Dissertations / Theses on the topic 'Photovoltaic'
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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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Wang, Menghong. "Degradation of Photovoltaic Packaging Materials and Power Output of Photovoltaic Systems: Scaling up Materials Science with Data Science." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1595416965256375.
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Liu, Guang. "Photovoltaic array simulators." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25103.
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Two basic types of photovoltaic (PV) array simulator have been designed and tested. The first involves the use of a pilot panel and variable light source. It is implemented with analogue circuits. A stability analysis based on Popov's method is presented for this simulator with resistance-inductance (R-L) loads. In the second, characteristic array curves are stored in the memory of a microprocessor-based simulator. The design of both simulators is based on the transfer function method. By using the computing facility available, a stability study for the Type I simulator and some dynamic simulations are carried out. Both simulators are capable of driving a special load, namely, an experimental solar pumping system. The experimental results for both types of' simulator are satisfactory in terms of steady state precision and dynamic behaviour when used with this load.
Compared with previously-reported PV array simulator designs [6,7,8,9,18], the two simulators described here have the following distinctive features:
1. A new method of sample curve generation for the Type II simulator results in relatively short sampling period and small memory size.
2. The sample curves of the type II simulator are based directly on the real PV array to be simulated. They are more accurate than the sample curves in references [6,7,9]. 3. Different loads (R, R-L and an experimental solar pumping system) have been considered in the design and have been tested in laboratory.
4. A stability analysis and some dynamic simulations are presented for the type I simulator. An analysis of this type has not been reported in previous studies [6,7,8,9,18].Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Carotenuto, Pietro Luigi. "Photovoltaic Systems Reconfiguration." Doctoral thesis, Universita degli studi di Salerno, 2015. http://hdl.handle.net/10556/2137.
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2013 - 2014A photovoltaic field is typically composed by series-connected panels, thus composing strings, which are then connected in parallel. By this way, the current and the voltage values of the photovoltaic generator are adapted to operating range of the power electronics systems that transform the generated energy, conveying it to the load and to the electrical grid. The performance of the photovoltaic systems are reduced when a partial shading of the field occurs. In this case, the modules could work under very different conditions from each other, so that the system components may not be able to maximize the generated energy and/or the operating constraints of power electronics systems are not respected. The reconfiguration of the electrical connections among the panels leads to maximize the performance of the photovoltaic systems but it requires additional hardware and it causes further energy consumptions that have to be minimized by executing the reconfiguration procedure only when the shading phenomena occur. The choice of the electrical configuration of the panels is determined by an appropriate algorithm and then it is actuated by a matrix of relays... [edited by author]
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Albarghouthi, Mohammad Talha. "Optimization of hydraulics and photovoltaics in a solar water heater with photovoltaic-powered pump." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ31541.pdf.
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Mallick, Tapas K. "Optics and heat transfer for asymmetric compound parabolic photovoltaic concentrators for building integrated photovoltaics." Thesis, University of Ulster, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288897.
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Alzubi, Feras. "Planar Organic Photovoltaic Devices." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5756.
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Organic Photovoltaic devices (OPV) are considered to be attractive candidates for clean and renewable energy source because of their potential for low cost of fabrication, easy processing, and their mechanical flexibility. The device efficiency of OPV cells are limited by several factors. Among them are: (i) donor-acceptor interface, (ii) morphology of the materials, (iii) electrode-organic semiconductor (OSC) interface and (iv) device architecture such as active material thickness and electrode separation. Although, the donor-acceptor interface has been studied in detail, the commonly prevalent vertical OPV device structure does not allow a good understanding of the other key issues as the vertical structure limits one of the electrode to be a transparent electrode as well as introducing inseparable relation between the electrodes separation and the active material thickness. In addition, it is also well known that the charge transport in OSC is anisotropic and the charge mobility is better in lateral direction rather than vertical direction. In order to address some of these issues, we fabricated OPV devices in a planar device structure where cathode and anode of dissimilar metals are in-plane with each other and their photovoltaic behaviors were studied. We used poly(3-hexylthiophene) and [6,6]-pheny1 C61-butyric acid methy1 ester (P3HT:PCBM) blend as an active material. In particular, we present a detailed study about the effects of the structural parameters such as the channel length, the active layer thickness, and the work function of the electrodes on the open circuit voltage (Voc), short circuit current (Isc), fill factor (FF) and the power conversion efficiency (PCE). In order to determine the suitable anode and cathode for the planar organic photovoltaic (P-OPV) structure, we first fabricated and measured organic field effect transistor (OFET) devices with different contacts and studied the effect of barrier height at the P3HT:PCBM/electrode interface on the device output and transport properties. The study showed a clear effect of varying the contact material on the charge injection mechanism and on the carriers mobilities. The results have also shown that Au with high hole mobility and on current in the p-channel can be used as an anode (holes extractor) in the P-OPV device while In, Cr, and Ti that showed a reasonable value of electron mobility can be good candidates for cathode (electron extractor). We also found that, Ag, Al, and Mg showed large barrier which resulted in large threshold voltage in the I-V curve making them undesired cathode materials in the P-OPV device. We then fabricated P-OPV devices with Au as an anode material and varied the cathode material to study the effect of the interface between the P3HT:PCBM layer and the cathode material. When Al, Mg, or Ag used as a cathode material no PV behavior was observed, while PV behavior was observed for In, Cr, and Ti cathode materials. The PV behavior and the characteristic parameters including Voc, Isc, FF and PCE were affected by varying the cathode material. The results have shown that the P-OPV device performance can be affected by the cathode material depending on the properties and the work function of the metal. We have also studied the effect of varying the P3HT:PCBM layer thickness at a fixed channel length for Cr and Ti cathode materials and Au as anode. While Voc and FF values do not change, Isc and PCE increase with increasing the layer thickness due to the increase of the light absorption and charges generation. Moreover, we studied the effect of varying the channel length at a fixed film thickness; and showed that the values of Isc and PCE increase with decreasing channel length while Voc and FF maintain the same value. In this thesis we will also present the results on experimentally defining and testing the illuminated area in the P-OPV device by using different measurement set-ups and different electrodes patterns. The results prove that the illuminated area in the P-OPV device is the area enclosed between the two electrodes. Lastly, we will present the effect of the P3HT:PCBM ratio on the P-OPV device performance. We show that 1:2 ratio is the optimized ratio for the P-OPV device. The detailed results in this thesis show a potential opportunity to help improving and understanding the design of OPV device by understanding the effects of the device structural parameters.Ph.D.
Doctorate
Physics
Sciences
Physics
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Snaith, Henry James. "Polymer based photovoltaic diodes." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614761.
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Tan, Swee Ching. "Photosynthetic proteins photovoltaic devices." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609050.
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Donkin, Richard Philip. "Plastic photovoltaic roof tiles." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/4397.
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Thesis presented in partial fulfilment of the requirements for
the degree of Master of Engineering in Renewable and
Sustainable Energy at the Stellenbosch University.Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: This project investigated the feasibility of incorporating photovoltaic cells into plastic roof tiles using injection moulding. Such tiles have the potential to provide robust and distributed electricity contained within the building envelope. Current-voltage curves of amorphous silicon modules were measured under illumination using the PVPM 2540C power measuring instrument, both before and after moulding. The efficiency after moulding was reduced by 53% to 88%, with modules that were heated for longer being degraded more. Thus the duration of exposure to high temperatures affected the extent of performance reduction during moulding. This suggested that faster moulding at a lower temperature or faster cooling could solve the problem. Economic feasibility was examined by calculating the levellised cost of electricity provided by the tiles. A large-scale development in the Western Cape was simulated using a typical meteorological year of weather data and using the anisotropic diffuse irradiance model of Perez et al. (1988). Avoided costs due to replaced roofing, avoided costs due to electricity distribution infrastructure, and Clean Development Mechanism credits were accounted for. The cost of energy calculated was R11/kWh in 2010 rands, which did not compete with the price of conventional grid-based electricity at R1.8/kWh. The importance of the cost of balance-of-system components, such as the inverter, and not only of the photovoltaic modules, was highlighted for future cost reductions. Several clear guidelines for manufacturing photovoltaic roof tiles were discovered. The most important of these was that many bypass diodes make the system more robust.
AFRIKAANSE OPSOMMING: Hierdie projek het die haalbaarheid van die integrasie van fotovoltaïse selle in plastiek dakteëls deur spuitvorming ondersoek. Sulke dakteëls het die vermoë om robuuste en verspreide elektrisiteit te lewer, sonder om die gebou se vorm te verander. Stroom-spanning kurwes van struktuurlose silikon eenhede is onder verligting gemeet met die PVPM 2540C kragmeet instrument, voor en na spuitvorming. Die doeltreffendheid na spuitvorming is met 53% tot 88% verminder, met groter vermindering in die eenhede wat langer warm was. Dus het die duur van blootstelling aan hoë temperature die mate van vermindering van doeltreffendheid beïnvloed. Dit het suggereer dat óf vinniger spuitvorming by laer temperature óf vinniger verkoeling die probleem kan oplos. Ekonomiese haalbaarheid is ondersoek deur die koste van die elektrisiteit wat deur die dakteëls gelewer is te bereken. ’n Groot behuisingsontwikkeling in die Wes-Kaap is gesimuleer deur ’n tipiese weerkundige jaar van weerdata en die anisotroop model vir verspreide ligstraling van Perez et al. (1988) te gebruik. Vermyde kostes van vervangde dakteëls, vermyde kostes van elektrisiteit distribusie infrastruktuur en krediete van die Meganisme vir Skoonontwikkeling is in ag geneem. Die elektrisiteitskoste was R11/kWh in 2010 se randwaarde, wat nie mededingend met die R1.8/kWh koste van gewone netwerk elektrisiteit was nie. Die belang van die kostes van die res van die installasieonderdele, soos die wisselrigter, en nie net die fotovoltaïse eenhede nie, is beklemtoon vir kostevermindering in die toekoms. Verskeie duidelike riglyne vir die vervaardiging van fotovoltaïse dakteëls is voorgestel. Die belangrikste van hierdie was dat meer omloopdiodes die installasie meer robuust maak.
Centre for Renewable and Sustainable Energy Studies
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Storey, Jonathan P. "Advanced reconfigurable photovoltaic arrays." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/386864/.
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This thesis describes works relating to advancements in the field of dynamic photovoltaic arrays (DPVA). This subject is becoming extremely active with a flurry of new papers appearing in recent times, all detailing ideas and developments regarding a range of engineering issues. One of the biggest problems with any photovoltaic system is the non-linear reduction in power output caused by the partial shading of the array surface. This is the main focal point of the developments discussed where new techniques regarding the reconfiguration of photovoltaic devices within a topology are identified and used to reduce the negative effects of non uniform insolation. In particular, the most successful type of dynamic array has been modified (the Irradiance Equalized Dynamic Photovoltaic Array) such that it now exhibits it's maximum flexibility and is able to show complete resilience to partial shading allowing for maximum power extraction. Furthermore, the operational speed of the device has been increased so that it can operate in real time with minimal computational effort and we have investigated the future of the device as source of electricity in a wide range of applications. On top of that, a second completely new type of dynamic array (the Optimise String Dynamic Photovoltaic Array) that demonstrates unique behaviour is presented and tested via a custom made simulator programmed into MATLAB. Both of these developments have included conceiving new sorting algorithms that are particularly rapid in their execution while obtaining a high level of optimisation. Three other classes of arrays found in literature are discussed and their characteristics are identified while concerns with their implementation are cross is examined. A new classification framework used in identifying all types of dynamic array has been introduced. This is very useful when discussing the main attributes associated with the various contributions made by authors of the literature. Not only this but it also allows for a comparative study between matrix architecture and device flexibility for arrays within the same class. A simulator that uses standard mathematical models to virtually realise irradiated solar cells and then perform the operations dictated by the sorting algorithms is presented. It reveals in detail the behaviour of featured DPVAs under a complete range of environments. Working with that, a new comprehensive test procedure has been developed that exercises the simulated arrays and documents their expected output under precisely controlled conditions. The resulting graphs are extremely useful in highlighting to the researcher the proficiency's and failings of the arrays under said conditions. This simulation environment interfaces to a real 16 section prototype array so that predictions can be verified by experimentation. The device can be used in such a way that it mimics the simulated dynamic array, while also providing a convenient terminal where more bespoke tests can be conducted. As will be discussed, all market bound DPVA research must be conducted with both a virtual and physical devices because each environment provides an incite that is of great importance to the designer. A later discussion introduces some abstract but potentially significant ideas about synthesising AC electricity using the switching mechanism. An argument suggesting why an industrially accepted synthesis method is not suitable for photovoltaic use is given and a more suitable solution is hypothesized. To finish there is a discussion about the remaining unexplored topics in the field which highlights how and why further research is required. The aim of this is to acknowledge that more work is needed but also to show the way to developing a completely new state of the art source of electricity which may one day help society effectively exploit the abundance of power being delivered to us by the Sun.
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Perez, de Larraya Espinosa Mikel. "Photovoltaic Power Plant Aging." Thesis, Högskolan i Gävle, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-33252.
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One of the most pressing problems nowadays is climate change and global warming. As it name indicates, it is a problem that concerns the whole earth. There is no doubt that the main cause for this to happen is human, and very related to non-renewable carbon-based energy resources. However, technology has evolved, and some alternatives have appeared in the energy conversion sector. Nevertheless, they are relatively young yet. Since the growth in renewable energies technologies wind power and PV are the ones that have taken the lead. Wind power is a relatively mature technology and even if it still has challenges to overcome the horizon is clear. However, in the PV case the technology is more recent. Even if it is true that PV modules have been used in space applications for more than 60 years, large scale production has not begun until last 10 years. This leaves the uncertainty of how will PV plants and modules age. The author will try to analyse the aging of a specific 63 kWp PV plant located in the roof of a building in Gävle, monitoring production and ambient condition data, to estimate the degradation and the new nominal power of the plant. It has been found out that the degradation of the system is not considerable. PV modules and solar inverters were studied, and even if there are more elements in the system, those are the principal ones. PV modules suffered a degradation of less than 5%, while solar inverters’ efficiency dropped from 95,4% to around 93%.
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Dzimano, Gwinyai J. "Modeling Of Photovoltaic Systems." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1228307443.
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Rakotomananandro, Falinirina F. "Study of Photovoltaic System." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306285848.
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Zhao, Lin. "Polymer-based photovoltaic devices /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202003%20ZHAO.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 79-82). Also available in electronic version. Access restricted to campus users.
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Saleh, Mojtaba. "Smoothing of Photovoltaic Generation." Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/66584.
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This study investigates the solutions to eliminate the intermittency of the photovoltaic (PV) generation resources in the electric grids. It addresses the battery storage backup as a conventional solution to absorb the sudden dips and rises in the PV generation, which are mainly attributed to passing clouds. This approach is further improved by incorporating the cloud prediction information produced by processing the real-time sky images. This proved to mitigate the reliance on the storage backup.
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Johnson, Grayden L. "Network connected photovoltaic array." Thesis, Queensland University of Technology, 1994. https://eprints.qut.edu.au/36234/1/36234_Johnson_1994.pdf.
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This research project is primarily concerned with the construction, testing and analysis of Australia's first residential roof mounted 1.3 kW photovoltaic array which is connected, via its associated power conditioning equipment, to the utility's electrical distribution network. Also included in this project
was the establishment of computer-based data acquisition systems to be used for monitoring and analysis of essential data. The test facility (SOLAR ONE) was built within The South East Queensland
Electricity Board's (SEQEB) supply area and is situated at Mt Coolum. Work undertaken included a critical review of relevant literature concerned with the interconnection of photovoltaics with the electrical distribution
network, analysis of relevant electrical distribution authority's policy, regulation and guidelines; co-ordinating the building of the test facility,
building the array, installing the associated power conditioning and data acquisition equipment and ongoing monitoring including interpretation of data up to the date of this submission. The results presented demonstrate the applicability of photovoltaics within
the electrical distribution network. Also presented is the analysis of the data gathered from the test facility illustrating the effects of such a system upon the electrical distribution network.
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Spencer, Ben. "Pump-probe spectroscopy of photovoltaic materials." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/pumpprobe-spectroscopy-of-photovoltaic-materials(f4b7f755-338a-4fad-814c-4dcc95d5b72d).html.
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The study of photovoltaic materials is important so as to develop new solar energy technologies: in particular, quantum-confined semiconductors could offer increased quantum efficiencies at a much lower manufacture cost. This thesis contains results from a number of pump-probe experiments designed to probe the carrier dynamics in bulk and quantum-confined photovoltaics. A THz time-domain spectrometer was designed, built and commissioned. The THz refractive indices and absorption coefficients of toluene and hexane were determined, and the spectrometer was benchmarked using a photoexcited GaAs wafer. Results are presented of time-resolved THz spectroscopy of photoexcited bulk InP as a function of laser excitation wavelength. These data were used to extract the quantum efficiency of bulk InP in order to compare with recent results for InP quantum dots. The quantum efficiency in quantum dots increases when the incident photon energy is at least twice the band gap energy, whereasthe efficiency of the bulk material is found to decrease. This is because of surface recombination, and these measurements therefore verify the potential superiority of quantum dot materials over bulk materials for use in solar energy applications. Initial measurements of quantum dots using THz spectroscopy highlighted the various experimental challenges involved and the upgrades required to study such samples in the future.The time-dependence of the photoinduced surface photovoltage (SPV) in Si was studied on nanosecond timescales by synchronizing an ultrafast laser system to a synchrotron radiation source (the SRS at Daresbury, UK), and measuring the resulting shift in the photoelectron spectrum. The equilibrium band bending was determined, and the decay of the SPV was attributed to the recombination of charge carriers across the band gap. Results are presented for the SPV in bulk ZnO and for PbS quantum dot chemically attached to ZnO. The fact that the PbS quantum dots were chemically attached to the surface without becoming oxidized was verified using X-ray photoelectron spectroscopy (XPS). The changes caused by photoexcitation occur on much longer timescales in ZnO than Si (sub-milliseconds rather than nanoseconds), and these timescales were conveniently accessed using the time-resolved XPS facility at the TEMPO beamline at Synchrotron SOLEIL (Paris, France). This is due to oxygen adsorption and desorption processes at the ZnO surface affectingthe transfer of charge carriers. The addition of PbS quantum dots to the ZnO surface was found to increase the speed of this charge transfer due to injection of carriers directly from the PbS quantum dot to the bulk ZnO conduction band.
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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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Echevarria, Troya Fernando. "Virtual instruments for photovoltaic measurements." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/482145.
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The present work is an effort to put together knowledge from several disciplines to obtain as result simple and affordable instruments for photovoltaic measurements. It could not be considered a research in advanced topics but it is a preliminary work in virtual instrumentation with broad prospects and useful and immediate applications. However, the established foundations and the acquired experience allow their application in the measurement of physical and physical-chemical parameters in various fields of science and engineering. One of them is the challenge of applying virtual instruments to Nanoscience and Nanotechnology. *
This work contains four Chapters, Conclusions and Recommendations. Several Annexes corresponding to each chapter are at the end of each chapter.
Chapter 1 introduces preliminary topics and basic definitions, the Electromagnetic Spectrum, the Planck’s Equation and Sunlight. Then summarizes the description of Light as Wave and Light as Photon. Annex 1 for Chapter 1 is a paper that procures conciliate this two descriptions using equations from electromagnetic theory and the basic equations of photons.
Chapter 2 introduces essential optical components and. procedures to design a simple spectrometer and monochromator. Useful electronic components, common light sensors and useful electronic stages for photovoltaic measurements are described. Finally, practical front end circuits used in this work are exposed.
Chapter 3 Is related with Data Acquisition and Control using Microcontrollers and Android Devices. Preliminary Topics, IOIO-OTG – the microcontroller board – characterization and interfacing, Programming Android Devices as Measuring Instruments, Interfacing front end Circuits with the microcontroller and the transparency Android ↔Windows data transfer are the topics dealt in this chapter.
Chapter 4 introduces the mathematical and graphic emulator used to develop the routines that are part of the proposed virtual instruments. The common algorithms for this project are described. Next, the individual virtual instruments algorithms are described. Finally, measurements made with the virtual instrument prototype and the Laboratory equipment has been intercompared and consistency has been verified in these results.
Every Chapter ends with Bibliography - numbered in [] – and Basic References –numbered in {}. Annexes for all chapters are at the end of each chapter.
Conclussions and Recommendations are presented at the end.
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Mahmood, Farhan. "Improving the Photovoltaic Modelin PowerFactory." Thesis, KTH, Elektriska energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105746.
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Liu, Guang. "A photovoltaic-powered pumping system." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/30592.
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This thesis studies the optimal design for a photovoltaic-powered medium-head (30 meters) water pumping system, with the emphasis on improving the efficiency and reducing the maintenance requirements of the electrical subsystem. The reduction of maintenance requirements is realized by replacing the conventional brush-type permanent magnet dc motor with a brushless dc (BLDC) motor. Different BLDC motor control techniques such as position-sensorless operation, sinusoidal and trapezoidal excitations are investigated. The improvement in efficiency is achieved by maximizing the output power from the photovoltaic array and by minimizing the losses in various parts of the electrical sub-system. A microprocessor-based double-loop maximum power tracking scheme is developed for maximization of the photovoltaic array output power. Over 99% utilization factor is achieved for a typical clear day regardless of the season of the year. The system losses are minimized mainly by performing loss analysis and selecting most suitable switching topologies and switching components. Experimental results show that the combined converter-motor efficiency is comparable to those of high-efficiency brush-type dc motor systems.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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NILSSON, DAVID. "Fault detection in photovoltaic systems." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-153945.
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This master’s thesis concerns three different areas in the field of fault detection in photovoltaic systems.Previous studies have concerned homogeneous systems with a large set of parameters being observed,while this study is focused on a more restrictive case. The first problem is to discover immediate faults occurring in solar panels. A new online algorithm is developed based on similarity measures with in a single installation. It performs reliably and is able to detect all significant faults over a certain threshold. The second problem concerns measuring degradation over time. A modified approachis taken based on repetitive conditions, and performs well given certain assumptions. Finally the third problem is to differentiate solar panel faults from partial shading. Here a clustering algorithm DBSCAN is applied on data in order to locate clusters of faults in the solar plane, demonstrating good performance in certain situations. It also demonstrates issues with misclassification of real faults due to clustering
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Xiao, Weidong. "Improved control of photovoltaic interfaces." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2393.
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Photovoltaic (solar electric) technology has shown significant potential as a source of practical and sustainable energy; this study focuses on increasing the performance of photovoltaic systems through the use of improved control and power interfaces. The main objective is to find an effective control algorithm and topology that are optimally suited to extracting the maximum power possible from photovoltaic modules. The thesis consists of the following primary subjects: photovoltaic modelling, the topological study of photovoltaic interfaces, the regulation of photovoltaic voltage, and maximum power tracking.
In photovoltaic power systems both photovoltaic modules and switching mode converters present non-linear and time-variant characteristics, resulting in a difficult control problem. This study applies in-depth modelling and analysis to quantify these inherent characteristics,s pecifically using successive linearization to create a simplified linear problem. Additionally, Youla Parameterisation is employed to design a stable control system for regulating the photovoltaic voltage. Finally, the thesis focuses on two critical aspects to improve the performance of maximum power point tracking. One improvement is to accurately locate the position of the maximum power point by using centred differentiation. The second is to reduce the oscillation around the steady-state maximum power point by controlling active perturbations. Adopting the method of steepest descent for maximum power point tracking, which delivers faster dynamic response and a smoother steady-state than the hill climbing method, enables these improvements. Comprehensive experimental evaluations have successfully illustrated the effectiveness of the proposed algorithms. Experimental evaluations show that the proposed control algorithm harvests about 1% more energy than the traditional method under the same evaluation platform and weather conditions without increasing the complexity of the hardware.
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Liu, Ying. "Advanced control of photovoltaic converters." Thesis, University of Leicester, 2009. http://hdl.handle.net/2381/7660.
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It is essential to always track maximum power from photovoltaic (PV) sources. Failure to track the global maximum power point under partial shading conditions is one of the major reasons that lead to significant power losses. Several maximum power point tracking methods have been proposed to deal with this problem. However, none of them were able to effectively identify the occurrence of partial shading. With the facility of Matlab modelling and simulation as well as the aid of a constructed solar emulator, the power-voltage characteristics of a PV panel under uniform and non-uniform irradiance conditions have been studied and some useful conclusions have been identified from observation. Based on these conclusions, a novel maximum power point tracking algorithm has been proposed, which is capable of identifying the occurrence of partial shading hence determining the need for a global scan over the operation range of PV panels for the true maximum power point. In the meantime, the effect of PV dynamics, due to the capacitance of PV cells, on maximum power point trackers has been investigated and some initial results and suggestions have been presented in this work.
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Le, Quesne John. "Organic materials for photovoltaic devices." Thesis, University of Nottingham, 1997. http://eprints.nottingham.ac.uk/13337/.
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This thesis is a contribution towards the understanding of the operation of bilayer solar cells, and the development of a theoretical basis for the selection of suitable pairs of materials for the fabrication of such cells. The work is divided into two main areas: (a) theoretical calculations on materials used in solar cells (b) fabrication of devices to test the calculations. Practically, many devices were made using some previously untried materials, the most successful of which was formed from dibromoanthanthrone and titanyl phthalocyanine. This sample was 0.30% efficient under incident white light of intensity 20mW/cm2 and had an open circuit voltage of 0.39V. Measurements of the response time of the sample were also recorded which provided information on the quality of the device made. Theoretically, calculations were performed using the extended Huckel method on potential materials for photovoltaic devices. Initially, these provided information on the variation of bandwidth with inter-ring separation for cofacially stacked phthalocyanines. They were also used to predict the position of the HOMO/LUMO for different materials. Then by deducing the position of the Fermi level, it is possible to simulate the junction formed between the two materials. Predicted behaviour for the phthalocyanine/perylene interface agreed with that found experimentally from UPS and optical absorption measurements of the ionisation potentials, work functions and band gaps for a similar junction. The calculations have also demonstrated how substituting or changing the two layers alters the performance of the device. This allowed a set of criteria to be established that should enable a more systematic approach to choosing potential pairs and then optimising their performance in future solar cells.
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Anderson, David James. "Energy rating of photovoltaic modules." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248767.
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Joseph, Savina Rita. "Current generation in photovoltaic cells." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:ed430576-6066-43bd-86fa-ead9c44c20c5.
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In this thesis we present an analysis of the operation of a particular type of hybrid photovoltaic device called a solid-state dye-sensitised solar cell. A mathematical model is used to describe the cell's operation, from the moment the photon reaches the surface of the device, until it is collected at the end electrodes. The invention of the solid-state dye-sensitised solar cells is recent and is part of the greater search for stable, low cost and efficient alternative means of energy generation. As the physical and chemical analysis has progressed in recent years, there is a need to establish a mathematical model to describe their behaviour. This thesis includes such mathematical analysis, based on our current knowledge of semiconductors and opto-electrochemical properties of solid-state material. The effect of these properties and of the geometry of the cell are examined in detail using analytical, but also numerical techniques that allow to circumvent the complexities involved. In this thesis, we show how conducting electrons can be generated by absorbing photons within an internal dye layer and are then transported via diffusion in the device until they reach the electrodes connecting it to an external electric circuit. While there are several limiting factors in the analysis, including the geometry of the device, the mathematical model appears to agree qualitatively well with available data on the current generation of solid-state dye-sensitised solar cells.
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Holder, Jenna Ka Ling. "Quantum structures in photovoltaic devices." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:d23c2660-bdba-4a4f-9d43-9860b9aabdb8.
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A study of three novel solar cells is presented, all of which incorporate a low-dimensional quantum confined component in a bid to enhance device performance. Firstly, intermediate band solar cells (IBSCs) based on InAs quantum dots (QDs) in a GaAs p-i-n structure are studied. The aim is to isolate the InAs QDs from the GaAs conduction band by surrounding them with wider band gap aluminium arsenide. An increase in open circuit voltage (VOC) and decrease in short circuit current (Jsc) is observed, causing no overall change in power conversion efficiency. Dark current - voltage measurements show that the increase in VOC is due to reduced recombination. Electroreflectance and external quantum efficiency measurements attribute the decrease in Jsc primarily to a reduction in InGaAs states between the InAs QD and GaAs which act as an extraction pathway for charges in the control device. A colloidal quantum dot (CQD) bulk heterojunction (BHJ) solar cell composed of a blend of PbS CQDs and ZnO nanoparticles is examined next. The aim of the BHJ is to increase charge separation by increasing the heterojunction interface. Different concentration ratios of each phase are tested and show no change in Jsc, due primarily to poor overall charge transport in the blend. VOC increases for a 30 wt% ZnO blend, and this is attributed largely to a reduction in shunt resistance in the BHJ devices. Finally, graphene is compared to indium tin oxide (ITO) as an alternative transparent electrode in squaraine/ C70 solar cells. Due to graphene’s high transparency, graphene devices have enhanced Jsc, however, its poor sheet resistance increases the series resistance through the device, leading to a poorer fill factor. VOC is raised by using MoO3 as a hole blocking layer. Absorption in the squaraine layer is found to be more conducive to current extraction than in the C70 layer. This is due to better matching of exciton diffusion length and layer thickness in the squaraine and to the minority carrier blocking layer adjacent to the squaraine being more effective than the one adjacent to the C70.
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Mihaylov, Blagovest V. "Uncertainty considerations in photovoltaic measurements." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/23251.
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Measurement uncertainty is an indication of the quality of a given measurement and ultimately translates into the confidence with which a decision can be made. In the context of PV, measurement uncertainties propagate into energy yield uncertainty, which in turn culminates into financial risk associated with an investment. This risk increases the cost of a PV installation. The aim of this thesis is to contribute towards the reduction of PV related measurement uncertainties. This is done in two ways. One is via developing and utilising more comprehensive methodologies for uncertainty propagation of complex measurands. The other is via more detailed estimates of the uncertainty contributors. In particular, the areas addressed in this thesis are the uncertainty estimation of the temperature coefficient measurements of modules; the uncertainty estimation of energy rating and module performance ratio measurements; and the uncertainties due to spectral effects on measurements performed with a flash solar simulator. The reported deviation in measurements of the temperature coefficients of P_MAX of modules is in the order of ±10% to ±15%. This is larger than the difference in the temperature coefficients of modules of the same type. The first step to improving the deviation between measurements is to estimate the uncertainty in a robust way. It was identified that there was no accepted approach of doing this. These measurements are strongly correlated, which complicates the uncertainty estimates. For the sake of simplicity, previously correlations have been avoided and conservative estimates used instead. In this work, uncertainties in both temperature and power and their correlations are estimated and propagated into the overall temperature coefficient uncertainty. Furthermore, temperature coefficients were calculated via weighing the measurements with their associated uncertainties. This was done for five different measurement setups that represent the majority of setups used worldwide. The approach was validated with measurement intercomparison of two modules measured on all systems. The approach reduced the overall uncertainty by half compared to the previous conservative estimates. It was demonstrated that uncertainties as low as 3% are achievable. The improved uncertainty estimates enabled the identification of a systematic effect due to a class B spectrum. This work culminated in the lowest reported measurement deviation of ±3.2% for module P_MAXtemperature coefficient measurements that was within the stated measurement uncertainties. The clear benefit of accounting for correlations was extended to measurements at different irradiance conditions and into the calculation of module performance ratio and energy rating. This was done via defining all the correlations between measurements and then propagating them with Monte Carlo simulations. The simulations are done with samples of a multivariate normal distribution with a variance-covariance matrix that corresponds to the estimated measurement correlations. It is demonstrated that both the energy rating and module performance ratio uncertainties strongly depend on the correlation estimates and that they cannot be conservatively overestimated. The module performance ratio uncertainty can be significantly lower than the measurement uncertainty at STC. This is because of the additional knowledge encoded into the selection of the underlying model used for calculating the energy rating. Therefore, the significance of the choice of model in the upcoming standard has been highlighted. It was confirmed that both bilinear interpolation and the proposed climatic datasets could be used for energy rating, but there are some areas that may need further investigation. An alternative way of improving uncertainty estimates and in turn reducing the associated uncertainty is via a more detailed characterisation of the uncertainty sources. A key uncertainty source is due to spectral effects in flash solar simulators. To better quantify this source, a complementary device was built to monitor the spectrum. The device is based on a matrix of photodiodes with commercially available interference filters situated on top and custom designed data acquisition electronics. This device is used in conjunction with the spectroradiometer to estimate the effects of flash-variation on the spectrum, the spectral temporal stability of the flash and spectral uniformity of the simulator and the attenuation masks used for altering the irradiance levels. It was demonstrated that the spectrum changes significantly during the flash and between flashes. While this effect is partially corrected for via the monitoring cell, it introduces additional uncertainty for non c-Si modules. This uncertainty is minimised by changes in the operational procedures. The spectral non-uniformity of the attenuation masks was shown to be significant, i.e. as large as 4%, in the NIR, prompting further investigation of the additional uncertainty for non c-Si modules. In this work, the methodology of estimating and propagating correlations in PV related measurements and the benefits of doing so are demonstrated. It is also highlighted that the uncertainty due to spectral effects goes beyond the uncertainty of spectroradiometer measurements. Finally, it is shown how they can be estimated with a complementary spectral monitor.
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Gousiopoulos, Athanasios. "The efficiency of photovoltaic systems." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/404709/.
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At this work the principle aim is to create new low cost hardware test circuitry that can emulate the behavior of solar cells under different insolation and temperature conditions. Another goal is to propose a new MPPT algorithm that could accurate and reliable estimate the maximum power operating point. The transcendental equation describing a solar cell IV characteristic contains current on both sides in a function of the form I = f (V, I). In this work, a current-independent voltage expression is derived for the maximum power point as a function of a new variable which is mathematically well defined. Validation is performed on four different photovoltaic modules. The best case scenario has shown a divergence in Pmpp of 0.08% while the worst 0.84%. The new method is examined for sensitivity, up to %5± on values of five fitting parameters (Rs, Rsh, n, Io, Iph), with Iph to have the higher impact effect (up to 5% error). Two topologies, of VBE multiplier, have been proposed that can reliably emulate solar cell operation. Analysis shows that both circuits have the potential to deliver good quality characteristic IV curves with small RMSE (10-3). The second improved VBE multiplier has the ability to operate over wider range of illumination and temperature conditions. Through this model it was possible to build a low cost (£230) fully functional prototype digital controlled emulator solar system “DiceSol”. A MPPT device has implemented based on a powerful mathematical modeling tool. The proposed method “Goose Waddle (GW)” was employed on a boost DC/DC converter configuration. Excellent static and dynamic performances were exhibited. At all cases considered convergence is higher than 98.53% while convergence time is on average 220 msec.
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Galagan, A. A. "High concentration photovoltaic thermal system." Thesis, Сумський державний університет, 2013. http://essuir.sumdu.edu.ua/handle/123456789/33625.
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Researchers from IBM have created a very impressive and affordable new photovoltaic system that is capable of concentrating solar radiation up to 2000 times. The system is also capable of converting 80% of incoming solar radiation into useful energy.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/33625
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Hurtasenko, D. S., O. I. Guzenko, Анатолій Сергійович Опанасюк, Анатолий Сергеевич Опанасюк, and Anatolii Serhiiovych Opanasiuk. "Designing of photovoltaic energy system." Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/45003.
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The problem of energy efficiency is one of the main problems of Ukraine, as our energy consumption in its economy considerably exceeds Western standards. Sumy State University(SSU) participates in the project on energy efficiency of higher education institutions of Ukraine "Higher Education. Energy and Sustainable Development "from the European Investment Bank. In this connection a comprehensive project "Energy Efficient University" was developed.
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Zakzouk, Nahla EzzEldin. "Photovoltaic system design and control." Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25932.
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Modern industrial society, increasing energy demands, and environmental issues have increased the need for new and clean renewable energy resources, among which photovoltaic energy has gained considerable interest. For best energy utilization, photovoltaic maximum power tracking and grid-integration aspects should be addressed. Generally, variable-step, incremental conductance maximum power point tracking technique has the merits of good tracking accuracy and fast convergence speed. Yet, the division processes in its algorithm create a computational burden. Also the conventional variable step-size encounters steady-state power oscillation and dynamic problems, especially under sudden irradiance changes. In this thesis, a division-free incremental conductance algorithm is proposed for photovoltaic maximum power tracking. It features a modified variable step-size and a direct converter control scheme. The proposed tracking technique does not only have the merits of superior steady-sta te and transient performance but also offers simple implementation and control. Thus, it can be practically implemented using low-cost microcontrollers, reducing overall system cost. Grid integration of photovoltaic systems using power electronic converters that vary in configurations, control loops and mandatory measured signals are investigated. A singlephase two-stage grid-interfaced photovoltaic system is presented in this thesis. It uses a boost chopper in the first stage for maximum power tracking and an H-bridge voltage source inverter in the second stage for grid interfacing. A novel DC-link voltage sensorless control technique is proposed for this topology. It eliminates the inverter outer DC-link voltage control loop, thus reducing system size, cost and control complexity. Additionally, system dynamics are enhanced during sudden changes. Single-stage based grid-tied photovoltaic power converters receive attention due to their merits of reduced footprint and losses, but at the cost of a limited degree-of-freedom. In this thesis, a single-phase single-stage grid-tied photovoltaic system is proposed. It adopts a single transformerless current source inverter to achieve photovoltaic maximum power tacking, whilst satisfying grid interfacing requirements. A proportional-resonant controller, associated with harmonic compensator units, is proposed for the inverter in order to limit injected grid current harmonics. Thus, a lower-sized inductor can be used in the inverter DC-link which enhances efficiency without sacrificing system performance. Simulation and experimental results validate all the proposed systems.
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Franklin, Ed. "Solar Photovoltaic (PV) Site Assessment." College of Agriculture, University of Arizona (Tucson, AZ), 2017. http://hdl.handle.net/10150/625447.
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5 p.An important consideration when installing a solar photovoltaic (PV) array for residential, commercial, or agricultural operations is determining the suitability of the site. A roof-top location for a residential application may have fewer options due to limited space (roof size), type of roofing material (such as a sloped shingle, or a flat roof), the orientation (south, east, or west), and roof-mounted structures such as vent pipe, chimney, heating & cooling units. A location with open space may utilize a ground-mount system or pole-mount system.
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Parlevliet, David Adam. "Silicon nanowires for photovoltaic applications /." Murdoch University Digital Theses Program, 2008. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20090930.140302.
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Franklin, Ed. "Types of Solar Photovoltaic Systems." College of Agriculture, University of Arizona (Tucson, AZ), 2017. http://hdl.handle.net/10150/625568.
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5 p.Solar energy systems can help Arizona individuals, families, and businesses achieve energy conservation goals beyond the adoption of energy-efficient appliances, and LED bulbs. Which type of system is the best? Knowing which system to select is the first important question. This factsheet will focus on solar photovoltaic energy systems. The term photovoltaic refers to the conversion of light energy to electricity.
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Smith, Kieren. "Degradation effects in photovoltaic modules." Thesis, Smith, Kieren (2016) Degradation effects in photovoltaic modules. Honours thesis, Murdoch University, 2016. https://researchrepository.murdoch.edu.au/id/eprint/33946/.
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This thesis focuses on the inspection of a set of photovoltaic (PV) modules for visual defects that may cause degradation in the modules performance, as well as analysing a module’s output characteristic through the use of a solar simulator such as the Spire 5600SLP. These modules were installed between 1996 and 1998 as part of a collaborative project. The study was conducted by the Japanese Quality Assurance Organisation (JQA) and the Murdoch University Energy Research Institute (MUERI) team, with the aim to evaluate the long-term performance of photovoltaic modules in various climatic conditions, with this particular set of modules having been exposed to the hot and dry climate of Perth.
Since production of the first PV modules decades ago, researchers and manufacturers have been striving to improve the efficiency and long term reliability of this renewable energy technology. The aim to become a reliable and practical source of alternative energy to that generated from the burning of fossil fuels has inspired the technological advances that the photovoltaic industry has undergone.
Through the use of new PV module designs, materials and manufacturing methods, PV modules have come a long way in terms of power output and long term performance. These days most modules are seeing manufacturer warranty periods of at least 20 years, ensuring that the power output remains above 80% of its original rated power within this time period [1,2,3]. To remain operating within warranty specifications, a module warranted with a 20 year, 20% maximum reduction in output power would be expected to see an average yearly degradation rate ( of less than 1%. A module that sees a reduction in power output of more than 20% of the rated power may be considered a failure and be up for warranty if it meets all manufacturer warranty conditions.
Three different photovoltaic cell technologies have been selected to be analysed for this thesis, with 3 monocrystalline silicon, 2 polycrystalline silicon and 4 amorphous silicon modules. It was found that the monocrystalline modules suffered from the lowest rate of degradation, experiencing a low median rate of 0.18% reduction in the modules power output per year of exposure. This rate of degradation was found to be under half the of 0.47% that Jordan & Kurtz found in their study and analysis of monocrystalline modules manufactured prior to 2000 [4]. The polycrystalline modules were the next best in terms of long term reliability, revealing a median of 0.41% per year. This value was again lower than that found in the Jordan & Kurtz study, with the Pre 2000 polycrystalline modules experiencing a rate of 0.61%/year. The amorphous silicon modules studied in this thesis were found to differ in their comparison to the J&K results, with the JQA modules revealing a high median of 1.94%/year, to that of 0.96%/year from J&K [4].
These rates of degradation mentioned above were then linked to observed defects experienced by the modules, providing reason for high degradation rates found occurring in the amorphous modules, as well as cause for the other two technologies to experience their . It was observed that two of the amorphous modules suffered from delamination of the PV cell and glass front, which lead to these modules experiencing the highest of 3.17% and 2.48%. This effect of delamination on the is likely a result of a combination of types of degradation and not just the delamination itself. The effect of degradation types on the performance degradation of a module is the key aspect in the objective for this thesis topic, and the reason behind many studies conducted on PV modules worldwide. There is a lot to learn from the performance of past technologies to help improve the future generations of PV modules in their pursuit of long term reliability as a renewable energy source.
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Noor, Hisham Nur Ain. "Self-cleaning Photovoltaic (PV) Modules." Thesis, Noor Hisham, Nur Ain (2017) Self-cleaning Photovoltaic (PV) Modules. Honours thesis, Murdoch University, 2017. https://researchrepository.murdoch.edu.au/id/eprint/41910/.
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The effect of soiling accumulation towards photovoltaic (PV) could cause a reduction in the PV system performance. The decrease in PV system output due to soiling has been proven crucial(Jiang, Lu, and Sun 2011). Thus signifies the significance of further research on the effect of soiling on a PV system. This project is a research based on the climate in Murdoch, Western Australia. This project consists of three parts; Photovoltaic (PV) performance testing, Air quality testing, Light transmittance testing. The PV performances were analysed based on three different dust mitigation conditions. The first module labelled as A is washed regularly as part of the dust mitigation strategies applied. The second module, labelled as B has a hydrophobic coating which functions when rainwater fall on the panel, the water would roll off the module at the same time rolling dust off the module. The third module, labelled as C is kept without any dust mitigation method. All three modules were tested out and washing performs the best giving a reduction in performance of 30.8% after 18 days, while B reduces in 47.4% performance and C has a 31.4% reduction in performance. Test 2 involves correlating the air quality with the dust accumulation on the PV modules. An optical dust sensor is used for this test. Test 3 has the same concept as Test 2 but is more closely related to the dust adhering to the PV modules. A glass panel is used to simulate the dust accumulation with a Light Emitting Diode (LED) and an Light Dependent Resistor (LDR) in between. A ratio-based calculation is made for test 3 to correlate the transmittance with voltage output and comparing the value when the glass is clean compared to dirty. The washed module performs the best with an average air quality of 0.025mg/m3. The worst module was the one without dust mitigation strategies, where the light transmittance reduced in 22% after two weeks of dust accumulation.
Consequently, to improve the performance of the PV in the industry, soiling should not be ignored as it should be a big issue in the PV industry.
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Cormode, Daniel. "Large and Small Photovoltaic Powerplants." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556469.
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The installed base of photovoltaic power plants in the United States has roughly doubled every 1 to 2 years between 2008 and 2015. The primary economic drivers of this are government mandates for renewable power, falling prices for all PV system components, 3rd party ownership models, and a generous tariff scheme known as net-metering. Other drivers include a desire for decreasing the environmental impact of electricity generation and a desire for some degree of independence from the local electric utility. The result is that in coming years, PV power will move from being a minor niche to a mainstream source of energy. As additional PV power comes online this will create challenges for the electric grid operators. We examine some problems related to large scale adoption of PV power in the United States. We do this by first discussing questions of reliability and efficiency at the PV system level. We measure the output of a fleet of small PV systems installed at Tucson Electric Power, and we characterize the degradation of those PV systems over several years. We develop methods to predict energy output from PV systems and quantify the impact of negatives such as partial shading, inverter inefficiency and malfunction of bypass diodes. Later we characterize the variability from large PV systems, including fleets of geographically diverse utility scale power plants. We also consider the power and energy requirements needed to smooth those systems, both from the perspective of an individual system and as a fleet. Finally we report on experiments from a utility scale PV plus battery hybrid system deployed near Tucson, Arizona where we characterize the ability of this system to produce smoothly ramping power as well as production of ancillary energy services such as frequency response.
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Doellner, Oscar Leonard. "Aircraft photovoltaic power-generating system." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185683.
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Photovoltaic cells, appropriately cooled and operating in the combustion-created high radiant-intensity environment of gas-turbine and jet engines, may replace the conventional (gearbox-driven) electrical power generators aboard jet aircraft. This study projects significant improvements not only in aircraft electrical power-generating-system performance, but also in overall aircraft performance. Jet-engine design modifications incorporating this concept not only save weight (and thus fuel), but are--in themselves--favorable to jet-engine performance. The dissertation concentrates on operational, constructional, structural, thermal, optical, radiometrical, thin-film, and solid-state theoretical aspects of the overall project. This new electrical power-generating system offers solid-state reliability with electrical power-output capability comparable to that of existing aircraft electromechanical power-generating systems (alternators and generators). In addition to improvements in aircraft performance, significant aircraft fuel- and weight-saving advantages are projected.
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Vale, Alistair Douglas John. "Organic:inorganic heterojunctions for photovoltaic devices." Thesis, Sheffield Hallam University, 2005. http://shura.shu.ac.uk/20472/.
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Thin films of TiO[2] with a thickness around 200nm were produced by DC reactive sputtering at room temperature. A variety of types of bandgap including direct allowed, direct forbidden, indirect allowed, and indirect forbidden were observed, with good fits of the Tauc model, between annealed and unannealed samples, and within the same sample. Planar conductivity was measured at 8.7x10[-3]O[-1]m[-1], falling to 7.4x10[-3]O[-1]m[-1] after annealing. Refractive index and extinction coefficient spectra were obtained via the Swanepoel technique and were found to be around 2.2 and 3x10[-3] respectively, in the region of weak absorption, with little change after annealing. Surface details in the micro and nano regimes showed flat films with few defects. XRD showed the Rutile phase dominating, and XPS showed correct stoichiometry. AFM showed the grain size to be in the range of 64nm rising to 82nm after annealing. TiO[2] films with an extended surface area were made using Degussa P25 and were deposited by the new technique of flood printing developed for this research. 2D profiles of thin films of P25 were measured at different concentrations and the thickness of the highly rough films was in the range of 5 mum to 15 mum rising with increasing concentration. AFM also showed films that were highly rough in the nanoscale. Thin films of CuPc and Rose Bengal were deposited on differently coated substrates; F:TO, TiO[2], and bare glass. The absorption spectra was seen to vary significantly with substrate, in particular, the 530nm peak of Rose Bengal was seen to diminish greatly when the dye was deposited on TiO[2]. Heterojunction photovoltaic devices based on dye layers adsorbed on semiconducting layers were produced in fifteen different designs with each design based on another to observe the effect of single parameters changes. Such changes included different thickness of porous TiO[2] layer, and whether a conducting polymer layer is applied. The devices were built up on F:TO coated glass slides and electrical contacts were made by DC sputtering platinum fingers on the top. The best device design gave a fill factor of 35.5%, and an overall conversion efficiency of 4.2x10[-3]%. Devices were thought to be greatly affected by series resistance from the top contact being applied to a highly rough surface. The top contact on different structures were electrically characterised and were found to have resistances in the region of kO, which manifests as a high series resistance in the final solar cells. This is one of the reasons for the low efficiency. The I(V) spectra of all the devices were fitted to a diode model using an algorithm developed for this research. The model fit gave reverse saturation currents in the range of 3.2x10[-9] A to 7.5x10[-3]A. Ideality factor varied from 3.8 to 80, series resistance varied from 15O to 500O, and parallel resistance varied from 117O to 778kO. An experimental setup capable of measuring the lifetime of photogenerated carriers in the dye films was developed that could produce pulses with a cut off time in the nano-seconds time regime, but can be simply improved to give cut off times in the sub nano-second regime, and only costs around £200 for the optical modulator.
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Hamada, Ali, and Fredrik Larsson. "EastWest : Solar tracking photovoltaic panel." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264471.
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The purpose of this project was to investigate how efficient it is to implement steering of a solar panel, in one or two axes. To determine how efficient it is, special consideration was taken to the energy usage of the driving system. Practical applications have also been considered with pros and cons. To answer the research questions a prototype was built and a controlled environment for testing was arranged. Rotating the panel in one axis resulted in a 26% energy increase and for the two-axis system a 56% energy increase compared to stationary panel. The use of stepper motors turned out to be not as efficient as needed, due to continuous use of energy at all times during operation.Syftet med detta projekt var att undersöka hur effektivt det är att implementera styrning av en solpanel i en eller två axlar. För att kunna avgöra nyttan så togs det hänsyn till drivsystemet och hur mycket energi det gick åt för styrningen. Även praktiska tillämpningar kontrollerades och vilka fördelar och nackdelar som skulle erhållas. För att svara på frågeställningarna, tillverkades en prototyp som testades i en kontrollerad miljö. Genom att rotera panelen runt en axel ökar energiupptaget 26 % och för det tvåaxliga systemet 56 % jämfört med en stationär panel. Användningen av stegmotorer visade sig inte vara speciellt effektiv då det krävdes kontinuerlig strömmatning för att erhålla det motormoment som krävdes för att hålla panelen på plats.
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Pancotti, Lorenzo <1977>. "Optical concentrators for photovoltaic use." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/349/1/tesi_Pancotti.pdf.
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Pancotti, Lorenzo <1977>. "Optical concentrators for photovoltaic use." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/349/.
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MUTTILLO, MIRCO. "Energy efficiency of photovoltaic panel." Doctoral thesis, Università degli Studi dell'Aquila, 2020. http://hdl.handle.net/11697/147991.
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The need to increase the share of electricity produced from renewable resources has pushed the installation of photovoltaic systems. Solar sources in recent years have experienced strong growth both in terms of investments and installations. In fact, in 2018, solar energy had a global generation capacity of 43% compared to all other power generation technologies. In the coming years, the use of solar energy will grow rapidly, especially for use in different applications. Therefore, studying the behavior of photovoltaic panels and having a model that accurately describes their behavior is essential for the design of the system. Furthermore, increasing the efficiency of the panel in anomalous conditions such as defects, breaks or partial shading is essential. As described, the doctoral thesis is focused on increasing the efficiency of the panels, on the modeling of photovoltaic panels and on the preliminary study of the causes of loss of efficiency and power produced by finding solutions through monitoring systems and applications for reconfigurable panels. After the introduction of the photovoltaic panels, the thesis is followed by a chapter dedicated to mathematical modeling using an equivalent electric model of a photovoltaic panel. This chapter allows to describe the behavior of a photovoltaic panel under normal operating conditions and variable environmental conditions. From a preliminary review of the methods in the literature for the estimations of the parameters, a new method for the extraction of the parameters is proposed. This method starts from the data provided by the manufacturer in the datasheet of the panel and estimates the five parameters. These parameters are needed to model a panel with a single diode equivalent circuit. The proposed method was compared with some works in the literature and the error concerning the data provided by the manufacturer was evaluated A chapter follows on the modeling and simulation of photovoltaic panels through the PSpice environment. In the literature, there are various more or less complex PV Spice models. Some Spice models do not take into account irradiation and temperature variation significant for the design of electronic circuits to be connected to the photovoltaic panels. This proposed model can simulate a photovoltaic panel with temperature and solar radiation variation. With the proposed Spice model as a block is possible to simulate photovoltaic plants both at low power and high power and force partial shading conditions to understand their behavior. After the description of models for photovoltaic panels, the study on possible anomalies present in photovoltaic systems due to defects on the panels or breakages was presented. Thanks to the combination of thermography and electrical measurements for the reconstruction of the IV characteristic of the individual panels, it was possible to understand the various anomalies. Indeed, it is possible to estimate thresholds that will serve to understand if a panel is still good or a replacement is necessary. For this reason, the comparison between thermography and electrical measurements and simulations is provided. Furthermore, this study has allowed us to understand and calculate the annual efficiency loss of the panels and the percentage of voltage variation concerning the temperature not supplied by the manufacturer. The next chapter describes the study and design of an electronic system for monitoring photovoltaic panels connected to a plant. The monitoring of the single panels allows the recognition of possible anomalies and to identify the panel that is the cause. Usually, monitoring is done at the inverter or string level, which however does not allow the faulty panel to be identified in the event of anomalies. The proposed parameter extraction methods and Spice model were used for the design of the monitoring board. Finally, the last activity developed concerns the increase in power lost during partial shading.
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Papírek, Jan. "Možnosti likvidace a recyklace fotovoltaických panelů v ČR." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-413548.
Full textAbstract:
This diploma thesis is focused on the assessment of the possibilities of disposal of photovoltaic panels installed in the Czech Republic. In addition to the basic theory of photovoltaic cells and panels, the theoretical parts describe legislation, subsidies in the field of photovoltaics and the development of photovoltaics in the Czech Republic. As part of recycling, their methods, work with the collective system, as well as the impact on the environment are analyzed. In the experimental part, using the data of the installed capacity and the average weights of the panels, various projections of the disposal of the panels over time are made, which take into account factors such as the life of the power plant or the capacity of the recycling line. Furthermore, according to the available literature, an analysis of the revenue from the sale of recycled materials contained in panels installed in our territory is performed. Subsequently, the needs of future implementers of proven estimates of labor and logical demands were assessed. Finally, an economic evaluation of the fundamental aspects of the FRELP recycling process was performed and the net prices of different recycling directions were determined.
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Thantsha, Nicolas Matome. "Spatially resolved opto-electric measurements of photovoltaic materials and devices." Thesis, Nelson Mandela Metropolitan University, 2010. http://hdl.handle.net/10948/1123.
Full textAbstract:
The objective of this study is to characterize and analyse defects in solar cell devices. Materials used to fabricate solar cells are not defects free and therefore, there is a need to investigate defects in cells. To investigate this, a topographical technique was developed and employed which uses a non-destructive methodology to analyse solar cells. A system was built which uses a technique based on a laser beam induced current (LBIC). LBIC technique involves focusing light on to a surface of a solar cell device in order to create a photo-generated current that can be measured in the external circuit for analyses. The advantage of this technique is that it allows parameter extraction. Parameters that can be extracted include short-circuit current, carrier lifetime and also the external and internal quantum efficiency of a solar cell. In this thesis, LBIC measurements in the form of picture maps are used to indicate the distribution of the localized beam induced current within solar cells. Areas with low minority carrier lifetime in solar cells are made visible by LBIC mapping. Surface reflection intensity measurements of cells can also be mapped using the LBIC system developed in this study. The system is also capable of mapping photo-generated current of a cell below and above room temperature. This thesis also presents an assessment procedure capable of assessing the device and performance parameters with reference to I-V measurements. The dark and illuminated I-V characteristics of solar cells were investigated. The illuminated I-V characteristics of solar cells were obtained using a defocused laser beam. Dark I-V measurements were performed by applying voltage across the cell in the dark and measuring a current through it. The device parameters which describe the behaviour of I-V characteristic were extracted from the I-V data using Particle Swarm Optimization (PSO) method based on a one-and two-diode solar cell models. Solar cells of different technologies were analysed, namely, single-crystalline (c-Si) and multicrystalline (mc-Si) silicon, Edge-defined Film-fed Growth Si (EFG-Si) and Cu(In,Ga)(Se,S)2 (CIGSS) thin film based cells. The LBIC results illustrated the effect of surface reflection features and material defects in the solar cell investigated. IQE at a wavelength of 660 nm were measured on these cells and the results in general emphasised the importance of correcting optical losses, i.e. reflection loss, when characterizing different types of defects. The agreement between the IQE measurements and I-V characteristics of a cell showed that the differences in crystal grains influence the performance of a mc-Si cell. The temperature-dependence of I-V characteristics of a CIGSS solar cell was investigated. The results showed that, for this material, the photo response is reduced at elevated temperatures. In addition to LBIC using a laser beam, solar spectral radiation was employed to obtained device performance parameters. The results emphasised the effect of grain boundaries as a recombination centres for photo-generated hole-pairs. Lastly, mesa diode characterizations of solar cells were investigated. Mesa diodes are achieved by etching down a solar cell so that the plateau regions are formed. Mesa diodes expose the p-n junction, and therefore mesa diode analysis provides a better way of determining and revealing the fundamental current conduction mechanism at the junction. Mesa diodes avoid possible edge effects. This study showed that mesa diodes can be used to characterize spatial non-uniformities in solar cells. The results obtained in this study indicate that LBIC is a useful tool for defect characterization in solar cells. Also LBIC complements other characterization techniques such as I-V characterization.
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Urban, H. "Three-dimensional device structures for photovoltaic applications." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:e308d352-b342-4c44-a5f6-53121e2cc267.
Full textAbstract:
Harnessing solar energy has become a promising clean and renewable energy source alternative to fossil fuels since the development of low-cost dye sensitized solar cells (DSSC) and organic photovoltaic solar cell devices. Their power-conversion efficiencies, below 13% and 9% respectively, still limit the economic viability of these technologies. The geometry and optical properties of photonic crystals can be used to improve the absorption and charge collection efficiencies of these devices. This thesis describes the fabrication of TiO2 DSSC and ZnO-polymer solar cell devices based on a three-dimensional photonic crystal structure. Photonic crystal polymer structures were produced by holographic lithography and thermally stabilized in order to be used as templates for atomic layer deposition (ALD) of various metal oxides. For this purpose, an ALD apparatus was built and ALD processes for the growth of TiO2, ZnO, Al2O3, ZnO:Al, and Zr3N4 were established and deposited on photonic crystal templates. After ALD, the template was removed by calcination at 500°C, at which ZnO:Al films lost their conductivity of 250 S/cm preventing their use as transparent conducting oxide (TCO) electrodes. The produced 90 nm TiO2 photonic crystal shell DSSC and TiO2 inverse replica devices based on the dye N-719 and iodine/iodide redox electrolyte provided power-conversion efficiencies of 0.9% and 0.49% respectively and their diffusion lengths were 2× and 3× longer than that of a nanocrystalline reference device respectively. ZnO-polymer devices, comprising a P3HT layer as absorber and PEDOT:PSS film as hole-transporter, were also investigated.
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Kijovský, František. "Fotovoltaický on-grid systém s akumulací." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219414.
Full textAbstract:
This thesis deals with processing the current issue of trends in on-grid photovoltaic system with accumulation. It examines the posibility of accumulation of photovoltaic systems, analyzing their strengths and weaknesses in the practical deployment. It compares the different storage technologies based on indicators of cycles, durability and price ranges. The practical part deals with the technical design of hybrid power system and then comparing with the standard on-grid system in technical and economical point of view.