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Showing papers on "Photovoltaic system published in 2009"


Journal ArticleDOI
TL;DR: In this article, the authors proposed a method of modeling and simulation of photovoltaic arrays by adjusting the curve at three points: open circuit, maximum power, and short circuit.
Abstract: This paper proposes a method of modeling and simulation of photovoltaic arrays. The main objective is to find the parameters of the nonlinear I-V equation by adjusting the curve at three points: open circuit, maximum power, and short circuit. Given these three points, which are provided by all commercial array data sheets, the method finds the best I-V equation for the single-diode photovoltaic (PV) model including the effect of the series and parallel resistances, and warranties that the maximum power of the model matches with the maximum power of the real array. With the parameters of the adjusted I-V equation, one can build a PV circuit model with any circuit simulator by using basic math blocks. The modeling method and the proposed circuit model are useful for power electronics designers who need a simple, fast, accurate, and easy-to-use modeling method for using in simulations of PV systems. In the first pages, the reader will find a tutorial on PV devices and will understand the parameters that compose the single-diode PV model. The modeling method is then introduced and presented in details. The model is validated with experimental data of commercial PV arrays.

3,811 citations


Journal ArticleDOI
TL;DR: An outlook is presented on what will be required to drive this young photovoltaic technology towards the next major milestone, a 10% power conversion efficiency, considered by many to represent the efficiency at which OPV can be adopted in wide-spread applications.
Abstract: Solution-processed bulk-heterojunction solar cells have gained serious attention during the last few years and are becoming established as one of the future photovoltaic technologies for low-cost power production. This article reviews the highlights of the last few years, and summarizes today's state-of-the-art performance. An outlook is given on relevant future materials and technologies that have the potential to guide this young photovoltaic technology towards the magic 10% regime. A cost model supplements the technical discussions, with practical aspects any photovoltaic technology needs to fulfil, and answers to the question as to whether low module costs can compensate lower lifetimes and performances.

3,084 citations


Journal ArticleDOI
TL;DR: In this article, the open-circuit voltage of polymer solar cells constructed based on the structure of a low-bandgap polymer, PBDTTT, can be tuned, step by step, using different functional groups.
Abstract: Following the development of the bulk heterojunction1 structure, recent years have seen a dramatic improvement in the efficiency of polymer solar cells. Maximizing the open-circuit voltage in a low-bandgap polymer is one of the critical factors towards enabling high-efficiency solar cells. Study of the relation between open-circuit voltage and the energy levels of the donor/acceptor2 in bulk heterojunction polymer solar cells has stimulated interest in modifying the open-circuit voltage by tuning the energy levels of polymers3. Here, we show that the open-circuit voltage of polymer solar cells constructed based on the structure of a low-bandgap polymer, PBDTTT4, can be tuned, step by step, using different functional groups, to achieve values as high as 0.76 V. This increased open-circuit voltage combined with a high short-circuit current density results in a polymer solar cell with a power conversion efficiency as high as 6.77%, as certified by the National Renewable Energy Laboratory. Adding electron-withdrawing groups to the backbone of the polymer PBDTTT is shown to increase the open-circuit voltage of photovoltaic cells, resulting in a polymer solar-cell that has a certified power-conversion efficiency of 6.77%.

3,029 citations


Journal ArticleDOI
TL;DR: Recent advances in molecular design and technological aspects of metal-free organic dyes for applications in dye-sensitized solar cells are focused on.
Abstract: Dye-sensitized solar cells (DSSC) have attracted considerable attention in recent years as they offer the possibility of low-cost conversion of photovoltaic energy This Review focuses on recent advances in molecular design and technological aspects of metal-free organic dyes for applications in dye-sensitized solar cells Special attention has been paid to the design principles of these dyes and on the effect of various electrolyte systems Cosensitization, an emerging technique to extend the absorption range, is also discussed as a way to improve the performance of the device In addition, we report on inverted dyes for photocathodes, which constitutes a relatively new approach for the production of tandem cells Special consideration has been paid to the correlation between the molecular structure and physical properties to their performance in DSSCs

2,549 citations


Journal ArticleDOI
TL;DR: In this article, a brief discussion is presented regarding the operating temperature of one-sun commercial grade silicon-based solar cells/modules and its effect upon the electrical performance of photovoltaic installations.

1,914 citations


Journal ArticleDOI
Yongye Liang1, Danqin Feng1, Yue Wu1, Szu Ting Tsai1, Gang Li1, Claire Ray1, Luping Yu1 
TL;DR: It was found that films with finely distributed polymer/fulleride interpenetrating network exhibited improved solar cell conversion efficiency, and the results proved that polymer solar cells have a bright future.
Abstract: This paper describes synthesis and photovoltaic studies of a series of new semiconducting polymers with alternating thieno[3,4-b]thiophene and benzodithiophene units. The physical properties of these polymers were finely tuned to optimize their photovoltaic effect. The substitution of alkoxy side chains to the less electron-donating alkyl chains or introduction of electron-withdrawing fluorine into the polymer backbone reduced the HOMO energy levels of polymers. The structural modifications optimized polymers’ spectral coverage of absorption and their hole mobility, as well as miscibility with fulleride, and enhanced polymer solar cell performances. The open circuit voltage, Voc, for polymer solar cells was increased by adjusting polymer energy levels. It was found that films with finely distributed polymer/fulleride interpenetrating network exhibited improved solar cell conversion efficiency. Efficiency over 6% has been achieved in simple solar cells based on fluorinated PTB4/PC61BM films prepared from m...

1,366 citations


Journal ArticleDOI
TL;DR: It is demonstrated that charge-transfer absorption and emission are shown to be related to each other and Voc is determined by the formation of these states in accordance with the assumptions of the detailed balance and quasi-equilibrium theory.
Abstract: The increasing amount of research on solution-processable, organic donor-acceptor bulk heterojunction photovoltaic systems, based on blends of conjugated polymers and fullerenes has resulted in devices with an overall power-conversion efficiency of 6%. For the best devices, absorbed photon-to-electron quantum efficiencies approaching 100% have been shown. Besides the produced current, the overall efficiency depends critically on the generated photovoltage. Therefore, understanding and optimization of the open-circuit voltage (Voc) of organic solar cells is of high importance. Here, we demonstrate that charge-transfer absorption and emission are shown to be related to each other and Voc in accordance with the assumptions of the detailed balance and quasi-equilibrium theory. We underline the importance of the weak ground-state interaction between the polymer and the fullerene and we confirm that Voc is determined by the formation of these states. Our work further suggests alternative pathways to improve Voc of donor-acceptor devices.

1,121 citations


Journal ArticleDOI
TL;DR: The direct growth of highly regular, single-crystalline nanopillar arrays of optically active semiconductors on aluminium substrates that are then configured as solar-cell modules for enabling highly versatile solar modules on both rigid and flexible substrates with enhanced carrier collection efficiency arising from the geometric configuration of the nanopillars.
Abstract: Solar energy represents one of the most abundant and yet least harvested sources of renewable energy. In recent years, tremendous progress has been made in developing photovoltaics that can be potentially mass deployed. Of particular interest to cost-effective solar cells is to use novel device structures and materials processing for enabling acceptable efficiencies. In this regard, here, we report the direct growth of highly regular, single-crystalline nanopillar arrays of optically active semiconductors on aluminium substrates that are then configured as solar-cell modules. As an example, we demonstrate a photovoltaic structure that incorporates three-dimensional, single-crystalline n-CdS nanopillars, embedded in polycrystalline thin films of p-CdTe, to enable high absorption of light and efficient collection of the carriers. Through experiments and modelling, we demonstrate the potency of this approach for enabling highly versatile solar modules on both rigid and flexible substrates with enhanced carrier collection efficiency arising from the geometric configuration of the nanopillars.

1,061 citations


Journal ArticleDOI
TL;DR: The approach to two problems in solar water splitting are described: the organization of molecules into assemblies that promote long-lived charge separation, and catalysis of the electrolysis reactions, in particular the four-electron oxidation of water.
Abstract: Researchers are intensively investigating photochemical water splitting as a means of converting solar to chemical energy in the form of fuels. Hydrogen is a key solar fuel because it can be used directly in combustion engines or fuel cells, or combined catalytically with CO2 to make carbon containing fuels. Different approaches to solar water splitting include semiconductor particles as photocatalysts and photoelectrodes, molecular donor-acceptor systems linked to catalysts for hydrogen and oxygen evolution, and photovoltaic cells coupled directly or indirectly to electrocatalysts. Despite several decades of research, solar hydrogen generation is efficient only in systems that use expensive photovoltaic cells to power water electrolysis. Direct photocatalytic water splitting is a challenging problem because the reaction is thermodynamically uphill. Light absorption results in the formation of energetic charge-separated states in both molecular donor−acceptor systems and semiconductor particles. Unfortuna...

930 citations


Journal ArticleDOI
TL;DR: In this article, the authors used a two-dimensional, periodic array of Ag strips on a silica-coated Si film supported by a silicon substrate to achieve a 43% enhancement in the short circuit current as compared to a cell without metallic structures.
Abstract: Basic design rules are developed for the use of metallic nanostructures to realize broadband absorption enhancements in thin-film solar cells. They are applied to a relevant and physically intuitive model system consisting of a two-dimensional, periodic array of Ag strips on a silica-coated Si film supported by a silica substrate. We illustrate how one can simultaneously take advantage of 1) the high near-fields surrounding the nanostructures close to their surface plasmon resonance frequency and 2) the effective coupling to waveguide modes supported by the thin Si film through an optimization of the array properties. Following this approach, we can attain a 43% enhancement in the short circuit current as compared to a cell without metallic structures. It is suggested that 3-dimensional nanoparticle arrays with even larger boosts in short circuit current can also be generated using the presented framework. Photovoltaic (PV) cells can provide virtually unlimited amounts of energy by effectively converting sunlight into clean electrical power. Silicon has been the material of choice for PV cells due to low cost, earth abundance, non-toxicity, and the availability of a very mature processing technology. The cost of current PV modules still needs to be significantly reduced and efficiency substantially increased to enable large scale implementation. Thin-film, second-generation Si solar cells may provide a viable pathway towards this goal because of their low materials and processing costs. Unfortunately the materials quality and resulting energy conversion efficiencies of such cells are still substantially lower than crystalline, wafer-based cells. This is a direct result of the large mismatch between electronic and photonic length scales in these devices; the absorption depth of light in Si is significantly longer than the electronic (minority carrier) diffusion length in deposited thin-film materials for photon energies close to the band-gap. As a result, charge extraction from optically thick cells is challenging due to carrier recombination in the bulk of the semiconductor. If light absorption could be improved in ultra-thin layers of active material it would lead directly to lower recombination currents, higher open circuit voltages, and higher conversion efficiencies. Conventional, planar anti-reflection (AR) coatings do not provide high transmission efficiencies over the entire solar spectrum and do not enable effective light trapping to increase absorption. Light trapping schemes using diffusely scattering surface textures were first suggested in the 1980s and are by now fairly-well understood. Texturing surfaces of thin film cells is not ideal as it leads to enhanced surface recombination. For this reason, some interesting alternative trapping configurations have been proposed that utilize structuring at length-scales orders of magnitude larger than the cell thickness. More than a decade ago, it was first proposed to use the unique optical properties of metallic (i.e., plasmonic) structures to boost the efficiency of PV cells; those metallic nanostructures exhibit easily accessible collective electron oscillations known as surface plasmons. Surface plasmon excitations enable unparalleled light concentration and trapping. Since these pioneering efforts, plasmonics has also been used to enable new photodetector designs that exploit lateral and in-depth light concentration to increase their signal-to-noise ratio and speed in the visible, near-IR, and mid-IR wavelength ranges. Recently, the use of metallic nanostructures for PV has received renewed attention with the availability of new nanofabrication tools and the growing understanding of their optical properties provided by the burgeoning field of plasmonics. In different cell designs both near-field light concentration close to the individual particle resonance and effective light trapping by nanometallics have been explored. Experimentally, high peak enhancements in the tens of percent range at specific wavelengths and overall efficiency enhancements of 40%, 8.3%, and 8% have been achieved with the use of plasmonic structures for cells employing organics, a-Si, and GaAs, respectively. Separate efforts have focused on increasing the more omni-directional absorption characteristics for solar tracking and operation in diffuse sunlight. These results are very promising, although no detailed comparisons have yet been made to cells employing alternative light trapping technologies. Moreover, there is a clear need for effective optimization strategies that lead to broadband absorption enhancements over the entire solar spectrum. This type of optimization for nanostructured solar cells is now within the realm of possibilities; the recent advances in full-field electromagnetic simulations and computer hardware have resulted in the development of extremely accurate and robust optimization tools that are now commonly used by the PV community. In this paper, we illustrate a straightforward and physically intuitive procedure to optimize the net overall absorption of a thin-film Si solar cell over the entire solar spectrum; this simultaneously takes advantage of 1) the high near-fields surrounding the nanostructures close to their surface plasmon C O M M U N IC A TI O N www.advmat.de

844 citations


Journal ArticleDOI
TL;DR: In this article, different types of sun tracking systems are reviewed and their pros and cons are discussed and the most efficient and popular sun tracking device was found to be in the form of polar-axis and azimuth/elevation types.
Abstract: Finding energy sources to satisfy the world's growing demand is one of society's foremost challenges for the next half-century. The challenge in converting sunlight to electricity via photovoltaic solar cells is dramatically reducing $/watt of delivered solar electricity. In this context the sun trackers are such devices for efficiency improvement. The diurnal and seasonal movement of earth affects the radiation intensity on the solar systems. Sun-trackers move the solar systems to compensate for these motions, keeping the best orientation relative to the sun. Although using sun-tracker is not essential, its use can boost the collected energy 10–100% in different periods of time and geographical conditions. However, it is not recommended to use tracking system for small solar panels because of high energy losses in the driving systems. It is found that the power consumption by tracking device is 2–3% of the increased energy. In this paper different types of sun-tracking systems are reviewed and their cons and pros are discussed. The most efficient and popular sun-tracking device was found to be in the form of polar-axis and azimuth/elevation types.

Journal ArticleDOI
TL;DR: The strategies for depositing CdSe quantum dots on nanostructured mesoporous TiO(2) electrodes are summarized and the methods that facilitate improvement in the performance and stability of QDSCs are discussed.
Abstract: Quantum dot sensitized solar cells (QDSCs) have attracted significant attention as promising third-generation photovoltaic devices. In the form of quantum dots (QDs), the semiconductor sensitizers have very useful and often tunable properties; moreover, their theoretical thermodynamic efficiency might be as high as 44%, better than the original 31% calculated ceiling. Unfortunately, the practical performance of these devices still lags behind that of dye-sensitized solar cells. In this Account, we summarize the strategies for depositing CdSe quantum dots on nanostructured mesoporous TiO2 electrodes and discuss the methods that facilitate improvement in the performance and stability of QDSCs. One particularly significant factor for solar cells that use polysulfide electrolyte as the redox couple, which provides the best performance among QDSCs, is the passivation of the photoanode surface with a ZnS coating, which leads to a dramatic increase of photocurrents and efficiencies. However, these solar cells us...

Journal ArticleDOI
TL;DR: This paper presents a single-phase cascaded H-bridge converter for a grid-connected photovoltaic (PV) application that offers other advantages such as the operation at lower switching frequency or lower current ripple compared to standard two-level topologies.
Abstract: This paper presents a single-phase cascaded H-bridge converter for a grid-connected photovoltaic (PV) application The multilevel topology consists of several H-bridge cells connected in series, each one connected to a string of PV modules The adopted control scheme permits the independent control of each dc-link voltage, enabling, in this way, the tracking of the maximum power point for each string of PV panels Additionally, low-ripple sinusoidal-current waveforms are generated with almost unity power factor The topology offers other advantages such as the operation at lower switching frequency or lower current ripple compared to standard two-level topologies Simulation and experimental results are presented for different operating conditions

Journal ArticleDOI
TL;DR: New synthetic methods and the application of starburst triarylamines are described, highlighting the applications in photovoltaic and optoelectrical fields.

Proceedings ArticleDOI
04 Dec 2009
TL;DR: An easy and accurate method of modeling photovoltaic arrays using information from the datasheet is presented and the model is validated with experimental data.
Abstract: This paper presents an easy and accurate method of modeling photovoltaic arrays. The method is used to obtain the parameters of the array model using information from the datasheet. The photovoltaic array model can be simulated with any circuit simulator. The equations of the model are presented in details and the model is validated with experimental data. Finally, simulation examples are presented. This paper is useful for power electronics designers and researchers who need an effective and straightforward way to model and simulate photovoltaic arrays.

Journal ArticleDOI
TL;DR: Results show that soluble molecular donors can lead to BHJ cells that combine high conversion efficiency with the distinct advantages of working with single molecules, including structural definition, synthesis, purification, and reproducibility.
Abstract: The predicted exhaustion of fossil energy resources and the pressure of environmental constraints are stimulating an intensification of research on renewable energy sources, in particular, on the photovoltaic conversion of solar energy. In this context, organic solar cells are attracting increasing interest that is motivated by the possibility of fabricating large-area, lightweight, and flexible devices using simple techniques with low environmental impact. Organic solar cells are based on a heterojunction resulting from the contact of a donor (D) and an acceptor (A) material. Absorption of solar photons creates excitons, Coulombically bound electron−hole pairs, which diffuse to the D/A interface, where they are dissociated into free holes and electrons by the electric field. D/A heterojunctions can be created with two types of architectures, namely, bilayer heterojunction and bulk heterojunction (BHJ) solar cells. BHJ cells combine the advantages of easier fabrication and higher conversion efficiency due...

Journal ArticleDOI
TL;DR: This communication demonstrates the colloidal synthesis of CZTS nanocrystals and their use in fabricating prototype solar cells with a power conversion efficiency of 0.23% under AM 1.5 illumination.
Abstract: Cu2ZnSnS4 (CZTS) is a promising new material for thin-film solar cells. Nanocrystal dispersions, or solar paints, present an opportunity to significantly reduce the production cost of photovoltaic devices. This communication demonstrates the colloidal synthesis of CZTS nanocrystals and their use in fabricating prototype solar cells with a power conversion efficiency of 0.23% under AM 1.5 illumination.

Journal ArticleDOI
TL;DR: An approach to predict regional PV power output based on forecasts up to three days ahead provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) and an approach to derive weather specific prediction intervals for irradiance forecasts are presented.
Abstract: The contribution of power production by photovoltaic (PV) systems to the electricity supply is constantly increasing. An efficient use of the fluctuating solar power production will highly benefit from forecast information on the expected power production. This forecast information is necessary for the management of the electricity grids and for solar energy trading. This paper presents an approach to predict regional PV power output based on forecasts up to three days ahead provided by the European Centre for Medium-Range Weather Forecasts (ECMWF). Focus of the paper is the description and evaluation of the approach of irradiance forecasting, which is the basis for PV power prediction. One day-ahead irradiance forecasts for single stations in Germany show a rRMSE of 36%. For regional forecasts, forecast accuracy is increasing in dependency on the size of the region. For the complete area of Germany, the rRMSE amounts to 13%. Besides the forecast accuracy, also the specification of the forecast uncertainty is an important issue for an effective application. We present and evaluate an approach to derive weather specific prediction intervals for irradiance forecasts. The accuracy of PV power prediction is investigated in a case study.

Journal ArticleDOI
TL;DR: In this article, an optimal design model for designing hybrid solar-wind systems employing battery banks for calculating the system optimum configurations and ensuring that the annualized cost of the systems is minimized while satisfying the custom required loss of power supply probability (LPSP).

Journal ArticleDOI
TL;DR: In this paper, a two-stage method is proposed to forecast hourly values of solar power for horizons of up to 36 h. The results indicate that for forecasts up to 2 hours ahead, the most important input is the available observations of PV power, while for longer horizons numerical weather predictions (NWPs) are the more important input.

Journal ArticleDOI
TL;DR: It is demonstrated how properly controlling the "nanomorphology", which is critically dependent on minute experimental details at every step, provides a clear path to >10% PCE BHJ cells, which can be fabricated at a fraction of the cost of conventional solar cells.
Abstract: As the global demand for low-cost renewable energy sources intensifies, interest in new routes for converting solar energy to electricity is rapidly increasing. Although photovoltaic cells have been commercially available for more than 50 years, only 0.1% of the total electricity generated in the United States comes directly from sunlight. The earliest commercial solar technology remains the basis for the most prevalent devices in current use, namely, highly-ordered crystalline, inorganic solar cells, commonly referred to as silicon cells. Another class of solar cells that has recently inspired significant academic and industrial excitement is the bulk heterojunction (BHJ) “plastic” solar cell. Research by a rapidly growing community of scientists across the globe is generating a steady stream of new insights into the fundamental physics, the materials design and synthesis, the film processing and morphology, and the device science and architecture of BHJ technology. Future progress in the fabrication of ...

Journal ArticleDOI
TL;DR: In this article, the simulation and optimization techniques, as well as the tools existing that are needed to simulate and design stand-alone hybrid renewable energy systems for the generation of electricity are discussed.
Abstract: Stand-alone hybrid renewable energy systems usually incur lower costs and demonstrate higher reliability than photovoltaic (PV) or wind systems. The most usual systems are PV–Wind–Battery and PV–Diesel–Battery. Energy storage is usually in batteries (normally of the lead-acid type). Another possible storage alternative, such as hydrogen, is not currently economically viable, given the high cost of the electrolyzers and fuel cells and the low efficiency in the electricity–hydrogen–electricity conversion. When the design of these systems is carried out, it is usually done resolve an optimization problem in which the Net Present Cost (NPC) is minimized or, in some cases, in relation to the Levelized Cost of Energy (LCE). The correct resolution of this optimization problem is a complex task because of the high number of variables and the non-linearity in the performance of some of the system components. This paper revises the simulation and optimization techniques, as well as the tools existing that are needed to simulate and design stand-alone hybrid systems for the generation of electricity.

Journal ArticleDOI
TL;DR: This paper presents a single-phase five-level photovoltaic inverter topology for grid-connected PV systems with a novel pulsewidth-modulated (PWM) control scheme that offers much less total harmonic distortion and can operate at near-unity power factor.
Abstract: This paper presents a single-phase five-level photovoltaic (PV) inverter topology for grid-connected PV systems with a novel pulsewidth-modulated (PWM) control scheme. Two reference signals identical to each other with an offset equivalent to the amplitude of the triangular carrier signal were used to generate PWM signals for the switches. A digital proportional-integral current control algorithm is implemented in DSP TMS320F2812 to keep the current injected into the grid sinusoidal and to have high dynamic performance with rapidly changing atmospheric conditions. The inverter offers much less total harmonic distortion and can operate at near-unity power factor. The proposed system is verified through simulation and is implemented in a prototype, and the experimental results are compared with that with the conventional single-phase three-level grid-connected PWM inverter.

Journal ArticleDOI
TL;DR: In this paper, the importance of solar cell/module operating temperature for the electrical performance of silicon-based photovoltaic installations is briefly discussed, and the explicit and implicit correlations found in the literature which link this temperature with standard weather variables and material/systemdependent properties, in an effort to facilitate the modeling/design process in this very promising area of renewable energy applications.

Journal ArticleDOI
TL;DR: The application of a luminescent down-shifting (LDS) layer has been proposed as a method for improving the poor spectral response (SR) of solar cells to short-wavelength light.

Journal ArticleDOI
TL;DR: A dynamical electrical array reconfiguration strategy is applied on the photovoltaic generator of a grid-connected PV system based on a plant-oriented configuration in order to improve its energy production when the operating conditions of the solar panels are different.
Abstract: This paper applies a dynamical electrical array reconfiguration (EAR) strategy on the photovoltaic (PV) generator of a grid-connected PV system based on a plant-oriented configuration, in order to improve its energy production when the operating conditions of the solar panels are different. The EAR strategy is carried out by inserting a controllable switching matrix between the PV generator and the central inverter, which allows the electrical reconnection of the available PV modules. As a result, the PV system exhibits a self-capacity for real-time adaptation to the PV generator external operating conditions and improves the energy extraction of the system. Experimental results are provided to validate the proposed approach.

Journal ArticleDOI
TL;DR: A portable solar PV system that effectively eliminates both of the aforementioned problems is described and proven and is capable of simultaneously maximizing the power generated by every PV cell in the PV panel.
Abstract: Solar photovoltaic (PV) arrays in portable applications are often subject to partial shading and rapid fluctuations of shading. In the usual series-connected wiring scheme, the residual energy generated by partially shaded cells either cannot be collected (if diode bypassed) or, worse, impedes collection of power from the remaining fully illuminated cells (if not bypassed). Rapid fluctuation of the shading pattern makes maximum power point (MPP) tracking difficult; generally, there will exist multiple local MPPs, and their values will change as rapidly as does the illumination. In this paper, a portable solar PV system that effectively eliminates both of the aforementioned problems is described and proven. This system is capable of simultaneously maximizing the power generated by every PV cell in the PV panel. The proposed configuration consists of an array of parallel-connected PV cells, a low-input-voltage step-up power converter, and a simple wide bandwidth MPP tracker. Parallel-configured PV systems are compared to traditional series-configured PV systems through both hardware experiments and computer simulations in this paper. Study results demonstrate that, under complex irradiance conditions, the power generated by the new configuration is approximately twice that of the traditional configuration. The solar PV system can be widely used in many consumer applications, such as PV vests for cell phones and music players.

Journal ArticleDOI
TL;DR: In this paper, a study of the appropriateness of glass cover on a thermosyphon-based water-heating photovoltaic-thermal (PV/T) system was carried out.

Journal ArticleDOI
TL;DR: In this paper, a new dye-sensitized solar cell architecture was proposed where high-energy photons are absorbed by highly photoluminescent chromophores unattached to the titania and undergo Forster resonant energy transfer to the sensitizing dye.
Abstract: Conventional dye-sensitized solar cells have excellent charge collection efficiencies, high open-circuit voltages and good fill factors. However, dye-sensitized solar cells do not completely absorb all of the photons from the visible and near-infrared domain and consequently have lower short-circuit photocurrent densities than inorganic photovoltaic devices. Here, we present a new design where high-energy photons are absorbed by highly photoluminescent chromophores unattached to the titania and undergo Forster resonant energy transfer to the sensitizing dye. This novel architecture allows for broader spectral absorption, an increase in dye loading, and relaxes the design requirements for the sensitizing dye. We demonstrate a 26% increase in power conversion efficiency when using an energy relay dye (PTCDI) with an organic sensitizing dye (TT1). We estimate the average excitation transfer efficiency in this system to be at least 47%. This system offers a viable pathway to develop more efficient dye-sensitized solar cells.

Journal ArticleDOI
TL;DR: It is shown that, under a suitable light concentration condition, and with a reasonable area ratio between the emitter and absorber, a STPV system employing such absorber-emitter pair and a single-junction solar cell can attain efficiency that exceeds the Shockley-Queisser limit.
Abstract: We present theoretical considerations as well as detailed numerical design of absorber and emitter for Solar Thermophotovoltaics (STPV) applications. The absorber, consisting of an array of tungsten pyramids, was designed to provide near-unity absorptivity over all solar wavelengths for a wide angular range, enabling it to absorb light effectively from solar sources regardless of concentration. The emitter, a tungsten slab with Si/SiO(2) multilayer stack, provides a sharp emissivity peak at the solar cell band-gap while suppressing emission at lower frequencies. We show that, under a suitable light concentration condition, and with a reasonable area ratio between the emitter and absorber, a STPV system employing such absorber-emitter pair and a single-junction solar cell can attain efficiency that exceeds the Shockley-Queisser limit.