Over the last 4 years, perovskite solar cells emerged as an attractive, highly efficient, and low-cost alternative to established, conventional photovoltaic technologies. The power conversion efficiency of these devices recorded an unprecedented rise, currently exceeding certified values of 20%. This thesis covers a number of technological advancements which lead to improved photovoltaic performance, as well as vital insight into some more fundamental aspects of the perovskite device operation. The focus of this body of work is primarily directed towards the electric contact in the PV stack which is responsible for electron collection. The motivation of the study presented here is given in Chapter 1, and includes a brief summary of the current energy landscape. Chapter 2 introduces the theoretical background of photovoltaic technology, starting from the basics of semiconductor physics, through to the principles of solar cell operation, as well as some characteristic properties of the perovskite materials. Details of the experimental methods used in this study are reported in Chapter 3. Chapter 4 reports the development of a low temperature process (sub-150 °C) for the manufacture of perovskite solar cells. Dispersions of pre-synthesised, highly crystalline TiO2 nanoparticles were used as an electron selective contact, which eliminated the high temperature sintering step. Chapters 5, 6 and 7, report the interface modification of an n-type contact, resulting in a substantially improved device operation and suppression of hysteresis phenomenon which is characteristic of perovskite photovoltaics. Fullerene-based materials have been found to make excellent electronic contact with halide perovskite materials, and are shown to be far superior to commonly used metal oxides. The facilitated electron collection allows enhancements in the photovoltaic performance of these devices. Furthermore, the organic layers used in this study can be processed at low temperatures. Finally, the development of transparent conductive electrodes based on silver nanowires is presented in Chapter 8. The fabricated electrodes exhibit low sheet resistance, high degree of transparency, and can be processed at low temperatures, allowing them to be compatible with processing on flexible substrates and multi-junction architectures. The application of silver nanowires in different perovskite solar cell architectures is also reported.

It is essential to make performance measurements of photovoltaics modules in order to quantify the power they will produce under operational conditions. Performance measurements are fundamental throughout the photovoltaic industry, from product development to quality control in manufacturing and installation in the field. Rapid and economic evaluation of photovoltaic performance requires measurements using pulsed illumination solar simulators. However some devices have characteristics which can cause difficulties making these measurements. The aim of this thesis is to overcome these measurement problems focusing particularly on two of the most prevalent and pressing of these problematic characteristics: high capacitance and metastability. A new method for measuring high capacitance modules in a pulsed simulator, based on tailor made voltage ramps, was developed. The voltage ramp is tailor made such that the measurement time is minimised while maintaining high accuracy (0.5 %), allowing the measurement of high capacitance modules in a single 10ms illumination pulse. The necessary inputs for this method are the capacitance and dark current as a function of voltage for each module. In order to make these measurements, at the high forward bias voltages required, a new system was developed. The tailored voltage ramp can be created individually for each module, since the process is rapid an automatic. This makes the method applicable to a production line or to test house measurements. In addition to their use as inputs for the voltage ramp design, the capacitance and dark current also contain other valuable information, including effective minority carrier lifetime. In several thin film technologies, such as CIGS, the efficiency is not a fixed value, rather the module is metastable and the efficiency changes depending on the previous exposure /preconditioning of the device. Preconditioning is normally applied to these devices before measurement in order to put them in a specific state that is repeatable and representative of outdoor operation. Improved preconditioning practices are vital for performance measurements in CIGS modules. Therefore the preconditioning behaviour of a variety of CIGS modules from different manufacturers was investigated. The effect of preconditioning varied for different modules, commonly the fill factor improved substantially, but often changes in open circuit voltage were also seen and in some cases also substantial changes in short circuit current. The rates of preconditioning and relaxation were found to follow stretched exponential behaviour, such that the changes occur linearly on a logarithmic timescale over several orders of magnitude in time. The total time for performance stabilisation was found to vary significantly between different types of module. Because of this stretched exponential behaviour, even though the module took days to fully relax to the dark state, there was significant relaxation within the tens of minutes that it would normally take a module to cool down after light soaking before it could be measured. The major implication of observed kinetics is that in order to achieve repeatable measurement the timing in each element of a preconditioning routine should be controlled such that the fractional error in the duration of each step is small. During the investigation an unexpectedly short timescale preconditioning effect was observed, which occurs on a millisecond timescale and relaxes in seconds. It was shown that the measurement artefacts introduced using this method can be eliminated by using electrical forward bias until immediately before the measurement. Another measurement system was developed to track the dark current and C-V characteristic of the modules during electrical bias preconditioning and subsequent relaxation. These measurements demonstrate that more than one process involved during preconditioning in CIGS. Changes occur both in the doping in the bulk of the absorber and also in charge accumulation occurring near to the absorber / buffer interface. The theoretical models for preconditioning in CIGS were reviewed and compared to the experimental results. A rate model was developed based on the theory of the metastable VSe-VCu defect. This model was shown to correspond well to the rates of preconditioning and relaxation in CIGS. The non-exponential behaviour was shown to be compatible with a distribution of activation energies for the transition between different defect states. The difference in the time taken for modules to stabilise is explained by differences in doping density and the density of VSe-VCu defects. The work presented facilitates more accurate, economical performance measurements for high capacitance devices and CIGS devices, thereby contributing to the large scale implementation of photovoltaics as power source.

In this work, data quality control and mitigation tools have been developed for improving the accuracy of photovoltaic (PV) system performance assessment. These tools allow to demonstrate the impact of ignoring erroneous or lost data on performance evaluation and fault detection. The work mainly focuses on residential PV systems where monitoring is limited to recording total generation and the lack of meteorological data makes quality control in that area truly challenging. Main quality issues addressed in this work are with regards to wrong system description and missing electrical and/or meteorological data in monitoring. An automatic detection of wrong input information such as system nominal capacity and azimuth is developed, based on statistical distributions of annual figures of PV system performance ratio (PR) and final yield. This approach is specifically useful in carrying out PV fleet analyses where only monthly or annual energy outputs are available. The evaluation is carried out based on synthetic weather data which is obtained by interpolating from a network of about 80 meteorological monitoring stations operated by the UK Meteorological Office. The procedures are used on a large PV domestic dataset, obtained by a social housing organisation, where a significant number of cases with wrong input information are found. Data interruption is identified as another challenge in PV monitoring data, although the effect of this is particularly under-researched in the area of PV. Disregarding missing energy generation data leads to falsely estimated performance figures, which consequently may lead to false alarms on performance and/or the lack of necessary requirements for the financial revenue of a domestic system through the feed-in-tariff scheme. In this work, the effect of missing data is mitigated by applying novel data inference methods based on empirical and artificial neural network approaches, training algorithms and remotely inferred weather data. Various cases of data loss are considered and case studies from the CREST monitoring system and the domestic dataset are used as test cases. When using back-filled energy output, monthly PR estimation yields more accurate results than when including prolonged data gaps in the analysis. Finally, to further discriminate more obscure data from system faults when higher temporal resolution data is available, a remote modelling and failure detection framework is ii developed based on a physical electrical model, remote input weather data and system description extracted from PV module and inverter manufacturer datasheets. The failure detection is based on the analysis of daily profiles and long-term PR comparison of neighbouring PV systems. By employing this tool on various case studies it is seen that undetected wrong data may severely obscure fault detection, affecting PV system s lifetime. Based on the results and conclusions of this work on the employed residential dataset, essential data requirements for domestic PV monitoring are introduced as a potential contribution to existing lessons learnt in PV monitoring.

abstract: A primary motivation of research in photovoltaic technology is to obtain higher efficiency photovoltaic devices at reduced cost of production so that solar electricity can be cost competitive. The majority of photovoltaic technologies are based on p-n junction, with efficiency potential being much lower than the thermodynamic limits of individual technologies and thereby providing substantial scope for further improvements in efficiency. The thesis explores photovoltaic devices using new physical processes that rely on thin layers and are capable of attaining the thermodynamic limit of photovoltaic technology. Silicon heterostructure is one of the candidate technologies in which thin films induce a minority carrier collecting junction in silicon and the devices can achieve efficiency close to the thermodynamic limits of silicon technology. The thesis proposes and experimentally establishes a new theory explaining the operation of silicon heterostructure solar cells. The theory will assist in identifying the optimum properties of thin film materials for silicon heterostructure and help in design and characterization of the devices, along with aiding in developing new devices based on this technology. The efficiency potential of silicon heterostructure is constrained by the thermodynamic limit (31%) of single junction solar cell and is considerably lower than the limit of photovoltaic conversion (~ 80 %). A further improvement in photovoltaic conversion efficiency is possible by implementing a multiple quasi-fermi level system (MQFL). A MQFL allows the absorption of sub band gap photons with current being extracted at a higher band-gap, thereby allowing to overcome the efficiency limit of single junction devices. A MQFL can be realized either by thin epitaxial layers of alternating higher and lower band gap material with nearly lattice matched (quantum well) or highly lattice mismatched (quantum dot) structure. The thesis identifies the material combination for quantum well structure and calculates the absorption coefficient of a MQFl based on quantum well. GaAsSb (barrier)/InAs(dot) was identified as a candidate material for MQFL using quantum dot. The thesis explains the growth mechanism of GaAsSb and the optimization of GaAsSb and GaAs heterointerface. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011

The consequences of over-reliance on fossil fuels for energy supply, namely climate change and security of supply, are pushing for the use of local, renewable energy sources which are usually variable in nature, prompting the need for energy storage. Today, there is a trend towards distributed energy storage, justified by the distributed nature of renewable energy sources and the important share of energy consumption in buildings. Important information on such small scale energy storage installations, however, is still missing and the results of the existing literature vary widely. To account for these research gaps, a thorough characterisation of energy storage technologies is performed, together with the dimensioning and optimisation of such installations in buildings, as well as some aspects of their impact on the grid.It is found that storage is still far from grid parity and expensive when compared to other solutions, although necessary for a high share of renewables. Also, energy storage is subject to important economies of scale and technical limitations that counter the reasoning for a distributed approach. There is an important lack of practical information on several energy storage technologies, and many studies on distributed storage use downsized values from large-scale installations that do not correctly depict smaller installations, leading to biased results. Nevertheless, today, lithium-ion batteries seem to be the most appropriate electrical energy storage technology for buildings, being well adapted to short term storage. On the other hand, a very high share of renewables will push for long term storage, itself a challenge given the high cost brought by a low utilisation factor. A high share of distributed generation also impacts the grid, a problem which most final consumers have no economic incentive to mitigate. Storage by itself, without a sound control strategy, does not help as it tends to increase the load variability while the peak load remains the same. Specific control algorithms could change that but incentives must be present, namely through the adaptation of current grid tariffs that do not correctly allocate existing costs. These findings are essential in the future planning of energy systems as well as in energy policy. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

>Magister Scientiae - MSc / One-dimensional silicon nanowires (SiNWs) are promising building blocks for solar cells as they provide a controlled, vectorial transport route for photo-generated charge carriers in the device as well as providing anti-reflection for incoming light. Two major approaches are followed to synthesise SiNWs, namely the bottom-up approach during vapour-liquid-solid mechanism which employs chemical vapour deposition techniques. The other method is the top-down approach via metal assisted chemical etching (MaCE). MaCE provides a simple, inexpensive and repeatable process that yields radially and vertically aligned SiNWs in which the structure is easily controlled by changing the etching time or chemical concentrations. During MaCE synthesis, a crystalline silicon (c-Si) substrate covered with metal nanoparticles (catalyst) is etched in a diluted hydrofluoric acid solution containing oxidising agents. Since the first report on SiNWs synthesised via MaCE, various publications have described the growth during the MaCE process. However lingering questions around the role of the catalyst during formation, dispersion and the eventual diameter of the nanowires remain. In addition, very little information pertaining to the changes in crystallinity and atomic bonding properties of the nanowires post synthesis is known. As such, this study investigates the evolution of vertical SiNWs from deposited silver nanoparticles by means of in-depth electron microscopy analyses. Changes in crystallinity during synthesis of the nanowires are probed using x-ray diffraction (XRD) and transmission electron microscopy (TEM). Deviations in the optical properties are quantified using optical reflectivity measurements by employing ultraviolet-visible (UV-Vis) spectroscopy, whereas the bonding configurations of the nanowires are probed by Raman and Fourier transforms infrared spectroscopy. Diameters of 50 – 200 nm vertical SiNWs were obtained from scanning electron micrographs and nanowires lengths linearly increased with etching time duration from about 130 nm after 30 seconds to over 15 μm after 80 minutes. No diameter modulations along nanowires axial direction and rough nanowires apexes were observed for nanowires obtained at longer etching times. These SiNWs remained crystalline as their bulk single crystalline Si wafers but had a thin amorphous layer on the surface, findings confirmed by TEM, XRD and Raman analysis. Nanowires were found to be partially passivated with oxygen with small traces of hydrogen termination, confirmed with infrared absorption studies. Finally, low optical reflection of less than 10% over visible range compared to an average of 30% for bulk Si were measured depicting an antireflective ability required in silicon solar cells.

A energia solar fotovoltaica é a forma de produção de eletricidade que mais cresce no mundo. A potência instalada mundial, até o ano de 2010, era de cerca de 40 GWP e a previsão é de que, somente em 2011, este cifra seja aumentada em mais 24 GWP. O inversor é o elemento central dos sistemas fotovoltaicos. Além de executar a conversão da energia elétrica em corrente contínua para corrente alternada, ele também é responsável pelo gerenciamento da energia entregue à rede e pelo seguimento do ponto de máxima potência. O seguimento do ponto de máxima potência (MPPT) é um processo de controle no qual o inversor procura manter o gerador fotovoltaico operando em uma região da sua curva característica na qual o produto corrente × tensão tenha o seu valor máximo, de forma a otimizar a extração de potência do gerador fotovoltaico. A eficiência de MPPT é um número que indica o grau de precisão, tanto em termos de rapidez como de magnitude, com que o seguidor do ponto de máxima potência atinge o seu objetivo. Assim podem ser definidas duas eficiências de MPPT: a eficiência estática, associada a situações em que a irradiância solar permanece constante durante o intervalo considerado, e a eficiência dinâmica de MPPT, que considera os momentos de variação na intensidade da irradiância, resultantes, por exemplo, da passagem de nuvens. As eficiências de MPPT (especialmente a dinâmica) são de difícil determinação, porém a tarefa fica muito facilitada com a utilização de um simulador de arranjos fotovoltaicos. A norma européia EN 50530:2010 Overall Efficiency of Photovoltaic Inverters propôs uma metodologia para a determinação da eficiência dinâmica de MPPT utilizando perfis variáveis de irradiância a serem programados no simulador de arranjos fotovoltaicos. O objetivo central da tese é fazer uma análise experimental da eficiência dinâmica do seguimento de máxima potência de inversores conectados à rede através da comparação dos resultados de eficiência obtidos seguindo a metodologia definida na norma citada com resultados obtidos a partir de medições em tempo real ao longo de um dia, verificando a adequação da norma às situações de campo. Para a obtenção dos dados de entrada do simulador foram medidas, por diversos dias, a irradiância e temperatura de uma célula de referência. Os inversores foram conectados à saída do simulador de arranjos fotovoltaicos e foram reproduzidas as condições de irradiância e temperatura de três dias selecionados em função do grau de nebulosidade, com comportamento dinâmico semelhante aos perfis de irradiância da norma. Os resultados foram, na maioria dos casos, discordantes. Uma análise dos resultados parciais de eficiência dinâmica indicou como causa desta discrepância a dependência que a eficiência dinâmica de MPPT tem com a taxa de variação da irradiância. Conclui-se que, embora as seqüências de irradiância propostas pela norma constituam uma eficiente ferramenta para o diagnóstico de eventuais deficiências no comportamento do seguidor de máxima potência de inversores, a média dos valores de eficiência de MPPT calculados a partir delas não pode, em princípio, ser considerada como representativa de valores diários. / Photovoltaic solar energy is the fastest growing electricity source in the world. The worldwide capacity until 2010 was about 40 GWP and, by the end of 2011, this figure will be increased by another 24 GWP. The inverter is the pivotal element of PV systems. In addition to performing the conversion of electrical energy from direct current to alternating current, the inverter is also responsible for the management of the energy delivered to the grid and for performing the maximum power point tracking. The maximum power point tracking (MPPT) is a control process by which the inverter tries to keep the PV generator operating in a region of its characteristic curve where the product current × voltage reaches its maximum value. The MPPT efficiency is a figure that indicates the degree of precision, both in terms of speed and magnitude, that the MPPT reaches its goal. Thus, two MPPT efficiencies can be defined: the static efficiency, associated to situations in which the solar irradiance does not vary during the considered interval, and also the dynamic MPPT efficiency, which considers the variation of the irradiance intensity as a result, for example, of the passage of clouds. MPPT efficiencies (especially the dynamic) are hard to determine, but the task becomes much easier with the use of a photovoltaic array simulator. The European standard EN 50530:2010 Overall Efficiency of Photovoltaic Inverters proposes a methodology for determining the dynamic efficiency of MPPT using variable irradiance profiles to be programmed into the photovoltaic array simulator. The main objective of this thesis is to make an experimental analysis of the dynamic MPPT efficiency of grid connected inverters by comparing the efficiency results obtained by following the methodology defined in the referred standard with results obtained from real time measurements in the course of a day, checking the adequacy of the standard when applied to field situations. In order to obtain the input data for the simulator, the irradiance and temperature of a reference cell were measured for several days. The inverters were connected to the output of the array simulator, which reproduced the conditions of irradiance and temperature for three days selected according to the degree of cloudiness, having a dynamic behavior similar to the standard irradiance profiles. The results, in most cases, disagree. An analysis of partial results of dynamic efficiency indicated the dependence of the dynamic MPPT efficiency to the rate of irradiance change as the cause of this discrepancy. As a conclusion, it can be stated that, although the sequences of irradiance proposed by the standard are an efficient tool for the diagnosis of deficiencies in the behavior of the MPP tracker, the average efficiency of MPPT calculated from the sequences cannot, in principle, to be considered as representative of the daily values of dynamic MPPT efficiency.

Understanding the fundamental chemistry of conjugated polymers and fullerenes has been the subject of intense research for the last three decades, with the last ten years seeing increased research toward the application of these materials into functional organic electronic devices such as organic photovoltaic devices (OPVs). This field has seen significant advances is cell efficiency in just the last few years (to >10%), in large part due to the development of new donor and acceptor materials, the fine tuning of fabrication parameters to control material nanostructure, as well as the introduction of new interfacial materials such as ionically functionalized conjugated polymers, also known as conjugated polyelectrolytes (CPEs). This dissertation aims to further understand the fundamental chemistry associated with charge injection processes in CPEs and ionically functionalized fullerenes. The role of ionic functionality on electrochemical, chemical, and interfacial charge injection processes is explored. The results presented demonstrate the use of ionic functionality to control the spatial doping profile of a bilayer structure of anionically and cationically functionalized CPEs to fabricate a p-n junction (Chapter II). The role of ionic functionality on chemical charge injection processes is explored via the reaction of polyacetylene and polythiophene based CPEs with molecular oxygen (Chapters III and IV). The results show the dramatic effect of ionic functionality, as well as the specific role of the counterion, on the photooxidative stability of CPEs. The control of reaction pathway via counterion charge density is also explored (Chapter IV) and shows a continuum of reaction pathways based on the charge density of the counter cation. Finally, the role of ionic functionality on interfacial charge injection processes in a functional OPV is explored using a cationically functionalized fullerene derivative (Chapters V and VI). Cell performance increases due to an increase in open-circuit voltage and substantial reduction in series resistance resulting from the high conductivity of the interfacial fullerene layer. The chemical origin of this high conductivity is explored in Chapter VI and shown to likely be the result of chemical reactions occurring between the counter anion and the fullerene core. This dissertation contains coauthored, previously published and unpublished work.

A energia solar fotovoltaica é a forma de produção de eletricidade que mais cresce no mundo. A potência instalada mundial, até o ano de 2010, era de cerca de 40 GWP e a previsão é de que, somente em 2011, este cifra seja aumentada em mais 24 GWP. O inversor é o elemento central dos sistemas fotovoltaicos. Além de executar a conversão da energia elétrica em corrente contínua para corrente alternada, ele também é responsável pelo gerenciamento da energia entregue à rede e pelo seguimento do ponto de máxima potência. O seguimento do ponto de máxima potência (MPPT) é um processo de controle no qual o inversor procura manter o gerador fotovoltaico operando em uma região da sua curva característica na qual o produto corrente × tensão tenha o seu valor máximo, de forma a otimizar a extração de potência do gerador fotovoltaico. A eficiência de MPPT é um número que indica o grau de precisão, tanto em termos de rapidez como de magnitude, com que o seguidor do ponto de máxima potência atinge o seu objetivo. Assim podem ser definidas duas eficiências de MPPT: a eficiência estática, associada a situações em que a irradiância solar permanece constante durante o intervalo considerado, e a eficiência dinâmica de MPPT, que considera os momentos de variação na intensidade da irradiância, resultantes, por exemplo, da passagem de nuvens. As eficiências de MPPT (especialmente a dinâmica) são de difícil determinação, porém a tarefa fica muito facilitada com a utilização de um simulador de arranjos fotovoltaicos. A norma européia EN 50530:2010 Overall Efficiency of Photovoltaic Inverters propôs uma metodologia para a determinação da eficiência dinâmica de MPPT utilizando perfis variáveis de irradiância a serem programados no simulador de arranjos fotovoltaicos. O objetivo central da tese é fazer uma análise experimental da eficiência dinâmica do seguimento de máxima potência de inversores conectados à rede através da comparação dos resultados de eficiência obtidos seguindo a metodologia definida na norma citada com resultados obtidos a partir de medições em tempo real ao longo de um dia, verificando a adequação da norma às situações de campo. Para a obtenção dos dados de entrada do simulador foram medidas, por diversos dias, a irradiância e temperatura de uma célula de referência. Os inversores foram conectados à saída do simulador de arranjos fotovoltaicos e foram reproduzidas as condições de irradiância e temperatura de três dias selecionados em função do grau de nebulosidade, com comportamento dinâmico semelhante aos perfis de irradiância da norma. Os resultados foram, na maioria dos casos, discordantes. Uma análise dos resultados parciais de eficiência dinâmica indicou como causa desta discrepância a dependência que a eficiência dinâmica de MPPT tem com a taxa de variação da irradiância. Conclui-se que, embora as seqüências de irradiância propostas pela norma constituam uma eficiente ferramenta para o diagnóstico de eventuais deficiências no comportamento do seguidor de máxima potência de inversores, a média dos valores de eficiência de MPPT calculados a partir delas não pode, em princípio, ser considerada como representativa de valores diários. / Photovoltaic solar energy is the fastest growing electricity source in the world. The worldwide capacity until 2010 was about 40 GWP and, by the end of 2011, this figure will be increased by another 24 GWP. The inverter is the pivotal element of PV systems. In addition to performing the conversion of electrical energy from direct current to alternating current, the inverter is also responsible for the management of the energy delivered to the grid and for performing the maximum power point tracking. The maximum power point tracking (MPPT) is a control process by which the inverter tries to keep the PV generator operating in a region of its characteristic curve where the product current × voltage reaches its maximum value. The MPPT efficiency is a figure that indicates the degree of precision, both in terms of speed and magnitude, that the MPPT reaches its goal. Thus, two MPPT efficiencies can be defined: the static efficiency, associated to situations in which the solar irradiance does not vary during the considered interval, and also the dynamic MPPT efficiency, which considers the variation of the irradiance intensity as a result, for example, of the passage of clouds. MPPT efficiencies (especially the dynamic) are hard to determine, but the task becomes much easier with the use of a photovoltaic array simulator. The European standard EN 50530:2010 Overall Efficiency of Photovoltaic Inverters proposes a methodology for determining the dynamic efficiency of MPPT using variable irradiance profiles to be programmed into the photovoltaic array simulator. The main objective of this thesis is to make an experimental analysis of the dynamic MPPT efficiency of grid connected inverters by comparing the efficiency results obtained by following the methodology defined in the referred standard with results obtained from real time measurements in the course of a day, checking the adequacy of the standard when applied to field situations. In order to obtain the input data for the simulator, the irradiance and temperature of a reference cell were measured for several days. The inverters were connected to the output of the array simulator, which reproduced the conditions of irradiance and temperature for three days selected according to the degree of cloudiness, having a dynamic behavior similar to the standard irradiance profiles. The results, in most cases, disagree. An analysis of partial results of dynamic efficiency indicated the dependence of the dynamic MPPT efficiency to the rate of irradiance change as the cause of this discrepancy. As a conclusion, it can be stated that, although the sequences of irradiance proposed by the standard are an efficient tool for the diagnosis of deficiencies in the behavior of the MPP tracker, the average efficiency of MPPT calculated from the sequences cannot, in principle, to be considered as representative of the daily values of dynamic MPPT efficiency.

abstract: At present, almost 70% of the electric energy in the United States is produced utilizing fossil fuels. Combustion of fossil fuels contributes CO2 to the atmosphere, potentially exacerbating the impact on global warming. To make the electric power system (EPS) more sustainable for the future, there has been an emphasis on scaling up generation of electric energy from wind and solar resources. These resources are renewable in nature and have pollution free operation. Various states in the US have set up different goals for achieving certain amount of electrical energy to be produced from renewable resources. The Southwestern region of the United States receives significant solar radiation throughout the year. High solar radiation makes concentrated solar power and solar PV the most suitable means of renewable energy production in this region. However, the majority of the projects that are presently being developed are either residential or utility owned solar PV plants. This research explores the impact of significant PV penetration on the steady state voltage profile of the electric power transmission system. This study also identifies the impact of PV penetration on the dynamic response of the transmission system such as rotor angle stability, frequency response and voltage response after a contingency. The light load case of spring 2010 and the peak load case of summer 2018 have been considered for analyzing the impact of PV. If the impact is found to be detrimental to the normal operation of the EPS, mitigation measures have been devised and presented in the thesis. Commercially available software tools/packages such as PSLF, PSS/E, DSA Tools have been used to analyze the power network and validate the results. / Dissertation/Thesis / M.S. Electrical Engineering 2013