Showing papers on "Photovoltaic system published in 2005"
TL;DR: In this article, the authors report highly efficient polymer solar cells based on a bulk heterojunction of polymer poly(3-hexylthiophene) and methanofullerene.
Abstract: Converting solar energy into electricity provides a much-needed solution to the energy crisis the world is facing today. Polymer solar cells have shown potential to harness solar energy in a cost-effective way. Significant efforts are underway to improve their efficiency to the level of practical applications. Here, we report highly efficient polymer solar cells based on a bulk heterojunction of polymer poly(3-hexylthiophene) and methanofullerene. Controlling the active layer growth rate results in an increased hole mobility and balanced charge transport. Together with increased absorption in the active layer, this results in much-improved device performance, particularly in external quantum efficiency. The power-conversion efficiency of 4.4% achieved here is the highest published so far for polymer-based solar cells. The solution process involved ensures that the fabrication cost remains low and the processing is simple. The high efficiency achieved in this work brings these devices one step closer to commercialization.
5,431 citations
TL;DR: In this article, the authors focus on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid and categorize the inverters into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single phase grid; 3) whether they utilizes a transformer (either line or high frequency) or not; and 4) the kind of grid-connected power stage.
Abstract: This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single-phase grid; 3) whether they utilizes a transformer (either line or high frequency) or not; and 4) the type of grid-connected power stage. Various inverter topologies are presented, compared, and evaluated against demands, lifetime, component ratings, and cost. Finally, some of the topologies are pointed out as the best candidates for either single PV module or multiple PV module applications.
3,530 citations
TL;DR: Developing solar cells that are based on the sensitization of mesoscopic oxide films by dyes or quantum dots, and the examples for the first outdoor application of such solar cells will be provided.
Abstract: The quality of human life depends to a large degree on the availability of energy. This is threatened unless renewable energy resources can be developed in the near future. Chemistry is expected to make important contributions to identify environmentally friendly solutions of the energy problem. One attractive strategy discussed in this Forum Article is the development of solar cells that are based on the sensitization of mesoscopic oxide films by dyes or quantum dots. These systems have already reached conversion efficiencies exceeding 11%. The underlying fundamental processes of light harvesting by the sensitizer, heterogeneous electron transfer from the electronically excited chromophore into the conduction band of the semiconductor oxide, and percolative migration of the injected electrons through the mesoporous film to the collector electrode will be described below in detail. A number of research topics will also be discussed, and the examples for the first outdoor application of such solar cells wi...
3,214 citations
TL;DR: In this article, the perturb and observe (PO) algorithm is used in photovoltaic (PV) systems to maximize the PV array output power by tracking continuously the maximum power point (MPP) which depends on panels temperature and on irradiance conditions.
Abstract: Maximum power point tracking (MPPT) techniques are used in photovoltaic (PV) systems to maximize the PV array output power by tracking continuously the maximum power point (MPP) which depends on panels temperature and on irradiance conditions. The issue of MPPT has been addressed in different ways in the literature but, especially for low-cost implementations, the perturb and observe (PO moreover, it is well known that the P&O algorithm can be confused during those time intervals characterized by rapidly changing atmospheric conditions. In this paper it is shown that, in order to limit the negative effects associated to the above drawbacks, the P&O MPPT parameters must be customized to the dynamic behavior of the specific converter adopted. A theoretical analysis allowing the optimal choice of such parameters is also carried out. Results of experimental measurements are in agreement with the predictions of theoretical analysis.
2,696 citations
TL;DR: An ultrathin donor-acceptor solar cell composed entirely of inorganic nanocrystals spin-cast from solution is introduced, elucidates a class of photovoltaic devices with potential for stable, low-cost power generation.
Abstract: We introduce an ultrathin donor-acceptor solar cell composed entirely of inorganic nanocrystals spin-cast from solution. These devices are stable in air, and post-fabrication processing allows for power conversion efficiencies approaching 3% in initial tests. This demonstration elucidates a class of photovoltaic devices with potential for stable, low-cost power generation.
1,701 citations
Patent•
06 Jun 2005
TL;DR: In this paper, an energy control unit includes one or more algorithms for scheduling the control of energy consumption devices on the basis of variables relating to forecast energy supply and demand, such as battery storage and alternative energy sources (e.g., photovoltaic cells).
Abstract: Methods and systems are provided for optimizing the control of energy supply and demand. An energy control unit includes one or more algorithms for scheduling the control of energy consumption devices on the basis of variables relating to forecast energy supply and demand. Devices for which energy consumption can be scheduled or deferred are activated during periods of cheapest energy usage. Battery storage and alternative energy sources (e.g., photovoltaic cells) are activated to sell energy to the power grid during periods that are determined to correspond to favorable cost conditions.
726 citations
TL;DR: In this paper, the authors present an overview of various cooling methods that can be employed for photovoltaic cells, including linear concentrators, single-cell arrangements, and densely packed photovolastic cells.
678 citations
TL;DR: In this paper, the authors present an overview of an Environmental Impact Assessment of solar energy systems and assess the potential environmental intrusions in order to ameliorate them with new technological innovations and good practices in the future power systems.
669 citations
TL;DR: In this article, the authors describe the motivation for pursuing research in this field and provide an overview of the various technical approaches that have been developed to date, and discuss the challenges that need to be overcome in order for organic photovoltaics to realize their potential as an economically viable path to harvesting energy from sunlight.
Abstract: Harvesting energy directly from sunlight using photovoltaic technology is a way to address growing global energy needs with a renewable resource while minimizing detrimental effects on the environment by reducing atmospheric emissions. This issue of MRS Bulletin on “Organic-Based Photovoltaics” looks at a new generation of solar cells that have the potential to be produced inexpensively. Recent advances in solar power conversion efficiencies have propelled organic-based photovoltaics out of the realm of strictly fundamental research at the university level and into the industrial laboratory setting. Fabricated from organic materials—polymers and molecules—these devices are potentially easier to manufacture than current technologies based on silicon or other materials. In this introductory article, we describe the motivation for pursuing research in this field and provide an overview of the various technical approaches that have been developed to date. We conclude by discussing the challenges that need to be overcome in order for organic photovoltaics to realize their potential as an economically viable path to harvesting energy from sunlight.
564 citations
523 citations
TL;DR: A PV-Diesel system optimised by HOGA is compared with a stand-alone PV-only system that has been dimensioned using a classical design method based on the available energy under worst-case conditions, where the demand and the solar irradiation are the same.
TL;DR: In this article, a comprehensive supervisor controller for a hybrid system that comprises wind and photovoltaic generation subsystems, a battery bank, and an ac load is developed, which aims to satisfy the load power demand and maintain the state of charge of the battery bank to prevent blackout and to extend the life of the batteries.
Abstract: A comprehensive supervisor control for a hybrid system that comprises wind and photovoltaic generation subsystems, a battery bank, and an ac load is developed in this paper. The objectives of the supervisor control are, primarily, to satisfy the load power demand and, second, to maintain the state of charge of the battery bank to prevent blackout and to extend the life of the batteries. For these purposes, the supervisor controller determines online the operation mode of both generation subsystems, switching from power regulation to maximum power conversion. Decision criteria for the supervisor based on measurable system variables are presented. Finally, the performance of the supervisor controller is extensively assessed through computer simulation using a comprehensive nonlinear model of the plant.
TL;DR: In this paper, the performance of a parabolic trough photovoltaic/thermal collector with a geometric concentration ratio of 37× is described and the impact of non-uniform illumination on the solar cells is investigated using purpose built equipment that moves a calibrated solar cell along the line of the receiver and measures short circuit current.
08 Aug 2005
TL;DR: The use of appropriate performance parameters facilitates the comparison of grid-connected photovoltaic (PV) systems that may differ with respect to design, technology, or geographic location as mentioned in this paper.
Abstract: The use of appropriate performance parameters facilitates the comparison of grid-connected photovoltaic (PV) systems that may differ with respect to design, technology, or geographic location. Four performance parameters that define the overall system performance with respect to the energy production, solar resource, and overall effect of system losses are the following: final PV system yield, reference yield, performance ratio, and PVUSA rating. These performance parameters are discussed for their suitability in providing desired information for PV system design and performance evaluation and are demonstrated for a variety of technologies, designs, and geographic locations. Also discussed are methodologies for determining system a.c. power ratings in the design phase using multipliers developed from measured performance parameters.
TL;DR: A solar updraft tower power plant is a solar thermal power plant utilizing a combination of solar air collector and central updraft tube to generate a solar induced convective flow which drives pressure staged turbines to generate electricity as mentioned in this paper.
Abstract: A solar updraft tower power plant-sometimes also called solar chimney, or just solar tower-is a solar thermal power plant utilizing a combination of solar air collector and central updraft tube to generate a solar induced convective flow which drives pressure staged turbines to generate electricity The paper presents theory, practical experience, and economy of solar updraft towers: First a simplified theory of the solar tower is described Then results from designing, building and operating a small scale prototype in Spain are presented Eventually technical issues and basic economic data for future commercial solar tower systems like the one being planned for Australia are discussed
TL;DR: The paper shows that the application of this novel sensorless current flyback inverter to an MPPT-operated PV system exhibits satisfactory MPPT performance similar to the one exhibited by the system with a dc current sensor as well.
Abstract: This paper presents a flyback inverter controlled by sensorless current maximum power point tracking (MPPT) for a small photovoltaic (PV) power system. Although the proposed system has small output power such as 300 W, a few sets of small PV power systems can be easily connected in parallel to yield higher output power. When a PV power system is constructed with a number of small power systems, the total system cost will increase and will be a matter of concern. To overcome this difficulty, this paper proposes a PV system that uses no expensive dc current sensor but utilizes the method of estimating the PV current from the PV voltage. The paper shows that the application of this novel sensorless current flyback inverter to an MPPT-operated PV system exhibits satisfactory MPPT performance similar to the one exhibited by the system with a dc current sensor as well. This paper also deals with the design method and the operation of the unique flyback inverter with center-tapped secondary winding.
29 Mar 2005
TL;DR: In this paper, the authors present a review of the history of organic photovoltaic materials and devices, and discuss the current state of the art in the field of solar cells.
Abstract: Foreword 1 Alan J. Heeger, Nobel Laureate, University of California at Santa Barbara Foreword 2 Aloysius F. Hepp and Sheila G. Bailey, Photovoltaic and Space Environments Branch, NASA Glenn Research Center Preface Acknowledgements Editors Contributors General Overviews The Story of Solar Cells J. Perlin Inorganic Photovoltaic Materials and Devices: Past, Present, and Future A.F. Hepp, S.G. Bailey, and R.P. Raffaelle Natural Organic Photosynthetic Solar Energy Transduction R.E. Blankenship Solid-State Organic Photovoltaics: A Review of Molecular and Polymeric Devices P.A. Lane and Z.H. Kafafi Mechanisms and Modeling Simulations of Optical Processes in Organic Photovoltaic Devices N-K. Persson and O. Inganas Coulomb Forces in Excitonic Solar Cells B.A. Gregg Electronic Structure of Organic Photovoltaic Materials: Modeling of Exciton-Dissociation and Charge-Recombination Processes J. Cornil, V. Lemaur, M.C. Steel, H. Dupin, A. Burquel, D. Beljonne, and J-L. Bredas Optimization of Organic Solar Cells in Both Space and Energy-Time Domains S-S. Sun and C.E. Bonner Materials and Devices Bulk Heterojunction Solar Cells H. Hoppe and N.S. Sariciftci Organic Solar Cells Incorporating a p-i-n Junction and a p-n Homojunction M. Hiramoto Liquid-Crystal Approaches to Organic Photovoltaics B. Kippelen, S. Yoo, J.A. Haddock, B. Domercq, S. Barlow, B. Minch, W. Xia, S.R. Marder, and N.R. Armstrong Photovoltaic Cells Based on Nanoporous Titania Films Filled with Conjugated Polymers K.M. Coakley and M.D. McGehee Solar Cells Based on Cyanine and Polymethine Dyes H. Tian and F. Meng Semiconductor Quantum Dot Based Nanocomposite Solar Cells M.H. Wu, A. Ueda, and R. Mu Solar Cells Based on Composites of Donor Conjugated Polymers and Carbon Nanotubes E. Kymakis and G.A.J. Amaratunga Photovoltaic Devices Based on Polythiophene/C60 L.S. Roman Alternating Fluorene Copolymer-Fullerene Blend Solar Cells O. Inganas, F. Zhang, X. Wang, A. Gadisa, N-K. Persson, M. Svensson, E. Perzon, W. Mammo, and M.R. Andersson Solar Cells Based on Diblock Copolymers: A PPV Donor Block and a Fullerene Derivatized Acceptor Block R.A. Segalman, C. Brochon, and G. Hadziioannou Interface Electronic Structure and Organic Photovoltaic Devices Y. Gao The Influence of the Electrode Choice on the Performance of Organic Solar Cells A.B. Djurisic' and C.Y. Kwong Conducting and Transparent Polymer Electrodes F. Zhang and O. Inganas Progress in Optically Transparent Conducting Polymers V. Seshadri and G.A. Sotzing Optoelectronic Properties of Conjugated Polymer/Fullerene Binary Pairs with Variety of LUMO Level Differences S. Sensfuss and M. Al-Ibrahim Polymer-Fullerene Concentration Gradient Photovoltaic Devices by Thermally Controlled Interdiffusion M. Drees, R.M. Davis, and R. Heflin Vertically Aligned Carbon Nanotubes for Organic Photovoltaic Devices M.H-C. Jin and L. Dai Index
01 Jan 2005
TL;DR: In this article, a complete control structure for the single-phase photovoltaic (PV) system is presented, where the main elements of the PV control structure are: - a maximum power point tracker (MPPT) algorithm using the incremental conductance method; - a synchronization method using the phase-locked-loop (PLL), based on delay; the input power control using the dc voltage controller and power feed-forward; - and the grid current controller implemented in two different ways, using the classical proportional integral (PI) and the novel proportional resonant (
Abstract: In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented. The main elements of the PV control structure are: - a maximum power point tracker (MPPT) algorithm using the incremental conductance method; - a synchronization method using the phase-locked-loop (PLL), based on delay; the input power control using the dc voltage controller and power feed-forward; - and the grid current controller implemented in two different ways, using the classical proportional integral (PI) and the novel proportional resonant (PR) controllers. The control strategy was tested experimentally on 1.5 kW PV inverter
TL;DR: In this article, the technical performance and energy requirements for production and transportation of a stand-alone photovoltaic (PV)-battery system at different operating conditions are presented.
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01 Jan 2005
TL;DR: In this paper, the authors discuss the future of photovoltaics and other CO2-free energy sources, including wind, solar, and bio-diesel technologies.
Abstract: What Is Photovoltaics?.- Physics of Solar Cells.- Silicon Solar Cell Material and Technology.- Crystalline Thin-Film Silicon.- Other Materials, New Concepts, and Future Developments.- Solar Cells and Solar Modules.- PV Systems.- PV Systems: Installation Possibilities.- Environmental Impacts by PV Systems.- Efficiency and Performance of PV Systems.- PV Markets Support Measures and Costs.- The Future of PV.- Other (Perhaps Competing) CO2-Free Energy Sources.- Popular Killing Arguments Against PV and Why They Are Not Valid.
TL;DR: In this paper, a high-boiling-point solvent, 1,2,4-trichlorobenzene, instead of chloroform for spin-coating, was used to obtain a threefold increase in solar power conversion efficiency in devices based on CdSe tetrapods and poly(p-phenylenvinylene) derivative OC1C10-PPV.
Abstract: Solution-processed photovoltaic devices based on blends of conjugated polymers and inorganic semiconductor tetrapods show high efficiencies due to the good electron transport perpendicular to the plane of the film. Here, we show that by using a high-boiling-point solvent, 1,2,4-trichlorobenzene, instead of chloroform for spin-coating, we can typically obtain a threefold increase in solar power conversion efficiency in devices based on CdSe tetrapods and the poly(p-phenylenvinylene) derivative OC1C10-PPV. The optimized devices show AM1.5 solar power conversion efficiencies of typically 2.1% with some devices as high as 2.8%. The results can be explained by the occurrence of vertical phase separation which leads to an optimal structure for charge collection. Evidence for this structure is obtained by environmental scanning electron microscopy, photocurrent action spectra measurements, time-resolved photoluminescence, and spectroscopic measurements of exciton dissociation and charge-carrier recombination.
TL;DR: In this paper, the authors present a solar radiation database of Europe developed in the geographical information system, and three interactive web applications providing an access to it, including monthly and yearly average values of the global irradiation on horizontal and inclined surfaces, as well as climatic parameters needed for assessing the potential PV electricity generation.
Abstract: Solar radiation is a key factor determining electricity produced by photovoltaic (PV) systems. This paper presents a solar radiation database of Europe developed in the geographical information system, and three interactive web applications providing an access to it. The database includes monthly and yearly average values of the global irradiation on horizontal and inclined surfaces, as well as climatic parameters needed for an assessment of the potential PV electricity generation (Linke atmospheric turbidity, the ratio of diffuse to global irradiation, an optimum inclination angle of modules to maximize energy yield). In the first web application, a user may browse radiation maps and query irradiation incident on a PV module for different inclination angles. The second application simulates daily profiles of irradiance for a chosen month and module inclination and orientation. The third web application estimates electricity generation for a chosen PV configuration. It also calculates optimal inclination ...
TL;DR: In this article, the authors describe the digital implementation of a PV-inverter with different advanced, robust control strategies and an embedded online technique to determine the utility grid impedance by injecting an interharmonic current and measuring the voltage response it is possible to estimate the grid impedance at the fundamental frequency.
Abstract: The steady increase in photovoltaic (PV) installations calls for new and better control methods in respect to the utility grid connection Limiting the harmonic distortion is essential to the power quality, but other requirements also contribute to a more safe grid-operation, especially in dispersed power generation networks For instance, the knowledge of the utility impedance at the fundamental frequency can be used to detect a utility failure A PV-inverter with this feature can anticipate a possible network problem and decouple it in time This paper describes the digital implementation of a PV-inverter with different advanced, robust control strategies and an embedded online technique to determine the utility grid impedance By injecting an interharmonic current and measuring the voltage response it is possible to estimate the grid impedance at the fundamental frequency The presented technique, which is implemented with the existing sensors and the CPU of the PV-inverter, provides a fast and low cost approach for online impedance measurement, which may be used for detection of islanding operation Practical tests on an existing PV-inverter validate the control methods, the impedance measurement, and the islanding detection
TL;DR: In this article, a short-term scheduling of battery in security-constrained unit commitment (SCUC) is presented, where the authors apply a Lagrangian relaxation-based optimization algorithm to determine the hourly charge/discharge commitment of battery and apply a network flow programming algorithm for the dispatch of committed battery units.
Abstract: We present in this paper a short-term scheduling of battery in security-constrained unit commitment (SCUC). For economical operation and control purposes, electric power users with photovoltaic (PV)/battery systems are interested in the availability and the dispatch of PV/battery power on an hourly basis, which is a cumbersome task due to the complicated operating patterns of PV/battery. The details of battery model in the PV/battery system are presented in this paper. The paper applies a Lagrangian relaxation-based optimization algorithm to determine the hourly charge/discharge commitment of battery in a utility grid. The paper also applies a network flow programming algorithm for the dispatch of committed battery units. The paper analyzes the impact of grid-connected PV/battery system on locational pricing, peak load shaving, and transmission congestion management. An eight-bus test system is used to study the operational pattern of aggregated PV/battery and demonstrate the advantages of utilizing PV/battery systems in the electric utility operation.
04 Mar 2005
TL;DR: In this article, the maximum power point tracker output voltage and current are used for control purposes, rather than for its input voltage or current, and it is shown that using the output parameters simplifies the MPPT controller.
Abstract: A new approach for tracking the maximum power point of photovoltaic arrays is presented. The maximum power point tracker output voltage and current are used for control purposes, rather than for its input voltage and current. It is shown that using the output parameters simplifies the maximum power point tracker controller. Moreover, using this approach, only one out of the two output parameters needs to be sensed. This observation is general and applies regardless of the power stage or the realisation control algorithm. Contrary to what might have previously been assumed, it is theoretically shown that the MPPT control that uses a single output control parameter applies to nearly all practical load types, regardless of the load nature.
TL;DR: In this paper, a PC-based maximum power point tracker (MPPT) for PV system using neural networks (NN) was developed and implemented, where the control action gives the driving signals to the MPPT.
DOI•
01 Jan 2005TL;DR: In this article, a three-point weight comparison method was proposed to avoid the oscillation problem of the perturbation and observation algorithm which is often employed to track the maximum power point.
Abstract: The electric power supplied by a photovoltaic power generation system depends on the solar radiation and temperature. Designing efficient PV systems heavily emphasizes to track the maximum power operating point. This work develops a novel three-point weight comparison method that avoids the oscillation problem of the perturbation and observation algorithm which is often employed to track the maximum power point. Furthermore, a low cost control unit is developed, based on a single chip to adjust the output voltage of the solar cell array. Finally, experimental results confirm the superior performance of the proposed method.
TL;DR: In this article, an economic analysis and environmental impacts of integrating a photovoltaic (PV) array into diesel-electric power systems for remote villages were discussed, where MATLAB Simulink is used to match the load with the demand and apportion the electrical production between the PV and diesel generator, and the simulation results were utilized to calculate the energy payback, the simple payback time for the PV module, and avoided costs of CO/sub 2/, NO/sub x/, and PM.
Abstract: This paper discusses the economic analysis and environmental impacts of integrating a photovoltaic (PV) array into diesel-electric power systems for remote villages. MATLAB Simulink is used to match the load with the demand and apportion the electrical production between the PV and diesel-electric generator. The economic part of the model calculates the fuel consumed, the kilowatthours obtained per gallon of fuel supplied, and the total cost of fuel. The environmental part of the model calculates the CO/sub 2/, particulate matter (PM), and the NO/sub x/ emitted to the atmosphere. Simulations based on an actual system in the remote Alaskan community of Lime Village were performed for three cases: 1) diesel only; 2) diesel-battery; and 3) PV with diesel-battery using a one-year time period. The simulation results were utilized to calculate the energy payback, the simple payback time for the PV module, and the avoided costs of CO/sub 2/, NO/sub x/, and PM. Post-simulation analysis includes the comparison of results with those predicted by Hybrid Optimization Model for Electric Renewables (HOMER). The life-cycle cost (LCC) and air emissions results of our Simulink model were comparable to those predicted by HOMER.
Book•
15 Jul 2005TL;DR: The search for clean, renewable energy sources has yielded enormous growth and new developments in these technologies in a few short years, driving down costs and encouraging utilities in many nations, both developed and developing, to add and expand wind and solar power capacity.
Abstract: The search for clean, renewable energy sources has yielded enormous growth and new developments in these technologies in a few short years, driving down costs and encouraging utilities in many nations, both developed and developing, to add and expand wind and solar power capacity. The first, best-selling edition of Wind and Solar Power Systems prov