decreases the efficiency of the entire system. Thus, it is necessary to maintain a high reflectivity factor in the mirrored surfaces of the heliostats through a regular cleaning. This work presents a proposal of an automated mechanism to clean up the reflective surfaces of heliostats. The development of this device, from its conception, through the stages of construction, installation and operation, regarding the cleaning efficiency standards, aimed at low production cost, ease of installation and minimizing the relevant environmental impacts, such as, low consumption of water during its operation. Through experiments in real situations, using a 8 m2 heliostat located in the Department of Rural Engineering of UNESP's Faculty of Agronomic Sciences, Botucatu campus, it was verified that the proposed device is an operationally and economically option for the solution to soiling when applied at Botucatu's region, especially if compared to other proposed methods of heliostats cleaning presented in the international and national scenarios. In addition, through studies on the environmental impacts of heliothermic plants, it was possible to suggest improvements in the environmental licensing process of CSP plants in Brazil.

The Lyman- spectral line, at 121.6 nm, is a wavelength of great interest for solar environment exploration and astrophysics. It is an important hydrogen emission line and can give information on the dynamics of heated regions of space like the solar photosphere and corona. Among others, the instrument METIS (Multi Element Telescope for Imaging and Spectroscopy) will be on board the mission Solar Orbiter, an ESA mission in collaboration with NASA, that from the year 2018 will undertake a trip towards the Sun to explore the dynamics of the solar dynamo and its connection with corona and heliosphere. METIS will take images of the corona in the visible range and at Lyman-, studying shape and evolution of the processes expanding from the Sun to the heliosphere. In the CNR-IFN UOS Padova laboratories I employed deposition and characterization facilities to study the characteristics of materials and devices to be used as optical elements at Lyman- wavelength. A morphological characterization was carried on with an atomic force microscope (AFM) and an optical characterization revealed the performances of materials and devices. Variations in performances were related to modications in the experimental conditions and the acquired knowledge was used to optimize the performances of the nal product. Annealing is an approach never fully explored before to increment the optical quality of magnesium uoride thin lms, and consequently the reectivity of VUV optical elements. I conducted a study of the phenomena involved in the process and applied the procedure to the realization of improved mirrors for this spectral region. This work will present all the experimental steps that led to the realization of the nal devices and describe the characteristics of this novel annealing approach.
La linea spettrale Lyman-, a 121.6 nm, è una lunghezza d'onda di grande interesse per l'esplorazione dell'ambiente solare e per l'astrosica. È un'importante linea di emissione dell'idrogeno e può dare informazioni sulle dinamiche di regioni calde dello spazio come la fotosfera solare e la corona. Lo strumento METIS (Multi Element Telescope for Imaging and Spectroscopy) sarà a bordo della missione Solar Orbiter, una missione dell'ESA in collaborazione con la NASA che dal 2018 intraprenderà un viaggio verso il Sole per esplorare le dinamiche della dinamo solare e la sua connessione con la corona e l'eliosfera. METIS acquisirà immagini nel visibile e alla lunghezza d'onda Lyman-, studiando la forma e l'evoluzione dei processi in espansione dal Sole verso l'eliosfera. Nei laboratori del CNR-IFN UOS Padova ho utilizato facility di deposizione e caratterizzazione per studiare le caratteristiche di materiali e dispositivi utilizzabili come elementi ottici per la lunghezza d'onda Lyman-. Grazie ad un microscopio a forza atomica (AFM) è stata realizzata una caratterizzazione di tipo morfologico mentre una caratterizzazione ottica ha rivelato le performance di materiali e dispositivi. Le variazioni di tali performance sono state ricondotte a modiche delle condizioni sperimentali e le conoscenze acquisite sono state utilizzate per ottimizzare le performance del prodotto nito. L'annealing è un aproccio che non è mai stato completamente esplorato e che può aumentare le qualità ottiche dei lm sottili di uoruro di magnesio, e di conseguenza aumentare la riettività degli elementi ottici per il range VUV. Io ho condotto uno studio dei fenomeni coinvolti nel processo e applicato la procedura alla realizzazione di migliori specchi per questa regione spettrale. In questo lavoro sono presentati tutti i passaggi sperimentali che hanno condotto alla realizzazione dei dispositivi ultimati e sono descritte le caratteristiche del nuovo approccio dell'annealing.

This thesis describes a concentrating solar power using a Stirling engine. The problems encountered during construction and operation. I focus mainly on problems derating dusting and icing. The second part of this work is the experimental design of the stand with long-term measurement of dusting depending on the reflectivity of mirrors and their degradation under various conditions. First measurement is stated and estimation of long-term results.

La durabilité des miroirs solaires est un point clé pour le développement des centrales solaires à concentration, du fait de l’investissement important, des 30 ans d’opération visés et des zones d’implantations aux climats agressifs. Ces travaux de recherche portent ainsi sur l’étude des modes de dégradation et de la durabilité de miroirs solaires en verre monolithiques ou laminés. Cette thèse a permis d’appliquer avec succès au CSP une méthodologie de prédiction de la durée de vie développée dans des domaines plus matures. Les corrélations entre les vieillissements accélérés et les expositions extérieures réalisées sur trois sites ont mis en avant le rôle prédominant de l’eau et de l’irradiance dans la dégradation des peintures de protection des miroirs monolithiques. Les essais en chaleur humide ont quant à eux été jugés trop agressifs pour les miroirs, considérant de plus les conditions climatiques des sites d’application potentiels. Les résultats expérimentaux des essais de vieillissements accélérés ont conduit à la détermination des paramètres cinétiques des miroirs inclus dans les relations mathématiques modélisant les principaux facteurs de stress identifiés précédemment. Les facteurs d’accélération ont ainsi été calculés pour des essais standards par rapport à des sites comportant des centrales CSP opérationnelles. Ce travail a permis au final d’estimer des durées de vie des miroirs sur les sites choisis, en considérant que seuls les facteurs de stress étudiés intervenaient dans la dégradation
Durability of solar mirrors is a key point for the development of concentrating solar power plants, because of the large investment, the goal of 30 years lifetime and of the implantations areas with hostile climates. This research work concerns the study of degradation modes and of monolithic or laminated glass solar mirrors durability. This thesis allows to successfully apply to CSP a lifetime prediction method already developed in more mature fields. Correlations between accelerated ageing tests and natural outdoor exposures performed on three sites evidence the predominant role of water and irradiance in protection paints of monolithic mirrors degradation. Damp heat tests were evaluated too aggressive for mirrors, considering thus the climatic conditions of potential application sites. Experimental results of accelerated ageing tests lead to the determination of kinetic parameters included in mathematical relationships modelling the main stress factors previously identified. Acceleration factors were then calculated for standard tests compared to sites with operational CSP plants. This work finally allows to estimate lifetimes of mirrors on specific sites, assuming that only the studied stress factors take part in degradation

The solar concentration performance of a tracking, flat-base, line-focusing Fresnel mirror was investigated in this study. The Fresnel mirror consists of flat mirror strips situated on a base and oriented at appropriate angles to focus incident light to a desired line. Simple optical ray tracing and energy conservation were used to develop a mathematical model of the concentrator assuming small or zero diurnal tracking errors. The model analyzed the concentrator design and provided detailed expressions for the geometric evaluation of the concentrated sunlight rays in the focal plane above the mirror. The local concentration ratio and the geometric concentration ratio were introduced to describe the intensity profile in the focal plane and the average concentration of sunlight on a target absorber. Included in the model were losses of incident sunlight due to imperfect reflection, nonreflecting portions of the base, and blockage by adjacent mirror strips when imperfect tracking occurs.Based on the analytical model and using the Ada high level language, a computer program was written to simulate the concentrator. To facilitate performance comparisons, a baseline concentrator design was adopted. To study the effects of imperfect tracking, performance data were generated for small tracking errors up to approximately two and one-half degrees. The effects of design variations were studied by varying the concentrator focal length, strip width, and base width.Simulation results demonstrated that the concentration characteristics were highly sensitive to tracking error. Intensity profile shifts relative to the target caused the highest losses in intercepted sunlight.Design decisions were found to dramatically affect the concentration character- istics. For the baseline concentrator under perfect tracking conditions, an optimum focal length was identified. Except for the disadvantage of added costs, decreased strip widths was found to be a way to increase both the maximum and average concentration ratio for the absorber. Using smaller strip widths might, however, critically affect the energy intercepted by the target under imperfect tracking. Increasing the concentrator base width increased the total amount of power in the focal plane, with a higher maximum concentration ratio and additional tailing of the intensity profile.
Department of Physics and Astronomy

Microcrystalline silicon solar cells require an enhanced absorption of photons in the near-bandgap region between 700-1150nm. Conventional textured mirrors scatter light and increase the path length of photons in the absorber by total internal reflection. However, these mirrors exhibit a high surface roughness which degrades the performance of the microcrystalline silicon device. An alternative solution is to use metal nanoparticles with low surface roughness to scatter light. An illuminated metal nanoparticle exhibits a resonant or plasmonic excitation which can be tuned to enable a strong scattering of light. This work aims to develop an efficient near-infrared light-scattering system using randomly arranged metal nanoparticles near a mirror. Situating the nanoparticles at the rear of the solar cell helps to target weakly absorbed photons and eliminate out-coupling losses by the inclusion of a rear mirror. Simulation results show that the electric field driving the plasmonic resonance can be tuned with particle-mirror separation distance. The plasmonic scattering is maximised when the peak of the driving field intensity coincides with the intrinsic resonance of the nanoparticle. An e-beam lithography process was developed to fabricate a pseudo-random array of Ag nanodiscs near a Ag mirror. The optimized plasmonic mirror, with 6% coverage of 200nm Ag discs, shows higher diffusive reflectivity than a conventional textured mirror in the near-infrared region, over a broad angular range. Unlike a mirror with self-organised Ag islands, the mirror with Ag nanodiscs exhibits a low surface roughness of 13.5nm and low broadband absorption losses of around 10%. An 8.20% efficient thin n-i-p μc-Si:H solar cell, with the plasmonic mirror integrated at the rear, has been successfully fabricated. The optimised plasmonic solar cell showed an increase of 2.3mA in the short-circuit current density (Jsc), 6mV in the open-circuit voltage (Voc) and 0.97% in the efficiency (η), when compared to the planar cell counterpart with no nanodiscs. The low surface roughness of the plasmonic mirror ensures no degradation in the electrical quality of the μc-Si:H layer – this is also confirmed by the constant value of the fill factor (FF). The increase in Jsc is demonstrated to be mainly due to optical absorption enhancement in the near-infrared region as a result of plasmonic scattering, by detailed calculation of the exact photogenerated current in the plasmonic and planar devices, for the 700-1150nm wavelength range.

The Monte Carlo-type statistical ray-tracing method was used to investigate the performance of the line-focusing Fresnel mirror solar concentrator. An optical model of the line-focusing Fresnel mirror concentrator using the statistical ray-tracing approach was developed. Many rays of sunlight from the solar disk were selected at random and traced through the concentrator in this model. This optical model permits calculation of the local and geometric concentration ratios. The latter requires an energyloss analysis. Small sun-tracking errors of the diurnal or transverse type were included in the model.Based on the optical model and the Monte Carlo-type statistical ray-tracing method, a computer program was written implementing the model and computations using Pascal. To facilitate performance comparisons, a baseline concentrator design was adopted. To study the effects of imperfect tracking, performance data were generated for small tracking errors up to approximately two and one-half degrees. The selected mirror configuration permitted comparisons between the statistical approach and previous applications of the "extreme ray" analysis for an imperfectly tracking mirror concentrator.Simulation results demonstrated that the concentration characteristics are highly sensitive to the tracking error. The geometric concentration ratio dramatically decreases when the tracking error increases, which is the same as the "extreme ray" analysis. Results of some typical numerical calculations are presented graphically and discussed.
Department of Physics and Astronomy

Concentrating solar power systems currently have a high capital cost when compared with other energy generating systems. The solar energy is captured in the form of thermal energy rather than directly electrical, which is attractive as thermal energy is easier and currently cheaper to store in large amounts. It is also used directly as processing heat including desalination and water purification. For the technology to compete against other generating systems it is important to reduce the electrical energy cost to the $0.05 per kilowatt-hour level. One of the significant capital costs is the solar field, which contains the concentrators. To reduce the cost of this field, novel constructions and improvements to the durability and lifetime of the concentrators are required. Techniques for characterising the shape, durability and optical properties of such novel mirrors are the focus of this thesis. The thesis describes the development and validation of an inexpensive, highly portable photogrammetry technique, which has been used to measure the shape of large mirror facets for solar collectors. Photogrammetry has demonstrated its versatility and portability by successful measurements across concentrating solar power sites globally. The accuracy of the technique has been validated to show a measurement capability of better than 100 µm using a large coordinate measuring machine. Measurements performed on novel thin glass mirrors and their comparison with conventional thick glass mirrors are presented, showing that the increased flexibility of thin mirrors is an important consideration during installation, but that it is possible for such novel mirrors to perform to the same level.

A novel type of parabolic trough collector was characterised using a very basic theoretical model. This model looked at an ideal case and provided a basic expectation that was compared to actual measurements. The model showed that greater improvements can be achieved if heat losses to the environment are limited or omitted. This can be achieved by using a glass shield to insulate the receiver in a vacuum to limit the effect wind has and therefore limit convective losses. The experimental characterisation of the PTC consisted of taking six different temperature measurements to better understand the energy balances taking place. Four different configurations were tested, using two different types of concentrator and in each case a receiver that was either unpainted or painted with a semi matte black paint. The different types of concentrator were either stainless steel sheet metal or discretised glass mirror strips, similar to a linear Fresnel collector. Experimental runs were conducted on cloudless days for an hour and 15 minutes. This allowed for three runs to be performed on a single day. Using the theoretical model and comparing it to the experimental data, an efficiency was calculated. This efficiency averaged 14 % when the receiver was unpainted and 13 % when the receiver was painted for the metal sheets. The glass mirror strips had average efficiencies of 54 % and 45 % for an unpainted and painted receiver respectively. The model is very basic and can be improved upon if more variables are taken into consideration, such as convective heat losses. It was also recommended that wind measurements are taken in future tests. A property looked at to evaluate the effectiveness of each type of configuration was the average energy supplied to the thermal heating fluid over the course of an experimental run. For this the averaged values over all the experimental runs conducted for stainless steel sheet metal were 258 W and 332 W for an unpainted and painted pipe respectively. When using the glass mirrors an average energy value of 1049 W was supplied when the pipe was unpainted and an average of 1181 W was gained in the runs conducted after the pipe had been painted. Painting the receiver had little to no effect. The surface temperature of the receiver after painting the pipe was not higher and a slight increase in the energy gained by water was observed. This was explained by inaccuracies during testing as scattered light may have caused an interference on some of the measurements. There were also human inaccuracies in testing which should be omitted in future tests by implementing, for one, a functional tracking system. Future tests should be designed in such a way to completely omit irradiance affecting the thermocouple taking the measurement. Glass mirrors fared far better than the stainless steel sheet metal counterpart. It was recommended that they are used as the concentrator of choice. Higher efficiencies were achieved and in some cases almost four times the energy was supplied to the water in the pipe. This was attributed to a much lower concentrator temperature, on average 11 °C lower than the temperature of the metal sheets, as well as a much better ability to concentrate sunlight onto a single focal point. However, the glass mirror strips were proven to be very fragile and as such, require protection from the elements. While the strips were lighter and caused less of a load during windy conditions, they were susceptible to oscillations from gusty wind. This led to a number of strips breaking and needed to be replaced. By discretising the strips into individual pieces, they had the benefit of only needing to replace the strips that were damaged. This is also true for all future runs. It is still recommended that a tarp be used to protect the glass mirrors. Using glass mirror strips as a concentrator combined LFC technology with PTC technology and a novel PTC design was achieved. The design still required the installation area of a PTC. The novel design was compared to Industrial Solar’s industrial LFC module, LF-11, as it shares many similarities to LFC technology. The peak thermal output of the rig was significantly lower at 346 W/m2 compared to the industrial value of 562 W/m2. However, the noteworthy differences in design and optimisation between the two modules meant the results achieved were comparable. It is expected that better and more comparable results can be realised once the inherent flaws in the design, such as tracking the sun, aperture size and adding a vacuum absorber, are addressed. It is recommended that more research and emphasis is put into this field as an alternative energy power plant for South Africa.
Dissertation (MEng)--University of Pretoria, 2017.
Chemical Engineering
MEng
Unrestricted

Daniel K. Inouye Solar Telescope (formerly known as Advanced Technology Solar Telescope) will be the largest optical solar telescope ever built to provide greatly improved image, spatial and spectral resolution and to collect sufficient light flux of Sun. To meet the requirements of the telescope the design adopted a 4m aperture off-axis parabolic primary mirror with challenging specifications of the surface quality including the surface figure, irregularity and BRDF. The mirror has been completed at the College of Optical Sciences in the University of Arizona and it meets every aspect of requirement with margin. In fact this mirror may be the smoothest large mirror ever made. This paper presents the detail fabrication process and metrology applied to the mirror from the grinding to finish, that include extremely stable hydraulic support, IR and Visible deflectometry, Interferometry and Computer Controlled fabrication process developed at the University of Arizona.

This project was a step forward in establishing an effective high-pressurised cleaning procedure to investigate soil detachment from CSP reflectors through fluid dynamic simulations evaluated the overall force generated by the jet on dust particles. Outcomes reveal an increase of cleaning efficiency of high-pressure spray jets when the standoff distance is in the range X = 6D-15D with the angle of impingement set to =75° and inlet pressure in the range Pin = 50-70 bar.

Самійленко, В. В. Дослідження властивостей сонячних модулів : випускна кваліфікаційна робота : 152 «Метрологія та інформаційно-вимірювальна техніка» / В. В. Самійленко ; керівник роботи П. І. Наумчик ; НУ "Чернігівська політехніка", кафедра електричної інженерії та інформаційно-вимірювальних технологій. – Чернігів, 2021. – 35 с.
Метою є встановлення умов для збільшення коефіцієнта перетворення фотоелектричних елементів Установка для проведення експериментального дослідження включала в себе універсальний проєкційний апарат з оптичною лавою ФОС-115, обладнаний лампою розжарення 500 Вт, лінза Френеля (27,5×27,5 см), люксметр DT-856A, сонячний модуль АК8045, мультиметр UT33C, увігнуте дзеркало, резистор ОМЛТ-1. У процесі досліджень за допомогою пристрою дослідження сонячних модулів встановлювали залежність потужності, яка виділяється на сонячному модулі, від освітленості природніх та штучних джерел світла. Проводили вимірювання з увігнутим дзеркалом та і лінзою в приміщенні: при кімнатній освітленості та із включеною лампою розжарення; на вулиці: при прямому попаданні сонячних променів на модуль, із дзеркалом та з лінзою, які були розташовані таким чиним, щоб зібране світло попадало одночасно на фотодетектор люксметра та на сонячний модуль АК8045. Загалом було проведено 9 серій експериментів. За отриманими даними побудували графік залежності потужності, яка виділяється на споживачі, від освітленості Сонця. Розібрали будову та принцип дії сонячних модулів, їх різновиди та властивості. Зробили висновки за результатами досліджень.
Object - photovoltaic cells The goal is to establish conditions for increasing the conversion factor of photovoltaic cells The installation for the experimental testing included a universal projection device with optical bench FOS-115, equipped with an incandescent lamp 500 W, Fresnel lens (27.5×27.5 cm), luxmeter DT-856A, solar module AK8045, multimeter UT33C, concave mirror, resistor OMLT-1. In the course of research, the dependence of the power released on the solar module on the illumination of natural and artificial light sources was established with the help of a device for studying solar modules. Measurements were performed with a concave mirror and a lens in the room: with room lighting and with an incandescent lamp on; on the street: when the sun's rays hit the module directly, with a mirror and a lens, which were arranged in such a way that the collected light fell at the same time on the photodetector of the luxmeter and on the solar module AK8045. In total of 9 series of experiments were performed. According to the obtained data, a graph of the dependence of the power released on consumers on the solar illumination was constructed. The structure and principle of operation of solar modules, their varieties and properties were analyzed. Made conclusions based on research results

La production actuelle d’énergie qui provient principalement des combustibles fossiles a un impact négatif sur l’environnement. Le développement des énergies renouvelables peut limiter cet impact. Si la conversion thermodynamique de l’énergie solaire obtenue en concentrant le rayonnement photonique permet d’atteindre des rendements élevés, l’enjeu est de réaliser, à faible coût, de grandes surfaces de réflecteurs souples et légers ayant une excellente propriété optique réfléchissante.Dans ce travail de recherche, nous avons étudié deux types de miroirs qui entrent dans la réalisation des concentrateurs solaires. Le premier miroir est constitué d’une plaque souple en polymère très transparent (indice de transmission le plus élevé possible) sur laquelle a été déposé un film réfléchissant. Cette couche est protégée contre la corrosion et les agressions environnementales par un revêtement organique opaque élaboré en face arrière. On obtient ainsi un système polymère/métal/ film organique. Le second miroir est constitué d’un substrat opaque souple sur lequel est déposé un film réfléchissant. Une couche mince protectrice organique ou céramique, ayant un indice optique de transmission le plus élevé possible, est élaborée en face avant sur la couche réfléchissante. On obtient ainsi un système céramique/métal/ organique.Cette couche réfléchissante étant indispensable dans les deux configurations de miroir, nous avons étudié l’élaboration d’une couche réfléchissante à base d’argent du fait que la technique de dépôt chimique dynamique, appelée encore technique JetMetalTM, permet d’obtenir des films d’argent à température ambiante et de façon rapide et peu coûteuse. D’autre part, cette technologie agrée « Green Tech » est bien adaptée pour l’élaboration de dépôt sur des grandes surfaces. Ce rapport décrit les étapes et les paramètres nécessaires pour obtenir des réflecteurs optiques à base d’argent de grandes qualités : qualité optique avec des réflectivités supérieures à 95%, qualité mécanique avec des interfaces polymère/métal pouvant encaisser des déformations, un rapport qualité/prix par l’optimisation des cinétiques de dépôt et d’épaisseur de film d’argent (environ 100nm) avec un temps très court d’élaboration. De nombreuses techniques d’analyses et de caractérisations (XPS, AFM, LRX, SEM…) ont été utilisées pour dégager les paramètres pertinents d’un miroir solaire à base d’argent.La propriété optique du film d’argent est stable à l’air et avec le temps. Néanmoins, une protection de l’argent est nécessaire en particulier en face avant. Cette protection doit adhérer au film d’argent, pouvoir être flexible et présenter un indice de transmission le plus élevé possible dans le domaine visible. Si différents vernis ont été étudiés, notre travail a surtout porté sur l’élaboration de revêtements protecteurs organiques (PMMA, PU), céramiques (SiO2, Al2O3) et surtout hybrides organique-céramique. Ce travail de recherche a permis d’identifier les domaines de pertinence de ces différents types de revêtements protecteurs sous contrainte radiative, leur compatibilité avec une couche réflective d’argent, pour conduire à des concentrateurs souples performants. Une solution originale est présentée en conclusion. Elle porte sur la réalisation d’un miroir souple élaboré sur une feuille de verre de 100 µm d’épaisseur revêtue d’un film de 100 nm d’argent. La réflectivité est supérieure à 95% dans le visible
The present production of energy that mainly comes from the burning of fossil fuels has a negative impact on our environment. The research and development of clean and renewable sources of energy can decrease this damage. If the thermodynamic conversion from solar energy obtained by photons radiation concentration allows us a higher efficiency, the challenge is to build at low cost, large areas for solar reflectors that are flexible and lightweight, with a powerful optical reflection.During this research a study was made on two types of mirrors for achieving solar concentrators. The first mirror is formed of a flexible polymer plate highly transparent (Transmission index as high as possible) in which was deposited a reflective layer. This layer is protected against corrosion and any other environmental aggression by an opaque organic coating built on the rear face. This produces a polymer/metal/organic film system. The second mirrors consist of a flexible opaque substrate in which, a reflective film is deposited. A thin organic or ceramic protector film with a transmission index as high as possible is prepared in front of the reflective layer. Thereby, a ceramic/metal/organic system was obtained.Being that the reflective layer is essential in both configurations of the mirror, research was carried out about the development of a reflective layer composed of silver with the dynamic chemical plating technique also called “Jet MetalTM technique” which allows the elaboration of silver films at room temperature in a fast and economical manner. Also, this approved technology <> is well adapted for the deposit development over large surfaces. This report describes the steps and necessary parameters to obtain optical reflectors based on high quality silver: optical quality with a higher reflectivity over 95%, mechanical quality with interfaces of polymer / metal that can absorb deformations, a relation quality/price through the optimization of the deposit kinetic and the silver film thickness (approximately 100 nm) with a very short elaboration time. Many analysis and characterization techniques (XPS, AFM, LRX, SEM…) have been performed to determine the parameters of a solar mirror made of silver.The optical property of the silver film is stable in air ambient and with time. However; the silver protection is necessary mainly on the front face. This protection must adhere to the silver film, be flexible and provide a high visual range. Different varnishes have been researched, and our work has been concentrated in the development of organic (PMMA, PU), ceramics (SiO2, Al2O3), and especially hybrid organic-ceramic covering protection. This research allowed us to identify the relevant areas of these different types of protection coatings under radiation stress, its compatibility with the silver layer to obtain efficient and flexible concentrators. An original solution is presented at the conclusion that corresponds in the elaboration of a flexible mirror, made up of a glass layer of 100 µm thick and covered in a silver film of 100 nm. The reflection is over 95% visible
La producción actual de energía que proviene principalmente de combustibles fósiles tiene un impacto negativo sobre el medio ambiente. El desarrollo de las energías renovables puede reducir este impacto. Si la conversión termodinámica de la energía solar obtenida por concentración de radiación de fotones permite alcanzar altos rendimientos, el reto es lograr realizar, a bajos costos, grandes áreas de reflectores flexibles y ligeros, con una excelente propiedad óptica reflejante.En esta investigación, se estudiaron dos tipos de espejos que intervienen en la consecución de los concentradores solares. El primer espejo está hecho de una placa flexible de polímero altamente transparente (índice de transmisión lo más alta posible) en el que se depositó una película reflejante. Esta capa está protegida contra la corrosión y el ataque del medio ambiente por un revestimiento orgánico opaco desarrollado en la parte trasera. Esto produce un sistema polímero/metal / película orgánica. El segundo espejo consiste en un sustrato opaco flexible en la que se deposita una película reflejante. Una película delgada y protectora orgánica o cerámica con un índice de transmisión lo más alto posible se prepara en frente de la capa reflejante. Por lo tanto, se obtiene un sistema cerámico / metal / orgánico.Siendo esta capa reflejante esencial en ambas configuraciones de espejo, se investigó el desarrollo de una capa reflejante a base de plata con la técnica de depósito químico dinámico, también llamada “JetMetalTM technique” que permite elaborar películas de plata a temperatura ambiente de manera rápida y económica. Además, esta tecnología, aprobada « Green Tech », está bien adaptada para el desarrollo de depósitos sobre superficies grandes. Este trabajo describe los pasos y los parámetros necesarios para obtener reflectores ópticos basados en plata de grandes cualidades: calidad óptica con reflectividad mayor a 95%, calidad mecánica con interfaces de polímero / metal que pueden absorber deformaciones, una relación calidad / precio mediante la optimización de la cinética de depósito y espesor de la película de plata (aproximadamente 100 nm) con un tiempo corto de elaboración. Numerosas técnicas de análisis y caracterización (XPS, AFM, LRX, SEM ...) han sido utilizadas para determinar los parámetros pertinentes de un espejo solar a base de plata. La propiedad óptica de la película de plata es estable en el aire y en el tiempo. Sin embargo, la protección de la plata es necesaria, en particular en el frente. Esta protección debe adherirse a la película de plata, ser flexible y proporcionar un índice de transmisión lo más alto posible en el rango visible. Se han estudiado diferentes barnices y nuestro trabajo ha sido centrado en el desarrollo de recubrimientos de protección orgánicos (PMMA, PU), cerámicos (SiO2, Al2O3) y especialmente en híbridos orgánico-cerámica. Esta investigación ha permitido identificar las áreas de relevancia de estos diferentes tipos de recubrimientos de protección bajo estrés por radiación y su compatibilidad con una capa reflejante de plata para obtener concentradores flexibles eficientes. Una solución original se presenta en la conclusión y corresponde en la realización de un espejo flexible elaborado en una hoja de vidrio de 100 µm de espesor y recubierto con una película de plata de 100 nm. La reflectividad es superior a 95% en el visible

Ce travail a pour objet de développer une nouvelle technologie de l’énergie solaire à concentration. Il porte sur la présentation du concept, la réalisation prototypique et l’étude optique et énergétique d’un nouveau concentrateur solaire QingSun™. Ce concentrateur a une forme de parallélépipède rectangulaire et comporte des lentilles de Fresnel linéaires, des parois tapissées de miroir et d’un récepteur solaire mobile entraîné par un système de suivi à l’intérieur du caisson de concentration. Un modèle optique et un modèle énergétique ont été élaborés et validés avec une série d’expériences. Ils ont permis d’étudier le fonctionnement et les performances énergétiques du concentrateur. Une étude de l’influence paramétrique de l’inclinaison et l’orientation a été effectuée et a montré que l’inclinaison a plus d’influence que l’orientation sur les performances. Enfin, les performances énergétiques optimales du concentrateur ont été estimées
This work is for the purpose to develop a new solar concentrating technology. It covers the presentation of the concept, the prototype realization and the optical and energy study of a new solar concentrator QingSun™. This concentrator has a shape of rectangular parallelepiped and includes linear Fresnel lenses, mirror-lined walls and a mobile solar receptor controlled by a tracking system inside the casing. An optical model and an energy model were developed and validated with a series of experiments. The both models permitted us to examine the function and the energy performance of the concentrator. A parametric study of the influence of the tilt and the orientation was performed and showed that the tilt had more influence than the orientation. Finally, the optimal energy performance of this concentrator was estimated

Par son activité intense et ses hautes températures, l’atmosphère solaire émet des rayonnements X et ultraviolets extrêmes (EUV) porteurs d’informations sur sa structure. Les télescopes spatiaux observant le Soleil dans ce domaine spectral atteignent des performances accrues grâce aux miroirs interférentiels multicouches. Cette thèse contribue à améliorer l’efficacité de ces revêtements optiques. On y évalue les constantes optiques des matériaux dans l’EUV pour les sélectionner plus précisément et affiner les simulations, ce qui nous permet d’établir des modélisations plus précises pour l’étalonnage du télescope EUV plein champ de Solar Orbiter. On propose aussi de nouveaux revêtements à base d’aluminium et de scandium ayant atteint des réflectivités record au-delà de 40 nm de longueur d’onde. S’agissant d’une région spectrale EUV encore peu explorée, les résultats de ces travaux ouvrent la voie à une nouvelle génération d’instruments d’observation solaire. Leurs conséquences sont aussi remarquables pour une communauté scientifique plus étendue ayant besoin d’instrumentation optique adaptée dans le domaine X/EUV pour les synchrotrons, la lithographie EUV, les diagnostics X, ou encore la microscopie X
X-rays and extreme ultraviolet (EUV) light are emitted by excited particles in the solar corona because of its intense activity and extreme temperatures. Recent solar space telescopes in this spectral region showed increased performances thanks to the interference multilayer mirrors on-board. This thesis aims at enhancing such optical coatings, starting with an evaluation of EUV optical constant values available in the literature to select materials more accurately, and to refine optical simulations. This work allows us to introduce better simulations for an accurate calibration of the EUV Full Sun Imager aboard Solar Orbiter. Also, we show that mastering thin films deposition and optical and structural characterization techniques allowed us to develop new Al/Sc-based multilayer coatings reaching record reflectivity values above 40 nm wavelength, which is still a quite unexplored region. These thesis results pave the way for a new and highly efficient generation of solar observation instruments in the EUV, but they also have a remarkable impact in a wider scientific community in need for ever more efficient optical instrumentation in the EUV such as synchrotrons, EUV lithography, X-ray diagnostics, or even X-ray microscopy

Les électrons et les protons suprathermiques, issus du soleil et précipitant dans l'atmosphère des hautes latitudes, constituent une source d'énergie de l'ionosphère terrestre. Ces particules interagissent avec le gaz thermique ambiant par collisions. L'équation de Boltzmann, fournissant les flux de particules en altitude, énergie et angle d'attaque, permet une description des plus complètes du transport de ces particules. Nous la redémontrons dans le cas dissipatif, le plus général, et nous proposons une résolution originale des équations de transport des protons et des atomes d 'hydrogène, équations couplées via les réactions de changement de charge. Cette résolution, fondée sur l'introduction de forces dissipatives pour décrire la dégradation énergétique des particules précipitant, permet la prise en compte des redistributions angulaires, d'origine collisionnelle ou magnétique, jusqu'alors négligées. Pourtant, leur effet a été observé, depuis le sol, sur les émissions des atomes d 'hydrogène, comme en témoigne la composante, décalée vers le rouge, du profil Doppler selon le zénith magnétique. La résolution adoptée ici est validée par comparaison avec un autre modèle, dans le cas classique sans redistribution angulaire. L'influence de l'effet de miroir magnétique est discutée: cet effet ne semble pas pouvoir expliquer, à lui seul, le décalage vers le rouge observé. La redistribution angulaire collisionnelle doit jouer un rôle significatif. Enfin, une comparaison de notre modèle avec les données de la fusée Proton 1 est proposée.

碩士
高苑科技大學
電子工程研究所
103
Because of the poor efficiency on solar cells,the replacement of solar panel from reflecting mirror inside solar concentrator will be our goal of research for this time. We use FRED to simulate solar solar concentrator for visible light owns the strongest energy and that is the main reason we choose the discrete sampling function from FRED to capture visible lights from spectrum as stimulate light source. Furthermore, we apply cutting sphere on solar concentrator and set up 50% covering on mask absorption to decrease solar panel functions and place reflecting mirror around to increase condenser effects via light reflecting. On the process we compare three settings, we found out average placement owns slightly better results than the other two. Also, the result shows the efficiency increased on every single light almost equal to 100% of original reflecting on solar concentrator while applied 7 solar panels.

Sunlight is an abundant and renewable source of energy, and the expanding solar industry uses many different methods to convert this energy to work. Some of these methods (engines) use mirrors to reflect radiation. However, the mirrors are not perfect and have slope, shape, tracking, and non-specularity errors. This thesis investigates the role that these errors play in decreasing the overall efficiency with which radiation is converted to work in a system that relies on reflection. Three theoretical approaches are taken. Taking a “black box” approach to an open cycle engine which converts radiation to work, basic relations are derived which express the work output as a function of entropy carried by the radiation. When radiation is reflected off a mirror with non-specularity error, entropy is generated. This entropy increase, and the associated decrease in work, are calculated for pillbox and Buie sunshape models. The change in engine efficiency in all cases tested is less than 0.25%. Slope, shape, and tracking errors may possibly be treated in the same way, however no rigorous proof of this is found. Attaining the maximum efficiency of the “black box” model requires several conditions to hold simultaneously, and there is no guarantee that this is possible. However, one conceptual engine commonly referred to in the literature attains this maximum efficiency when operating on radiation enclosed in a perfectly reflective container. The radiation enclosed in this conceptual engine is converted to work by exerting (radiation) pressure on a piston in the same fashion as a classical gas engine. This thesis considers a modified version of this enclosed radiation engine in the hope of better understanding the link (or lack thereof) between conceptual radiation engines that operate on enclosed radiation, and engines that operate with a steady flow of input radiation. The efficiencies computed for the modified engine are far lower than the maximum efficiencies of open cycle engines, meaning that no general conclusions can be made. The effect of slope, shape, and tracking errors on this modified engine are determined, but these results cannot be translated into other engine designs because the efficiency of this engine is lower than the maximum efficiency of an open cycle engine. The most common use for mirrors in solar applications is to concentrate sunlight, before converting it to heat, and then to work. The final part of this thesis considers the implications of converting radiation first to heat, then to work, and the effect that mirror errors have on overall system efficiency. It is demonstrated that maximal concentration of incident radiation is beneficial in such a system, and that slope, shape, and tracking errors decrease the maximum concentration that can be achieved. This decrease is quantified using a pillbox sunshape, and the corresponding decrease in system efficiency is calculated. For errors of a typical magnitude, this loss of efficiency is up to 8.5%.

碩士
國立臺灣科技大學
光電工程研究所
102
This paper presents a solar concentrator module which is used in the daylighting system. In the module, plane mirrors are used to reflect the collected sunlight to its destination. Due to the position of the sun changes over time, the plane mirror reflects only certain angles of the light, therefore, we design the free-form mirror to improve the daylighting system performance. The simulation results show the light transmission of the solar concentrator module which uses the free-form mirror design increase 40.6%、38.9% and 52.4% at 11:00 AM、12:00 PM and 1:00 PM, respectively.

碩士
國立中興大學
精密工程學系所
98
This thesis presents performance comparison between a GaAs/mirror/copper thin-film solar cell and a conventional GaAs solar cell with a thick GaAs substrate. The GaAs thin-film solar cell is fabricated by transferring a GaAs solar cell onto a AuGe/Au mirror-coated copper substrate. The device performance of GaAs solar cell with different base layer thickness for thin-film and conventional solar cell will be discussed and compared. The base layer thickness leads the performance of solar cell and results in increased photocurrent. The copper substrate thickness of thin films solar cell are 50, 100, 150 and 200 μm, respectively. With the aid of the excellent copper conductor, the thin-film solar cell exhibits significant improvement in both open-circuit voltage (Voc) and short-circuit current (Jsc) density in one-sun AM 1.5G light source. The improved current-voltage (I-V) performance of the thin-film solar cell originates from the following two factors: reduced reverse saturation current by good heat dissipation of copper and enhanced light absorption by the highly reflective AuGe/Au mirror. The role of the mirror can further be verified in the measurement of external quantum efficiency (EQE) response where the thin-film solar cell exhibits a larger EQE response in the wavelength range of 700~900 nm than the conventional GaAs solar cell with the same active absorbing thickness. The device properties of conventional solar cell versus different working temperature show the degradation of cell performance for open circuit voltage and fill factor (FF) due to the degradation of bulk semiconductor material. The GaAs thin films solar cell significantly is improved temperature coefficient of FF by transferring onto a copper substrate. A combined analysis on dVoc/dT, dJsc/dT and dFF/dT, the degradation of the conversion efficiency for conventional GaAs solar cell is improved by the thin-film solar cell with thick copper sub (thickness is 200 μm). The dη/dT value of conventional GaAs solar cell can be alleviated from -0.0235 %/°C to -0.01077 %/°C.

碩士
環球科技大學
觀光與生態旅遊系環境資源管理碩士班
102
With the dwindling extraction volume and soaring prices of fossil fuel, people are actively seeking to develop clean, renewable and sustainable energy. Our government has implemented the " Million Rooftop PVs Project" in 2012. Solar tracking PV system was considered one of the more efficient ways of generating solar power. This study aimed to design a simple low-concentration PV system, which is based on the use of the Fresnel lens as the collimation tube, and the installation of mirror-augmented device to improve the efficiency. The results showed that the accuracy of tracking can achieve two degrees or less; although the surface temperature was 6.5℃ higher than the ordinary PV systems, the efficiency can improve up to 27.5%. Furthermore, with careful calculation, the payback period was about nine months. Our suggestions included miniaturization of Fresnel lens and collimation tube; installation of automatic closing mechanism to protect the panels; or reinforcing the cooling device to increase power generation efficiency.