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Photovoltaics, IEEE Journal of

Issue 4 • Date Oct. 2012

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  • Table of contents

    Publication Year: 2012 , Page(s): C1 - C4
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  • IEEE Journal of Photovoltaics publication information

    Publication Year: 2012 , Page(s): C2
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  • Influence of a-Si:H Deposition Temperature on Surface Passivation Property and Thermal Stability of a-Si:H/SiN _{x} :H Stack

    Publication Year: 2012 , Page(s): 405 - 410
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB) |  | HTML iconHTML  

    The inability to withstand temperatures much above the deposition temperature without significant degradation has limited the application of hydrogenated amorphous silicon (a-Si:H) for surface passivation. To address this limitation, in this paper, the surface passivation quality and thermal stability of a stack-passivating system, combining a layer of intrinsic amorphous silicon and a capping layer of silicon nitride (SiNx:H), on p-type crystalline silicon wafers is studied for different deposition temperatures for the underlying a-Si:H layer. Both effective minority carrier lifetime τeff measurement and Fourier transform infrared spectrometry were employed to study the passivating quality and thermal stability of the a-Si:H/SiNx:H stacks. It is established that the lowest a-Si:H deposition temperature (160°C in this study) could result in improved as-deposited surface passivation but degrade quicker under an excessive thermal budget compared with layers with higher deposition temperatures. The more dihydride-rich film composition deposited at lower temperature is suggested to be beneficial for bond restructuring by hydrogen interchanges; however, it is also more susceptible to the provision of channels for hydrogen out-effusion, which could be responsible for the poorer thermal stability compared with stacks with underlying a-Si:H deposited at higher temperature. View full abstract»

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  • An Infant Mortality Study of III–V Multijunction Concentrator Cells

    Publication Year: 2012 , Page(s): 411 - 416
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    Six hundred and forty III-V triple-junction solar cells were evaluated in this study. The cells were initially electrically and optically characterized prior to being packaged and placed on-sun for a short exposure. Following exposure, the cells were partitioned according to their performance change. An infant mortality rate of 0.5% was observed and attributed to preexisting voids in the die attach that promoted thermal runaway. All other cells that significantly degraded following exposure were initially measured with shunt currents >;100 mA at 1.5 V; therefore, a similar limit would serve as an appropriate screening current and only reduce yield by ~1.5% . While many cells both above and below this shunt current limit exhibited artifacts in their electroluminescence (EL) emission, it was not found to predict subsequent performance. The current investigation, however, focused on detecting a short-term degradation and did not evaluate how artifacts in the EL emission or a short-term change in shunt current may correlate with other wear out mechanisms. View full abstract»

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  • The Effect of Spectrum Variation on the Energy Production of Triple-Junction Solar Cells

    Publication Year: 2012 , Page(s): 417 - 423
    Cited by:  Papers (1)
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    We analyze the energy production of a current-matched, two-terminal triple-junction solar cell under different spectrum conditions. We compare this energy production with that of a separate-terminal three subcell system. Under real-spectrum conditions, the energy loss of the two-terminal system can be greater than 9% because of the current mismatch that frequently occurs in real meteorological conditions. The quantitative analysis of energy production between two-terminal and separate-terminal triple-junction solar cells opens up important opportunities in the design and optimization of concentration photovoltaic solar cells and modules. View full abstract»

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  • Using Phase Effects to Understand Measurements of the Quantum Efficiency and Related Luminescent Coupling in a Multijunction Solar Cell

    Publication Year: 2012 , Page(s): 424 - 433
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (771 KB) |  | HTML iconHTML  

    We analyze the quantum efficiency measurement of a series-connected multijunction solar cell by modeling the cell as an ac resistive-capacitive circuit and studying the complex current as a function of the light biasing. The photocurrent induced by directly absorbed photons is modeled as an independent current source, whereas the luminescent coupling current from higher bandgap to lower bandgap subcells is modeled as a dependent current source in the bottom subcell. We derive expressions for the equivalent impedance and the complex current in measurements of the top and bottom subcells of a two-junction device. High light biasing of the nonlimiting cell drives the magnitude and phase shift of the current toward well-defined limits, but insufficient light biasing yields a composite response that is not fully characteristic of either subcell. We recommend that the experimenter always monitor the phase shift of the signal for signs of insufficient light biasing, and to help identify genuine luminescent coupling effects. View full abstract»

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  • GeSiSn Photodiodes With 1 eV Optical Gaps Grown on Si(100) and Ge(100) Platforms

    Publication Year: 2012 , Page(s): 434 - 440
    Cited by:  Papers (1)
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    Ge1-x-ySixSny alloys have reached a level of maturity that permits the creation of prototype devices on group-IV platforms. Here, we compare the optical and electrical properties of GeSiSn diodes with similar target compositions (Si; 10-11%, Sn; 1.7-2.3%) grown directly on Si(100) and Ge(100) using low-temperature ultrahigh vacuum chemical vapor deposition reactions of designer hydrides. The diodes grown on Ge substrates have relatively low ideality factors in the 1.3-1.4 range and low dark currents with a sizable diffusion component. The corresponding characteristics of the analogous devices grown on Si are significantly degraded due to mismatch-induced reduction in crystal quality. Quantum efficiency measurements show that both sets of diodes have absorption edges near 1 eV with collection efficiencies reaching at least 76% in the devices grown on Ge. Collectively, these results suggest that Ge1-x-ySixSny alloys represent a viable alternative as the long sought photovoltaic material with a lattice constant equal to that of Ge and a bandgap around 1 eV. View full abstract»

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  • A Review and Comparison of One- and Two-Dimensional Simulations of Solar Cells Featuring Selective Emitters

    Publication Year: 2012 , Page(s): 441 - 449
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5091 KB) |  | HTML iconHTML  

    The optimization of the metallization pattern and the emitter doping profiles and geometry for selective emitter solar cells require reliable and fast simulation models. The computational effort of one-dimensional models is usually much lower than that of two-dimensional models, which in turn allow for more realistic calculations. We review the literature on one-dimensional and two-dimensional models for the simulation of selective emitter solar cells. We compare the approaches for various emitter profiles and widths of the highly doped areas. We show that the one-dimensional and the two-dimensional approaches show similar trends and only small deviations concerning the short-circuit current density and the open-circuit voltage. Concerning the fill factor and the efficiency, the agreement is still reasonable for the investigated selective emitter structures. However, the one-dimensional approach leads to a more profound understanding and a more realistic simulation of the fill factor. View full abstract»

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  • Analysis of Phosphorus-Doped Silicon Oxide Layers Deposited by Means of PECVD as a Dopant Source in Diffusion Processes

    Publication Year: 2012 , Page(s): 450 - 456
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (617 KB) |  | HTML iconHTML  

    In order to increase the conversion efficiencies of silicon solar cells, advanced cell structures with selectively doped areas have received increasing interest. There is a strong need to separate the contacted diffusion profiles from the noncontacted. On the one hand, a high dopant concentration in the contact regime reduces the series resistance losses mainly due to lowered contact resistance. Additionally, recombination is reduced by shielding the minority charge carriers from surface at the contact. On the other hand, a low dopant concentration in the noncontact regime reduces the recombination losses and optimizes the spectral response of the cell. In this paper, phosphorus-doped silicon oxide layers are used as a diffusion source for tube furnace diffusion processes. It is shown that the sheet resistance of the diffused area is controlled by the silane gas flow during the deposition of phosphorus-doped silicon oxide. In order to analyze the influence of the diffused areas on the saturation current densities, symmetrical carrier lifetime samples are prepared. Therefore, a stack system consisting of a thermally grown silicon dioxide and silicon nitride is used for passivation purposes on textured samples. View full abstract»

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  • Isotextured Silicon Solar Cell Analysis and Modeling 1: Optics

    Publication Year: 2012 , Page(s): 457 - 464
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1562 KB) |  | HTML iconHTML  

    A comprehensive investigation reveals three useful approximations to the optical behavior of isotextured silicon solar cells. First, we confirm experimentally that front-surface reflectance is accurately modeled with “spherical cap” geometry. Second, we find that light reflected from the surface has a Lambertian distribution. Random upright pyramid texturing results in a less favorable distribution so that, when encapsulated, photogeneration in an isotextured cell approaches 99% of that achieved in an equivalent pyramidally textured device. Third, we perform ray tracing simulations to determine the 1-D photogeneration profile beneath isotexture. On their first pass, rays traverse the substrate at angle θ1 with respect to the macroscopic normal such that they are distributed according to cos(3 θ1/2). This approximation to the ray trajectory establishes, for isotexture, a useful simulation tool that has been available for application to pyramidally textured devices for two decades. This paper is followed by a contribution that investigates recombination at isotextured surfaces, coupling results with optical analyses to model the performance of isotextured solar cells. View full abstract»

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  • Isotextured Silicon Solar Cell Analysis and Modeling 2: Recombination and Device Modeling

    Publication Year: 2012 , Page(s): 465 - 472
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (976 KB) |  | HTML iconHTML  

    We extend our analysis of isotextured silicon solar cells by 1) examining experimentally the role played by isotexture in determining the surface recombination velocity at silicon surfaces and 2) combining these experimental results with our model for photogeneration in order to simulate in one dimension typical solar cell devices with isotextured surfaces. We examine both undiffused and diffused n-type isotextured silicon surfaces, and we find that the rate of surface recombination usually decreases with increasing isotexture etch depth. However, when undiffused surfaces are passivated with hydrogenated SiO2 or SiNx, surface recombination velocity is, counterintuitively perhaps, found to be independent of surface texture-this is despite a surface area that is up to 1.9-fold larger than a planar equivalent. We demonstrate the utility of our analysis of isotextured surfaces by simulating various device structures in one dimension. In one case, where device parameters are chosen to approximate a typical screen-printed cell with full-area back surface field, simulation results indicate that the optimal isotexture etch depth is 1-3 μm. This optimum etch depth is slightly below the one deduced from published experimental results, indicating that surface recombination on samples observed in this study is uniquely independent of isotexture morphology. View full abstract»

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  • Reverse Saturation Current Density Imaging of Highly Doped Regions in Silicon Employing Photoluminescence Measurements

    Publication Year: 2012 , Page(s): 473 - 478
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (610 KB) |  | HTML iconHTML  

    We present a camera-based technique for the local determination of reverse saturation current densities J0 of highly doped regions in silicon wafers utilizing photoconductance-calibrated photoluminescence (PL) imaging at different illumination intensities. We apply this approach to 12.5 × 12.5 cm2 float zone silicon (Si) samples with textured surfaces and a homogeneous phosphorous diffusion with sheet resistances between 24 and 230 Ω/□. We find enhanced PL emission at metallized regions of a sample due to reflection of long-wavelength light at the sample rear. In order to allow for a transfer of the calibration function relating the camera PL signal to the excess charge carrier density Δn, our measurement setup comprises an optical short-pass filter in front of the camera that effectively blocks wavelengths above 970 nm. Investigating samples comprising local metal contacts to the highly doped regions prepared by screen printing of silver paste, we find a significantly higher J0,metallized = 1000 fA/cm2 for the metalized areas compared with the nonmetallized area characterized by J0,nonmetallized = 330 fA/cm2. View full abstract»

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  • Investigating Internal Gettering of Iron at Grain Boundaries in Multicrystalline Silicon via Photoluminescence Imaging

    Publication Year: 2012 , Page(s): 479 - 484
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (513 KB) |  | HTML iconHTML  

    In this paper, we present measurements and modeling of the reduction in dissolved iron Fe; concentrations near grain boundaries in multicrystalline silicon (mc-Si) wafers. The measurements of the interstitial Fe concentrations are obtained via photoluminescence images taken before and after iron-boron pair dissociation. A simple diffusion-capture model was developed to characterize the removal of interstitial Fe by the gettering sites. The model is based on a numerical solution to the 1-D diffusion equation with two fitting parameters: the diffusion length of dissolved Fe atoms and the effective gettering velocity at the gettering site. By comparing the simulation with a controlled phosphorous gettering process, the model is shown to give good estimation of the diffusion length of Fe atoms. For as-cut multicrystalline silicon wafers from different parts of the ingot, that is, wafers with different average dissolved Fe concentrations [Fei], the diffusion lengths of Fe atoms are found to decrease with decreasing average [Fei] This suggests the presence of relaxation precipitation during the internal gettering of dissolved Fe by the grain boundaries in mc-Si during ingot cooling. View full abstract»

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  • Geometrical Analysis of Solar Cells With Partial Rear Contacts

    Publication Year: 2012 , Page(s): 485 - 493
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (541 KB) |  | HTML iconHTML  

    The analysis of solar cells where the posterior metal contact is formed only on part of the rear surface, which is mostly covered by a nonconductive, passivating layer, is both important and complex. A possible approach, based on a geometrical representation of the device structure, is examined here. As minority carriers flow toward the localized rear contact, they crowd inside a diminishing cross-sectional area, resulting in a high current density. The latter demands a strong gradient in their concentration, which leads to an increase of the open-circuit voltage Voc. Similarly, the crowding of majority carriers requires a strong gradient of the electrostatic potential, which leads to an increased series resistance Rs. These effects of carrier crowding are described here with simple mathematical expressions that permit an approximate evaluation of Voc and Rs for partial rear contact solar cells. View full abstract»

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  • Colored Ribbons Achieve +0.28% _{\bf abs.} Efficiency Gain

    Publication Year: 2012 , Page(s): 494 - 498
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    Flat metallic ribbons connect the solar cells in conventional crystalline silicon modules. Acting like a mirror, they reflect incoming radiation out of the module. The area covered by the ribbons (around 3.5%) is mainly lost for photovoltaic conversion. We present colored cell connectors which scatter incident irradiation. Due to subsequent total internal reflection at the glass/air interface, the photons get a second chance to reach the active module area. White ribbons increase the module efficiency from η = 14.7% by Δη = 0.28%abs. to nearly 15%. Applying ultraviolet (UV) fluorescent dye on top of the white paint increases the quantum efficiency of lower wavelengths even further. Reduced optical losses allow a novel optimization of optical versus electrical losses. A simulation determines the optimum amount of white painted ribbons, balancing of the lower optical shadowing, and the higher series resistance of the module. The simulation predicts an efficiency gain Δη = 0.33%abs.. View full abstract»

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  • A Crystalline Metallic Copper Network Application Film Produced by High-Temperature Atmospheric Sintering

    Publication Year: 2012 , Page(s): 499 - 505
    Cited by:  Papers (1)
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    We show the first production of a copper (Cu) application film (AF) consisting of a novel network of crystalline metallic Cu embedded with copper-phosphorus-oxygen glasses (Cu 2(PO4) and Cu 2P2O 7) to provide new feedstock materials for crystalline silicon (Si) photovoltaics (PVs). The Cu crystal network was preferentially grown in AF, and thus, a Cu AF with low-electrical resistivity was formed in air at elevated temperatures of ≥ 450°C by using a copper-phosphorus (Cu-P) alloy paste as a starting material for the sintering. The Cu-P alloy had the role that governed deoxidization of a cuprous oxide, which was formed on heating during the sintering, by virtue of a concurrent oxidation of the Cu phosphide at elevated temperatures. Our results may open the way to the widespread use of atmospherically sintered Cu AFs for mass-production of next-generation crystalline Si PVs. View full abstract»

    Open Access
  • Hot Carrier Solar Cells: Controlling Thermalization in Ultrathin Devices

    Publication Year: 2012 , Page(s): 506 - 511
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (714 KB) |  | HTML iconHTML  

    In operating hot carrier solar cells, a steady-state hot carrier distribution is established in the absorber in such a way that the excess kinetic energy of carriers can be collected. A high-carrier concentration is normally favorable to the formation of a nonequilibrium hot-carrier population. A small absorber thickness is thus expected to improve the efficiency of hot carrier solar cells, but no quantitative analysis of the impact of the cell thickness on its performance has been done so far. Here, the potential of efficiency improvement using thinned absorber is investigated by simulating the absorption, heat losses, and efficiency of a hot carrier solar cell with varying absorber thickness. Efficiency improvement requires efficient light trapping to maintain absorption in ultrathin layers. Solutions are proposed to achieve strong absorption in a 25-50-nm-thick absorber, resulting in cell efficiencies that are higher than the Shockley-Queisser limit corresponding to the absorber's bandgap. View full abstract»

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  • Temperature Dependence of Open-Circuit Voltage and UPS Study for P3HT:PCBM Organic Solar Cells

    Publication Year: 2012 , Page(s): 512 - 518
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (778 KB) |  | HTML iconHTML  

    In this paper, the open-circuit voltage Voc of a poly(3-hexylthiophene-2,5-diyl) (P3HT) and a [6,6]-phenyl C61 -butyric acid methyl ester (PCBM) bulk heterojunction organic solar cell device was measured at temperatures ranging from 15°C to 145°C. The temperature dependence of the vacuum shift and of the highest occupied molecular orbital (HOMO) energy level of P3HT and PCBM were measured by ultraviolet photoelectron spectroscopy in the same temperature range. The temperature dependence of the absorption edge was also studied in the same temperature range to obtain the temperature variation of the optical band gap energy Eg. The measured Voc of the devices shows a clear decreasing trend with increasing operating temperature, and the total decrease is found to be about 0.1 V. However, by utilizing the measured values of the HOMO for the P3HT (donor) and of the determined lowest unoccupied molecular orbital (LUMO) for the PCBM (acceptor), we have found that the calculated values of Voc and its temperature dependence do not agree with the measured Voc values. This is a clear indication that the expression (HOMO-LUMO)-exciton energy does not hold and that other factors are impacting the value of Voc. View full abstract»

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  • An Investigation of the Surface Properties of (Ag,Cu)(In,Ga)Se _{\bf 2} Thin Films

    Publication Year: 2012 , Page(s): 519 - 523
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (557 KB) |  | HTML iconHTML  

    (Ag,Cu)(In,Ga)Se2 alloy absorber layers with various Ga/(Ga+In) and Ag/(Ag+Cu) ratios were deposited using multisource elemental evaporation and analyzed by glancing incidence X-ray diffraction and energy dispersive X-ray spectroscopy. All films exhibit chalcopyrite reflections in the X-ray diffraction pattern and films with 0.5 ≤ Ga/(Ga+In) <; 1 and Ag/(Ag+Cu) >; 0.5 have additional reflections consistent with an ordered defect phase which is limited to the near-surface region of the film. X-ray photoelectron spectroscopy measurements show that all films studied have low (Ag+Cu)/Se and (Ag+Cu)/(Ga+In) ratios near the surface relative to the bulk composition, consistent with an ordered defect compound identified as (Ag,Cu)(In,Ga)5Se8. Additionally, the near-surface region of (Ag,Cu)(In,Ga)Se2 films contains a higher Ag/(Ag+Cu) ratio than the bulk and the Ag(In,Ga)Se2 film contains excess Ag near the surface. View full abstract»

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  • Performance Analysis of a Single-Axis Tracking PV System

    Publication Year: 2012 , Page(s): 524 - 531
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1044 KB) |  | HTML iconHTML  

    In this paper a performance analysis of a photovoltaic (PV) tracking system is conducted, to study its efficiency based on experimental results of a specific power plant. A single-axis system is analyzed, taking into account different indexes to better characterize the overall system performance. Experimental data have been collected by an on-site monitoring system over a period of one year, bringing some final considerations and comparative results on PV-system efficiency. View full abstract»

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  • Control and Circuit Techniques to Mitigate Partial Shading Effects in Photovoltaic Arrays

    Publication Year: 2012 , Page(s): 532 - 546
    Cited by:  Papers (34)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1649 KB) |  | HTML iconHTML  

    Partial shading in photovoltaic (PV) arrays renders conventional maximum power point tracking (MPPT) techniques ineffective. The reduced efficiency of shaded PV arrays is a significant obstacle in the rapid growth of the solar power systems. Thus, addressing the output power mismatch and partial shading effects is of paramount value. Extracting the maximum power of partially shaded PV arrays has been widely investigated in the literature. The proposed solutions can be categorized into four main groups. The first group includes modified MPPT techniques that properly detect the global MPP. They include power curve slope, load-line MPPT, dividing rectangles techniques, the power increment technique, instantaneous operating power optimization, Fibonacci search, neural networks, and particle swarm optimization. The second category includes different array configurations for interconnecting PV modules, namely series-parallel, total-cross-tie, and bridge-link configurations. The third category includes different PV system architectures, namely centralized architecture, series-connected microconverters, parallel-connected microconverters, and microinverters. The fourth category includes different converter topologies, namely multilevel converters, voltage injection circuits, generation control circuits, module-integrated converters, and multiple-input converters. This paper surveys the proposed approaches in each category and provides a brief discussion of their characteristics. View full abstract»

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  • Limits of Advisability for Master–Slave Configuration of DC–AC Converters in Photovoltaic Systems

    Publication Year: 2012 , Page(s): 547 - 554
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (670 KB) |  | HTML iconHTML  

    Several feed-in tariffs are now available for photovoltaic (PV) systems, and thus, the maximization of the productivity is very important; this goal can be achieved by solar cell technologies with high efficiency and low temperature losses, one axis or dual axis sun-tracking systems, proper cooling techniques for PV modules in building integrated applications, master-slave (M-S) control for the inverters in large grid-connected PV plants, etc. About the last item, this paper deals with the advisability of the master-slave concept versus the centralized inverter layout. Here, attention is focused on the influence of the installation site with its irradiation peculiarities, the tilt angle of the PV modules, the efficiency curve of the inverters, and the number of slaves. The simulated productions put into evidence energy gains up to 4% per year, considering the only cloudy-day contribution. On the basis of these comparisons, the M-S concept can be profitable if the number of cloudy days is sufficiently high, the tilt angle is adequate, and the dc-ac efficiency curve is “well shaped”. View full abstract»

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  • Maximum-Power-Based PV Performance Validation Method: Application to Single-Axis Tracking and Fixed-Tilt c-Si Systems in the Italian Alpine Region

    Publication Year: 2012 , Page(s): 555 - 563
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1482 KB) |  | HTML iconHTML  

    This paper presents springtime monitoring results for different crystalline-silicon (c-Si) photovoltaic (PV) systems installed at the multitechnology ground-mounted PV test field at the Airport Bolzano Dolomiti (ABD) located in the Italian Alps. The system data are analyzed and discussed.The main purpose of this paper is to validate the performance evaluation through a methodology based on the effective maximum power of the PV modules. This approach could be useful when dealing, as in the present case, with commercial monitoring systems. Three different silicon-based technologies are taken into consideration: polycrystalline silicon, high-efficiency monocrystalline silicon, and hybrid monocrystalline silicon that have been positioned both on a single-axis tracker and on fixed 30°-tilted supports. The systems are connected to different types of inverter, through which the power monitoring is performed. The assessment shows indicators, such as final yield and performance ratio, for both tracked and fixed-tilt systems. The PV systems are evaluated in relation to irradiance data registered by two identical c-Si reference devices positioned on the tracker and on the fixed supports. Results show that an average difference of ±14 W exists between the module's label and the actual peak power. This difference is in line with the power tolerance declared by manufacturers. The maximum-power-based PV performance validation method could initially highlight cases in which a faulty module hides in the system, having the potential for application in fault detection and reliability analysis, followed by more specific evaluations. View full abstract»

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  • Dynamic Stability of Three-Phase Grid-Connected Photovoltaic System Using Zero Dynamic Design Approach

    Publication Year: 2012 , Page(s): 564 - 571
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (722 KB) |  | HTML iconHTML  

    This paper presents a new approach to control the grid current and dc-link voltage for maximum power point tracking and improvement of the dynamic response of a three-phase grid-connected photovoltaic (PV) system. To control the grid current and dc-link voltage, the zero dynamic design approach of feedback linearization is used, which linearizes the system partially and enables controller design for reduced-order PV system. This paper also describes the zero dynamic stability of the three-phase grid-connected PV system, which is a key requirement for the implementation of such controllers. Simulation results on a large-scale grid-connected PV system show the effectiveness of the proposed control scheme in terms of delivering maximum power into the grid. View full abstract»

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  • Simulation Tool for Equivalent Circuit Modeling of Photovoltaic Devices

    Publication Year: 2012 , Page(s): 572 - 579
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB) |  | HTML iconHTML  

    We describe an open-source simulation tool for the modeling of photovoltaic devices with equivalent circuit networks. Our SpiceGUI interconnects devices with known current voltage characteristics and calculates the current density-voltage curve of the combined device. The SpiceGUI is written as hybrid Octave/MATLAB code and has a flexible graphical user interface. It supports batch simulations with the SPICE tools LTspice, NGspice, and SMARTspice. The available postprocessing functions include convenient batch parameter plots and power loss analysis diagrams. We present two simulation examples. The first example simulates a solar cell with front contact fingers. It assists the reader in understanding the SpiceGUI unit tree and serves as starting point for the development of custom models. This first example also shows that the SpiceGUI yields reliable results, even for very demanding models that exceed 4 GB working memory. The second example models back-contacted thin-film silicon solar cells. We use measured Jsc-Voc curves as input data for the current sources of the network. Additional resistive elements complete the network. The simulated JV curves of the combined device agree well with the measured JV curves. The distributed nature of the resistances is essential to describing the shape of the measured JV curves. View full abstract»

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Aims & Scope

The IEEE Journal of Photovoltaics is a peer-reviewed, archival publication reporting original and significant research results that advance the field of photovoltaics (PV).

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Meet Our Editors

Editor-in-Chief
Timothy J. Anderson
Chemical Engineering Department
University of Florida