New Publications are available for Photoelectric conversion; solar cells and arrays
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New Publications are available now online for this publication.
Please follow the links to view the publication.Design and implementation of a solar thermal / photovoltaic energy system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0739
Toward go green, the main aim of this paper is presentation of a proposal for the integration and implementation of photovoltaic(PV) technologies in buildings considering aesthetic effects, particularized for the Iran through a case study. Our main objective is the selection of the most appropriate technical solution (PV and thermal) for the integration of renewable energy in buildings and electricity grid interconnection in near future. The proposed energy system is employed for energy supply in a residential building for different end uses such as hot water and electricity, a major part of electricity required for lighting, domestic appliances (elevator and electric garage door) that is generated through a PV system. Both the solar thermal and PV systems are installed on the building roof. (4 pages)Impact of ripple current on the average output power of solar cells
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0333
This paper presents an analysis of the effects of power converter induced ripple on solar cells. The majority of analysis presented on maximum power point tracking (MPPT) schemes and switched mode power converters (SMPCs) assume smooth DC current is drawn from the cell. In this paper, results from simulation and experimental work are presented to elucidate these effects, showing a significant degradation in the maximum average power when ripple current is accounted for. The effects of power converter switching frequency are also given showing an improvement in the average power from the PV module at greater frequencies. (5 pages)Numerical simulation model of compositionally graded optimized radiation hard InGaN multi-junction space solar cell
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0453
Radiation hard and changeable band gap ternary InGaN multi junction series connected solar cell is theoretically investigated and also numerically modelled and analysed using modern TCAD tool. Significant high theoretical efficiency up-to 39.20% is achieved for triple junction InGaN cell using realistic material parameters. Optimisation is performed by varying Indium composition, resulting in a change of an optical property and band gap energy that closely matches for the AMO solar spectrum illumination. Then, the model has been validated with experimental data from various recent literatures. The results of this simulation demonstrate that InGaN is potentially an excellent semiconductor photovoltaic material especially for space application.Comparison of photo voltaic array based different topologies of cascaded H-bridge multilevel inverter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0344
This paper mainly deals with three different topologies of cascaded H-Bridge multilevel inverter. The Topology-I is a general type of multilevel inverter (MLI) which has two Photo Voltaic Arrays (PV Arrays) for each phase. In Topology-II the number of PV Arrays has been reduced to one for all the three phases and the usage of transformers come into picture. Topology-Ill uses only one PV Array for all the three phases and the number of switches have been reduced than compared to all other topologies of Cascaded H-bridge multilevel inverter. MATLAB simulations have been carried out for all three Topologies and have been compared with each other.Optimisation of concentrator in the solar photonic optoelectronic transformer: optical gain analysis
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0201
The Solar Photonic Optoelectronic Transformer (SPOT) is one of the components of the SolarBrane, a Building Integrated Photovoltaic (BIPV) system developed by SolarEmpower Ltd. Recently, an optimised design for the optical concentrator in the SPOT has been proposed to further improve its performance. The optimised design uses a dielectric totally internally reflecting concentrator (DTIRC) based on the maximum concentration method (MCM). Firstly this paper, provides an overview of SolarBrane followed by the optimised design of the SolarBrane concentrator indicating the geometrical concentration gain improvement when compared to the current design. An optical gain simulation is then presented, showing the angular analysis of the optimised concentrator in two cases; by varying the front surface arc angle and changing the half-acceptance angle of the DTIRC. From the simulation study, it can be concluded that the optimised design provides higher optical gain when compared with the existing design. (6 pages)Less could be more: architectural integration of active solar systems in existing urban centres
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0917
This paper investigates the different possibilities of architectural integration of active solar systems on the facades and roofs of existing buildings, as well as in the urban open spaces of urban centres of countries such as Greece and Cyprus. It includes the presentation of the various possibilities of architectural integration of active solar systems and an analysis of the benefits and the difficulties caused by the particularities of the urban fabric and of the buildings that define it. (7 pages)Advantages of P-I-N photovoltaic structures
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0854
Direct conversion of solar energy into electricity using the photovoltaic effect suffers of low efficiency. Thus, increasing the efficiency conversion becomes the major goal of solar cells manufacturers. One way to increase efficiency is by applying intrinsic semiconductor widening layer in the depletion zone of a P-N junction. P-I-N based Photovoltaic structures on single-crystalline silicon were built using "Sheet Plasma" sputtering method. Intrinsic silicon films and indium oxide films were grown in series on a conventional p-type silicon wafer. Optical and electrical properties of the deposited films were investigated using laboratory equipment. It was found that the bandgap of the intrinsic silicon layer equals to 1.3 eV and the bandgap of the emitter layer (In2O3) equals to 3.04 eV. Resistivity of the obtained emitter layer was equal to 5.24-10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">-3</sup> Ω·cm. Efficiency of the photovoltaic structures was no more than 2%. This paper proves feasibility of growing photovoltaic devices using Sheet Plasma sputtering methods. (4 pages)A note on parameters of photovoltaic cells in dependence on irradiance and temperature
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0896
This paper provides an analysis of the irradiance influence on photovoltaic cell efficiency in dependence on the cell construction, using the standard equivalent circuit describing solar cell. The influence of the series resistance is discussed in details and results of simulations are completed with experimental result obtained by measuring both crystalline silicon and CIS cells in broad intervals of irradiance and temperature. (4 pages)Solar cells based on atomic layer deposition
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1227
The advantages of atomic layer deposition (ALD) include highly controlled deposition parameters, deposition uniformity, ultra-precise film thickness and good step coverage. Its prominent characteristics have drew attention to researchers in the fields of solar cells. The heterojunction, core-shell structure and surface passivation of solar cells can be preparated by ALD to get better system performance. For example, the photoelectric conversion efficiency is improved by reducing electrons and holes recombination and protecting the cells to fulfill the utilization of energy.Polymer electronics - towards the future
http://dl-live.theiet.org/content/conferences/10.1049/ic.2009.0061
This presentation discusses some key characteristics of polymers and several polymer-based electronic devices such as polymer light-emitting diodes, photovoltaic diodes, organic solar cells, field-effect transistor, and electrophoretic display. (31 pages)Solar photovoltaic power systems
http://dl-live.theiet.org/content/conferences/10.1049/ic_20070787
A collection of slides from the author's conference presentation is given.Design and construction of a modular electronic photo-voltaic simulator
http://dl-live.theiet.org/content/conferences/10.1049/cp_20000231
The design and construction of a modular electronic photovoltaic (PV) simulator is presented. This is to be used to develop a reliable and repeatable methodology for the assessment of maximum power point tracking (MPPT) performance. As part of the design process the simulator was modelled using Ispice and Simulink. A linearised model was derived which is used to obtain an optimal compromise between accuracy and dynamic performance for the controller.Laser cutting thin films for solar panels
http://dl-live.theiet.org/content/conferences/10.1049/ic_19960680
The thin films used in the fabrication of solar panels can all be cut using lasers. Narrow tracks must be cut in order to section the films to create cells which are linked in series to generate a useful voltage from a single-sheet solar panel. Ideal tracks should be as narrow as possible to maximize the fill factor, yet still able to ensure a high electrical impedance across the cut. Each cut should not damage the underlying thin film. Track widths of the order of 15 μm have been cut in ITO (transparent tin oxide), amorphous silicon and aluminium, and various anti-reflection layers. For the cutting process, which is extremely fast and therefore highly cost effective, the optimum laser wavelength depends upon the film itself. Machines have been constructed which use 1.06 μm and 503 nm Nd:YAG wavelengths and 248 nm excimer laser wavelength. (1 page)Photovoltaics: built-in power generation
http://dl-live.theiet.org/content/conferences/10.1049/ic_19960679
The author briefly discusses the use of photovoltaic technology as compact power sources for diverse applications. In particular the author discusses thin film solar cells and their use in electrical products. The future of photovoltaics in electricity generation is also discussed. (2 pages)Development of a model for photovoltaic arrays suitable for use in simulation studies of solar energy conversion systems
http://dl-live.theiet.org/content/conferences/10.1049/cp_19960890
The work described in this paper was carried out as part of the development of an advanced solar photovoltaic (PV) conversion system. During the design of the system, simulation of both the power chain and the control algorithms was found to be useful, but to simulate a system as a whole requires a non-application specific circuit-based simulation model of a PV array for a simulator such as Saber, or the well known SPICE. There were found to be no such models readily available and thus the development of one became necessary. This work successfully sought to develop a cheap, but effective system to characterize existing cells and generate the device-dependent data that provides the link between the environmental variables irradiance and temperature, and the electrical characteristics of the device.Modelling and control of photovoltaic panels utilising the incremental conductance method for maximum power point tracking
http://dl-live.theiet.org/content/journals/10.1049/iet-rpg.2011.0052
For photovoltaic panels, maximum power point tracking (MPPT) is a crucial process to ensure energy capture is maximised. Various tracking algorithms are available for this purpose. Of these, one of the more common presently implemented is the incremental conductance method. However, no linearised small signal model incorporating an incremental conductance-based MPPT process exists. As will be demonstrated, this is attributed to the formation of a degenerate model when conventional linearisation techniques are applied. In this study, a modelling approach is developed that overcomes this deficiency and permits linearisation of the incremental conductance MPPT algorithm. As a case study adopting this developed approach, a complete small signal dynamic model of the incremental conductance method utilising a boost converter is derived. The model is validated against simulations in PSCAD/EMTDC. This study also presents some applications of the model, such as controller design and stability testing. The results demonstrate that the system is highly robust to variations in the lighting condition.Closed-form model for the open circuit voltage of solar cells with shunt resistance, bias-dependent photocurrent and double exponential terms
http://dl-live.theiet.org/content/journals/10.1049/iet-cds.2011.0173
The parasitic shunt resistance, bias dependence of the photocurrent and phenomena causing a second exponential term in the current density (<i xmlns="http://pub2web.metastore.ingenta.com/ns/">J</i>)–voltage (<i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i>) equation reduce the open circuit voltage, <i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">oc</sub>, of illuminated solar cells below the ideal value predicted by the <i xmlns="http://pub2web.metastore.ingenta.com/ns/">J</i>–<i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i> equation having only a single exponential term. This study reports an approximate closed-from solution of the transcendental <i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">oc</sub> equation which directly reflects these losses. The solution estimates <i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">oc</sub> as a weighted parallel combination of the limiting <i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">oc</sub> values corresponding to the domination of one of the several terms of the <i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">oc</sub> equation. The solution allows quick design calculation of the <i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">oc</sub> of a wide variety of cells in terms of all physical parameters, and provides insight into the influence of losses owing to various factors.Controllable synthesis of rutile TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> nanorod array, nanoflowers and microspheres directly on fluorine-doped tin oxide for dye-sensitised solar cells
http://dl-live.theiet.org/content/journals/10.1049/mnl.2012.0398
TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> films with different morphology directly grown on fluorine-doped tin oxide (FTO) substrate were prepared via a facile hydrothermal method. Rutile TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> nanorod arrays, nanoflowers film and microspheres film were obtained by changing the volume ratios of HCl and CH<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub>COOH in solvent with other conditions unchanged, as confirmed by X-ray diffraction, scanning electron microscopy, transmission electron microscope (TEM) and high-resolution TEM. Dye-sensitised solar cell (DSSC) assembled with the TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> microsphere films grown on FTO substrate as photoanode achieves an overall photoelectric conversion efficiency of 1.94% and a short-circuit current intensity of 5.12 mA cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">−2</sup> owing to the rough surface, which is higher than those of nanorod array and nanoflower-based DSSCs. The photovoltaic performance of rutile TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> film-based DSSCs is related to the morphology of the film.Low-power FOCV MPPT controller with automatic adjustment of the sample&hold
http://dl-live.theiet.org/content/journals/10.1049/el.2012.1345
A simple maximum power pointer tracker (MPPT) controller for low-power photovoltaic (PV) panels is proposed. The MPPT is based on a fractional open circuit voltage controller that dynamically adjusts the sample time and period accordingly to the power of the PV panel. That allows the converter to obtain a good trade-off between the power efficiency and the dynamic response for a wide range of PV powers.Detection of tab wire soldering defects on silicon solar cells using terahertz time-domain spectroscopy
http://dl-live.theiet.org/content/journals/10.1049/el.2012.1995
Terahertz time-domain spectroscopy was applied to measure the reflectivity spectra of a silicon solar cell with tab wire soldering defects. It was demonstrated that THz phase imaging data allows a reliable estimation of height differences of bulging tab wires within 22% as tested for 0.63 and 1.07 mm loop peaks. Such measurements can be implemented for automated defect correction in future solar module production lines.Maximum photovoltaic power tracking: an algorithm for rapidly changing atmospheric conditions
http://dl-live.theiet.org/content/journals/10.1049/ip-gtd_19951577
As the maximum power operating point (MPOP) of photovoltaic (PV) power generation systems changes with changing atmospheric conditions (e.g. solar radiation and temperature), an important consideration in the design of efficient PV systems is to track the MPOP correctly. Many maximum power tracking (MPT) techniques have been considered in the past but techniques using microprocessors with appropriate MPT algorithms are favoured because of their flexibility and compatibility with different PV arrays. Although the efficiency of these MPT algorithms is usually high, it drops noticeably in cases of rapidly changing atmospheric conditions. The authors have developed a new MPT algorithm based on the fact that the MPOP of a PV generator can be tracked accurately by comparing the incremental and instantaneous conductances of the PV array. The work was carried out by both simulation and experiment, with results showing that the developed incremental conductance (IncCond) algorithm has successfully tracked the MPOP, even in cases of rapidly changing atmospheric conditions, and has higher efficiency than ordinary algorithms in terms of total PV energy transferred to the load.Recombination in silicon thin-film solar cells: a study of electrically detected magnetic resonance
http://dl-live.theiet.org/content/journals/10.1049/ip-cds_20030578
A review of recombination in silicon thin-film solar cells studied by means of electrically detected magnetic resonance (EDMR) is presented. It is shown that the EDMR results in μc-Si:H p-i-n solar cells can be described by a simple diffusion model that was developed for crystalline silicon p-n junctions assuming that recombination is dominated by dangling bonds in the space charge region. The results are compared to a-Si:H p-i-n cells and discussed in a recombination model involving the excited states of charged dangling bonds.Microcrystalline Si:H solar cells fabricated using ECR plasma deposition
http://dl-live.theiet.org/content/journals/10.1049/ip-cds_20030629
The properties of microcrystalline Si:H materials and solar cells fabricated using remote, low pressure ECR (electron cyclotron resonance) plasma deposition are described. p+nn+ junction solar cells were deposited at 275–325°C on stainless steel substrates using mixtures of silane and hydrogen. Microcrystalline layers and solar cells could be produced even for low dilution ratio of hydrogen/silane of 8:1. It was found that once crystallisation started, one could decrease the hydrogen/silane ratio and still obtain microcrystalline Si:H solar cells. The voltage of the solar cells could be improved by tailoring the interface between p+ and n layers. An amorphous interfacial layer improved the voltage. A thin amorphous Si:H layer at the back, between n+ and n layers was used to significantly reduce the shunt resistance. Standard device analyses, including dark I(V) curves and capacitance measured at several frequencies, revealed that device characteristics could be understood in terms of a standard Si diode model. The doping densities in the n layer were found to be in the 1×10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">15</sup> to 2×10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">16</sup>/cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sup> range and could be adjusted by altering the amount of compensatory B doping of the layer. The influence of the addition of He dilution to the mixture was also studied, and it was found that He degraded the crystallinity, though it increased the growth rate and open-circuit voltage.1/<i xmlns="http://pub2web.metastore.ingenta.com/ns/">f</i> noise in hydrogenated amorphous silicon–germanium alloys
http://dl-live.theiet.org/content/journals/10.1049/ip-cds_20030749
Measurements were made of conductance noise of a-Si:H and a-Si<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">1−<i>x</i></sub>Ge<sub xmlns="http://pub2web.metastore.ingenta.com/ns/"><i>x</i></sub>:H in two different geometries: one where the current flow is transverse to the surface and the other where it is longitudinal to the surface. Because of the large change in sample resistance between the two geometries, it was not possible to measure both geometries at the same temperature. For both geometries, alloying with up to 40% Ge reduces the noise magnitude by several orders of magnitude over that found in a-Si:H. The decrease is incompatible with several popular noise models. Extrapolating the temperature trends for each geometry shows that it is possible that the noise observed in the transverse samples has the same origin as the higher frequency part of the double power law spectra observed in the longitudinal samples.Stability of microcrystalline silicon for thin film solar cell applications
http://dl-live.theiet.org/content/journals/10.1049/ip-cds_20030636
The development of microcrystalline silicon (<i xmlns="http://pub2web.metastore.ingenta.com/ns/">μ</i>c-Si:H) for solar cells has made good progress with efficiencies better than those of amorphous silicon (a-Si:H) devices. Of particular interest is the absence of light-induced degradation in highly crystalline <i xmlns="http://pub2web.metastore.ingenta.com/ns/">μ</i>c-Si:H. However, the highest efficiencies are obtained with material which may still include a-Si:H regions and light-induced changes may be expected in such material. On the other hand, material of high crystallinity is susceptible to in-diffusion of atmospheric gases which, through adsorption or oxidation, affect the electronic transport. Investigations are presented of such effects concerning the stability of <i xmlns="http://pub2web.metastore.ingenta.com/ns/">μ</i>c-Si:H films and solar cells prepared by plasma-enhanced chemical vapour deposition and hot wire chemical vapour deposition.Thin film polycrystalline silicon solar cell on ceramics with a seeding layer formed via aluminium-induced crystallisation of amorphous silicon
http://dl-live.theiet.org/content/journals/10.1049/ip-cds_20030630
Thin film polycrystalline silicon solar cells on foreign substrates are viewed as one of the most promising approaches to cost reduction in photovoltaics. To enhance the quality of the film, the use of ‘seeding layers’ prior to deposition of active material is being investigated. It has been shown that a phenomenon suitable to create such a seeding layer is the aluminium-induced crystallisation of amorphous silicon. Previous work mainly considered glass as the substrate of choice, thereby introducing limitations on the deposition temperature. Results concerning the application of such a technique to ceramic substrates (allowing the use of high-temperature CVD) are described. Also, the first reported results of a solar cell made in silicon deposited on these seeding layers are presented.Thin film silicon materials and solar cells grown by pulsed PECVD technique
http://dl-live.theiet.org/content/journals/10.1049/ip-cds_20030627
Pulsed plasma enhanced chemical vapour deposition (PECVD) involves modulation of standard 13.56 MHz RF plasma in the kilohertz range. This allows an increase in the electron density during the ‘ON’ cycle, while in the ‘OFF’ cycle, neutralising the ions responsible for dust formation in the plasma. The authors report the development of state-of-the-art nanocrystalline Si (nc-Si:H) materials using a pulsed PECVD technique with 220 crystallite orientation, grain size of ∼200 Å, low O concentration and a minority carrier diffusion length <i xmlns="http://pub2web.metastore.ingenta.com/ns/">L</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">d</sub> of ∼1.2 μm. The crucial effects of the p/i interface and the incubation layer have been investigated and an efficiency of ∼7.5% for a single junction nc-Si:H p-i-n device has been achieved for an i-layer thickness of 1.4 μm, using non-optimised textured substrates.Microcrystalline and polycrystalline silicon films for solar cells obtained by gas-jet electron-beam PECVD method
http://dl-live.theiet.org/content/journals/10.1049/ip-cds_20030665
A new gas-jet electron beam plasma enhanced chemical vapour deposition (GJEB PECVD) method for high-rate deposition of crystalline silicon films is presented. The method is based on the activation of initial gas molecules in an electron beam plasma and fast convective transfer of the radicals to a substrate by means of a supersonic free jet. Nanocrystalline, microcrystalline and polycrystalline Si film growth on different foreign substrates is investigated using morphological and optical analyses in dependence on the temperature of the substrate and its distance from the nozzle. It is shown that a middle range of substrate distance is required to avoid crystallinity damage by heavy ions while still keeping their effect on grain nucleation. In this case, well shaped crystalline grains embedded with a ‘highly ordered’ amorphous phase are found in Si films grown at a low temperature at the edge of crystalline growth.Modelling of solar cells and modules using piecewise linear parallel branches
http://dl-live.theiet.org/content/journals/10.1049/iet-rpg.2010.0134
This study proposes a novel equivalent circuit model for solar cells and modules. The proposed model approximates the non-linear <i xmlns="http://pub2web.metastore.ingenta.com/ns/">I</i>–<i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i> characteristic of a photovoltaic cell or module by a number of linear circuit branches connected in parallel. The number of these linear circuit branches is adjustable according to the required accuracy. An algorithm based on an equal-area criterion for determining the parameters of the equivalent circuit is also proposed. This algorithm, if incorporated into the software that simulates the proposed model, allows variations of solar irradiance and cell temperature to be taken into account during the simulation. Two numerical examples simulated by electromagnetic transient programme software are presented to demonstrate the performance of the model.Low-cost charge collector of photovoltaic power conditioning system based dynamic DC/DC topology
http://dl-live.theiet.org/content/journals/10.1049/iet-rpg.2009.0199
The development of battery-buffered photovoltaic (PV) power conditioning systems (PCSs) is challenged by its cost/W. It compels the users to optimise the system's configuration in order to maximise the power generation. An alternative solution to this problem based on a charge collector (CC), which has the ability of maximising the charge collection of battery is shown here. The design of the CC is derived from the linear approximation model resolving prior probability distribution and dynamic DC/DC topology with micro-controller to meet the low-cost application. A simulation system has been made and analysed to verify the better performances of the CC over the traditional ones, and an empirical PV PCS example based on the laboratory prototype has been conducted to highlight the CC's natures. Results from the demonstrations, including LED lighting projections of PV PCS, show that the proposed low-cost CC with 4 ms settling time has about more than 20% efficiency and less than 50% sensitivity to system's parameters compared with the simple controller.Boost-converter-based solar harvester for low power applications
http://dl-live.theiet.org/content/journals/10.1049/el.2010.2903
A novel implementation of a solar harvester circuit based on a boost DC/DC converter topology is presented. The proposed circuit is able to harvest solar energy down to a power level of 1.6 mW while maintaining comparable performance with previously presented results at higher power levels.Electrophoretic graphene for transparent counter electrodes in dye-sensitised solar cells
http://dl-live.theiet.org/content/journals/10.1049/el.2010.2897
Graphene counter electrodes (GCEs) prepared by electrophoretic deposition (EPD) have been investigated. Half cells were fabricated to examine the electrochemical properties of GCEs with different deposition times. Accordingly, dye-sensitised solar cells (DSSCs) were fabricated with those GCEs in order to examine the conversion efficiencies and effect of GCEs with different deposition times. The possibility of GCEs by EPD as a counter electrode of DSSCs is suggested.Air-bridge-type electrodes for high-efficiency photovoltaic cell
http://dl-live.theiet.org/content/journals/10.1049/mnl.2011.0096
Recently, the important issues relating to the photovoltaic cell have featured low cost and high efficiency. To make a low-cost and high-efficiency photovoltaic cell, there are many aspects such as the development of inexpensive wafers, process simplification and improvement of optical and electrical properties. In this study, the two-step texturing method using a microblaster was developed to decrease the reflection of incident lights. Bridge-type electrode structures are suggested to expand the effective surface area and decrease the series resistance of finger electrodes. The authors decided to use 10 µm size powders since the efficiency of the solar cell could rather be reduced by using 50 µm size powders because of their extremely rough surface. And the surface of the wafer after microblaster etching was treated with a chemical etching method using HNA (HF:HNO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub>:CH<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub>COOH=4:9:7) solution, a dry etching method using reactive ion etching and a oxide etching method.Ultra-high efficiency solar cells: the path for mass penetration of solar electricity
http://dl-live.theiet.org/content/journals/10.1049/el_20081154
For achieving a photovoltaic penetration above one-third of the world demand for electricity in the first half of this century, the importance of a fast manufacturing learning curve that is linked to the capacity of developing cells of increasing efficiency is stressed. Progress in multijunction cells is described as well as three novel concepts promising very high efficiency. It is explained why these concepts will probably be used in concentrator systems.Photovoltaic maximum power point tracking for mobile applications
http://dl-live.theiet.org/content/journals/10.1049/el.2010.2479
The photovoltaic maximum power point tracking (MPPT) algorithm based on incremental conductance is found to have an error mode which prevents its normal operation under conditions of rapidly changing/oscillating solar input (insolation). An enhancement to the algorithm is investigated and experimentally evaluated. It can be readily added around an existing MPPT algorithm to enable it to be used more reliably in mobile applications.Carbon nanotubes as counter electrode for dye-sensitised solar cells
http://dl-live.theiet.org/content/journals/10.1049/el_20072867
Carbon nanotubes (CNTs) with different diameters as a counter electrode to fabricate dye-sensitised solar cells with high conversion efficiency are investigated. The CNT electrodes with large diameter demonstrated better redox reaction and higher energy conversion efficiency.Improvement of short-circuit current of InP/InGaAsP/InP double heterojunction solar cells
http://dl-live.theiet.org/content/journals/10.1049/el_20050005
The InP/InGaAsP double heterojunction (DH) solar cell to increase the short-circuit current is investigated. The InP/InGaAsP DH solar cell has been newly designed having a 1.12 eV InGaAsP absorption layer. Increases of 100% in short-circuit current and 50.18% in efficiency for the DH device are observed over the control sample.Application of commercialised single-crystalline silicon solar cells on thin plastic concentrator
http://dl-live.theiet.org/content/journals/10.1049/el.2010.3313
Investigation shows that the application of commercialised single-crystalline silicon solar cells on a low power-magnifying thin plastic concentrator can improve the output of the solar cells. The output current of the solar cells can be maximised from 60.1 mA up to 101.6 mA. In addition, an inexpensive and simple concentrator can even lift the output current of the commercialised single-crystalline silicon solar cell with flaws from 18.5 up to 73.1 mA which is 1.2 times the output current of the regular solar cells that is only 60 mA. The reuse of the resources can not only save cost, but also protect the environment. This research also investigated the output current and IV property of the cells.Method based on single variable to evaluate all parameters of solar cells
http://dl-live.theiet.org/content/journals/10.1049/el.2010.1170
A simple and accurate method is proposed to assess the single diode model parameters of an illuminated and dark solar cell (SC). A description of the method and its application in the parameters evaluation from experimental <i xmlns="http://pub2web.metastore.ingenta.com/ns/">i</i>–<i xmlns="http://pub2web.metastore.ingenta.com/ns/">v</i> curves of a commercial SC are reported. A coefficient of determination, <i xmlns="http://pub2web.metastore.ingenta.com/ns/">R</i><sup xmlns="http://pub2web.metastore.ingenta.com/ns/"><i>2</i></sup>, is obtained, which is higher than 0.9999.GaInP/AlInP tunnel junction for GaInP/GaAs tandem solar cells
http://dl-live.theiet.org/content/journals/10.1049/el_19980324
A GaInP/AlInP tunnel diode has been grown by a gas-source molecular beam epitaxy method. A high conductance of 15 mA/cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup> at 2.7 mV has been achieved. Using closely optimised growth conditions, very high carrier concentrations, both in GaInP and AlInP, have been obtained.Favourable photovoltaic effects in InGaN <i xmlns="http://pub2web.metastore.ingenta.com/ns/">pin</i> homojunction solar cell
http://dl-live.theiet.org/content/journals/10.1049/el.2009.2094
InGaN <i xmlns="http://pub2web.metastore.ingenta.com/ns/">pin</i> homojunction solar cells with different In content (x=0.02/0.12/0.15) have been fabricated. The measured open-circuit voltages (<i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">oc</sub>) are 2.24, 1.34 and 0.96 V, respectively. All the devices exhibit large fill factors of more than 64% and enhanced response in the short wavelength region, suggesting the high potential of InGaN-based <i xmlns="http://pub2web.metastore.ingenta.com/ns/">pin</i> homojunction solar cells.Behaviour of CuInGaSe<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> solar cells under light irradiation
http://dl-live.theiet.org/content/journals/10.1049/el_20001176
The behaviour of CIGS solar cells using a light irradiation test is investigated. The conversion efficiency after the test increases by ~25 %. This is mainly due to the increase in <i xmlns="http://pub2web.metastore.ingenta.com/ns/">Isc</i> and <i xmlns="http://pub2web.metastore.ingenta.com/ns/">FF</i> and the lowering of the series resistance. It is also shown that the performance of the diode decreases, because the value of the diode factor increases from 1.9 to 2.4. In addition, the changes in the junction condition and generation of defects are suggested to be based on the measurement of electro-luminescence and the photo-absorption current spectrum by the light below the sensitivity of the cell.High V<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">OC</sub> dye sensitised solar cell using RF-sputtered TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> compact layers
http://dl-live.theiet.org/content/journals/10.1049/el.2009.3527
Presented is a dye sensitised solar cell (DSSC) with very high open circuit voltage (V<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">oc</sub>) and shunt resistance (R<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">SH</sub>) using an RF-sputtered titanium dioxide compact layer. TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> films of about 100 nm thickness were RF-sputtered at room temperature on indium-tin-oxide coated glass substrates and used as the compact layer for fabrication of DSSCs. Current-voltage characteristics of the DSSCs under AM 1.5 illumination condition showed a very high V<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">OC</sub> of 780 mV, high R<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">SH</sub> of 400 KΩ, short circuit current density (J<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">sc</sub>) of 12.3 mA/cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup>, and fill factor (FF) of 0.61, while the V<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">OC</sub>, R<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">SH</sub>, J<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">SC</sub>, and FF of a DSSC fabricated using a conventional sol-gel processed TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> compact layer were 520 mV, 463 Ω, 5.4 mA/cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup>, and 0.46, respectively.Evaluation of acceleration test for degradation of each layer in stacked amorphous silicon solar cell
http://dl-live.theiet.org/content/journals/10.1049/el_19991351
The results of an evaluation of the degradation of each separate level and their subsequent recovery process for solar cells made of a three-layer stacked structure are presented. The spectral sensitivity characteristic and conversion efficiency are used as evaluation parameters. The results indicate that the degradation pattern for the bottom layer should be chosen as the standard as far as the evaluation of the overall conversion efficiency is concerned. This is because the absolute value of spectral sensitivity for the bottom layer is the smallest.Technique for enhancing generation power density of silicon photovoltaic devices
http://dl-live.theiet.org/content/journals/10.1049/el_20045267
A new type of photovoltaic system with higher generation power density has been studied in detail. The feature of the proposed system is a V-shaped structure with two polycrystalline solar cells. Compared to solar cells in a conventional approach, the V-shaped structure enhances external quantum efficiency and leads to an increase of 24% in power conversion efficiency.Thermally evaporated SnS:Cu thin films for solar cells
http://dl-live.theiet.org/content/journals/10.1049/mnl.2011.0121
Cu-doped tin sulphide (SnS) films with a thickness of about 300 nm have been grown on glass substrates by thermal evaporation technique. Different Cu-doped SnS films were obtained by controlling the Cu evaporation time to roughly alter Cu-doping concentration in SnS films (from 5.7 to 23 atom%). Then they were annealed at a temperature of 250°C and a pressure of 5.0×10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">−3</sup> Pa for 90 min. The structural, optical and electrical properties of the films were characterised by X-ray diffraction, atomic force microscopy, ultraviolet–visible–near infrared spectrometer and Hall-effect measurement system. All the films are polycrystalline SnS with orthorhombic structure, and the crystallites in the films are all exclusively oriented along (111) direction. Annealing can optimise the crystallinity of all the films. With the increase of Cu-doping concentration, the grain size of the films becomes larger and larger, but the roughness decreases. Meanwhile, the evaluated direct bandgap <i xmlns="http://pub2web.metastore.ingenta.com/ns/">E</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">g</sub> of the SnS:Cu films initially decreases, reaches a minimum value of 1.38 eV with 15 atom% Cu and then increases thereafter. The carrier concentration of the films increases sharply, while the resistivity of the films decreases straightly. All the films are of <i xmlns="http://pub2web.metastore.ingenta.com/ns/">p</i>-type conductivity. Using the optimised conditions, it is possible to prepare SnS:Cu thin films suitable for absorbers of thin film solar cells.Enhanced energy conversion efficiencies of solar cells by multiple carrier excitation
http://dl-live.theiet.org/content/journals/10.1049/el_20071039
Energy conversion efficiencies for solar cells utilising multiple carrier excitation were calculated for various solar concentration factors based on the detailed balance limit formalism. The theoretical efficiency limit for the solar cells generating up to eight electron-hole pairs from one photon was 58% under a 1000-sun illumination relative to 38% without multiple carrier excitation with their optimised energy bandgaps.Spindle-like TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> with high crystallinity and its application in dye sensitised solar cell
http://dl-live.theiet.org/content/journals/10.1049/mnl.2011.0317
TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> spindles with high crystallinity were synthesised by a two-step solvothermal reaction with the aid of diethylamine. Compared with Degussa P25, the dye sensitised solar cell (DSSC) based on a TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> spindles photoanode demonstrated superior characteristics including higher affinity to N719 dye, higher light scattering effect than P25, better conductance and longer recombination lifetime. Photovoltaic measurement indicated that the TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> spindles-based DSSC possesses higher short-circuit current density (<i xmlns="http://pub2web.metastore.ingenta.com/ns/">J</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">sc</sub>) and open-circuit voltage (<i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">oc</sub>), hence, a 29% higher overall photovoltaic performance (η) than that of P25 was achieved.Photovoltaic effect in CdS on flexible substrate
http://dl-live.theiet.org/content/journals/10.1049/el_20010328
The authors report on the photovoltaic effect in CdS/CuS films deposited on flexible substrates at temperatures close to room temperature from using the water solutions of complex-salt compounds. The results demonstrate the feasibility of using this material for photovoltaic applications requiring covering of large complex surfaces.Enhanced efficiency in dye-sensitised solar cells using a TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>-based sandwiched film as photoanode
http://dl-live.theiet.org/content/journals/10.1049/mnl.2011.0225
A multi-layered film with a TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>-based nanotubes/nanoparticles/nanotubes sandwich structure has been developed to increase light-harvesting efficiency by enhancing light scattering. Compared to a double-layered film of nanotubes/nanoparticles, the sandwiched film exhibited greatly improved light-absorption properties. An obviously improved total energy-conversion efficiency of 6.11% was obtained in the sandwiched film, which is 27.3, 46.1 and 213% higher than those of the double-layered film, nanoparticle film and nanotube film, respectively. A possible mechanism for the enhancement of light harvesting in the sandwiched film is proposed, whereby the observed enhancement is owing to effective scattering by the bottom layer and reflection of escaped light by the top layer.