International Journal of Photoenergy http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Performance Characterisation of a Hybrid Flat-Plate Vacuum Insulated Photovoltaic/Thermal Solar Power Module in Subtropical Climate Sun, 25 Sep 2016 13:28:37 +0000 http://www.hindawi.com/journals/ijp/2016/6145127/ A flat-plate Vacuum Insulated Photovoltaic and Thermal (VIPV/T) system has been thermodynamically simulated and experimentally evaluated to assess the thermal and electrical performance as well as energy conversion efficiencies under a subtropical climate. A simulation model made of specified components is developed in Transient Systems (TRNSYS) environment into which numerical energy balance equations are implemented. The influence of vacuum insulation on the system’s electrical and thermal yields has been evaluated using temperatures, current, voltage, and power flows over daily and annual cycles under local meteorological conditions. The results from an experiment conducted under steady-state conditions in Durban, South Africa, are compared with the simulation based on the actual daily weather data. The VIPV/T has shown improved overall and thermal efficiencies of 9.5% and 16.8%, respectively, while electrical efficiency marginally reduced by 0.02% compared to the conventional PV/T. The simulated annual overall efficiency of 29% (i.e., 18% thermal and 11% electrical) has been realised, in addition to the solar fraction, overall exergy, and primary energy saving efficiencies of 39%, 29%, and 27%, respectively. Andrew Y. A. Oyieke and Freddie L. Inambao Copyright © 2016 Andrew Y. A. Oyieke and Freddie L. Inambao. All rights reserved. Effect of Plasma, RF, and RIE Treatments on Properties of Double-Sided High Voltage Solar Cells with Vertically Aligned p-n Junctions Thu, 22 Sep 2016 14:15:28 +0000 http://www.hindawi.com/journals/ijp/2016/1815205/ Si-based solar cells with vertically aligned p-n junctions operating at high voltage were designed and fabricated. The plasma treatments and antireflection coating deposition on the working surfaces of both single- and multijunction cells were made using the special holders. It was shown that additional treatment of solar cells in argon plasma prior to hydrogen plasma treatment and deposition of diamond-like carbon antireflection films led to the improvement of the cell efficiency by up to 60%. Radio frequency waves support plasma generation and improve photoelectric conversion mainly due to reduction of internal stresses at the interfaces. Application of reactive ion etching technique removes the broken layer, reduces elastic strain in the wafer, decreases recombination of charge carriers in the bulk, and provides cell efficiency increase by up to ten times. Mykola O. Semenenko, Mykhailo G. Dusheiko, Sergiy V. Mamykin, Valeriy O. Ganus, Mykhailo V. Kirichenko, Roman V. Zaitsev, Mykola M. Kharchenko, and N. I. Klyui Copyright © 2016 Mykola O. Semenenko et al. All rights reserved. Modeling and Analysis of New Multilevel Inverter for Solar Photovoltaic Power Plant Wed, 21 Sep 2016 14:09:20 +0000 http://www.hindawi.com/journals/ijp/2016/4063167/ Solar photovoltaic (PV) power plant is an effective way to utilize the renewable energy sources. EMI is one of the major concerns in PV power plant. Typically, the multilevel inverters are used in high voltage PV power plant. However, the conventional multilevel inverters require more semiconductors, which complicate the circuit structure and control algorithm. In this paper, a novel five-level inverter is introduced for the high voltage PV power plant applications. The model of the inverter is analyzed. With the redundant switching states, a new modulation strategy is proposed to reduce the common-mode voltage and EMI. The proposed approach is able to eliminate the common-mode voltage; meanwhile it has the capability of balancing the capacitor voltages. The cosimulation tests with the Matlab/Simulink and S-function are carried out. The results verify the effectiveness of the proposed method. Xiaoqiang Guo, Ran He, and Mehdi Narimani Copyright © 2016 Xiaoqiang Guo et al. All rights reserved. Highly Reflective Dielectric Back Reflector for Improved Efficiency of Tandem Thin-Film Solar Cells Wed, 21 Sep 2016 13:46:54 +0000 http://www.hindawi.com/journals/ijp/2016/7390974/ We report on the prototyping and development of a highly reflective dielectric back reflector for application in thin-film solar cells. The back reflector is fabricated by Snow Globe Coating (SGC), an innovative, simple, and cheap process to deposit a uniform layer of TiO2 particles which shows remarkably high reflectance over a broad spectrum (average reflectance of 99% from 500 nm to 1100 nm). We apply the highly reflective back reflector to tandem thin-film silicon solar cells and compare its performance with conventional ZnO:Al/Ag reflector. By using SGC back reflector, an enhancement of 0.5 mA/cm2 in external quantum efficiency of the bottom solar cell and an absolute value of 0.2% enhancement in overall power conversion efficiency are achieved. We also show that the increase in power conversion efficiency is due to the reduction of parasitic absorption at the back contact; that is, the use of the dielectric reflector avoids plasmonic losses at the reference ZnO:Al/Ag back reflector. The Snow Globe Coating process is compatible with other types of solar cells such as crystalline silicon, III–V, and organic photovoltaics. Due to its cost effectiveness, stability, and excellent reflectivity above a wavelength of 400 nm, it has high potential to be applied in industry. Chog Barugkin, Ulrich W. Paetzold, Kylie R. Catchpole, Angelika Basch, and Reinhard Carius Copyright © 2016 Chog Barugkin et al. All rights reserved. Photovoltaic Materials and Devices 2016 Sun, 18 Sep 2016 11:00:19 +0000 http://www.hindawi.com/journals/ijp/2016/9427450/ Bhushan Sopori, Prakash Basnyat, and Vishal Mehta Copyright © 2016 Bhushan Sopori et al. All rights reserved. Sliding Mode Real-Time Control of Photovoltaic Systems Using Neural Estimators Wed, 14 Sep 2016 13:48:43 +0000 http://www.hindawi.com/journals/ijp/2016/5214061/ The maximum power point tracking (MPPT) problem has attracted the attention of many researchers, because it is convenient to obtain the maximum power of a photovoltaic module regardless of the weather conditions and the load. In this paper, a novel control for a boost DC/DC converter has been introduced. It is based on a sliding mode controller (SMC) that takes a current signal as reference instead of a voltage, which is generated by a neuronal reference current generator. That reference current indicates the current () at the maximum power point (MPP) for given weather conditions. In order to test the designed control system, a photovoltaic module model based on a second artificial neuronal network (ANN) has been obtained from experimental data gathered during 18 months in the Faculty of Engineering Vitoria-Gasteiz (Spain). We have analyzed the performance of such model and we found that it is very accurate (MSE = 0.062 A and = 0.991 with test dataset). We also have tested the performance of the overall SMC design with both simulated and real tests, concluding that it guarantees that the power in the output of the converter is very close to the power of the photovoltaic module output. J. A. Ramos-Hernanz, O. Barambones, J. M. Lopez-Guede, I. Zamora, P. Eguia, and M. Farhat Copyright © 2016 J. A. Ramos-Hernanz et al. All rights reserved. Ag-Doped TiO2 Nanotube Arrays Composite Film as a Photoanode for Enhancing the Photoelectric Conversion Efficiency in DSSCs Thu, 08 Sep 2016 06:32:32 +0000 http://www.hindawi.com/journals/ijp/2016/2736257/ A Ag-doped double-layer composite film with TiO2 nanoparticles (P25) as the underlayer and TiO2 nanotube (TNT) arrays with the Ag-doped nanoparticles as the overlayer was fabricated as the photoanode in dye-sensitized solar cells (DSSCs). Five different concentrations of Ag-doped TNT arrays photoelectrode were compared with the pure TNT arrays composite photoelectrode. It is found that the photoelectric conversion efficiency of the TNT arrays composite photoanode is gradually improved from 3.00% of the pure TNT arrays composite photoanode to 6.12% of the Ag-doped TNT arrays photoanode with the increasing of the doping concentration, reaching up to the maximum in the 0.04 mol/L AgNO3 solution, and then slightly decreased to 5.43% after continuing to increase the doping concentration. The reason is mainly that the cluster structure of the Ag nanoparticles with large surface area contributes to dye adsorption and the Surface Plasmon Resonance Effect of the Ag nanoparticles improved the photocatalytic ability of the TNT arrays film. Jinghua Hu, Jiejie Cheng, Shengqiang Tong, Yingping Yang, Mengwei Chen, and Shiwu Hu Copyright © 2016 Jinghua Hu et al. All rights reserved. High Quality GaAs Epilayers Grown on Si Substrate Using 100 nm Ge Buffer Layer Wed, 07 Sep 2016 10:09:25 +0000 http://www.hindawi.com/journals/ijp/2016/7218310/ We present high quality GaAs epilayers that grow on virtual substrate with 100 nm Ge buffer layers. The thin Ge buffer layers were modulated by hydrogen flow rate from 60 to 90 sccm to improve crystal quality by electron cyclotron resonance chemical vapor deposition (ECR-CVD) at low growth temperature (180°C). The GaAs and Ge epilayers quality was verified by X-ray diffraction (XRD) and spectroscopy ellipsometry (SE). The full width at half maximum (FWHM) of the Ge and GaAs epilayers in XRD is 406 arcsec and 220 arcsec, respectively. In addition, the GaAs/Ge/Si interface is observed by transmission electron microscopy (TEM) to demonstrate the epitaxial growth. The defects at GaAs/Ge interface are localized within a few nanometers. It is clearly showed that the dislocation is well suppressed. The quality of the Ge buffer layer is the key of III–V/Si tandem cell. Therefore, the high quality GaAs epilayers that grow on virtual substrate with 100 nm Ge buffer layers is suitable to develop the low cost and high efficiency III–V/Si tandem solar cells. Wei-Cheng Kuo, Hung-Chi Hsieh, Wu Chih-Hung, Huang Wen-Hsiang, Chien-Chieh Lee, and Jenq-Yang Chang Copyright © 2016 Wei-Cheng Kuo et al. All rights reserved. Synthesis and Characterization of Graphene Oxide-Modified Bi2WO6 and Its Use as Photocatalyst Mon, 05 Sep 2016 14:09:16 +0000 http://www.hindawi.com/journals/ijp/2016/8730806/ A Bi2WO6 photocatalyst modified with graphene was synthesized in a two-step template-free hydrothermal process. The prepared samples were characterized to explore their properties. The photocatalytic activities of the prepared samples were investigated by degrading dye model, Rhodamine B (RhB), under visible light irradiation. This showed that the modified Bi2WO6 photocatalyst with 1.2 wt% of graphene greatly improved photocatalytic activity during the degradation of dye pollutants, compared to pure Bi2WO6. The enhancement can be interpreted as the integrated effects of ultrahigh charge carriers’ mobility and high adsorption of RhB on graphene. Additionally, effects including catalysts dosage amount, pH of RhB solution, and temperature of reactor on the photocatalytically degrading RhB were also studied and discussed. Xiaoyue Hu, Xiangchao Meng, and Zisheng Zhang Copyright © 2016 Xiaoyue Hu et al. All rights reserved. Photocatalytic Activity and Optical Properties of Blue Persistent Phosphors under UV and Solar Irradiation Thu, 01 Sep 2016 09:28:41 +0000 http://www.hindawi.com/journals/ijp/2016/1303247/ Blue phosphorescent strontium aluminosilicate powders were prepared by combustion synthesis route and a postannealing treatments at different temperatures. X-ray diffraction analysis showed that phosphors are composed of two main hexagonal phases: SrAl2O4 and Sr3Al32O51. The morphology of the phosphors changed from micrograins (1000°C) to a mixture of bars and hexagons (1200°C) and finally to only hexagons (1300°C) as the annealing temperature is increased. Photoluminescence spectra showed a strong blue-green phosphorescent emission centered at  nm, which is associated with transition of the Eu2+. The sample annealed at 1200°C presents the highest luminance value (40 Cd/m2) with CIE coordinates (0.1589, 0.1972). Also, the photocatalytic degradation of methylene blue (MB) under UV light (at 365 nm) was monitored. Samples annealed at 1000°C and 1300°C presented the highest percentage of degradation (32% and 38.5%, resp.) after 360 min. In the case of photocatalytic activity under solar irradiation, the samples annealed at 1000°C, 1150°C, and 1200°C produced total degradation of MB after only 300 min. Hence, the results obtained with solar photocatalysis suggest that our powders could be useful for water cleaning in water treatment plants. C. R. García, L. A. Diaz-Torres, J. Oliva, M. T. Romero, and P. Salas Copyright © 2016 C. R. García et al. All rights reserved. A Simple Technique for Sustaining Solar Energy Production in Active Convective Coastal Regions Tue, 30 Aug 2016 13:44:25 +0000 http://www.hindawi.com/journals/ijp/2016/3567502/ The climatic factors in the coastal areas are cogent in planning a stable and functional solar farm. 3D simulations relating the surface temperature, sunshine hour, and solar irradiance were adopted to see the effect of minute changes of other meteorological parameters on solar irradiance. This enabled the day-to-day solar radiation monitoring with the primary objective to examine the best technique for maximum power generation via solar option in coastal locations. The month of January had the highest turbulent features, showing the influence of weather and the poorest solar radiance due to low sunshine hour. Twenty-year weather parameters in the research area were simulated to express the systematic influence of weather of PV performance. A theoretical solar farm was illustrated to generate stable power supply with emphasis on the longevity of the PV module proposed by introducing an electronic concentrator pillar (CP). The pictorial and operational model of the solar farm was adequately explained. Moses E. Emetere, Marvel L. Akinyemi, and Etimbuk B. Edeghe Copyright © 2016 Moses E. Emetere et al. All rights reserved. Effect of Codoping Cl Anion and 5-AVA Cation on Performance of Large-Area Perovskite Solar Cells with Double-Mesoporous Layers Tue, 30 Aug 2016 08:57:39 +0000 http://www.hindawi.com/journals/ijp/2016/2953592/ For the perovskite solar cells (PSCs), the performance of the PSCs has become the focus of the research by improving the quality of the perovskite absorption layer. So far, the performance of the large-area PSCs is lower than that of small-area PSCs. In the paper, the experiments were designed to improve the photovoltaic performance of the large-area PSCs by improved processing technique. Here we investigated the optoelectronic properties of the prototypical CH3NH3PbI3 (MAPbI3) further modulated by introducing other extrinsic ions (specifically codoped Cl− and 5-AVA+). Moreover, we used inorganic electron extraction layer to achieve very rapid photogenerated carrier extraction eliminating local structural defects over large areas. Ultimately, we fabricated a best-performing perovskite solar cell based on codoping Cl anion and 5-AVA cation which uses a double layer of mesoporous TiO2 and ZrO2 as a scaffold infiltrated with perovskite and does not require a hole-conducting layer. The experiment results indicated that an average efficiency of double-mesoporous layer-based devices with codoping Cl anion and 5-AVA cation was obtained with exceeding 50% enhancement, compared to that of pure single-mesoporous layer-based device. Yaxian Pei, Xiaoping Zou, Yingxiang Guan, and Gongqing Teng Copyright © 2016 Yaxian Pei et al. All rights reserved. Wide-Range Enhancement of Spectral Response by Highly Conductive and Transparent μc-SiOx:H Doped Layers in μc-Si:H and a-Si:H/μc-Si:H Thin-Film Solar Cells Wed, 24 Aug 2016 09:58:28 +0000 http://www.hindawi.com/journals/ijp/2016/8172518/ The enhancement of optical absorption of silicon thin-film solar cells by the p- and n-type μc-SiOx:H as doped and functional layers was presented. The effects of deposition conditions and oxygen content on optical, electrical, and structural properties of μc-SiOx:H films were also discussed. Regarding the doped μc-SiOx:H films, the wide optical band gap () of 2.33 eV while maintaining a high conductivity of 0.2 S/cm could be obtained with oxygen incorporation of 20 at.%. Compared to the conventional μc-Si:H(p) as window layer in μc-Si:H single-junction solar cells, the application of μc-SiOx:H(p) increased the and led to a significant enhancement in the short-wavelength spectral response. Meanwhile, the employment of μc-SiOx:H(n) instead of conventional ITO as back reflecting layer (BRL) enhanced the external quantum efficiency (EQE) of μc-Si:H single-junction cell in the long-wavelength region, leading to a relative efficiency gain of 10%. Compared to the reference cell, the optimized a-Si:H/μc-Si:H tandem cell by applying p- and n-type μc-SiOx:H films achieved a of 1.37 V, of 10.55 mA/cm2, FF of 73.67%, and efficiency of 10.51%, which was a relative enhancement of 16%. Pei-Ling Chen, Po-Wei Chen, Min-Wen Hsiao, Cheng-Hang Hsu, and Chuang-Chuang Tsai Copyright © 2016 Pei-Ling Chen et al. All rights reserved. Heterogeneous Photochemistry: Solar Energy Conversion and Environmental Remediation Sun, 21 Aug 2016 08:24:50 +0000 http://www.hindawi.com/journals/ijp/2016/2083696/ Daniele Dondi, Sandra Babić, Irene Michael, Giovanni Palmisano, and Andrea Speltini Copyright © 2016 Daniele Dondi et al. All rights reserved. Preparation of a Textile-Based Dye-Sensitized Solar Cell Sun, 14 Aug 2016 07:14:15 +0000 http://www.hindawi.com/journals/ijp/2016/3796074/ Solar energy conversion is an object of continuous research, focusing on improving the energy efficiency as well as the structure of photovoltaic cells. With efficiencies continuously increasing, state-of-the-art PV cells offer a good solution to harvest solar energy. However, they are still lacking the flexibility and conformability to be integrated into common objects or clothing. Moreover, many sun-exposed surface areas are textile-based such as garments, tents, truck coverings, boat sails, and home or outdoor textiles. Here, we present a new textile-based dye-sensitized solar cell (DSC) which takes advantage from the properties inherent to fabrics: flexibility, low weight, and mechanical robustness. Due to the necessary thermostability during manufacturing, our DSC design is based on heat-resistant glass-fiber fabrics. After applying all needed layers, the overall structure was covered by a transparent and simultaneously conductive protective film. The light and still flexible large-area devices (up to 6 cm2 per individual unit) are working with efficiencies up to 1.8% at 1/5 of the sun. Stability tests assure no loss of photovoltaic activity over a period of at least seven weeks. Therefore, our technology has paved the way for a new generation of flexible photovoltaic devices, which can be used for the generation of power in the mentioned applications as well as in modern textile architecture. Klaus Opwis, Jochen Stefan Gutmann, Ana Rosa Lagunas Alonso, Maria Jesus Rodriguez Henche, Mikel Ezquer Mayo, Fanny Breuil, Enrico Leonardi, and Luca Sorbello Copyright © 2016 Klaus Opwis et al. All rights reserved. Study of Transition Region of p-Type SiO:H as Window Layer in a-Si:H/a-SiGe:H Multijunction Solar Cells Mon, 08 Aug 2016 16:27:11 +0000 http://www.hindawi.com/journals/ijp/2016/3095758/ We have studied the p-type hydrogenated silicon oxide (:H) films prepared in the amorphous-to-microcrystalline transition region as a window layer in a-Si:H/a-:H multijunction solar cells. By increasing the -to- flow ratio () from 10 to 167, the :H(p) films remained amorphous and exhibited an increased hydrogen content from 10.2% to 12.2%. Compared to the amorphous :H(p) film prepared at low , the :H(p) film deposited at of 167 exhibited a higher bandgap of 2.04 eV and a higher conductivity of 1.15 × 10−5 S/cm. With the employment of :H(p) films prepared by increasing from 10 to 167 in a-Si:H single-junction cell, the FF improved from 65% to 70% and the efficiency increased from 7.4% to 8.7%, owing to the enhanced optoelectrical properties of :H(p) and the improved p/i interface. However, the cell that employed :H(p) film with over 175 degraded the p/i interface and degraded the cell performance, which were arising from the onset of crystallization in the window layer. Compared to the cell using standard a-:H(p), the a-Si:H/a-:H tandem cells employing :H(p) deposited with of 167 showed an improved efficiency from 9.3% to 10.3%, with of 1.60 V, of 9.3 mA/cm2, and FF of 68.9%. Pei-Ling Chen, Po-Wei Chen, and Chuang-Chuang Tsai Copyright © 2016 Pei-Ling Chen et al. All rights reserved. A Population Classification Evolution Algorithm for the Parameter Extraction of Solar Cell Models Mon, 08 Aug 2016 13:19:29 +0000 http://www.hindawi.com/journals/ijp/2016/2174573/ To quickly and precisely extract the parameters for solar cell models, inspired by simplified bird mating optimizer (SBMO), a new optimization technology referred to as population classification evolution (PCE) is proposed. PCE divides the population into two groups, elite and ordinary, to reach a better compromise between exploitation and exploration. For the evolution of elite individuals, we adopt the idea of parthenogenesis in nature to afford a fast exploitation. For the evolution of ordinary individuals, we adopt an effective differential evolution strategy and a random movement of small probability is added to strengthen the ability to jump out of a local optimum, which affords a fast exploration. The proposed PCE is first estimated on 13 classic benchmark functions. The experimental results demonstrate that PCE yields the best results on 11 functions by comparing it with six evolutional algorithms. Then, PCE is applied to extract the parameters for solar cell models, that is, the single diode and the double diode. The experimental analyses demonstrate that the proposed PCE is superior when comparing it with other optimization algorithms for parameter identification. Moreover, PCE is tested using three different sources of data with good accuracy. Yiqun Zhang, Peijie Lin, Zhicong Chen, and Shuying Cheng Copyright © 2016 Yiqun Zhang et al. All rights reserved. Carrier Formation Dynamics in Prototypical Organic Solar Cells as Investigated by Transient Absorption Spectroscopy Mon, 08 Aug 2016 13:19:18 +0000 http://www.hindawi.com/journals/ijp/2016/9105460/ Subpicosecond transient absorption spectroscopy is a powerful tool used to clarify the exciton and carrier dynamics within the organic solar cells (OSCs). In this review article, we introduce a method to determine the absolute numbers of the excitons and carriers against delay time (t) only from the photoinduced absorption (PIA) and electrochemically induced absorption (EIA) spectra. Application of this method to rr-P3HT-, PTB7-, and SMDPPEH-based OSCs revealed common aspects of the carrier formation dynamics. First, the temporal evolution of the numbers of the excitons and carriers indicates that the late decay component of exciton does not contribute to the carrier formation process. This is probably because the late component has not enough excess energy to separate into the electron and hole across the donor/acceptor (D/A) interface. Secondly, the spectroscopy revealed that the exciton-to-carrier conversion process is insensitive to temperature. This observation, together with the fast carrier formation time in OSCs, is consistent with the hot exciton picture. Yutaka Moritomo, Kouhei Yonezawa, and Takeshi Yasuda Copyright © 2016 Yutaka Moritomo et al. All rights reserved. The Influence of Heating Time and Temperature on the Properties of CIGSSe Solar Cells Sun, 07 Aug 2016 12:56:24 +0000 http://www.hindawi.com/journals/ijp/2016/4089369/ Nonencapsulated CIGSSe solar cells, with a silver grid, were exposed to different temperatures for various periods in order to measure the effect of the heat exposure in CIGSSe modules. The heat treatment time and temperature were varied during the experiments, which were executed at atmospheric conditions. In all the cases, after reaching a temperature of about 300°C, the IV measurement showed a reduction of 2-3% in terms of and . This is confirmed, respectively, by Raman and EQE measurements as well. The efficiency drop was −7%, −29%, and −48%, respectively, for 30 seconds, 300 seconds, and 600 seconds of exposure time. With temperatures larger than 225°C, the series resistance starts to increase exponentially and a secondary barrier becomes visible in the IV curve. This barrier prevents the extraction of electrons and consequently reducing the solar cells efficiency. Lock-in thermography demonstrated the formation of shunts on the mechanical scribes only for 300 and 600 seconds exposure times. The shunt resistance reduction is in the range of 5% for all time periods. Marco Giacomo Flammini, Nicola Debernardi, Maxime Le Ster, Brendan Dunne, Johan Bosman, and Mirjam Theelen Copyright © 2016 Marco Giacomo Flammini et al. All rights reserved. Accelerated Life Test for Photovoltaic Cells Using Concentrated Light Sun, 07 Aug 2016 08:24:56 +0000 http://www.hindawi.com/journals/ijp/2016/9825683/ This paper presents a new method developed to significantly reduce the necessary time for the ageing tests for different types of photovoltaic cells. Two ageing factors have been applied to the photovoltaic cells: the concentrated light and the temperature. The maximum power of the photovoltaic cells was monitored during the ageing process. The electrical dc and ac parameters of the photovoltaic cells were measured and analyzed at 1 sun irradiance, before and after the test stress. During the test, two photovoltaic cells are kept at maximum power point and the other two are kept at open circuit voltage point. The method is validated through the results obtained for the monocrystalline silicon solar cell. Daniel Tudor Cotfas, Petru Adrian Cotfas, Dan Ion Floroian, and Laura Floroian Copyright © 2016 Daniel Tudor Cotfas et al. All rights reserved. Adhesion Improvement and Characterization of Magnetron Sputter Deposited Bilayer Molybdenum Thin Films for Rear Contact Application in CIGS Solar Cells Tue, 02 Aug 2016 11:18:28 +0000 http://www.hindawi.com/journals/ijp/2016/2124087/ Molybdenum (Mo) thin films are widely used as rear electrodes in copper indium gallium diselenide (CIGS) solar cells. The challenge in Mo deposition by magnetron sputtering lies in simultaneously achieving good adhesion to the substrates while retaining the electrical and optical properties. Bilayer Mo films, comprising five different thickness ratios of a high pressure (HP) deposited bottom layer and a low pressure (LP) deposited top layer, were deposited on 40 cm × 30 cm soda-lime glass substrates by DC magnetron sputtering. We focus on understanding the effects of the individual layer properties on the resulting bilayer Mo films, such as microstructure, surface morphology, and surface oxidation. We show that the thickness of the bottom HP Mo layer plays a major role in determining the micromechanical and physical properties of the bilayer Mo stack. Our studies reveal that a thicker HP Mo bottom layer not only improves the adhesion of the bilayer Mo, but also helps to improve the film crystallinity along the preferred [] direction. However, the surface roughness and the porosity of the bilayer Mo films are found to increase with increasing bottom layer thickness, which leads to lower optical reflectance and a higher probability for oxidation at the Mo surface. Weimin Li, Xia Yan, Armin G. Aberle, and Selvaraj Venkataraj Copyright © 2016 Weimin Li et al. All rights reserved. Sorbents Coupled to Solar Light TiO2-Based Photocatalysts for Olive Mill Wastewater Treatment Sun, 31 Jul 2016 11:56:37 +0000 http://www.hindawi.com/journals/ijp/2016/8793841/ The aim of this work was to couple physical-chemical approaches with photocatalysis to reduce by a simple, inexpensive way the organic load of olive mill wastewater (OMW), mandatorily prior to the final discharge. Before irradiation, different sorbents were tested to remove part of the organic fraction, monitored by measuring chemical oxygen demand (COD) and polyphenols (PP). Different low-cost, safe materials were tested, that is, Y zeolite (ZY), montmorillonite, and sepiolite. Considerable decrease of organic load was obtained, with the highest abatement (40%) provided by ZY (10 g L−1 in 1 : 10 OMW). Use of the three sorbents, in particular ZY, was convenient compared to commercial activated carbons. UV light photocatalytic tests, performed using P25 TiO2 on ZY-treated OMW, yielded quantitative remediation (ca. 90%). Also solar light provided significative results, PP being lowered by 74% and COD by 56%. Sol-gel anatase TiO2 and N-doped anatase TiO2 were also tested, obtaining good results, around 80% PP and 40% COD. Finally, an integrated approach was experimented by ZY-supported anatase TiO2 (TiO2@ZY). This photoreactive sorbent allowed one-pot treatment of OMW significative abatements of PP (77%) and COD (39%) with only 1 g L−1 material, under solar light. Andrea Speltini, Federica Maraschi, Michela Sturini, Valentina Caratto, Maurizio Ferretti, and Antonella Profumo Copyright © 2016 Andrea Speltini et al. All rights reserved. Evaluation of Hydrocalumite-Like Compounds as Catalyst Precursors in the Photodegradation of 2,4-Dichlorophenoxyacetic Acid Sun, 31 Jul 2016 07:20:30 +0000 http://www.hindawi.com/journals/ijp/2016/5256941/ Three hydrocalumite-like compounds in a Ca/Al ratio of 2 containing nitrate and acetate anions in the interlaminar region were prepared by a simple, economic, and environmentally friendly method. The solids were characterized by X-ray powder diffraction (XRD), thermogravimetric (TG) analysis, nitrogen adsorption-desorption at −196°C, scanning electron microscopy (SEM), infrared spectroscopy (FTIR), and UV-Vis Diffuse Reflectance Spectroscopy (DRS). The catalytic activity of the calcined solids at 700°C was tested in the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) where 57% degradation of 2,4-D (40 ppm) and a mineralization percentage of 60% were accomplished within 150 minutes. The photocatalytic properties were attributed to mayenite hydration, since the oxide ions in the cages are capable of reacting with water to form hydroxide anions capable of breaking down the 2,4-D molecules. Manuel Sánchez-Cantú, Clara Barcelos-Santiago, Claudia M. Gomez, Esthela Ramos-Ramírez, Ma. de Lourdes Ruiz Peralta, Nancy Tepale, Valeria J. González-Coronel, A. Mantilla, and Francisco Tzompantzi Copyright © 2016 Manuel Sánchez-Cantú et al. All rights reserved. Heuristic Storage System Sizing for Optimal Operation of Electric Vehicles Powered by Photovoltaic Charging Station Thu, 28 Jul 2016 13:25:13 +0000 http://www.hindawi.com/journals/ijp/2016/3980284/ This paper discusses the utilisation of PV systems for electric vehicles charging for transportation requirements of smart cities. The gap between PV power output and vehicles charging demand is highly variable. Therefore, there is a need for additional support from a public distribution grid or a storage device in order to handle the residual power. Long term measurement data retrieved from a charging station for 15 vehicles equipped with a PV system were used in the research. Low and high irradiation seasons influenced the PV output. The charging demand of electric vehicles varied over the course of a year and was correlated to weather conditions. Therefore, the sizing and performance of a supportive storage device should be evaluated in a statistical manner using long period observations. Erik Blasius, Erik Federau, Przemyslaw Janik, and Zbigniew Leonowicz Copyright © 2016 Erik Blasius et al. All rights reserved. Multicore PSO Operation for Maximum Power Point Tracking of a Distributed Photovoltaic System under Partially Shading Condition Mon, 25 Jul 2016 11:57:02 +0000 http://www.hindawi.com/journals/ijp/2016/9754514/ This paper identifies the partial shading problem of a PV module using the one-diode model and simulating the characteristics exhibiting multiple-peak power output condition that is similar to a PV array. A modified particle swarm optimization (PSO) algorithm based on the suggested search-agent deployment, retracking condition, and multicore operation is proposed in order to continuously locate the global maximum power point for the PV system. Partial shading simulation results for up to 16 modules in series/parallel formats are presented. A distributed PV system consisting of up to 8 a-silicon thin film PV panels and also having a dedicated DC/DC buck converter on each of the modules is tested. The converter reaches its steady state voltage output in 10 ms. However for MPPT operation, voltage, and current measurement interval is set to 20 ms to avoid unnecessary noise from the entire electric circuit. Based on the simulation and experiment results, each core of the proposed PSO operation should control no more than 4 PV modules in order to have the maximum tracking accuracy and minimum overall tracking time. Tracking for the global maximum power point of a distributed PV system under various partial shading conditions can be done within 1.3 seconds. Ru-Min Chao, Ahmad Nasirudin, I-Kai Wang, and Po-Lung Chen Copyright © 2016 Ru-Min Chao et al. All rights reserved. Solar Energy Validation for Strategic Investment Planning via Comparative Data Mining Methods: An Expanded Example within the Cities of Turkey Mon, 04 Jul 2016 12:32:57 +0000 http://www.hindawi.com/journals/ijp/2016/8506193/ Energy supply together with the data management is one of the key challenges of our century. Specifically, to decrease the climate change effects as energy requirement increases day by day poses a serious dilemma. It can be adequately reconciled with innovative data management in (renewable) energy technologies. The new environmental-friendly planning methods and investments that are discussed by researchers, governments, NGOs, and companies will give the basic and most important variables in shaping the future. We use modern data mining methods (SOM and -Means) and official governmental statistics for clustering cities according to their consumption similarities, the level of welfare, and growth rate and compare them with their potential of renewable resources with the help of Rapid Miner 5.1 and MATLAB software. The data mining was chosen to make the possible secret relations visible within the variables that can be unpredictable at first sight. Here, we aim to see the success level of the chosen algorithms in validation process simultaneously with the utilized software. Additionally, we aim to improve innovative approach for decision-makers and stakeholders about which renewable resource is the most suitable for an exact region by taking care of different variables at the same time. Oya H. Yuregir and Cagri Sagiroglu Copyright © 2016 Oya H. Yuregir and Cagri Sagiroglu. All rights reserved. Solar Energy for a Solvent Recovery Stage in a Biodiesel Production Process Mon, 04 Jul 2016 09:52:00 +0000 http://www.hindawi.com/journals/ijp/2016/1048095/ Recent research and development of clean energy have become essential due to the global climate change problem, which is caused largely by fossil fuels burning. Therefore, biodiesel, a renewable and ecofriendly biofuel with less environmental impact than diesel, continues expanding worldwide. The process for biodiesel production involves a significant energy demand, specifically in the methanol recovery stage through a flash separator and a distillation column. Traditionally, the energy required for this process is supplied by fossil fuels. It represents an opportunity for the application of renewable energy. Hence, the current study presents a system of thermal energy storage modeled in TRNSYS® and supported by simulations performed in ASPEN PLUS®. The aim of this research was to supply solar energy for a methanol recovery stage in a biodiesel production process. The results highlighted that it is feasible to meet 91% of the energy demand with an array of 9 parabolic trough collectors. The array obtained from the simulation was 3 in series and 3 in parallel, with a total area of 118.8 m2. It represents an energy saving of 70 MWh per year. José A. León, Gisela Montero, Marcos Coronado, José R. Ayala, Conrado García, Aníbal Luna, and Ana M. Vázquez Copyright © 2016 José A. León et al. All rights reserved. Investigation of Boron Thermal Diffusion from Atmospheric Pressure Chemical Vapor Deposited Boron Silicate Glass for N-Type Solar Cell Process Application Sun, 03 Jul 2016 11:35:37 +0000 http://www.hindawi.com/journals/ijp/2016/8183673/ An atmospheric pressure chemical vapor deposition (AP-CVD) system has been newly developed for boron silicate glass (BSG) film deposition dedicating to solar cell manufacturing. Using the system, thermal boron diffusion from the BSG film is investigated and confirmed in terms of process stability for surface property before BSG deposition and BSG thickness. No degradation in carrier lifetime is also confirmed. A boron diffusion simulator has been newly developed and demonstrated for optimization of this process. Then, the boron thermal diffusion from AP-CVD BSG is considered to be the suitable method for N-type silicon solar cell manufacturing. Ikuo Kurachi and Kentaro Yoshioka Copyright © 2016 Ikuo Kurachi and Kentaro Yoshioka. All rights reserved. Data-Driven Photovoltaic System Modeling Based on Nonlinear System Identification Thu, 30 Jun 2016 07:15:33 +0000 http://www.hindawi.com/journals/ijp/2016/2923731/ Solar photovoltaic (PV) energy sources are rapidly gaining potential growth and popularity compared to conventional fossil fuel sources. As the merging of PV systems with existing power sources increases, reliable and accurate PV system identification is essential, to address the highly nonlinear change in PV system dynamic and operational characteristics. This paper deals with the identification of a PV system characteristic with a switch-mode power converter. Measured input-output data are collected from a real PV panel to be used for the identification. The data are divided into estimation and validation sets. The identification methodology is discussed. A Hammerstein-Wiener model is identified and selected due to its suitability to best capture the PV system dynamics, and results and discussion are provided to demonstrate the accuracy of the selected model structure. Ayedh Alqahtani, Mohammad Alsaffar, Mohamed El-Sayed, and Bader Alajmi Copyright © 2016 Ayedh Alqahtani et al. All rights reserved. Evaluation of Shunt Losses in Industrial Silicon Solar Cells Wed, 29 Jun 2016 11:46:08 +0000 http://www.hindawi.com/journals/ijp/2016/8029608/ Shunting is one of the key issues in industrial silicon solar cells which degrade cell performance. This paper presents an approach for investigation of the performance degradation caused by the presence of ohmic extended shunts at various locations in industrial silicon solar cells. Location, nature, and area of the shunts existing in solar cells have been examined by lock-in infrared thermography (LIT). Based on LIT images and experimental dark I-V curves of solar cell, shunted cell has been modeled, from which loss in fill factor and efficiency due to the specific shunt has been obtained. Distributed diode modeling approach of solar cell has been exploited for obtaining simulation results which were supported by experimental measurements. The presented approach is useful to estimate performance reduction due to specific shunts and to quantify losses, which can help in improving the efficiency of solar cell during production by tackling the shunt related problems based on the level of severity and tolerance. P. Somasundaran and R. Gupta Copyright © 2016 P. Somasundaran and R. Gupta. All rights reserved.