Dissertations / Theses: 'Concentrating photovoltaic'

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Coventry, Joseph Sydney, and Joe Coventry@anu edu au. "A solar concentrating photovoltaic/thermal collector." The Australian National University. Faculty of Engineering and Information Technology, 2004. http://thesis.anu.edu.au./public/adt-ANU20041019.152046.

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This thesis discusses aspects of a novel solar concentrating photovoltaic / thermal (PV/T) collector that has been designed to produce both electricity and hot water. The motivation for the development of the Combined Heat and Power Solar (CHAPS) collector is twofold: in the short term, to produce photovoltaic power and solar hot water at a cost which is competitive with other renewable energy technologies, and in the longer term, at a cost which is lower than possible with current technologies. To the authors knowledge, the CHAPS collector is the first PV/T system using a reflective linear concentrator with a concentration ratio in the range 20-40x. The work contained in this thesis is a thorough study of all facets of the CHAPS collector, through a combination of theoretical and experimental investigation. A theoretical discussion of the concept of energy value is presented, with the aim of developing methodologies that could be used in optimisation studies to compare the value of electrical and thermal energy. Three approaches are discussed; thermodynamic methods, using second law concepts of energy usefulness; economic valuation of the hot water and electricity through levelised energy costs; and environmental valuation, based on the greenhouse gas emissions associated with the generation of hot water and electricity. It is proposed that the value of electrical energy and thermal energy is best compared using a simple ratio. Experimental measurement of the thermal and electrical efficiency of a CHAPS receiver was carried out for a range of operating temperatures and fluid flow rates. The effectiveness of internal fins incorporated to augment heat transfer was examined. The glass surface temperature was measured using an infrared camera, to assist in the calculation of thermal losses, and to help determine the extent of radiation absorbed in the cover materials. FEA analysis, using the software package Strand7, examines the conductive heat transfer within the receiver body to obtain a temperature profile under operating conditions. Electrical efficiency is not only affected by temperature, but by non-uniformities in the radiation flux profile. Highly non-uniform illumination across the cells was found to reduce the efficiency by about 10% relative. The radiation flux profile longitudinal to the receivers was measured by a custom-built flux scanning device. The results show significant fluctuations in the flux profile and, at worst, the minimum flux intensity is as much as 27% lower than the median. A single cell with low flux intensity limits the current and performance of all cells in series, causing a significant drop in overall output. Therefore, a detailed understanding of the causes of flux non-uniformities is essential for the design of a single-axis tracking PV trough concentrator. Simulation of the flux profile was carried out using the ray tracing software Opticad, and good agreement was achieved between the simulated and measured results. The ray tracing allows the effect of the receiver supports, the gap between mirrors and the mirror shape imperfections to be examined individually. A detailed analytical model simulating the CHAPS collector was developed in the TRNSYS simulation environment. The accuracy of the new component was tested against measured data, with acceptable results. A system model was created to demonstrate how sub components of the collector, such as the insulation thickness and the conductivity of the tape bonding the cells to the receiver, can be examined as part of a long term simulation.

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Coventry, Joseph Sydney. "A solar concentrating photovoltaic/thermal collector /." View thesis entry in Australian Digital Theses Program, 2004. http://thesis.anu.edu.au/public/adt-ANU20041019.152046/index.html.

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Arnaoutakis, Georgios E. "Novel up-conversion concentrating photovoltaic concepts." Thesis, Heriot-Watt University, 2015. http://hdl.handle.net/10399/2933.

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This thesis summarises a set of experiments towards the integration of concentrating optics into up-conversion photovoltaics. Up-conversion in rare earths has been investigated here. This optical process is non-linear therefore a high solar irradiance is required. High solar irradiance is achievable by solar concentration. Two concentrating approaches were investigated in this thesis: The first approach involved the concentration of the incident solar irradiance into optical fibres. An optical system with spherical lenses and dielectric tapers was designed accordingly. A solar concentration of 2000 suns was realised at the end of a single optical fibre. In addition to the total solar concentration, the spectral dependence was characterised to account for the effect of chromatic aberrations. Then, the solar concentration could be transferred into rare earth-doped fibres. For this reason, a series of experiments on double-clad erbium-doped silicate fibres was carried out. Although up-conversion in this type of fibre is minimised, the measured power dependence agrees with up-conversion via excited state absorption. In the second approach, concentrating optics were integrated in up-conversion solar cells. The role of the optics was to couple the photons transmitted by the solar cell to the rare earth up-converter. Therefore, imaging and non-imaging optics were investigated, with the latter exhibiting ideal coupling characteristics; concentration and high transmission of the incident irradiance, but also efficient collection of the up-converted emission. Out of the non-imaging optics, the dielectric compound parabolic concentrator fulfilled these characteristics, indicating its novel use in up-conversion solar cells. Two erbium-doped up-converters were utilised in this approach, beta-phase hexagonal sodium yttrium tetrafluoride (β-NaYF4:25%Er3+) and barium diyttrium octafluoride (BaY2F8:30%Er3+). The latter performed best, with an external quantum efficiency (EQE) of 2.07% under 1493 nm illumination, while the former exhibited an EQE of 1.80% under 1523 nm illumination both at an irradiance of 0.02 W/cm2. This corresponds to a relative conversion efficiency of 0.199% and 0.163% under sub-band-gap illumination, respectively, for a solar cell of 17.6% under standard AM1.5G conditions. These values are among the highest in literature for up-conversion solar cells and show the potential of the concentrating concept that can be important for future directions of photovoltaics.

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Bentley, R. W. "A manually-repositioned concentrating photovoltaic water pump." Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376208.

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Dickinson, Michael Design Studies College of Fine Arts UNSW. "Design of a Static Concentrating Photovoltaic Roof Tile." Awarded by:University of New South Wales. School of Design Studies, 2001. http://handle.unsw.edu.au/1959.4/18229.

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The aim of this document is to investigate through industrial design the potential of a high efficiency photovoltaic concentrator theory. The investigation directs a proposed layout for the design of a device, which specifically addresses the incorporation of the concentrator theory into the design of a photovoltaic ????????roof tile????????. The focus of the investigation has been the integration of theoretical constructs and physical realities. The objective is to facilitate this transition from theory to reality: to contribute to the quest of creating viable manufacturable designs for the generation of clean low cost electrical power. The use of a roof tile as the focus of the incorporating device served two purposes. Number one: it provided a sensible, existing platform, which is under utilised, presented potential and fitted within established building practices. It was not the objective of this thesis to argue that tile integration is the best, only or even the most financially viable direction to pursue; it was one option among many. This brings us to the second purpose; the consideration of existing roofing tiles forced the theory to be applied within set limitations, in particular existing size restrictions. The imposition of a framework to work within highlighted the design issues, which would have to be addressed in the actualisation of the theory. The theory????????s broad strategy for economic viability has been to reduce the actual silicone cell content of panel designs by approximately one third. This is achieved by the use of numerically fewer cells in combination with a concentration method, which does not cost more than the savings gained by the use of fewer cells. This document records the design process undertaken and presents the findings so that further development can be undertaken.

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Baig, Hasan. "Enhancing performance of building integrated concentrating photovoltaic systems." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/17301.

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Buildings both commercial and residential are the largest consumers of electricity. Integrating Photovoltaic technology in building architecture or Building Integrated Photovoltaics (BIPV) provides an effective means for meeting this huge energy demands and provides an energy hub at the place of its immediate requirement. However, this technology is challenged with problems like low efficiency and high cost. An effective way of improving the solar cell efficiency and reducing the cost of photovoltaic systems is either by reducing solar cell manufacturing cost or illuminating the solar cells with a higher light intensity than is naturally available by the use of optical concentrators which is also known as Concentrating Photovoltaic (CPV) technology. Integrating this technology in the architecture is referred as Building integrated Concentrating Photovoltaics (BICPV). This thesis presents a detailed performance analysis of different designs used as BICPV systems and proposes further advancements necessary for improving the system design and minimizing losses. The systems under study include a Dielectric Asymmetric Compound Parabolic Concentrator (DiACPC) designed for 2.8×, a three-dimensional Cross compound parabolic concentrator (3DCCPC) designed for 3.6× and a Square Elliptical Hyperbolic (SEH) concentrator designed for 6×. A detailed analysis procedure is presented showcasing the optical, electrical, thermal and overall analysis of these systems. A particular issue for CPV technology is the non-uniformity of the incident flux which tends to cause hot spots, current mismatch and reduce the overall efficiency of the system. Emphasis is placed on modelling the effects of non-uniformity while evaluating the performance of these systems. The optical analysis of the concentrators is carried out using ray tracing and finite element methods are employed to determine electrical and thermal performance of the system. Based on the optical analysis, the outgoing flux from the concentrators is predicted for different incident angles for each of the concentrators. A finite element model for the solar cell was developed to evaluate its electrical performance using the outputs obtained from the optical analysis. The model can also be applied for the optimization of the front grid pattern of Si Solar cells. The model is further coupled within the thermal analysis of the system, where the temperature of the solar cell is predicted under operating conditions and used to evaluate the overall performance under steady state conditions. During the analysis of the DiACPC it was found that the maximum cell temperature reached was 349.5 K under an incident solar radiation of 1000 W/m2. Results from the study carried on the 3DCCPC showed that a maximum cell temperature of 332 K is reached under normal incidence, this tends to bring down the overall power production by 14.6%. In the case of the SEH based system a maximum temperature of 319 K was observed on the solar cell surface under normal incidence. An average drop of 11.7% was found making the effective power ratio of the system 3.4. The non-uniformity introduced due to the concentrator profile causes hotspots in the BICPV system. The non-uniformity was found to reduce the efficiency of the solar cell in the range of 0.5-1 % in all the three studies. The overall performance can be improved by addressing losses occurring within different components of the system. It was found that optical losses occurred at the interface region formed due to the encapsulant spillage along the edges of the concentrator. Using a reflective film along the edge of the concentrating element was found to improve the optical efficiency of the system. Case studies highlighting the improvement are presented. A reflective film was attached along the interface region of the concentrator and the encapsulant. In the case of a DiACPC, an increase of 6% could be seen in the overall power production. Similar case study was performed for a 3DCCPC and a maximum of 6.7% was seen in the power output. To further improve the system performance a new design incorporating conjugate reflective-refractive device was evaluated. The device benefits from high optical efficiency due to the reflection and greater acceptance angle due to refraction. Finally, recommendations are made for development of a new generation of designs to be used in BiCPV applications. Efforts are made towards improving the overall performance and reducing the non-uniformity of the concentrated illumination.

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Yandt, Mark. "Characterization and Performance Analysis of High Efficiency Solar Cells and Concentrating Photovoltaic Systems." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20535.

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As part of the SUNRISE project (Semiconductors Using Nanostructures for Record Increases in Solar-cell Efficiency), high efficiency, III-V semiconductor, quantum-dot-enhanced, triple-junction solar cells designed and manufactured by Cyrium Technologies Inc. were integrated into OPEL Solar, MK-I, Fresnel-lens-based, 550x concentrating modules carried on a dual axis tracker. Over its first year of operation 1.8 MWh of AC electrical energy was exported to the grid. Measurements of the direct and indirect components of the insolation, as well as the spectral irradiance of light incident on the demonstrator in Ottawa, Canada are presented. The system efficiency is measured and compared to that predicted by a system model to identify loss mechanisms so that they can be minimized in future deployments.

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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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Muron, Aaron C. D. "Field Installation of a Fully Instrumented Prototype Solar Concentrator System: Thermal and Photovoltaic Analysis." Thesis, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26245.

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Concentrator photovoltaics (CPV) is one of the most promising renewable technologies owing to its high efficiency, scalability, low operating expense, and small environmental impact. However, there is much research and advancements to be made before CPV is established as a cost competitive energy technology. To this end, Morgan Solar has developed the Sun Simba, an innovative light weight and low cost CPV module. Under the “Advancing Photonics for Economical Concentration Systems” (APECS) project, outdoor CPV test and measurement systems were designed and constructed at the University of Ottawa and at Little Rock, CA. The performance and reliability of development stage Sun Simba modules installed at the University of Ottawa is assessed. The Little Rock test system was constructed for purposes of future comparison and assessment. To properly assess the performance, instrumentation and data acquisition systems to measure meterological parameters and the associated electrical performance are described and the long-term performance of Sun Simba modules installed at the University of Ottawa is summarized. A finite element model of a cell-on-carrier assembly was constructed to explore the parameter space of the carrier and suggest improvements in carrier design. The effect of carrier geometry, material choices, and convective boundary conditions and their influence on the cell efficiency is determined. The modelling results connected to the measured data is used to estimate the heat sinking capability of the second generation Sun Simba modules.

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Conte, Jeffrey E. "Analysis of a Fresnel concentrating spectral divider for a photovoltaic system." Virtual Press, 1987. http://liblink.bsu.edu/uhtbin/catkey/494976.

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To improve photovoltaic system efficiencies, concentrating spectral dividers are used to separate solar light, and to focus each spectral portion onto photovoltaic cells of matching spectral response. In this investigation, an optical analysis is developed to study the feasibility for use of a Fresnel half-lens as a concentrating spectral divider. To facilitate the analysis, an existing curved-base linear Fresnel lens ray-trace model has been modified and expanded. Solar limb-darkening has been incorporated into the theory by means of a digitized sun model. The lens model allows for variation of lens geometrical characteristics. Transmission losses due to Fresnel reflection and bulk absorption are taken into account. The distribution of the concentrated solar flux in the lens image plane is modeled such that spectral regions may be examined separately. Concentration ratio profiles are used to derive and evaluate a quantity of spectral separation.A computer program has been used to generate data, based on the theoretical model, for example lenses. The spectral separation, transmission and concentration properties for each example lens have been systematically studied with respect to lens geometry. The effects of solar limb-darkening are determined by comparison with the data from a model that assumes a uniform solar source. Results of the study are discussed in detail.Ball State UniversityMuncie, IN 47306

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Micheli, Leonardo. "Enhancing electrical and heat transfer performance of high-concentrating photovoltaic receivers." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/18484.

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In a world that is constantly in need of a continuous, reliable and sustainable energy supply, concentrating photovoltaic technologies have the potential to become a cost effective solution for large scale power generation. In this light, important progresses have been made in terms of cell’s design and efficiency, but the concentrating photovoltaic industry sector still struggles to gain market share and to achieve adequate economic returns. The work presented in this thesis is focused on the development of innovative solutions for high concentrating photovoltaics receivers. The design, the fabrication and the characterization of a large cell assembly for high concentrations are described. The assembly is designed to accommodate 144 multijunction cells and is rated to supply energy up to 2.6kWe at 500 suns. The original outline of the conductive copper layer limits the Joule losses to the 0.7% of the global power output, by reducing the number of interconnections. All the challenges and the issues faced in the manufacturing stage are accounted for and the reliability of the fabrication has been proven by quality tests and experimental investigations conducted on the prototype. An indoor characterization shows the receiver’s potential to supply a short-circuit current of 5.77A and an open circuit voltage per cell of 3.08V at 500×, under standard test conditions, only 4.80% and 2.06% respectively lower than those obtained by a commercial single-cell assembly. An electrical efficiency of 29.4% is expected at 500 suns, under standard conditions. A prototype’s cost of $0.91/Wp, in line with the actual price of CPV systems, has been recorded: a cost breakdown is reported and the way to further reduce the cost have been identified and is accounted. In a second approach, the design of a natural convective micro-finned array to be integrated in a single cell receiver has been successfully attempted. Passive cooling systems are usually cheaper, simpler and considered more reliable than active ones. After a detailed review of micro-cooling solutions, an experimental investigation on the thermal behaviour of micro-fins has been conducted and has been combined with a multiphysics software model. A micro-finned heat sink shows the potential to keep the CPV temperature below 100°C under standard conditions and the ability to handle the heat flux when the cell’s efficiency drops to zero. Moreover, a micro-finned heat sink demonstrates the potential to introduce significant benefits in terms of material usage and weight reduction: compared to those commercially available, a micro-finned heat sink has a power-to-weight ratio between 6 and 8 times higher, which results in lower costs and reduced loads for the CPV tracker.

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Brogren, Maria. "Optical Efficiency of Low-Concentrating Solar Energy Systems with Parabolic Reflectors." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3988.

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Sarmah, Nabin. "Design and performance evaluation of a low concentrating line-axis dielectric photovoltaic system." Thesis, Heriot-Watt University, 2012. http://hdl.handle.net/10399/2656.

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This thesis presents a detailed investigation of the design optimisation and performance analysis of a dielectric concentrator for building façade integration at high latitudes (>55°). Considering the seasonal variation of the sun’s position at these latitudes, a concentrating photovoltaic (CPV) system with stationary concentrators of large acceptance angle and low concentration ratio is a suitable alternative to conventional flat plate photovoltaic (PV) modules. A well designed dielectric asymmetric compound parabolic concentrator (ACPC) is a suitable choice to achieve optimum range of acceptance angles and concentration ratio for building façade integration in the Edinburgh and higher latitudes. A theoretical study of the optical performance shows that a truncated dielectric ACPC with acceptance half-angles of 0o and 55o (termed as DiACPC-55) is the optimum design, when compared to the dielectric ACPC designs with acceptance half angles of (0o and 66o) and (0o and 77o) in Edinburgh and higher latitudes. An increase in the range of acceptance angles is achieved by truncating the concentrator profile. Ray tracing simulations show the DiACPC-55 exhibits the widest range of acceptance angles compared to the other designs. The maximum optical efficiency of the DiACPC-55 is found to be 83%. In addition it is found to have a better intensity distribution at the receiver and a higher total annual energy collection, compared to the other designs. Thermal modelling of a CPV system with the DiACPC-55 concentrator shows that the solar cell and rear plate temperature can reach up to 41.6oC for 1000 W/m2 irradiance, when operating with an average ambient temperature of 10oC. The maximum power ratio of the CPV module (fabricated using the DiACPC-55 concentrator) to a similar non-concentrating counterpart is found to be 2.32, when characterised in an indoor controlled environment using a solar simulator. An average electrical conversion efficiency of 9.5% is measured for the entire range of acceptance angles. The optical loss analysis shows that incident light can escape from the parabolic sides and concentrator-encapsulation interface. The outdoor characterisation of the CPV module with the DiACPC-55 concentrator shows that a maximum power ratio of 2.22 can be achieved on a sunny day. In comparison, a maximum power ratio of 1.9 is observed on a rainy day. These results reveal that the designed dielectric concentrator is capable of collecting 68% of the diffuse radiation. The maximum electrical conversion efficiency of the CPV module in outdoor condition is found to be 9.4%. Module degradation due to the delamination of the solar cell is observed in the long term investigation study, which reduces the module efficiency to 8.6% on a clear sunny day. The fabricated CPV system with the DiACPC-55 concentrator is found to be £190.3/m2 cheaper than similar sized conventional glass-glass laminated modules. Therefore the cost of the CPV module is found to be £0.53/Wp cheaper than the conventional glass-glass laminated modules for building facade integration at high latitudes.

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Menoufi, Karim Ali Ibrahim. "Life Cycle Assessment of novel Building Integrated Concentrating Photovoltaic systems through environmental and energy evaluations." Doctoral thesis, Universitat de Lleida, 2014. http://hdl.handle.net/10803/131056.

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La realització d'estudis de LCA per a sistemes fotovoltaics és una eina essencial per mesurar el seu nivell de sostenibilitat En aquest sentit, i després de la realització d' una anàlisi teòrica dels estudis publicats de LCA dels sistemes fotovoltaics, s'han trobat algunes llacunes. Aquestes llacunes es refereixen a la manca de varietat d'indicadors de LCA, on la majoria dels estudis depenen del temps de retorn energètic, sent aquest gairebé l'únic indicador (no es té en compte l'ús dels mètodes de perfil ambiental). A més, s'observen dues bretxes relatives a la manca d'estudis de LCA destacant la integració en edificis d'energia solar d'una banda, i l'ús de la tecnologia fotovoltaica de concentració per un altre. Per tant, en aquesta tesi, es presenta una nova aportació al camp dels estudis LCA dels sistemes fotovoltaics integrats en edificis. Això s'aconsegueix a través de l'avaluació ambiental i energètica dels sistemes de concentració fotovoltaica integrats en edificis (BICPV). Els resultats es presenten en termes de metodologies d'avaluació de l' impacte del cicle de vida (perfil mediambiental), així com el temps d'amortització de l'Energia i el Factor de Retorn (perfil energètic). Els resultats, amb el suport de les anàlisis de sensibilitat i la comparació amb un sistema convencional fotovoltaic per a integració en edificis (BIPV), mostren beneficis ambientals significatius que poden ser obtinguts a través de sistemes BICPV. A Finalment, es discuteixen les recomanacions per a treballs i millores futures.
Conducting LCA studies for PV systems is an essential tool for measuring the sustainability level of a corresponding system. In this sense, and after conducting a theoretical analysis of the LCA studies of PV systems in literature within the context of energy generation, some gaps have been found. These gaps are briefly represented in the lack of variety of LCA indicators, where most of the studies are dependent on the Energy Payback Time as almost the sole environmental indicator, disregarding the use of environmental profile methods. In addition, another two gaps are observed concerning the lack of LCA studies highlighting the building integration from one side, and the use of the concentrating PV technology from another side. Hence, in this thesis, a novel contribution to the field of LCA studies of PV systems is presented. This is achieved through environmentally and energetically evaluating novel Building Integrated Concentrating Photovoltaic (BICPV) systems. The results are presented in terms of Life Cycle Impact Assessment methodologies (environmental profile), as well as the Energy Payback Time and the Energy Return Factor (Energy profile). The results, supported by sensitivity analyses and comparison to a conventional Building Integrated Photovoltaic (BIPV) system, show the significant environmental benefits that can be acquired through BICPV systems. Finally, recommendations for future work and improvements are discussed as well.
La realización de estudios de LCA para sistemas fotovoltaicos es una herramienta esencial para medir su nivel de sostenibilidad. En este sentido, y después de la realización de un análisis teórico de los estudios de LCA de los sistemas fotovoltaicos en la literatura en el contexto de la generación de energía, se han encontrado algunas lagunas. Algunas de estas lagunas se refieren: la falta de variedad de indicadores de LCA, donde la mayoría de los estudios dependen del tiempo de retorno energético, siendo este casi el único indicador medioambiental (no se tiene en cuenta el uso de los métodos de perfil medioambiental). Además, se observan otras dos brechas relativas a la falta de estudios de LCA destacando la integración en edificios de energía solar por un lado, y el uso de la tecnología fotovoltaica de concentración por otro. Por lo tanto, en esta tesis, se presenta una nueva aportación al campo de los estudios LCA de los sistemas fotovoltaicos integrados en edificios. Esto se logra a través de la evaluación medioambiental y energética de los sistemas de concentración fotovoltaica integrados en edificios (BICPV). Los resultados se presentan en términos de metodologías de evaluación del impacto del ciclo de vida (perfil medioambiental), así como el tiempo de amortización de la Energía y su Factor de Retorno (perfil de la Energía). Los resultados, con el apoyo de los análisis de sensibilidad y la comparación con un sistema convencional fotovoltaico para integración en edificios (BIPV), muestran beneficios ambientales significativos que pueden ser obtenidos a través de sistemas BICPV. Finalmente, se discuten las recomendaciones para trabajos y mejoras futuros.

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Theristis, Marios. "Development of a spectral dependent electrical & thermal model for high concentrating photovoltaic (HCPV) receivers." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3177.

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High concentrating photovoltaic (HCPV) systems employ III-V multijunction (MJ) solar cells. Such solar cells are monolithically connected in-series and therefore present a strong dependence on the solar spectrum variations. In addition, the concentrated solar flux contributes to the heat generation within the solar cells and, in combination with the current mismatch between the subcells, can force the device to operate in elevated temperatures. It is important therefore, to investigate the influence of the atmospheric parameters on the electrical performance of HCPV and also to quantify the cooling requirements based on the spectrum changes. In this thesis, a spectral dependent electrical model has been developed to calculate the electrical characteristics and quantify the heat power of a multijunction solar cell. A three-dimensional finite element analysis is also used to predict the solar cell's operating temperature and cooling requirements for a range of ambient temperatures. The combination of these models improves the prediction accuracy of the electrical and thermal behaviour of triple-junction solar cells. The convective heat transfer coefficient between the back-plate and ambient air is quantified based on input spectra. A theoretical investigation is performed to analyse the influence of air mass (AM), aerosol optical depth (AOD) and precipitable water (PW) on the performance of each subcell and whole. It has been shown that the AM and AOD have a negative impact on the spectral and electrical performance of 3J solar cells while the PW has a positive effect, although, to a lesser degree. In order to get a more realistic assessment and also to investigate the effect of heat transfer coefficient on the annual energy yield, the methodology is applied to four US locations using data from a typical meteorological year (TMY3). The integrated modelling procedure is validated experimentally using field measurements from Albuquerque, NM. The importance of the effect of atmospheric parameters on the solar spectrum and hence the performance of HCPV systems is highlighted in this work. The outdoor characterisation provides with useful insight of the influence of spectrum on the performance of a HCPV monomodule and the current CSOC and CSTC ratings are evaluated based on different spectral filtering criteria.

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Stalter, Olivier. "Inverter-integrated, sensorless and power-optimized position control of a concentrating photovoltaic dual-axis tracker." Grenoble INPG, 2009. http://www.theses.fr/2009INPG0186.

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L’intérêt du photovoltaïque à concentration (CPV) réside autant dans le faible volume de semi-conducteur que dans le fort rendement des cellules solaires III-V. Toutefois, du fait du dispositif optique, un positionnement mécanique très précis du générateur CPV via un traqueur solaire à deux axes de rotation est nécessaire. La première partie du travail de thèse consista à développer un onduleur hybride ou « Tracking Inverter » capable d’injecter le courant produit par un traqueur CPV tout en réalisant son positionnement. La seconde partie consista à implémenter les procédés de tracking classiques (capteur solaire, calcul astronomique ou hybride) afin d’évaluer leurs performances et leurs limites. Enfin, la réalisation majeure de la thèse fût le développement d’un nouveau procédé de tracking sans capteur et basé sur la puissance électrique de l’onduleur. La précision, la sensibilité et la fiabilité du Mechanical Maximum Power Point Tracker (MPPTm) en modes dégradés vinrent clore l’étude.

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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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Saizar, Zubeldia Xabier, and Montagut Gerard Vila. "Analysis of the Solarus C-PVT solar collector and design of a new prototype : Market review and Production process guideline." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-21679.

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Finding cleaner and sustainable energy resources is one of the most important concerns for the development of humanity. Solar energy is taking an essential role in this matter as the production cost of solar collectors is decreasing and more solar installations are being set up every year throughout the world. One way of reducing the cost of solar panels is by using concentrators that are cheaper than the costly photovoltaic cells and can increase their output. Solarus AB designed a Photovoltaic Thermal (PVT) hybrid collector that uses this principle and which is a variation of the Maximum Reflector Collector (MaReCo) design and is a Compound Parabolic Collector (CPC). This thesis has two main objectives. The first one is to design variations of the actual Solarus’ design and some alternative MaReCo designs and pure parabola designs. These designs include new solar cell cuts which are based on 4 busbar solar cells. In this way a future in-depth analysis may be carried out by comparing different receiver designs and collector boxes. The second goal is to investigate the current electrical and thermal performance of the collectors from Solarus AB which are installed in the Hus 45 of HiG. The appropriate data of the installation has been obtained using simulations and specific software, and it has been analysed with Microsoft Excel®. Concerning the new designs of the receivers and boxes, everything has been prepared for the future construction of the prototypes. All the measurements and their adjustments have been taken into account to define the size of the components and the process of building has been set up. Moreover, some future work has been planned in order to move forward the project. Regarding the analysis of the HiG installation, both electrical and thermal performance have resulted to be significantly lower compared with their estimated simulation, being their real output around 60 % of the estimated one. In the thermal part, the losses in the pipeline result to be more than a third part of the produced heat. In the electrical part, the production varies a lot between different collectors due to some of them do not work properly, consequence of poor condition of the solar panels (broken cells, dirt, shading, etc.).

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Selimoglu, Ozgur. "Design And Realization Of A New Concentrating Photovoltaic Solar Energy Module Based On Lossless Horizontally Staggered Light Guide." Phd thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615639/index.pdf.

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Concentrating Photovoltaic systems are good candidates for low cost and clean electricity generation from solar energy. CPV means replacing much of the expensive semiconductor photovoltaic cells with the cheaper optics. Although the idea is simple, CPV systems have several problems inherent to their system design, such as module thickness, expensive PV cells and overheating. Light guide systems are good alternatives to classical CPV systems that can clear off most of the problems of those systems. In this thesis we explore a new light-guide based solar concentrator by optical design and simulations. It is shown that this solar concentrator can reach 1000x geometric concentration, 96.5% optical efficiency with a ±
1 degree acceptance angle. As a result of simulations, effectiveness of the horizontally staggered light guide solar concentrators is proved. A practical module study is carried on to improve the knowledge related to light guide CPV systems. The concentrator geometry is fabricated as a medium concentrator system with a geometric concentration of 45x and +-2 degrees acceptance angle. With the prototype level injection molding 74% optical efficiency is achieved and can be improved with a better mold manufacturing. A cost analyses is also performed with real manufacturing parameters and it is shown that grid parity can be achieved with this kind of light guide solar concentrators.

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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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Almingol, Oscar. "Construction of a C-PV prototype." Thesis, Högskolan i Gävle, Elektronik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-25083.

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The following Master Thesis will talk about a C-PV prototype using bifacial PV technology, based on the Solarus Collector. The Solarus Collector consists in two PV cells built on a metallic receiver, where there are some water channels flowing through it, allowing to cool down the PV cells, thus increasing their efficiency. The collector also presents a reflector to provide irradiance to the back part of the receiver, where the other PV cells are located. The new prototype will present bifacial PV cells but not a metallic receiver. This construction aims to reduce the price of the receiver, but will not have a system to cool down the solar cells. This Master Thesis will be developed in the Solarus facilities, in collaboration with the Solarus members. In order to grasp an idea of this prototype, two main procedures will be done. Regarding the bifacial technology, a bifacial PV module will be measured under different conditions, depending on which sides can be illuminated or shaded. On the other hand, a thermodynamic simulation will be carried out on different geometries of the reflector and receiver, in order to figure out the evolution of the temperatures on the new prototype. This simulation will be done with a finite element method, widely known in this applications. The results will show several problems concerning this prototype. Although the measurements of the bifacial PV module will result beneficial and informative, the problem with the temperature will tend to back down this prototype. The lack of some system to cool down the bifacial cells will imply that the receiver could reach unacceptable temperatures. This hypothesis will be drawn under some specific conditions, so they will not be completely devastating to the idea of using bifacial cells, but perhaps a different approach should be used in case it is desired to continue this work.

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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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23

Madaeni, Seyed Hossein. "Challenges in Renewable Energy Integration." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1342628585.

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Tassew, Wondesen. "Photovoltaic concentration at ultra-high flux /." [Beersheba, Israel] : Ben-Gurion University of the Negev, 2006. http://aranne5.lib.ad.bgu.ac.il/others/TassewWondesen.pdf.

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25

Kaur, Manpreet. "Dual Spin-Cast Thermally Interdiffused Polymeric Photovoltaic Devices." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77159.

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An in depth study of the performance of thermally interdiffused concentration gradient polymer photovoltaic devices is carried out with particular attention to the effect of the thickness and the thermal treatments on the power conversion efficiency, short circuit current, open circuit voltage and other key electrical properties. Bilayer films of sequentially spin-cast donor and acceptor materials are exposed to various heat treatments in order to induce the interdiffusion. The depth profiles show concentration gradients in the donor and acceptor as a result of interdiffusion and these devices show an order of magnitude increase in the device performance compared to the bilayer devices. Dual spin-cast poly (3-octylthiophene-2,5-diyl) (P3OT)- [6,6] phenyl C61 butyric acid methyl ester (PCBM) and poly (3-hexylthiophene-2,5-diyl) (P3HT)-PCBM interdiffused devices are studied in detail by varying the thickness of the donor and acceptor layers as well as the annealing conditions for initial polymer layer and the time and temperature of the interdiffusion process. Auger spectroscopy and X-ray photoelectron spectroscopy along with ion beam milling are used to investigate the concentration gradient formed as a result of the interdiffusion. The sulfur signal present in the P3OT and P3HT backbone is detected to identify the concentration profiles in the P3OT-PCBM and P3HT-PCBM devices. The interdiffusion conditions and thickness of the active layers have been optimized to obtain the highest power conversion efficiency. The best device performance of the P3OT-PCBM interdiffused devices is achieved when the interdiffusion is carried out at 150°C for 20 minutes and the P3OT thickness is maintained at 70 nm and the PCBM thickness at 40-50 nm. The highest efficiency achieved for P3OT-PCBM interdiffused devices is 1.0% under AM1.5G solar simulated spectrum. In order to further increase the efficiency, P3OT is replaced by (P3HT) which has higher hole mobility. P3HT- PCBM based concentration gradient devices show improved device performance over P3OT-PCBM devices. Power conversion efficiency of the order of ~3.0% is obtained for P3HT-PCBM interdiffused devices when the interdiffusion is carried out at 150°C for 20 minutes. For both P3OT:PCBM and P3HT:PCBM devices, the optimum performance occurs when the concentration gradient extends across the entire film and is correlated with an increase in the short circuit current density and fill factor as well as a decrease in the series resistance. The results demonstrate that an interdiffused bilayer fabrication approach is a novel and efficient approach for fabrication of polymer solar cell devices. In addition, porphyrin derivative 5, 10, 15, 20-Tetraphenyl-21H, 23H-porphine zinc (ZnTPP) is studied as a new donor material for organic solar cells. ZnTPP: PCBM blend devices are investigated in detail by varying the weight ratio of the donor and acceptor materials in blend devices. The devices with ZnTPP: PCBM in 1:9 ratios showed the best device performance and the efficiency of the order of 0.2% is achieved under AM1.5G solar simulated conditions. Trimetallic Nitride Tempelated (TNT) endohedral fullerenes are also examined in this thesis as the novel acceptor materials. Bulk heterojunction or blend devices are fabricated with P3HT as the donor material and several TNT endohedral fullerenes as the acceptor material. Y3N@C₈₀PCBH based devices which are annealed both before and after the electrode deposition show improvement in the device performance compared to devices that are only annealed before the electrode deposition. The highest power conversion efficiency achieved for TNT endohedral fullerene devices is only 0.06%, suggesting that substantial additional work must be done to optimize the compatibility of the donor and acceptor as well as the device fabrication parameters.
Ph. D.

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26

Adkins, Deborah Anne. "Experimental and numerical modelling of mid-concentration photovoltaic concentrator systems." Thesis, University of Nottingham, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.594866.

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For photovoltaics to achieve wide-scale implementation it is essential that their cost is reduced while maintaining or exceeding the present level of solar to electrical conversion performance. Concentrating solar energy onto a photovoltaic cell allows a reduction in the output electricity cost, if the cost of the concentrator is less than that of the displaced photovoltaic materials. Photovoltaic cell efficiency is shown to decrease with increasing temperature, causing the photovoltaic cells to exhibit both short-term (efficiency loss) and long term (irreversible damage) degradation due to excessive temperatures. Hence the analysis of thermal management is an important issue in photovoltaic power generating systems for both one-sun (lx) and concentrated applications. This thesis presents an experimental and numerical study of solar cell temperature in a midconcentration silicon photovoltaic concentrator (CPV), with a geometric concentration ratio of 42X. Experimental and computational fluid dynamic (CFO) modelling of heat transfer in six designs of CPV device is carried out. A detailed experimental study was designed and carried out in order to investigate the temperature and initial boundary conditions of the two initial CPV prototypes, with a without passive cooling arrangements, operating under standard test conditions (STC) in conjunction with the effect of environmental variables, namely the irradiance incident on the plane-of-array of the CPV module, the local wind speed and the ambient temperature on the operating temperatures of the CPV prototypes. The operating temperature is shown to depend strongly on the irradiance, less so on the wind speed and is found to be insensitive to short term fluctuations in ambient temperature. Temperature profiles of the CPV prototypes were measured experimentally with thermocouples placed both internally and externally along the enclosure and walls aJong the length of each CPV module. To investigate the performance of the CPV devices under a fixed set of repeatable environmental conditions, a solar simulator was designed and built to facilitate indoor testing at a range of illumination levels (0 to 1000W 1m2) and environmental conditions. Reviewing the results it was found that the spectrum and uniformity of irradiance source incident the plane of a single module (1 x 0.lm) is of great importance. The solar simulator was also found to artificially increase the module operating temperature, with greater temperatures recorded during indoor testing. Wind speed and direction measurements were taken in order to establish the module convective heat transfer coefficient (CHTC) which was determined to relatively insensitive to wind direction and to be a power law function of the mean wind speed. In the second phase of the work, three dimensional numerical studies of the photovoltaic concentrator prototypes were developed using ANSYS Fluent Computational Fluid Dynamic (CFD) software to solve the mass, momentum and energy transfer governing equations. The simulations provided thermal and dynamic maps of the fluid flow and the heat transfer between the cell and the passive cooling systems. The results show that a maximum of seven radial fins (CPV design 3) of 27mm height, 3.3mm thickness with a 4 degree taper can be effectively used to reduce the solar cell temperature, from 97.8"C with no cooling fins to 67.7"C with seven fins, measured at nominal operating cell temperature (NOCT) conditions. In addition. to validate the model. experimental measurements of temperature and flow characteristics are compared with experimental data. Numerical results of the CPV operating temperature are shown to have a strong correlation with experimental data with a maximum 0.3% deviation from experimental data for prototype one and a maximum 1.5% deviation from experimental data for prototype two. Simulation models are shown to be important design tools for predicting a photovoltaic concentrator's experimental and real world performance. Informed design decision making and optimisation is a significant goal of this work.

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Paul, Damasen Ikwaba. "Characterisation of solar concentrating systems for photovoltaics and their impact on performance." Thesis, University of Ulster, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549700.

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The use of concentrating systems has a great potential to become the lowest-cost PV option if the high energy flux in the concentrated PV module can be utilised efficiently. In this study, a PV module with isolated cells was designed and fabricated with the purpose of examining the performance of each cell under concentrated (using CPC and V-trough) and non-concentrated light. Before the experimental characterisation, a detailed optical analysis for the CPC and V-trough collectors was undertaken. It was found that in spite of both concentrators having the same concentration ratio and aperture area, the angular acceptance and optical efficiency for the CPC were always higher than those of the V-trough for incidence angles above ± 20° and ± 10° , respectively. A comparison of flux distribution on the absorber of the two concentrators indicated that the energy flux was more uniform in the V -trough collector than in the CPC collector. The experimental energy flux concentration for the CPC collector (at normal incidence angle) varied from 0.9 to 3.6, with higher irradiance concentrated near the edges of the PV module. As a result, the CPC performed better with cells located near the edges of the PV module than those at the centre. On the other hand, the energy concentration for the V -trough collector varied from 1.3 to 2.5, with higher irradiance concentrated at the centre of the PV module. The use of the CPC and V-trough concentrators increased the power output of a PV module by 25% and 46%, respectively, compared to a similar non-concentrated PV module. The fabricated isolated cells PV module was used to evaluate, theoretically and experimentally, the energy flux distribution on the surface of a concentrated PV module under CPC and V -trough concentrators. From the analysis, it was found that in both collectors, the experimental optical efficiency (indoor and outdoor) results follow the theoretical ones with reasonable accuracy, especially the outdoor experimental results. The comparison between outdoor and indoor experimental optical efficiencies in each collector showed that there was good agreement between the two results, both for low and high incidence angles. The effects of non-uniform illumination on the performance of a single standard PV cell, at low and medium energy flux concentration ratios as well as the effect of orientation, size and geometrical shapes of non-uniform illumination were studied. It was found that the effect of non-uniform illumination on various cell performance parameters becomes noticeable at medium energy flux concentration ratio. The results also indicated that the performance of a single conventional PV cell depends neither on the location and size of the non-uniform illumination nor the geometrical shape of the non-uniform illumination. A novel hybrid PV cell consisting of low and high efficiency PV cells was designed and fabricated. The electrical energy produced by the hybrid cell was compared, theoretically and experimentally, with a similar low efficiency single PV (LESPV) cell in a low- concentrating symmetric CPC suitable for facade, sloping roof, flat roof and rear side building integration. Both results, simulation and experimental, showed that the daily electrical energy produced by a hybrid cell for different Belfast (UK) sky conditions was higher than that of the LESPV cell, but not to the expected value.

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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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Marín, Sáez Julia. "Design, Construction and Characterization of Holographic Optical Elements for Building-Integrated Concentrating Photovoltaics." Doctoral thesis, Universitat de Lleida, 2019. http://hdl.handle.net/10803/669230.

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El principal objectiu d'aquesta tesi és el disseny, construcció i caracterització d'un sistema de concentració solar format per dues lents cilíndriques hologràfiques i una cèl•lula fotovoltaica de silici per integració arquitectònica en façanes. L'ús d'Elements Òptics Hologràfics (EOHs) en lloc d'elements refractius o miralls suposa avantatges com la selectivitat cromàtica i la facilitat d'integració en façanes. D'altra banda, cal fer seguiment en una direcció. Els EOHs han estat dissenyats de manera que s'acobla l'espectre solar amb la resposta espectral de la cèl•lula per obtenir una concentració òptica màxima en el rang espectral desitjat i per tant, corrent elèctrica màxima. S'ha desenvolupat un algoritme de traçat de raigs basat en la Teoria d'Ones Acoblades per analitzar local i globalment EOHs i sistemes hologràfics. Les simulacions han estat validades amb resultats experimentals de EOHs registrats a fotopolímer Bayfol HX. També s'han estudiat EOHs que operen en el règim de transició entre el règim de Bragg i el de Raman-Nath, observant els avantatges que ofereix per a aplicacions d'il•luminació amb espectre ample.
El principal objetivo de esta tesis es el diseño, construcción y caracterización de un sistema de concentración solar formado por dos lentes cilíndricas holográficas y una célula fotovoltaica de Silicio para integración arquitectónica en fachada. El uso de Elementos Ópticos Holográficos (EOHs) en lugar de elementos refractivos o espejos supone ventajas como la selectividad cromática y la facilidad de integración en fachada. Por otro lado, es necesario realizar seguimiento en una dirección. Los EOHs han sido diseñados de forma que se acopla el espectro solar con la respuesta espectral de la célula para obtener una concentración óptica máxima en el rango espectral deseado y por lo tanto, corriente eléctrica máxima. Se ha desarrollado un algoritmo de trazado de rayos basado en la Teoría de Ondas Acopladas para analizar local y globalmente EOHs y sistemas holográficos. Las simulaciones han sido validadas con resultados experimentales de EOHs registrados en fotopolímero Bayfol HX. También se han estudiado EOHs que operan en el régimen de transición entre el régimen de Bragg y el de Raman-Nath, observándose las ventajas que ofrece para aplicaciones de iluminación con espectro ancho.
The main objective of this thesis is the design, construction and characterization of a solar concentrating system formed by two cylindrical holographic lenses and a Silicon PV cell for the scope of façade building integration. The use of Holographic Optical Elements (HOEs) instead of refractive or reflective elements implies advantages such as chromatic selectivity and ease of integration on a façade. On the other hand, tracking is necessary in one direction. The HOEs have been designed to couple the solar spectrum with the spectral response of the PV cell in order to provide maximal optical concentration on the target spectral range and therefore maximal electrical current. A ray-tracing algorithm based on Coupled Wave Theory has been developed to locally and globally analyze HOEs and holographic systems. Simulations have been validated with experimental results of HOEs recorded on Bayfol HX photopolymer. HOEs operating in the transition regime between the Bragg regime and Raman-Nath regime have also been studied, showing the promising advantages it offers for broadband spectrum illumination applications.

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Verma, Darpan. "Hybrid Solar Energy System with integrated Concentration Photovoltaic Cells and Thermoelectric Devices." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553613351859182.

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Proise, Florian. "Study and realisation of micro/nano photovoltaic cells and their concentration systems." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066470/document.

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Dans cette thèse nous évaluons la concentration optique sur cellules photovoltaïques micrométriques et nanométriques sans système de suivi de Soleil. Cette étude a deux objectifs principaux. La première partie est dédiée à l’évaluation de la faisabilité de la concentration optique sur des microcellules à base de Cu(In,Ga)Se2 via un concentrateur luminescent (LSC). Le LSC est bas-coût, concentre la lumière directe et diffuse, et est non imageant, ce qui très avantageux pour la concentration sur microcellules. Néanmoins, la sensibilité extrême aux non-idéalités explique la différence entre les performances théoriques et expérimentales. Un code de simulation est développé pour analyser ce système et ses mécanismes de perte. Un nouveau formalisme basé sur des données statistiques est proposé pour décrire les propriétés du LSC. Le couplage LSC/microcellules est effectué expérimentalement et des pistes d’amélioration explorées. La seconde partie tire profit de la fonction de conversion spectrale des LSC et développe un nouveau concept de nano-antenne photovoltaïque mono-résonant à base d’InP. Des simulations optiques montrent qu’un rendement de conversion de 10.7% peut être atteint avec une épaisseur moyenne d’absorbeur de moins de 20 nm. Les étapes technologiques de fabrication sont identifiées et réalisées en salle blanche. Le fort ratio surface/volume nous a amené à étudier la passivation de l’InP par du polyphosphazène. Des mesures de luminescence montrent que la surface est stabilisée durablement. Les résultats de cette thèse démontrent que le couplage nano-photonique / LSC est prometteur, alliant de très faibles volumes à d’excellentes efficacités optiques
In this thesis we explore light concentration on nano and micro photovoltaic cells without Sun tracking. This study has two main aims. The first part is dedicated to the evaluation of light concentration feasibility on Cu(In,Ga)Se2-based microcells with luminescent solar concentrator (LSC). LSC is cheap, allows both direct and diffuse light concentration and is non imaging, making it advantageous for microcells concentration. Yet, the extremely high sensitivity to non ideality explains the gap between theoretical and real systems. A simulation code is developed to analyze the system and its loss mechanisms. A new formalism based on statistical data is proposed to describe LSC properties. LSC and microcells coupling is experimentally achieved and improving tracks investigated. The second part takes advantage of the LSC down-shifting effect to propose a new mono-resonant InP-based photovoltaic nano-antenna. Optical modeling on this new device shows that 10.7 % efficiency can be obtained with an absorber averaged thickness lower than 20 nm. Technological process steps to fabricate this device are identified and realized in a clean-room environment. The high ratio surface over volume leads us to study InP passivation through a mono-atomic polyphosphazen film. Luminescent measurements show that passivated InP surface is long-term stabilized. The results of this thesis demonstrate that nano-photonic / LSC coupling is promising, enabling high optical efficiency in extremely low volume

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Sharma, Pratibha. "Modeling, Optimization, and Characterization of High Concentration Photovoltaic Systems Using Multijunction Solar Cells." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35917.

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Recent advancements in the development of high-efficiency multijunction solar cells have led to a renewed interest in the design and implementation of high concentration photovoltaic systems. With the emergence of novel materials and design structures, understanding the operation of multijunction solar cells has become a challenging task. Modeling and simulation hence play an important role in the analysis of such devices. In this dissertation, techniques for accurate optoelectrical modeling of concentrating photovoltaic systems, based on multijunction solar cells, are proposed. A 2-dimensional, distributed circuit model is proposed, parametrized to values obtained by numerical modeling of three multijunction cell designs, namely: a three-junction, lattice matched design, a three-junction lattice-mismatched, inverted metamorphic design, and a four-junction,lattice matched design. Cell performance for all the three designs is evaluated under both uniform and nonuniform illumination profiles at high concentrations and efficiency enhancement by optimizing finger spacing is proposed. The effect of luminescent coupling from higher bandgap subcells is also determined.Fresnel-lens based, refractive concentrating optical systems are modeled and optimized using an optical ray-tracing simulator at two different concentrations, with and without a secondary optical element. The corresponding optical efficiency, acceptance angle, and the degree of nonuniformity are determined for each optical system. An integrated approach,combining optical design with electrical modeling is proposed for optimizing the multijunction solar cell in tandem with the corresponding concentrating optics. The approach is validated by on-sun, acceptance angle measurements, using a three-junction,lattice-matched cell. Also, temperature effects are modeled and are experimentally validated for a three-junction, lattice-matched design. Experimental results with a single-junction, dilute-nitride cell, targeted for four-junction operation, are presented as well. A modified distributed circuit model is used for analysis of temperature effects in a four-junction solar cell, and the results under both uniform and nonuniform temperature profiles are presented. When implemented, the designs and their corresponding analyses, may result in new insights into the development of CPV systems, thereby enabling enhanced efficiencies at higher concentrations.

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Al, Siyabi I. "Enhancing the performance of concentrating photovoltaics through multi-layered microchannel heat sink and phase change materials." Thesis, University of Exeter, 2019. http://hdl.handle.net/10871/35932.

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Concentrating Photovoltaic technology is considered now as a promising option for solar electricity generation along with the conventional flat plate PV technology especially in high direct normal irradiance areas. However, the concentrating photovoltaic industry sector still struggles to gain market share and to achieve adequate economic returns due to challenges such as the high temperature of the solar cell which causes a reduction its efficiency. The work presented in this thesis is targeted to influence the overall performance of a high concentrated photovoltaic system by integrating both the multi-layered microchannel heat sink technique and a phase change material storage system. The proposed integrated system is composed of a multi-layered microchannel heat sink attached to a single solar cell high concentrated photovoltaic module for thermal regulation purposes. This is expected to reduce the solar cell temperature hence increasing the electrical output power. The high concentrated photovoltaic and multi-layered microchannel heat sink system is then connected to a phase change material thermal storage system to store efficiently the thermal energy discharged by the high concentrated photovoltaic and multi-layered microchannel heat sink system. The first part of the thesis discusses the influence of the multi-layered microchannel heat sink on the high concentrated photovoltaic module using both the numerical and experimental approaches. The multi-layered microchannel heat sink has been integrated for the first time with the single cell receiver and tested successfully. A numerical analysis of the high concentrated photovoltaic and multi-layered microchannel heat sink system shows the potential of the heat sink to reduce the solar cell maximum temperature and its uniformity. The thermal behaviour of the multi-layered microchannel heat sink under non-uniform heat source was experimentally investigated. The results show that in extreme heating load of 30W/cm² and in heat transfer fluid flow rate of 30ml/min, increasing the number of layers from 1-layer to 4-layers reduced the heat source temperature from 88.55°C to 73.57°C, respectively. In addition, the single layer multi-layered microchannel heat sink suffers of the most heat source temperature non-uniform compared to the heat sinks with higher number of layers. Also, the results show that increasing the number of layers from 1-layer to 4-layers reduced the pressure drop from 16.6mm H2O to 3.34 mm H2O. The indoor characterization of the high concentrated photovoltaic and multi-layered microchannel heat sink system investigated the effect of the number of layers, the homogeniser materials, and the heat transfer fluid flow rate and inlet temperature on the electrical and thermal performance of the system. The results show that the maximum power of the high concentrated photovoltaic module with glass homogeniser is 3.46W compared to 2.49W when using the crystal resin homogeniser for the 2-layers multi-layered microchannel heat sink and 30ml/min under 1000W/m² irradiance intensity. Increasing the number of layers from 1-layer to 3-layers on the high concentrated photovoltaic and multi-layered microchannel heat sink system increased the maximum electrical power by 10% and decreased the solar cell temperature 3.15°C for the heat transfer fluid flow rate of 30ml/min. This gives an increase in the maximum electrical power of 98.4mW/°C. The outdoor characterisation of the high concentrated photovoltaic and multi-layered microchannel heat sink system performance was evaluated at the University of Exeter, Penryn Campus, UK. The achieved maximum output electrical power of the system was 4.59W, filling factor of 75.1%, short circuit current of 1.96A and extracted heat of 12.84W which represents of 74.9% of the maximum solar irradiance of 881W/m². In addition, the maximum solar cell temperature reached to 60.25°C. Secondly, the experimental studies were carried out in order to investigate the performance of the phase change material storage system using paraffin wax as the PCM materials. The thermal storage system performance was evaluated in various conditions. The results show that inclination of the phase change material storage influences the melting behaviour of the phase change material where the phase change material storage of 45º inclination position melts faster than the phase change material storages in the 0º and 90º inclination positions. The phase change material melting time is reduced in the PCM storage of 45º inclination position by 13% compared to the 0º inclination position. The last part of the thesis discusses the integration of the phase change material storage with the high concentrated photovoltaic and multi-layered microchannel heat sink system. A 3D numerical model was developed to predict the behaviour of the integrated high concentrated photovoltaic and multi-layered microchannel heat sink system with the phase change material storage system using variable source conditions. The results show a higher heat absorption rate on phase change material storage that uses a lower melting temperature phase change material compared to the higher phase change material melting temperature. The multi-stages storage with different phase change materials melting temperature showed a lower heat absorption compared to the phase change material arrangement with the lower melting temperature. Also, the rate of the absorbed heat fluctuation is less affected by the phase change material arrangement with higher melting temperature.

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Coughenour, Blake Michael. "Photovoltaic concentrator optical system design| Solar energy engineering from physics to field." Thesis, The University of Arizona, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3619002.

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This dissertation describes the design, development, and field validation of a concentrator photovoltaic (CPV) solar energy system. The challenges of creating a highly efficient yet low-cost system architecture come from many sources. The solid-state physics of photovoltaic devices present fundamental limits to photoelectron conversion efficiency, while the electrical and thermal characteristics of widely available materials limit the design arena. Furthermore, the need for high solar spectral throughput, evenly concentrated sunlight, and tolerance to off-axis pointing places strict illumination requirements on the optical design. To be commercially viable, the cost associated with all components must be minimized so that when taken together, the absolute installed cost of the system in kWh is lower than any other solar energy method, and competitive with fossil fuel power generation.

The work detailed herein focuses specifically on unique optical design and illumination concepts discovered when developing a viable commercial CPV system. By designing from the ground up with the fundamental physics of photovoltaic devices and the required system tolerances in mind, a select range of optical designs are determined and modeled. Component cost analysis, assembly effort, and development time frame further influence design choices to arrive at a final optical system design.

When coupled with the collecting mirror, the final optical hardware unit placed at the focus generates more than 800W, yet is small and lightweight enough to hold in your hand. After fabrication and installation, the completed system's illumination, spectral, and thermal performance is validated with on-sun operational testing.

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Riverola, Lacasta Alberto. "Dielectric solar concentrators for building integration of hybrid photovoltaic-thermal systems." Doctoral thesis, Universitat de Lleida, 2018. http://hdl.handle.net/10803/663116.

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L'objectiu de la present tesi és desenvolupar, optimitzar, fabricar i caracteritzar experimentalment un sistema solar de baixa concentració, fotovoltaic i tèrmic, per a integració arquitectònica en façanes on les cèl·lules estan submergides en un líquid dielèctric. L'objectiu està alineat cap al compliment de la directiva sobre eficiència energètica en edificis establerta per la Comissió Europea. Els sistemes solars fotovoltaics i tèrmics per integració en edificis permeten la cogeneració d'electricitat i calor al mateix edifici amb unes eficiències globals al voltant del 70% i utilitzen una menor superfície comparat amb un col·lector tèrmic i un mòdul fotovoltaic independents. D'altra banda, els sistemes de baixa concentració permeten reduir costos utilitzant cèl·lules solars estàndards, amb una àrea reduïda i seguiment en un sol eix. A més, la immersió de les cèl·lules en líquids dielèctrics comporta uns beneficis agregats com ara la reducció de les pèrdues de Fresnel i un millor control de la temperatura. La necessitat d'estudiar i desenvolupar aquests sistemes per a la seva integració en edificis ve donada per les qualitats prèviament descrites i per l’estudi de l'estat de l'art realitzat. El disseny proposat està compost d'un xassís cilíndric i una cavitat interna per on circula el líquid dielèctric (aigua desionitzada o alcohol isopropílic) en el qual hi ha les cèl·lules submergides. Cada mòdul segueix l'altura solar rotant i està dissenyat per ser col·locat en files formant una matriu. L'aparença del conjunt és similar a la de les lames que es troben normalment en les finestres. S’ha implementat un moviment secundari que controla la distància vertical entre mòduls per evitar l’ombra entre ells mateixos i controla la il·luminació interior. Per dur a terme un desenvolupament òptim, s'ha modelat la distribució espectral de la llum solar incident a la qual es veuen exposades les cèl·lules solars en condicions reals. S’ha dut a terme un anàlisis exhaustiu dels líquids dielèctrics susceptibles de complir amb els requeriments per a la present aplicació. S'ha modelat la absortivitat / emissivitat de les cèl·lules de silici comercials en un rang espectral que va des del ultraviolat fins a l'infraroig mitjà i s'ha validat experimentalment. A partir d'aquí, s’ha desenvolupat un algoritme de traçat de raigs que computa l'energia per optimitzar el disseny òptic del concentrador per posteriorment fabricar-lo i analitzar-lo mitjançant una simulació CFD. Fet que ens permet caracteritzar el sistema tèrmicament i òpticament. Finalment, s'ha realitzat una simulació energètica amb el sistema instal·lat a les finestres d'una casa estàndard per tal d'avaluar quines parts de les demandes energètiques de l'edifici és capaç de satisfer. Aquesta simulació s’ha dut a terme en tres localitzacions diferents. El rendiment del sistema ha estat estudiat en llocs caracteritzats per hiverns suaus i altures solars no molt elevades, obtenint resultats satisfactoris cobrint una gran part de la demanda de climatització, d'aigua calenta sanitària i elèctrica.
El objetivo de la presente tesis es desarrollar, optimizar, fabricar y caracterizar experimentalmente un sistema solar de baja concentración, fotovoltaico y térmico, para integración arquitectónica en fachadas donde las células están sumergidas en un líquido dieléctrico. Este objetivo está perfectamente alineado con el cumplimiento de la directiva sobre eficiencia energética en edificios establecida por la Comisión Europea. Los sistemas solares fotovoltaicos y térmicos para integración en edificios atesoran la cogeneración de electricidad y calor en el mismo edificio con unas eficiencias globales alrededor del 70% y utilizando una menor superficie que si incorporamos un colector térmico y un módulo fotovoltaico separados. Por otra parte, los sistemas de baja concentración permiten reducir costes utilizando células solares estándar, con un área reducida y seguimiento en un solo eje. Además, la inmersión de las células en líquidos dieléctricos conlleva unos beneficios agregados como son la reducción de las pérdidas de Fresnel y un mejor control de la temperatura. Del estado del arte realizado y las cualidades previamente descritas, se desprende la necesidad de estudiar y desarrollar estos sistemas para su integración en edificios. El diseño propuesto está compuesto de un chasis cilíndrico y una cavidad interna por donde circula el líquido dieléctrico (agua desionizada o alcohol isopropílico) en el cual están las células sumergidas. Cada módulo sigue la altura solar rotando y está diseñado para ser colocado en filas formando una matriz. De este modo, la apariencia del conjunto es similar a la de las lamas que se encuentran comúnmente en ventanas. Además, un movimiento secundario que regula la distancia vertical entre los módulos para evitar sombreo entre ellos mismos y controlar la iluminación interior, ha sido implementado. Para llevar a cabo un desarrollo óptimo, se ha modelado la distribución espectral de la luz solar incidente a la cual se ven expuestas las células solares en condiciones reales. Se ha realizado un análisis exhaustivo de los líquidos dieléctricos susceptibles de cumplir con los requerimientos para la presente aplicación. Se ha modelado la absortividad/emisividad de las células de silicio comerciales en un rango espectral que va desde el ultravioleta hasta el infrarrojo medio y se ha validado experimentalmente. A partir de aquí, se ha desarrollado un algoritmo de trazado de rayos para optimizar el diseño óptico del concentrador con el fin de posteriormente fabricarlo y analizarlo mediante una simulación CFD. Hecho que nos permite caracterizarlo ópticamente y térmicamente. Finalmente, se ha realizado una simulación energética con el sistema instalado sobre las ventanas de una casa estándar para evaluar que parte de las demandas energéticas del edificio es capaz de satisfacer. Esta simulación se ha realizado en tres localizaciones distintas. El rendimiento del sistema ha sido estudiado en lugares caracterizados por inviernos suaves y alturas solares no muy elevadas, cubriéndose una gran parte de las demandas de agua caliente sanitaria, eléctricas y de climatización.
The goal of this thesis is to develop, optimize, fabricate and experimentally test a low-concentrating photovoltaic thermal system (CPVT) for building façade integration where the cells are directly immersed in a dielectric liquid. The objective sought is perfectly aligned with the Energy Performance Building Directive established by the European Commission in terms of energy efficiency. Building-integrated PVT systems present an on-site cogeneration of electricity and heat with global efficiencies around 70% and lower space utilization compared to a separate thermal collector and PV module. On the other hand, low-concentrating systems improve the cost effectiveness by using standard cells, single axis-tracking and reduced cell areas. In addition, direct-immersion of solar cells in dielectric liquids brings associated benefits such as a reduction of Fresnel losses and a better temperature control. From the state-of-the-art performed and the previous facts, the need for further developing and studying these systems for building integration purposes was found. The proposed design is composed by a cylindrical chassis and an inner cavity filled with the circulating dielectric liquid (deionized water or isopropyl alcohol) in which the cells are immersed. The module tracks the solar height by rotation and it is designed to be placed in rows as an array so that the appearance is akin to ordinary window blinds. A secondary movement has been implemented to control the vertical distance between modules and to avoid shading between them while provide lighting control. For an appropriate development, the spectral distribution of the incident solar irradiance to which solar cells are exposed under real working conditions has been modelled. An in-depth analysis of suitable dielectric liquid candidates based on the required properties for this application has been performed. The absorptivity/emissivity of standard silicon solar cells has been modeled from the ultraviolet to the mid-infrared and validated by an experimental measurement. Then, a full ray-tracing algorithm was developed to optimize the concentrator optical design and the optimum collector was fabricated and analyzed by a CFD simulation to thermally characterize the system. Finally, an energetic simulation with the concentrators superimposed in front of the windows in a standard house aiming to partially cover the building demands has been performed for three locations. The system performance has been studied for locations with mild winters and latitudes not achieving very high solar heights with satisfactory solar fractions regarding domestic hot water, electrical and space heating and cooling demands.

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Gopal, Anamika. "Effects of Thickness, Morphology and Molecular Structure of Donor and Acceptor Layers in Thermally Interdiffused Polymer Photovoltaics." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27279.

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An in-depth study of concentration gradients in thermally-interdiffused polymer – fullerene photovoltaic devices, with a focus on thickness and heat treatments, is presented in this thesis. Device performance is improved from the bilayer by the creation of a concentration gradient of the donor and acceptor materials throughout the active layer of the device. Concentration gradients are expected to improve device performance by optimizing the charge transfer, transport and collection processes. This is achieved through heat-induced interdiffusion of the two materials at temperatures above the glass transition temperature of the polymer. Investigation of the poly(3-octylthiophene) (P3OT) – C₆₀ system show a three-fold improvement in the external quantum efficiencies (EQE) as compared with bilayer devices. Auger spectroscopy, combined with argon-ion beam milling, serves to record the concentration depth profile and identify concentration gradients in the device through detection of the sulfur in the P3OT backbone. Concentration gradients are optimized to yield the best devices through a thickness variation study conducted on the P3OT – C₆₀ system for fixed thermal interdiffusion conditions at 118 °C for 5 minutes. An optimum thickness of 40 to 60 nm is obtained for the two materials that yields the ideal morphology of a concentration gradient as recorded by Auger spectroscopy. For such devices, the concentration gradient is seen to extend through the device, ending in a thin layer of pure material at each electrode. A monochromatic power conversion efficiency of 2.05% is obtained for 5.3 mW/cm²⁺ illumination at 470 nm. A brief study is also presented to optimize the concentration gradient profile through variations of the thermal parameters. The dependence of the concentration gradient on the interdiffusion time and temperature is investigated. The merits of heat treatment on the crystallinity of P3OT and the overall device performance are also discussed. It is shown in some case that devices with annealed P3OT layers show almost twice the EQE as non-annealed P3OT layer devices. Potential alternatives for C₆₀ in interdiffused devices with P3OT have been presented. [6,6]-phenyl C₆₁-butyric acid methyl ester (PCBM), a well-investigated acceptor for blend devices, is studied as an acceptor in concentration gradient devices. A method for spin-coating uniform bilayers of P3OT and PCBM, without solution damage to either layer, is presented. A thermal variation study of the interdiffusion conditions on this system indicated higher interdiffusion temperatures and times are preferred for P3OT – PCBM systems. For interdiffusion at 150 °C for ten minutes, EQE values approaching 35 % at 500 nm are obtained. Auger spectroscopy studies on this system yielded the same conclusions about the concentration gradient device morphology that gives optimum device output. 1:1 and 1:2 blends of P3OT – PCBM are also studied. The influence of various thermal treatments on these devices is described. The endohedral fullerene Sc₃N@C₈₀ is introduced as a new acceptor material. The endohedral fullerene consists of Sc₃N cluster enclosed in a C₈₀ cage. An order of magnitude increase is seen in device performance upon sublimation of these molecules on a P3OT layer confirming its effectiveness as an acceptor. Preliminary studies done on this system indicated the need for greater thermal treatment to produce optimum concentration gradients. An in depth study for varying temperatures and times is presented. The best device performance was seen for interdiffusion at 160 °C for 25 minutes. The endohedral fullerene devices also show a long-term deterioration and so best result are presented from a set of devices fabricated within the same time period. The study of these three donor-acceptor systems confirms that the conclusions on the thickness dependence and device performance study conducted for the P3OT – C₆₀ system extend to other acceptors. A model of EQE for varying thicknesses based on absorption in the interdiffused concentration gradient regions is also presented. This model effectively highlights the influence of P3OT layer thickness on the trends observed in the EQE. It did not, however, reproduce the experimental thickness variation results for varying C₆₀ thicknesses. Incorporation of the effects of the electric field intensity distribution is expected to correct for this. Suggestions have been given on how this might be achieved.
Ph. D.

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Cole, Ian R. "Modelling CPV." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/18050.

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A methodology for the simulation of CPV systems is presented in four distinct sections: input, optics, uncertainty and electrical output. In the input section, existing methods of describing the solar irradiation that is incident at the primary optical element of a CPV system are discussed, the inadequacies of the existing methods are explored and conditions of validity for their use drawn. An improved and spectrally extended model for a variable, spatially resolved solar image is arrived at. The model is used to analyse losses at the primary concentration device stage under varying solar profiles and air masses. A contextual analysis of an example Seattle based CPV system operating with constant solar tracking errors of 0.3-0.4° show a corresponding loss in isolation available to the optical system of 5-20%, respectively. In the optics section, an optical ray trace model is developed specifically for this work. The optical ray trace model is capable of the spectrally resolved ray tracing of all insolation input models discussed above. Plano-convex and Fresnel lenses are designed, investigated and compared using each of the insolation models described in the input section. Common CPV component material samples for the plano-convex and Fresnel lenses are analysed for their spectrally resolved optical properties. The computational expense of high resolution spatial and spectral modelling is addressed by means of a spectrally weighted banding method. The optical properties parameter spectral weighting method can be applied to any arbitrary spectral band. The bands used herein correspond to the active ranges of a typical triple-junction solar cell. Each band shows a different spectral dependency. Banded beam irradiation proportions are shown to change by as much as 10% in absolute terms within the air mass range of 1 to 3. Significant variations in spectrally banded illumination profiles are found with the extended light source insolation model. These banded variations are mostly unaccounted for with the use of approximated insolation models, further compounding the argument for extended light source Sun models in CPV system simulations. In the uncertainty section, the limitations of the manufacturing process are explored. Manufacturing tolerance errors from manufacturer datasheets are presented. These production uncertainties are used in the design of an erroneous plano-convex lens which is then analysed with the optical modelled presented in the optics section and compared to the ideal design specification. A 15% variation in maximum intensity value is found alongside a linear shift in the focal crossover point of approximately 0.2mm, although the optical efficiency of the lens remains the same. Framing manufacture errors are investigated for a square Fresnel lens system resulting in a linear shift of the focal centre of approximately 0.85mm. A process for the calculation of wind loading force on a CPV array is also presented. The process uses real 2 second resolution wind data and highlights the chaotic nature of loading force. A maximum force of 1.4kN was found on an example day for a 3m by 3m by 0.1m cuboid (i.e. CPV array); corresponding to a wind speed of approximately 13m/s, which is well within the typical operating range of a CPV tracking system. In the electrical output section, a spatially resolved solar cell model is identified and used for the investigation of solar cell performance under the inhomogeneous cell illumination profiles produced in the uncertainty section. Significant differences in the maximum power point of the cell IVs are found for the ideal and erroneous system illumination profiles. Approximately, a 15% variation is found in the plano-convex lens example, with a relative difference of 4% attributable to illumination profile distortion, and a 6% variation in the module framing component example. These results further highlight the need for the consideration of production uncertainties in CPV system simulation.

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Besson, Pierre. "Compréhension des comportements électrique et optique des modules photovoltaïques à haute concentration, et développement d’outils de caractérisations adaptés." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI013/document.

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Le travail de thèse effectué a pour objectif d'amener vers une meilleure compréhension des comportements électrique et optique des modules CPV, dans des conditions environnantes variables. La première partie est consacrée à l’étude de la performance des modules en conditions réelles de fonctionnement. Quatre technologies de module, toutes équipées de cellules triple-jonctions, mais de concentrateurs optiques différents, ont été testées en extérieur sur des périodes de un mois à deux ans. Les résultats montrent que la sensibilité à la température de lentille, la température de cellule et au spectre incident varie selon le type d'architecture optique. La sensibilité la plus importante à la température de lentille a été obtenue pour un dispositif sans optique secondaire. Le coefficient en température de la tension Voc a été calculé et varie entre les technologies. Enfin, les variations importantes de facteur de forme avec le spectre incident observées pour une technologie, mettent en évidence la nécessité d'étudier les phénomènes de non-uniformités d'irradiance sur la cellule. Dans une deuxième partie, le développement d’un banc de test en intérieur permettant de mesurer les performances électriques et optiques est présenté. Ce banc a pour objectif de permettre la reproduction des conditions réelles de fonctionnement des modules de façon contrôlée en intérieur. Un système d’imagerie est utilisé pour déterminer la distribution spatiale et spectrale d’irradiance sur la cellule. Associé à un traceur de courbes IV, il vise à caractériser les effets de flux non-uniformes sur la cellule. Le banc de mesure a pour avantage de découpler les paramètres d’études, telles que la température de la lentille et la température de la cellule, et permet ainsi de décorréler leurs effets respectifs sur l'ensemble optique-cellule, ce qui n’est que difficilement possible sur des mesures en extérieur. Le procédé de calibration et la validation du dispositif sont détaillés dans le manuscrit. Enfin, dans une dernière partie, le banc développé est utilisé pour caractériser trois différents dispositifs CPV : un sans optique secondaire, et deux avec des optiques secondaires différentes. Les impacts de la distance lentille-cellule et de la température de lentille sur les performances de la cellule sont quantifiés optiquement et électriquement. Les résultats montrent comment ces paramètres modifient la distribution de densités de courant des sous-cellules, et donc le comportement électrique du dispositif. Ils soulignent plus spécifiquement comment les non-uniformités spectrales et spatiales affectent les performances de la cellule pour les différents concentrateurs. Le dispositif sans optique secondaire montre une sensibilité importante à la température de la lentille et la distance optique primaire-cellule, qui se traduit par une perte de production d'énergie dans des conditions réelles de fonctionnement
The goal of this doctoral thesis is to bring answers to a better understanding of the electrical and optical behavior of CPV modules, under different operating conditions. In the first part, a study on module performance under real conditions is presented. Using an outdoor automated test bench, the sensitivity of four different CPV module technologies to most operating conditions relevant to CPV systems has been studied, namely DNI, spectrum, cell and lens temperature and clearness of the sky. In order to isolate the influence of a single operation parameter, the analysis of outdoor monitoring data from one month to two years is performed. The results show how the optical design influences the sensitivity of the electrical parameters to the mentionned operating conditions. The effect of lens temperature on cell current has been found to be maximum for the CPV module without Secondary Optical Element. Also the $V_{oc}$ thermal coefficient was found to vary between module technologies. Finally, the important variations of the fill factor for one technology underlines the need of studying non-uniformities effects on the cell performance. According to the results observed outdoors, an indoor tool was developed in order to uncorrelate outdoor parameters. A test bench that measures multi-spectral irradiance profiles, through CMOS imaging and bandpass filters in conjunction with electrical $IV$ curves, is used as a mean to visualize and characterize the effects of chromatic aberrations and nonuniform flux profiles under controllable testing conditions. The bench allows decoupling the temperatures of the Primary Optical Element and cell allowing the analyze of their respective effects on optical and electrical performance. In varying the temperature of the Primary Optical Element, the effects on electrical efficiency, focal distance, spectral sensitivity, acceptance angle, or multi-junction current matching profiles can be quantified. Calibration procedures and validation process are detailed. Finally, the developed testbench is used for analyzing the behvaior of three different CPV devices : one without Secondary Optical Element, and two with different Secondary Optical Elements. The impacts of cell position and lens temperature on the cell performance are quantified optically and electrically. The results show how these parameters modify the current density distribution of the subcells, and hence the electrical behavior of the device. They underline more specifically how spectral and spatial non-uniformities affect the cell performance for the different devices. The device without SOE shows a strong sensitivity to lens temperature and POE-cell distance, that will correspond to a decrease of energy production under real conditions of operation

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Jutteau, Sébastien. "Design, prototyping and characterization of micro-concentrated photovoltaic systems based on Cu(In,Ga) Se2 solar cells." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066666/document.

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Dans cette thèse, nous avons étudié la conception, le prototypage et la caractérisation de microsystèmes photovoltaïques à concentration à base de cellules solaires Cu(In,Ga)Se2. L'objectif est de réduire l'utilisation de matériaux rares en utilisant la concentration de la lumière, et bénéficier des effets de la miniaturisation, comme la dissipation de la chaleur et des pertes résistives inférieurs. Tout d'abord, la conception optique des systèmes à concentration sur la base des microlentilles sphériques est présentée. À l'aide d'un logiciel de tracés de rayon Zemax OpticStudio, nous avons évalué la meilleure combinaison d'éléments, l'épaisseur et les rayons de courbure des lentilles, ainsi que les tolérances de fabrication et de positionnement du système. Un système optique de 1 mm d'épaisseur avec un rapport géométrique de 100 et une tolérance angulaire de +/- 3,5 ° a été conçu. D'autre part, des procédés de fabrication ont été créés et optimisés pour fabriquer un prototype de 5x5 cm² avec 2500 microcellules. Le meilleur mini-module a montré un facteur de concentration de 72x avec une augmentation en valeur absolue de l'efficacité de + 1,6%. Ensuite, des études numériques et expérimentales ont été réalisées sur des systèmes basés sur des concentrateurs luminescents (LSC) et des concentrateurs paraboliques (CPC). Les LSC ont montré un facteur de concentration faible et souffraient de problèmes de répétabilité tandis que les CPC sont une solution très efficace, mais très difficile à fabriquer à l¿échelle du micron. Enfin, nous avons développé un code MATLAB pour estimer l'énergie produite des systèmes conçus, pour évaluer la pertinence des choix technologiques futurs
In this thesis, we studied the design, prototyping and characterization of micro-concentrated photovoltaic systems based on Cu(In,Ga)Se2 solar cells. The objective is to reduce the use of rare materials using the concentration of light, and benefit from the effect of miniaturization such as heat dissipation and lower resistive losses. First, the optical design of 1D and 2D concentrating systems based on spherical microlenses is presented. Using a ray-tracing software Zemax OpticStudio, we evaluated the best combination of elements, thickness and radii of curvature of the lenses, as well as the tolerances of fabrication and positioning of the system. An optical system of 1 mm thickness with a geometrical ratio of 100 and an angular tolerance of +/- 3.5° has been designed. Second, fabrication processes have been created and optimized to fabricate a 5x5 cm² prototypes with 2500 microcells. The best mini-module showed a concentration factor of 72x with an absolute increase of the efficiency of +1.6%. Third, numerical and experimental studies have been performed on concentrating systems based on Luminescent Solar Concentrators (LSC) and Compound Parabolic Concentrators (CPC). The LSC showed a low concentration factor and suffered from repeatability issues while the CPC is a very efficient solution but its specific geometry makes it difficult to fabricate at the micron scale. Finally, we developed a MATLAB code to estimate the producible energy of the designed systems, in order to evaluate the relevance of future technological choices that will be made

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Walker, Alexandre W. "Bandgap Engineering of Multi-Junction Solar Cells for Enhanced Performance Under Concentration." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26240.

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This doctorate thesis focuses on investigating the parameter space involved in numerically modeling the bandgap engineering of a GaInP/InGaAs/Ge lattice matched multi-junction solar cell (MJSC) using InAs/InGaAs quantum dots (QDs) in the middle sub-cell. The simulation environment – TCAD Sentaurus – solves the semiconductor equations using finite element and finite difference methods throughout well-defined meshes in the device to simulate the optoelectronic behavior first for single junction solar cells and subsequently for MJSCs with and without quantum dots under concentrated illumination of up to 1000 suns’ equivalent intensity. The MJSC device models include appropriate quantum tunneling effects arising in the tunnel junctions which serve as transparent sub-cell interconnects. These tunneling models are calibrated to measurements of AlGaAs/GaAs and AlGaAs/AlGaAs tunnel junctions reaching tunneling peak current densities above 1000 A/cm^2. Self-assembled InAs/GaAs quantum dots (QDs) are treated as an effective medium through a description of appropriate generation and recombination processes. The former includes analytical expressions for the absorption coefficient that amalgamates the contributions from the quantum dot, the InAs wetting layer (WL) and the bulk states. The latter includes radiative and non-radiative lifetimes with carrier capture and escape considerations from the confinement potentials of the QDs. The simulated external quantum efficiency was calibrated to a commercial device from Cyrium Technologies Inc., and required 130 layers of the QD effective medium to match the contribution from the QD ground state. The current – voltage simulations under standard testing conditions (1 kW/cm^2, T=298 K) demonstrated an efficiency of 29.1%, an absolute drop of 1.5% over a control structure. Although a 5% relative increase in photocurrent was observed, a 5% relative drop in open circuit voltage and an absolute drop of 3.4% in fill factor resulted from integrating lower bandgap nanostructures with shorter minority carrier lifetimes. However, these results are considered a worst case scenario since maximum capture and minimum escape rates are assumed for the effective medium model. Decreasing the band offsets demonstrated an absolute boost in efficiency of 0.5% over a control structure, thus outlining the potential benefits of using nanostructures in bandgap engineering MJSCs.

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Ramos, Carina Alexandra Rebelo. "Potential of CPV receivers integrating screen-printed solar cells." Master's thesis, Faculdade de Ciências e Tecnologia, 2011. http://hdl.handle.net/10362/11020.

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Dissertação para obtenção do Grau de Mestre em Energias Renováveis – Conversão Eléctrica e Utilização Sustentável
Photovoltaic systems present themselves as an excellent alternative for clean energy production. To reach large applications, obstructions as high silicon prices must be overcome. Solar concentration systems are a potential solution since silicon is replaced by cheaper material (like mirrors or lenses). Nevertheless, there are still many issues and challenges yet to overcome. One of these challenges is the economic cost of the solar cells, since the CPV systems need to integrate expensive high efficiency solar cells specially designed to operate at high levels of radiation. Thus, it is necessary to explore new approaches. In this thesis presents a study of the potential of the screen-printed silicon solar cells to integrate the CPV systems, concretely the HSUN system. Two solar cells, conventional 1Sun and conventional 15Suns, were analyzed and integrated in the HSUN sub-receivers, in order to understand their behavior under several levels of concentration and when integrated in series in sub-receivers. After the first part of the experimental campaign (electrical characterization of solar cells) it was concluded that the conventional standard silicon solar cells are unsustainable for use in the HSUN system (which operates a 15 suns), since these solar cells only work properly up to a concentration of 5 suns. Regarding the Upgraded 1-sun silicon solar cells, the results were satisfactory regarding their behavior under concentration, until a concentration level of 20 suns. In the second part of the experimental campaign, the Upgraded 1-sun solar cells were integrated in the HSUN sub-receivers and their behavior was analyzed. The results taking from this part of the experimental campaign prove the good performance of the Upgraded solar cells and that their performance is unaffected by their integration in the sub-receivers. Associated to this part of the experiments, was also performed the optimization of the mounting process of the sub-receivers. This optimization provided a faster process with a lower probability of damaging the solar cells. To a complete study of the potential of these solar cells, it is important to take into account the economic viability of the solar cells. Comparing the cost-efficiency of the standard conventional solar cells, the LGBC solar cells (cells used actually in the HSUN system) and the Upgraded 1-sun solar cells, it was concluded that the solar cells more viable up to a concentration level of 24 suns are the Upgraded 1-sun solar cells, being that from this concentration level the LGBC solar cells solar cells present themselves as the most viable. Therefore, and taking into account all the work developed along this thesis, it was concluded that the most cost-efficient solar cells to integrate the HSUN system are the conventional solar cells with some characteristics optimized for the required concentration levels.

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Crampette, Laurent. "Contribution à la réalisation de cellules photovoltaïques à concentration à base de silicium monocristallin." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20102/document.

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Les cellules LGBC (Laser Grooves Buried Contact) ont été inventées et développées par M. GRENN au sein de l'UNSW. Elles présentent des contacts métal/silicium enterrés permettant d'optimiser le contact métal/silicium sans augmenter le taux d'ombrage de la cellule. Dans ce manuscrit nous étudierons toutes les étapes clefs nécessaires à la réalisation de ce type de cellules de façon à les rendre industrialisables. Dans un premier temps nous étudierons la réalisation de tranchées dans le silicium via deux lasers (vert & IR). Les paramètres de ces tranchées seront comparées pour sélectionner les plus adaptées à notre technologie en nous assurant qu'il est possible de réaliser une diffusion thermique dans ces tranchées. Nous développerons ensuite deux techniques pour réaliser des émetteurs sélectifs, par double diffusion et par diffusion à travers une couche de nitrure de silicium. Enfin nous étudierons deux méthodes de dépôt de nickel par voie chimique une électrolytique et un electroless
LGBC (Laser Grooved Buried Contact) solar cells was invented and developed by M.GREEN at UNSW. Grooved contact allow to reach a good serial resistivity without incresing the shadowing of the solar cell. In this report we will study the different step necessarry to build this kind of photovoltaic cells. Fisrt we will see the impact of laser effects on silicon and the different parameters to adapte red and green laser for grooved contct. The we will study to way to create selective emitter, on by two diffusion and the second one by diffusion throught a silicon nitride layer. Then we will develope two nickel metallisation one electrolytique and one electroless

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Chroufa, Mohamed. "??tude et caract??risation du comportement thermom??canique de r??cepteur d'un syst??me photovolta??que concentr??" Mémoire, Universit?? de Sherbrooke, 2014. http://savoirs.usherbrooke.ca/handle/11143/117.

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Le d??veloppement dans la derni??re d??cennie des syst??mes photovolta??ques concentr??s a augment?? le besoin de g??rer le budget thermique dans le r??cepteur pour emp??cher sa surchauffe et g??rer les pertes de performances li??es ?? la temp??rature. Ce projet de ma??trise s'inscrit dans le cadre du d??veloppement d???un syst??me solaire fortement concentr?? en collaboration avec des partenaires industriels. Notre partenaire industriel a mis au point une solution de production d?????nergie photovolta??que de haute concentration ?? l?????chelle commerciale, mais il reste ?? valider la conception du syst??me adopt??. Le projet concerne l'??tude du r??cepteur photovolta??que qui est compos?? d???un r??seau dense de 800 cellules solaires triple jonctions, mont??es sur un substrat. Ce dernier est compos?? d???un empilement de couches et un ??changeur de chaleur pour refroidir le r??cepteur. Puisque notre r??cepteur absorbera un grand flux de chaleur, il y aura des contraintes dues ?? la non-concordance des coefficients de dilatation thermique entre ses diff??rentes couches. Ces d??formations pourraient provoquer la rupture de contact entre les cellules solaires, et ainsi la d??faillance ??lectrique du r??cepteur. Pour cela, ces travaux de recherche ont port?? sur une ??tude thermom??canique du r??cepteur. En effet, l?????tude de la dilatation de l'assemblage multicouche a permis d???acqu??rir une connaissance d???analyse thermom??canique de la tenue de la structure multicouche vis-??-vis d???un chargement thermique. Puis, le comportement des ??poxys, conducteur et isolant ??lectrique utilis??s pour fixer les cellules sur le substrat, a ??t?? ??tudi?? en fonction de plusieurs param??tres g??om??triques et des propri??t??s mat??rielles. La diff??rence des coefficients d???expansion thermiques (CTE) des ??poxys, ??tait le param??tre cl?? pour varier les contraintes dans les interconnexions. Cons??quemment, on a utilis?? deux ??poxys avec deux CTE proches pour diminuer les contraintes induites dans les deux ??poxys. De plus, vu que la structure se compose des couches usin??es, on a cr???? des abaques de variation de rigidit?? effective en fonction des facteurs de formes dimensionnels des couches usin??es. Enfin, le travail a permis de mettre en place des essais exp??rimentaux pour s???assurer du fonctionnement du r??cepteur ?? haute temp??rature. Par cons??quent, on a valid?? l???utilisation de l?????poxy dans la conception adopt??e vu que la d??formation maximale support??e par ce dernier ([epsilon Minuscule][indice inf??rieur m ax]=0.167 %) est sup??rieure ?? la d??formation maximale qu???il peut avoir au cours de l'op??ration ([epsilon Minuscule][indice inf??rieur ??poxy]=0.0048%). Ensuite, les exigences de r??cepteur en termes de fonctionnement ?? haute temp??rature ont ??t?? fix??es, comme l?????cart maximal que l?????poxy peut supporter pour la liaison des cellules entre deux unit??s du r??cepteur qui est [delta Majuscule]Gap[indice inf??rieur limite] [epsilon Minuscule] [[Plus ou moins]46 [mu Minuscule]m, [Plus ou moins]53 [mu Minuscule]m].

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Blot, Xavier. "Réalisation, caractérisation et modélisation de collages de matériaux III-V pour cellules photovoltaïques à concentration." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT108/document.

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La production d'énergie photovoltaïque est une option d'avenir pour répondre au développement économique de notre société tout en réduisant notre impact sur l'environnement. Mais pour devenir compétitive, cette filière doit améliorer le rendement des cellules solaires. Une technologie d'avenir consiste à combiner différents matériaux via une croissance par épitaxie et l'usage du collage direct. Cette thèse, financée par SOITEC, vise au développement du collage d'arseniure de gallium (GaAs) sur le phosphure d'indium (InP) pour la cellule SmartCell. L'objectif est d'optimiser son comportement électrique via un modèle numérique prenant en compte son état physico-chimique. Nous présentons d'abord un ensemble d'outils de caractérisations électriques pour réaliser une mesure I(V) précises de l'interface de collage. En fonction des cas, nous détaillons des contacts métalliques adaptés pour améliorer cette caractérisation. Une étude détaillée de l'hétérostructure GaAs/InP et des homostructures GaAs/GaAs et InP/InP amène ensuite à une compréhension de leur mécanisme de collage. Après recuit thermique, le procédé de collage hydrophile engendre des oxydes d'interfaces qui se résorbent dans le cas de l'InP et se fragmentent pour le GaAs. A paramètres constants, les empilements obtenus sont meilleurs que ceux de l'état de l'art au niveau électrique et mécanique. Nous poursuivons avec des propositions de procédés innovants pour maitriser l'oxyde d'interface et optimiser l'hétérostructure. Parmi ces options nous validons l'approche avec exposition ozone qui vise à générer sélectivement un oxyde avant mise en contact. L'empilement obtenu affiche une résistance proche de nos mesures de référence et a un fort potentiel. Enfin l'étude se conclue sur la présentation d'un modèle numérique inédit reliant procédé de collage, état d'interface et comportement électrique. A recuit donné, l'interface est hétérogène avec une zone reconstruite (conduction thermo-électronique) et une zone avec oxyde (conduction tunnel). Ces régions s'activent préférentiellement en fonction de la température de fonctionnement. Elles sont pondérés par un critère qui détermine le niveau de reconstruction du collage et qui sera utile pour de futurs développements de l'application
The solar photovoltaic is a promising way to support our economical growth while it can reduce the environmental impact of our society. But, to be truly competitive, the sector has to develop more efficient solar cells. An interesting option aims at combining different materials either by epitaxy growth and direct bonding. The Ph.D. was funded by the SOITEC company with the goal to develop the bonding of the gallium arsenide (GaAs) on the indium phosphide (InP) for the SmartCell architecture. We had to optimize its electrical behavior with a numerical model taking into account the bonding interface state. We introduce the study with a wide range of I(V) tools to precisely characterize the bonding interface. Depending on the case, we detail suitable metal contacts to improve the test. A study in deep of the GaAs/InP heterostructure and the GaAs/GaAs and the InP/InP homostructures leads to a better understanding of the bonding mechanisms. After a thermal annealing, the hydrophilic bonding process generates oxyde compounds at the interface which are absorbed in the InP case and are fragmented in the GaAs case. For given parameters, our stacks are electrically and mechanically better than the state of the art. Then we propose innovative processes to control the interface oxyde and thus optimize the heterostructure. Among them, we validate a new approach with ozone exposure that selectively generates an oxyde prior to bonding. The interface resistance of the stack is therefore closed to our best results and has great potentials. To conclude, the study focuses on a novel numerical model connecting the bonding process, the interface state and the electrical behavior. For a given annealing, the interface is heterogenous with reconstructed areas (thermionic conduction) and oxyde areas (tunnel conduction). These regions are preferentially activated as a function of the operating temperature. They are weighted by a criteria determining the level of the bonding reconstruction which will be useful for the future developments of the application

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Abdel, Nour Christine. "Modélisation d’une installation photovoltaïque avec réflecteurs en vue de l’intégration dans un réseau intelligent." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS146.

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Dans un but d’amélioration des performances d’une installation photovoltaïque (PV), une approche complémentaire à l’amélioration du rendement des modules PV est l’augmentation de la collecte des photons par faible concentration du flux solaire sur les modules. Les réflecteurs plans sont une solution a priori simple et économique. Ils permettent d’augmenter la production électrique sans surcoût important. Cependant, l’estimation de ce gain demande une prise en compte fine de l’éclairement non uniforme apporté par ces réflecteurs. L’objectif de ce travail de thèse est de tester le potentiel d’un système PV-réflecteurs avec la possibilité d’un ajustement périodique des angles d’inclinaison du plan des réflecteurs et du plan des modules PV. Dans ce but, il a été nécessaire de mettre en place un démonstrateur PV-réflecteurs avec des modules industriels, ainsi que de développer et de valider expérimentalement un outil de modélisation simple. Dans un premier temps, un modèle d’estimation de l’irradiation du plan des modules « plane of array, POA » basé sur l’optique cartésienne et des hypothèses de rayonnement isotrope de l’atmosphère et de réflexion lambertienne des surfaces est développé. Il s’appuie en entrée, sur des mesures au sol ou des images satellite. Ce modèle validé a ensuite permis d’optimiser la géométrie d’une installation PV-réflecteurs en considérant une installation fixe ou à géométrie variable, avec des ajustements périodiques différents (mensuels, saisonniers) des angles d’inclinaison des modules PV et des réflecteurs, ainsi que différentes longueurs de réflecteurs. Cette stratégie d’optimisation géométrique de l’irradiation POA a été appliquée dans six lieux dans le monde ayant des conditions météorologiques très différentes. Un modèle d’estimation analytique est ensuite élaboré pour passer de l’irradiance POA à la puissance PV. L'ajout de réflecteurs plans introduit une distribution non uniforme de l’irradiance sur les modules PV pouvant provoquer l’activation de diodes bypass. Ce modèle photo-électrique a été évalué expérimentalement pour un module PV avec éclairement non uniforme. Finalement, un démonstrateur PV est construit au laboratoire GeePs (avec 6 modules au Silicium cristallin connectés en série) et équipé de réflecteurs plans, de capteurs d’irradiance POA et de température. Une analyse de la production de cette installation a été conduite sur une année en absence et en présence de réflecteurs. Le modèle analytique développé précédemment a permis de choisir l’architecture fixe de ce démonstrateur ainsi que de mener des études de performances. Les résultats soulignent l’importance d’optimiser spécifiquement l’architecture d’un système PV-réflecteurs selon la zone géographique et la saison ou le mois de l’année. Ils montrent également qu’une étude en irradiation permet d’optimiser un potentiel local indépendamment de la technologie des modules mais en aucun cas elle, n’est suffisante pour optimiser la géométrie d’une installation. Enfin, le modèle théorique est nécessairement simplificateur : non prise en compte de l’horizon très proche, hypothèse de rangées infinies, hypothèse d’une atmosphère uniforme et isotrope, coefficient de réflexion des miroirs constants, approche pessimiste concernant l’activation des diodes de bypass… et les mesures localisées nécessairement limitées et présentant des incertitudes. La mise en place des démonstrateurs a notamment permis d’apporter des réponses et des éléments de discussion autour de ces aspects
In order to improve the performance of a photovoltaic (PV) installation, a complementary approach to improving the efficiency of PV modules is to increase the collection of photons using low concentration of the solar flux on the modules. Flat reflectors are a simple and economical solution for that purpose. They allow increasing electrical production without significant additional cost. However, the estimation of this gain requires careful consideration of the non-uniform illumination provided by these reflectors. The objective of this thesis work is to test the potential of a PV-reflector system with the possibility of periodic adjustment of the tilt angles of the plane of the reflectors and the plane of the PV modules. To this end, it was necessary to set up a PV-reflector demonstrator with industrial modules, as well as to develop a simple modeling tool and validate it experimentally. First, an estimation model of the plane of array, POA, based on Cartesian optics and hypotheses of isotropic radiation of the atmosphere and Lambertian reflection of surfaces is developed. It is based on ground measurements or satellite images inputs. This model experimentally validated allowed to optimize the geometry of a PV-reflector installation by considering a fixed installation or variable geometry, with different periodic adjustments (monthly, seasonal) of the tilt angles of the PV modules and the reflectors, as well as different lengths of reflectors. This strategy for geometrical optimization of POA irradiation has been applied in six locations around the world with very different weather conditions. An analytical estimation photoelectric model is then developed to move from POA irradiance to PV power estimation. Adding flat reflectors introduces a non-uniform distribution of the irradiance on the PV modules which can cause the activation of bypass diodes. This photoelectric model has been tested experimentally for a PV module with non-uniform illumination. Finally, a PV demonstrator is built at the GeePs laboratory (with 6 crystalline Silicon modules connected in series) and equipped with planar reflectors, POA irradiance sensors and temperature sensors. An analysis of power production of this installation was carried out over a year in the absence and presence of reflectors. The analytical model developed previously made it possible to choose the suitable fixed architecture of this demonstrator as well as to conduct performance studies. The results highlight the importance of optimizing the architecture of a PV-reflector system according to the geographic area and the season or the month of the year. They also show that an irradiation study makes it possible to optimize a local potential of such system independently of the technology of the modules, but in no case, it is sufficient to optimize the geometry of an installation. Finally, the theoretical model is simplified: not taking into account the very near horizon, assumption of infinite rows, assumption of a uniform and isotropic atmosphere, constant coefficient of mirrors reflection, pessimistic approach concerning the activation of the bypass diodes… and limited local measurements presenting uncertainties. The installation of demonstrators has made it effectively possible to provide answers and elements of discussion around these aspects

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Albert, Pierre. "Développement de cellules multijonctions submillimétriques pour le photovoltaïque à concentration (micro-CPV) et évaluation de leur robustesse." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0209.

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Les dispositifs photovoltaïques, dominés par les panneaux en silicium, ont su évoluer pour proposer aujourd’hui des coûts d’électricité concurrentiels aux sources fossiles. Parmi les technologies émergentes, le photovoltaïque à concentration (CPV pour Concentrator Photovoltaics) repose sur l’utilisation de systèmes optiques (miroirs ou lentilles) qui concentrent la lumière sur des cellules de faibles dimensions (< cm2) mais très efficaces (> 40%). Malgré les performances élevées des modules CPV, cette technologie n’a pas su s’imposer en raison d’un coût élevé découlant de limitations technologiques (gestion thermique, pertes résistives…). Le micro-CPV promet de répondre à ces limitations en se basant sur l’utilisation de microcellules (< mm2). Cependant, des défis restent à relever : les procédés de fabrication et d’assemblage des microcellules doivent être adaptés, en s’inspirant de la microélectronique notamment, pour permettre de fortes efficacités et un coût restreint. Aussi, la fiabilité de ce nouveau type de dispositifs n’est pas connue. Ce mémoire de thèse a l’ambition de traiter de ces sujets, en se focalisant particulièrement sur les procédés de fabrication critiques
Photovoltaic systems, dominated by silicon panels, have evolved to propose competitive electricity costs compared to fossil sources. Among emerging technologies, Concentrator Photovoltaics relies on the use of optical systems (mirrors or lenses) that concentrate sunlight onto small (< cm2) solar cells with high efficiency (> 40%). Whereas high efficiency is achievable by CPV modules, this technology has not been widely adopted due to its high cost arising from technological limitations (thermal management, resistive losses…). Micro-CPV promises to tackle these limitations using microcells (< mm2). However, challenges remain ahead: fabrication processes and assembly of microcells must be adapted, by learning from microelectronics for example, to allow high performance at a restrained cost. Moreover, reliability of such novel devices is not known. This thesis deals with these topics, by particularly assessing critical fabrication processes

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47

Guillo, Lohan Benoit. "Modélisation, élaboration et caractérisation de cellules photovoltaïques à base de silicium cristallin pour des applications sous concentration." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI093/document.

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Les performances électriques des cellules photovoltaïques à base de silicium sont fortement dégradées lorsque leur température augmente. Cette problématique, pourtant bien connue, n’est pas suffisamment prise en considération dans l’industrie du photovoltaïque. Pour parer à cette dégradation, deux voies d’améliorations peuvent être explorées : diminuer la température de fonctionnement des cellules ou réduire leurs coefficients de dégradation en température. Cette étude est d’autant plus importante pour les applications sous concentrations, un éclairement élevé favorisant l’échauffement des cellules. Pour les facteurs de concentration élevés, l’utilisation de systèmes de refroidissement actifs réduit drastiquement la température de fonctionnement. Pour les faibles éclairements, le refroidissement passif est préféré, bien moins coûteux en énergie. Ce travail de thèse est focalisé sur l’étude du comportement thermo-électrique des cellules sous faible concentration du rayonnement incident. Un banc de caractérisation innovant développé dans cette thèse a rendu possible la quantification des variations de la température de la cellule avec la tension de polarisation sous différents facteurs de concentration. Avec l’augmentation de la polarisation, une évolution du facteur d’émission thermique est observée du fait des variations de la concentration de porteurs de charge minoritaires. Le refroidissement radiatif est minimal au courant de court-circuit et est maximal à la tension de circuit ouvert : la température atteinte au point de court-circuit est supérieure à celle atteinte en circuit ouvert. Pour une cellule donnée, sous un éclairement de 3 soleils, un écart de température de 6.2 °C a pu être mesuré entre ces deux points. La fabrication de cellules avec des propriétés différentes nous a permis de confirmer l’importance du dopage de la base et de l’architecture sur l’augmentation du refroidissement radiatif avec la polarisation. De plus, la comparaison du comportement thermo-électrique des cellules de type de dopages différents a mis en avant de plus faibles coefficients de dégradation en température de la tension en circuit ouvert pour les cellules ayant un substrat de type n. Par exemple, pour une température de et sous un éclairement de 1 soleil, un coefficient de dégradation en température du Voc de −0.45% %·°C-1 a été mesuré sur une cellule de type n contre −0.49%·°C-1 pour une cellule de type p
The electrical performances of silicon based solar cells strongly degrade when increasing their temperature. However, such a well-known issue is too scarcely considered in the phovoltaic industry. To prevent the degradation of silicon based solar cells, two ways of improvement can be explored : one can either decrease the cells’ functionning temperature or either reduce the temperature degradation coefficient. As light intensity tends to favor cell heating, the study is even more important under concentrated sunlight. Regarding high light intensities, active cooling systems can be used to drastically reduce the cell temperature. For low light intensities, passive cooling systems, such as radiative cooling, are more energetically savy. The thesis aims at studying the electro-thermal behavior of cells under low light intensities. An innovative experimental set-up has been developped during this thesis to quantify the variation of the cell temperature with the applied bias voltage. When increasing the bias, an evolution of the cell emissivity is observed because of a variation of the minorities carrier concentration. The radiative cooling is at its lowest at the short circuit current and peaks its highest value at the open circuit voltage : as a result, the reached temperature is higher at the short circuit current than at the open circuit voltage. For a given solar cell, under 3 suns, a temperature shift of 6.2 °C was measured between these two points. The control of the fabrication process gives the opportunity to analyse the influence of the base doping and cell architecture on the evolution of the radiative cooling with the applied bias. Furthermore, the comparison between the electro-thermal behaviors of solar cells, which are related to their type of doping, has shown a lower thermal degradation coefficient of the open circuit voltage for n-type based dope solar cells. For example, at 60°C and under 1 sun, we measured a thermal degradation coefficient BVoc = −0.45% %·°C-1 for a n type solar cell whereas the p type solar cell recorded BVoc = −0.49% %·°C-1

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Koval, Filip. "Efektivnost provozu fotovoltaických generátorů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217629.

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Objective of master’s thesis theoretical part is especially to illustrate influence of operation conditions, such as solar radiation, temperature or pollution of photovoltaic generator active area, on load and power characteristics of photovoltaic generator, or more precisely on photovoltaic conversion efficiency. Possible variants of increasing effectivity of using photovoltaic generator are explored, such as solar radiation concentration, photovoltaic generator active area cooling or aplication of optimalization circuit. Pivotal part of master‘s thesis is focused on experimental device practical realisation, concretely type MSQ36-10 photovoltaic generator with oriented concentrators of solar radiation. Practical realisation includes design of master‘s thesis experimental part construction with subsequent design of photovoltaic generator motion cycle necessary for adequate simulation of configuration variants solved using single testing photovoltaic generator. Description of own experimental device construction with list of measuring places used in task takes up. It is used automatic monitoring system working as independent measurement task for required values measuring and consecutive data collecting. It is done in two phases. First phase is measurement of all required values, in second phase measurement with attached optimalization circuit is made. Optimalization circuit sets best working point of photovoltaic generator according to actual working conditions. Master‘s thesis intention is experimental verification of solar radiation concentrators application convenience, orientation of photovoltaic generator or its mutual combination, namely using type MSQ36-10 photovoltaic generator. Objective is evaluation of reached energetic gain for all experimental device layouts in variable operating conditions.

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Chenche, Luz Elena Peñaranda. "Avaliação dos métodos de modelagem e parametrização de dispositivos fotovoltaicos mono e multi junção." Universidade Federal de Uberlândia, 2015. https://repositorio.ufu.br/handle/123456789/14984.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
This work deals with the analysis applied to the main methodologies found in literature for estimating the properties related to the physical phenomena in photovoltaic devices (parametrization), as well as the most important mathematical models used in the calculation of operating electrical characteristics of these devices (characterization). These devices are related to the mono and multi-junction technologies, when they are exposed to a condition where the temperature and solar radiation vary. Therefore, four parametrization methods were shown, including three analytical, and five models of electrical characterization, where two of them are specifically for multi-junction devices. Thus, several case studies were proposed which defined different situations for comparing the performance of the methods evaluated. In this way, the procedures that best fit to each type of photovoltaic technology were identified. Finally, according to the results obtained in the parameterization, the method based on the Generalized Reduced Gradient (GRG) nonlinear algorithm showed greater accuracy for all case studies and for all photovoltaic devices. As for the characterization, the main advantages and disadvantages of all models were determined, highlighting Domínguez, et al. (2010) model, due to the highest robustness and wide application range.
Esta dissertação apresenta uma análise aplicada às principais metodologias encontradas na literatura que permitem determinar as propriedades físicas relativas aos fenômenos que ocorrem nos dispositivos fotovoltaicos (etapa de parametrização), assim como dos modelos matemáticos de maior importância utilizados no cálculo das características elétricas operacionais destes dispositivos (etapa de caraterização). Tais dispositivos referem-se às tecnologias mono e multi junção quando submetidos à variações de temperatura e radiação solar. Portanto, foram apresentados quatro métodos de parametrização, entre eles três analíticos e cinco modelos de caracterização elétrica, sendo dois especificamente para dispositivos multi junção. Assim, estabeleceram-se vários estudos de caso para os quais foram definidas diferentes situações que permitiram comparar o desempenho de cada um dos métodos avaliados. Em consequência, foram identificados os procedimentos que melhor se ajustaram a cada tipo de tecnologia fotovoltaica. Dessa forma, de acordo com os resultados obtidos na parametrização, a metodologia baseada na aplicação do algoritmo de Gradiente Reduzido Generalizado (GRG) não linear, demonstrou maior exatidão para todos os estudos de caso e para todos os dispositivos fotovoltaicos. Já para a caraterização, foram determinadas as principais vantagens e desvantagens entre os modelos aplicados, destacando o modelo de Domínguez, et al. (2010), que apresentou maior robustez e ampla faixa de aplicação.
Mestre em Engenharia Mecânica

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Zeitouny, Joya. "Advanced strategies for ultra-high PV efficiency." Thesis, Perpignan, 2018. http://www.theses.fr/2018PERP0056.

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La limite théorique de rendement des cellules photovoltaïques simple-jonction est de l’ordre de 33% d’après le modèle de Shockley-Queisser, ce qui reste éloigné de la limite de Carnot, prédisant une limite maximale de conversion énergie solaire → électricité de 93%. L’écart important entre ces deux limites découle des pertes intrinsèques, essentiellement liées à la conversion inefficace du spectre solaire et à la disparité entre les angles solides d’absorption et d’émission. Pour surmonter ces pertes et se rapprocher de la limite de Carnot, trois stratégies sont envisagées dans cette thèse : les cellules multi-jonction àconcentration, la combinaison de la concentration et de la restriction angulaire et les systèmes hybrides PV/CSP. Chacune de ces stratégies est limitée par des mécanismes qui dégradent leur performance.L’objectif de cette thèse est donc de comprendre dans quelle mesure les différents mécanismes limitants sont susceptibles d’affecter les performances des différentes stratégies étudiées, et d’optimiser l’architecture des cellules dans le but d’accroitre leur efficacité de conversion. Dans ce but, un modèle détaillé de cellule solaire tenant compte des principaux mécanismes limitant a été développé. Un outil d’optimisation par algorithme génétique a également été mis au point, afin d’explorer l’espace des différents paramètres étudiés pour identifier les conditions d’opération optimales. Nous démontrons l’importance majeure que revêt l’adaptation des propriétés optoélectroniques des matériaux utilisés aux conditions opératoires, que ce soit dans le cas des cellules solaires à concentration endurant des pertes résistives significatives, ou encore dans le cas de cellules solaires fonctionnant à des niveaux de températures très supérieurs à l’ambiante. Enfin, nous avons déterminé l’effet des principaux facteurs limitant que constituent les pertes résistives et les recombinaisons non-radiatives sur les cellules solairessimultanément soumises au flux solaire concentré et à la restriction angulaire du rayonnement émis
The maximum efficiency limit attainable with a single-junction PV cell is ~ 33% according to the detailed balance formalism (also known as Shockley-Queisser model), which remains far from the Carnot limit, predicting a solar to electricity efficiency upper value of 93%. The large gap between both limits is due to intrinsic loss mechanisms, including the inefficient conversion of the solar spectrum and the large discrepancy between the solid angles of absorption and emission. To overcome these losses and get closer to the Carnot limit, three different strategies are considered in this thesis: concentrated multi-junction solarcells, the combination of solar concentration and angular confinement, and hybrid PV/CSP systems. Each strategy is inherently limited by several loss mechanisms that degrade their performances. The objective of this thesis is, hence, to better understand the extent to which these strategies are likely to be penalized by these losses, and to tailor the cell properties toward maximizing their efficiencies. To address these questions, a detailed-balance model of PV cell accounting for the main loss mechanisms was developed. A genetic-algorithm optimization tool was also implemented, aiming at exploring the parameter space and identifying the optimal operation conditions. We demonstrate the uttermost importance of tailoring the electronic properties of the materials used with both multi-junction solar cells undergoing significant series resistance losses, and PV cells operating at temperature levels exceeding ambient temperature. We also investigate the extent to which series resistances losses and non-radiative recombination are likely to affect the ability of PV cells simultaneously submitted to concentrated sunlight and angular restriction of the light emitted by band-to-band recombination

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Dissertations / Theses on the topic 'Concentrating photovoltaic'

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