International Journal of Photoenergy The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Construction and Testing of Lightweight and Low-Cost Pneumatically Inflated Solar Concentrators Mon, 08 Feb 2016 11:59:07 +0000 Design, construction, and evaluation of a cylindrical-trough solar concentrator with 1.3 m aperture, 2.15 m length, and 0.54 m focal length, with heat-pipe or vacuum tube receiver and one axis tracking system, are presented. Design performance was tested under ASHRAE standard 93-1986 (RA 91). The concentrator system is lightweight and inexpensive since it was made of polymeric membranes and was pneumatically inflated to acquire its cylindrical shape achieving good optical quality. Further implementation of a flat and a cylindrical extension of the concentrating mirror as secondary mirrors was incorporated into the concentrator design in order to compensate for seasonal variations of collected radiation. Total initial investment of $163.30 or $58.5/m2 and efficiencies ranging from 33 to 25% for 25 up to 65°C show an excellent cost-performance ratio. Construction, costs, and efficiencies obtained by us and developed by other groups are compared to emphasize the high cost/benefit ratio and efficiencies of this approach. F. M. I. De Los Santos-García, Y. Nahmad-Molinari, J. Nieto-Navarro, C. Alanís-Ruiz, and Felipe Patiño-Jiménez Copyright © 2016 F. M. I. De Los Santos-García et al. All rights reserved. Behavior of Photovoltaic System during Solar Eclipse in Prague Tue, 02 Feb 2016 14:17:09 +0000 PV power plants have been recently installed in very large scale. So the effects of the solar eclipse are of big importance especially for grid connected photovoltaic (PV) systems. There was a partial solar eclipse in Prague on 20th March 2015. We have evaluated the data from our facility in order to monitor the impact of this natural phenomenon on the behavior of PV system, and these results are presented in the paper. The behavior of PV system corresponds with the theoretical assumption. The power decrease of the PV array corresponds with the relative size of the solar eclipse. - characteristics of the PV panel correspond to the theoretical model presented in our previous work. Martin Libra, Pavel Kouřím, and Vladislav Poulek Copyright © 2016 Martin Libra et al. All rights reserved. Electron Paramagnetic Resonance Examination of Free Radical Formation in Salicylic Acid and Urea Exposed to UV Irradiation Tue, 02 Feb 2016 06:17:41 +0000 Free radicals formed by UV irradiation of the two magistral formulas applied on the skin, salicylic acid and urea, were examined by X-band (9.3 GHz) EPR spectroscopy. The influence of the time of UVA (315–400 nm) irradiation on free radical properties and concentrations in the drug samples was determined. The nonirradiated magistral formula did not contain free radicals. Amplitudes () and linewidths () of EPR spectra were analysed. Fast spin-lattice relaxation process existed in the tested drugs. UV irradiation did not change spin-lattice interactions in the tested magistral formula. Concentrations of free radicals formed by UV irradiation in salicylic acid and urea were ~1017–1018 spins/g. The strongest formation of free radicals under UV irradiation was observed for salicylic acid than for urea. Free radical concentration in salicylic acid increased with the increase of UV irradiation time from 15 minutes to 30 minutes, and after its value remained unchanged. The increase of free radical concentration in urea with UV irradiation time was stated. Salicylic acid is characterized with higher photosensitivity than urea. Salicylic acid, urea, and the skin treated by them should not be stored on UV exposure. The usefulness of EPR spectroscopy to optimize storage conditions of recipe drugs was conformed. Paweł Ramos and Barbara Pilawa Copyright © 2016 Paweł Ramos and Barbara Pilawa. All rights reserved. Solar Thermochemical Hydrogen Production via Terbium Oxide Based Redox Reactions Tue, 26 Jan 2016 11:25:15 +0000 The computational thermodynamic modeling of the terbium oxide based two-step solar thermochemical water splitting (Tb-WS) cycle is reported. The 1st step of the Tb-WS cycle involves thermal reduction of TbO2 into Tb and O2, whereas the 2nd step corresponds to the production of H2 through Tb oxidation by water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined via HSC simulations. Influence of oxygen partial pressure in the inert gas on thermal reduction of TbO2 and effect of water splitting temperature () on Gibbs free energy related to the H2 production step were examined in detail. The cycle () and solar-to-fuel energy conversion () efficiency of the Tb-WS cycle were determined by performing the second-law thermodynamic analysis. Results obtained indicate that and increase with the decrease in oxygen partial pressure in the inert flushing gas and thermal reduction temperature (). It was also realized that the recuperation of the heat released by the water splitting reactor and quench unit further enhances the solar reactor efficiency. At  K, by applying 60% heat recuperation, maximum of 39.0% and of 47.1% for the Tb-WS cycle can be attained. Rahul Bhosale, Anand Kumar, and Fares AlMomani Copyright © 2016 Rahul Bhosale et al. All rights reserved. Theoretical Study of the π-Bridge Influence with Different Units of Thiophene and Thiazole in Coumarin Dye-Sensitized Solar Cells Mon, 18 Jan 2016 16:27:35 +0000 Eight coumarin derivative dyes were studied by varying the π-bridge size with different thiophene and thiazole units for their potential use in dye-sensitized solar cells (DSSC). Geometry optimization, the energy levels and electron density of the Highest Occupied Molecular Orbital and the Lowest Unoccupied Molecular Orbital, and ultraviolet-visible absorption spectra were calculated by Density Functional Theory (DFT) and Time-Dependent-DFT. All molecular properties were analyzed to decide which dye was the most efficient. Furthermore, chemical reactivity parameters, such as chemical hardness, electrophilicity index, and electroaccepting power, were obtained and analyzed, whose values predicted the properties of the dyes in addition to the rest of the studied molecular properties. Our calculations allow us to qualitatively study dye molecules and choose the best for use in a DSSC. The effects of π-bridges based on thiophenes, thiazoles, and combinations of the two were reviewed; dyes with three units mainly of thiazole were chosen as the best photosensitizers for DSSC. Rody Soto-Rojo, Jesús Baldenebro-López, and Daniel Glossman-Mitnik Copyright © 2016 Rody Soto-Rojo et al. All rights reserved. Design, Fabrication, and Efficiency Study of a Novel Solar Thermal Water Heating System: Towards Sustainable Development Wed, 13 Jan 2016 14:03:11 +0000 This paper investigated a novel loop-heat-pipe based solar thermal heat-pump system for small scale hot water production for household purposes. The effective use of solar energy is hindered by the intermittent nature of its availability, limiting its use and effectiveness in domestic and industrial applications especially in water heating. The easiest and the most used method is the conversion of solar energy into thermal energy. We developed a prototype solar water heating system for experimental test. We reported the investigation of solar thermal conversion efficiency in different seasons which is 29.24% in summer, 14.75% in winter, and 15.53% in rainy season. This paper also discusses the DC heater for backup system and the current by using thermoelectric generator which are 3.20 V in summer, 2.120 V in winter, and 1.843 V in rainy season. This solar water heating system is mostly suited for its ease of operation and simple maintenance. It is expected that such novel solar thermal technology would further contribute to the development of the renewable energy (solar) driven heating/hot water service and therefore lead to significant environmental benefits. M. Z. H. Khan, M. R. Al-Mamun, S. Sikdar, P. K. Halder, and M. R. Hasan Copyright © 2016 M. Z. H. Khan et al. All rights reserved. Influence of Acid Modification Multiwall Carbon Nanotube Counter Electrodes on the Glass and Flexible Dye-Sensitized Solar Cell Performance Mon, 11 Jan 2016 07:59:02 +0000 Multiwall carbon nanotubes (MWCNTs) were modified by acids (H2SO4 : HNO3) for generating active groups on the nanotube surface. Unmodified- and modified-carbon nanotubes were coated on the conductive glass and conductive plastic substrates by a slurry paste method, and they were used as the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). Scanning electron microscopy reveals that carbon nanotubes are evenly deposited on the conductive glass. The efficiency of the glass based DSSCs of unmodified- and modified-carbon nanotubes and Pt CEs is ~4.73%, ~5.66%, and ~6.08%, respectively. The efficiency of the plastic based DSSCs of the unmodified- and modified-carbon nanotubes CEs is ~0.80% and ~2.11%, respectively. The voltammogram and electrochemical impedance spectroscopy results suggest that the superior performance of the modified-carbon nanotubes DSSCs is attributable to the high electrocatalytic activity and the low charge-transfer resistance of the modified-carbon nanotubes film over the unmodified-carbon nanotubes film. Wasan Maiaugree, Samuk Pimanpang, Wirat Jarernboon, and Vittaya Amornkitbamrung Copyright © 2016 Wasan Maiaugree et al. All rights reserved. Competitiveness Level of Photovoltaic Solar Systems in Ouagadougou (Burkina Faso): Study Based on the Domestic Electric Meters Calibration Tue, 05 Jan 2016 13:31:14 +0000 The mean cost price of electricity in Burkina Faso at the end of the last quarter of 2012 was 158 FCFA/kWh for a country where more than 46% of the population lives below the national poverty threshold. To look for solution to that problem, the resort to photovoltaic solar energy is justified for that country. The purpose of this study is to promote the integration of both technical and economical surveys in solar energy preliminary projects in Ouagadougou. To reach that, investigations were carried out in some households and attention was paid from the calibration of the domestic electric meters. Energy demands collected within each household allow us to design a corresponding solar kit through optimization rules. An estimate was edited and financial viability study for each household was also carried out thereafter. In this study, only households using the national electricity network calibration meter on their disadvantage favorably answered to all financial indicators and appear as the only one that could profit from such project. This work is helpful to note that photovoltaic solar energy still stays at a primitive level of competitiveness compared to conventional energy resources for small systems in Ouagadougou. Konan Lambert Amani, Raguilignaba Sam, and François Zougmoré Copyright © 2016 Konan Lambert Amani et al. All rights reserved. Design and Implementation of Automatic Wheat Mower Based on Smart Sensor Fed by a Photovoltaic Mon, 04 Jan 2016 11:40:34 +0000 The biggest problems of our time are environmental pollution and the reduction of fossil fuel resources. In recent years, photovoltaic (PV) has started to be used efficiently in order to produce electrical energy from solar energy throughout the world. In this study, a wheat mover machine taking its energy with PV technology transformation from the sun was designed supported by smart sensors. The designed vehicle was tested in two wheat fields in Sivas in Turkey. It was seen that daily average sunshine rates were not lower than 700 Watt/m2 during the testing dates and time. The amounts of electrical charge used to mow 5 m2 and 50 m2 areas are obtained as 500 mAh and 3395 mAh, respectively. Also maximum power is calculated from used PV panel as 26.15 Watt during the day of the experiments. The range of solar radiation intensity is found 4.5 kWh/m2/day at the studied kWh which was 0.140 USD on the date of November 2015. This system is 94.5% more economic than conventional mowers over an area of 1000 m2. Hikmet Esen, Abdullah Kapicioglu, and Onur Ozsolak Copyright © 2016 Hikmet Esen et al. All rights reserved. Regression Model to Predict Global Solar Irradiance in Malaysia Thu, 31 Dec 2015 16:03:18 +0000 A novel regression model is developed to estimate the monthly global solar irradiance in Malaysia. The model is developed based on different available meteorological parameters, including temperature, cloud cover, rain precipitate, relative humidity, wind speed, pressure, and gust speed, by implementing regression analysis. This paper reports on the details of the analysis of the effect of each prediction parameter to identify the parameters that are relevant to estimating global solar irradiance. In addition, the proposed model is compared in terms of the root mean square error (RMSE), mean bias error (MBE), and the coefficient of determination () with other models available from literature studies. Seven models based on single parameters (PM1 to PM7) and five multiple-parameter models (PM7 to PM12) are proposed. The new models perform well, with RMSE ranging from 0.429% to 1.774%, ranging from 0.942 to 0.992, and MBE ranging from −0.1571% to 0.6025%. In general, cloud cover significantly affects the estimation of global solar irradiance. However, cloud cover in Malaysia lacks sufficient influence when included into multiple-parameter models although it performs fairly well in single-parameter prediction models. Hairuniza Ahmed Kutty, Muhammad Hazim Masral, and Parvathy Rajendran Copyright © 2015 Hairuniza Ahmed Kutty et al. All rights reserved. Effect of Installation of Solar Collector on Performance of Balcony Split Type Solar Water Heaters Thu, 31 Dec 2015 15:46:15 +0000 The influences of surface orientation and slope of solar collectors on solar radiation collection of balcony split type solar water heaters for six cities in China were analyzed by employing software TRNSYS. The surface azimuth had greater effect on solar radiation collection in high latitude regions. For deviation of the surface slope angle within ±20° around the optimized angle, the variation of the total annual collecting solar radiation was less than 5%. However, with deviation of 70° to 90°, the variation was up to 20%. The effects of water cycle mode, reverse slope placement of solar collector, and water tank installation height on system efficiency were experimentally studied. The thermal efficiencies of solar water heater with single row horizontal arrangement all-glass evacuated tubular collector were higher than those with vertical arrangement at the fixed surface slope angle of 90°. Compared with solar water heaters with flat-plate collector under natural circulation, the system thermal efficiency was raised up to 63% under forced circulation. For collector at reverse slope placement, the temperature-based water stratification in water tank deteriorated, and thus the thermal efficiency became low. For improving the system efficiency, an appropriate installation height of the water tank was suggested. Xu Ji, Ming Li, Weidong Lin, Tufeng Zheng, and Yunfeng Wang Copyright © 2015 Xu Ji et al. All rights reserved. Effect of the Side Chains and Anode Material on Thermal Stability and Performance of Bulk-Heterojunction Solar Cells Using DPP(TBFu)2 Derivatives as Donor Materials Tue, 29 Dec 2015 14:19:36 +0000 An optimized fabrication of bulk-heterojunction solar cells (BHJ SCs) based on previously reported diketopyrrolopyrrole donor, ethyl-hexylated DPP(TBFu)2, as well as two new DPP(TBFu)2 derivatives with ethyl-hexyl acetate and diethyl acetal solubilizing side-chains and PC60BM as an acceptor is demonstrated. Slow gradual annealing of the solar cell causing the effective donor-acceptor reorganization, and as a result higher power conversion efficiency (PCE), is described. By replacing a hole transporting layer PEDOT:PSS with MoO3 we obtained higher PCE values as well as higher thermal stability of the anode contact interface. DPP(TBFu)2 derivative containing ethyl-hexyl acetate solubilizing side-chains possessed the best as-cast self-assembly and high crystallinity. However, the presence of ethyl-hexyl acetate and diethyl acetal electrophilic side-chains stabilizes HOMO energy of isolated DPP(TBFu)2 donors with respect to the ethyl-hexylated one, according to cyclic voltammetry. Alexander Kovalenko, Jana Honová, Martin Vala, Stanislav Luňák, Ladislav Fekete, Petra Horáková, Lenka Dokládalová, Lubomír Kubáč, and Martin Weiter Copyright © 2015 Alexander Kovalenko et al. All rights reserved. Photostability of Loratadine Inclusion Complexes with Natural Cyclodextrins Sun, 27 Dec 2015 06:35:51 +0000 The purpose of this study was to evaluate the photostability of inclusion complexes of the histamine antagonist loratadine (LORA) with -, -, and -cyclodextrins (CDs). Accordingly, binary drug-CD complexes were prepared using the coevaporation method at 1 : 1, 1 : 2, and 1 : 3 stoichiometric ratios, which were characterized by thermal analysis. Subsequently, solutions of the complexes at 500 μg mL−1 in HCl 0.1 M were subjected to irradiation in a photostability chamber for 12 hours, and the content of the remaining active ingredient was quantified by means of high-performance liquid chromatography. It is possible to observe the presence of two products originating from photodegradation (P1 and P2), which were identified in solutions of loratadine with - and -CD. By means of statistical analysis, we conclude that the drug:-CD and drug:-CD (1 : 1) complexes proved to be more efficient in the photostability assay, obtaining a nonsignificant level of degradation and full recovery of LORA. Patricia Elizabeth Rivas-Granizo, Leandro Giorgetti, and Humberto Gomes Ferraz Copyright © 2015 Patricia Elizabeth Rivas-Granizo et al. All rights reserved. Simple Moving Voltage Average Incremental Conductance MPPT Technique with Direct Control Method under Nonuniform Solar Irradiance Conditions Mon, 21 Dec 2015 14:01:15 +0000 A new simple moving voltage average (SMVA) technique with fixed step direct control incremental conductance method is introduced to reduce solar photovoltaic voltage () oscillation under nonuniform solar irradiation conditions. To evaluate and validate the performance of the proposed SMVA method in comparison with the conventional fixed step direct control incremental conductance method under extreme conditions, different scenarios were simulated. Simulation results show that in most cases SMVA gives better results with more stability as compared to traditional fixed step direct control INC with faster tracking system along with reduction in sustained oscillations and possesses fast steady state response and robustness. The steady state oscillations are almost eliminated because of extremely small around maximum power (MP), which verify that the proposed method is suitable for standalone PV system under extreme weather conditions not only in terms of bus voltage stability but also in overall system efficiency. Amjad Ali, Wuhua Li, and Xiangning He Copyright © 2015 Amjad Ali et al. All rights reserved. How to Control Component Ratio of Conducting Polymer Blend for Organic Photovoltaic Devices by Annealing Mon, 21 Dec 2015 11:36:43 +0000 There are various conducting polymer blends which are used as hole transporting layers (HTL) in organic photovoltaic devices (OPV). The electrical performance of these conducting polymer blends depends crucially on its surface compositions and morphology. In this paper, we studied poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) or PEDOT:PSS as an example of the HTL conducting polymer blends used in OPV. We have investigated the effect of annealing PEDOT:PSS in different atmospheres such as vacuum, N2, and air at different temperatures. It was found that the component ratio of the polymer blend is changing with annealing temperature and atmosphere. PSS/PEDOT ratio was found to have clear influence on the electrical performance of the material. In practice, we found that annealing can be used as a method to control component ratio of the HTL conducting polymer blend to achieve better electrical performance in OPV devices. The component ratio changes of the polymer with annealing were understood by X-ray photoelectron spectroscopy (XPS). Annealing in N2 atmosphere at 220°C for 1 hour gave best electrical performance for the polymer and the PSS/PEDOT ratio at that condition was close to 1.1, while the initial ratio was 2.5. Optimizing HTL layer by simple conductivity measurement does not guarantee best performance in OPV since surface property changes during annealing might affect the deposition of successive active layers on top and thus final device. Thus we have optimized annealing condition of the HTL layer according to the OPV performance itself. Bobins Augustine and Tapio Fabritius Copyright © 2015 Bobins Augustine and Tapio Fabritius. All rights reserved. Removal of Refractory Organics from Biologically Treated Landfill Leachate by Microwave Discharge Electrodeless Lamp Assisted Fenton Process Wed, 16 Dec 2015 06:56:32 +0000 Biologically treated leachate usually contains considerable amount of refractory organics and trace concentrations of xenobiotic pollutants. Removal of refractory organics from biologically treated landfill leachate by a novel microwave discharge electrodeless lamp (MDEL) assisted Fenton process was investigated in the present study in comparison to conventional Fenton and ultraviolet Fenton processes. Conventional Fenton and ultraviolet Fenton processes could substantially remove up to 70% of the refractory organics in a membrane bioreactor treated leachate. MDEL assisted Fenton process achieved excellent removal performance of the refractory components, and the effluent chemical oxygen demand concentration was lower than 100 mg L−1. Most organic matters were transformed into smaller compounds with molecular weights less than 1000 Da. Ten different polycyclic aromatic hydrocarbons were detected in the biologically treated leachate, most of which were effectively removed by MDEL-Fenton treatment. MDEL-Fenton process provides powerful capability in degradation of refractory and xenobiotic organic pollutants in landfill leachate and could be adopted as a single-stage polishing process for biologically treated landfill leachate to meet the stringent discharge limit. Jiuyi Li, Lele Qin, Lei Zhao, Aimin Wang, Yong Chen, Liao Meng, Zhongguo Zhang, Xiujun Tian, and Yanmei Zhou Copyright © 2015 Jiuyi Li et al. All rights reserved. Safety Analysis of Solar Module under Partial Shading Wed, 09 Dec 2015 12:51:44 +0000 Hot spot often occurs in a module when the qualities of solar cells mismatch and bypass diodes are proved to be an efficient alternative to reduce the effect of hot spot. However, these principles choosing a diode are based on the parameters of bypass diodes and PV cells without consideration of the maximum heating power of the shaded cell, which may cause serious consequences. On this basis, this paper presents a new approach to investigate partially shaded cells in different numbers of PV cells and different shading scenarios, including inhomogeneous illumination among solar cells and incomplete shading in one cell, which innovatively combines the same cells or divides one affected cell into many small single cells and then combines the same ones, and analyzes the shaded cell. The results indicate that the maximum power dissipation of the shaded cell occurs at short-circuit conditions. With the number of solar cells increasing, the shaded cell transfers from generating power to dissipating power and there is a maximum point of power dissipation in different shading situations that may lead to severe hot spot. Adding up the heat converted from solar energy, the heating power can be higher. In this case, some improvements about bypass diodes are proposed to reduce hot spot. Wei He, Fengshou Liu, Jie Ji, Shengyao Zhang, and Hongbing Chen Copyright © 2015 Wei He et al. All rights reserved. Design of Solar Optical Fiber Lighting System for Enhanced Lighting in Highway Tunnel Threshold Zone: A Case Study of Huashuyan Tunnel in China Mon, 07 Dec 2015 13:37:15 +0000 In this paper, the principle, structural composition, materials, and characteristics of solar optical fiber lighting system were discussed. The different luminance requirements of different zones of highway tunnel were identified on the basis of the analysis of tunnel lighting considering drivers’ visually self-accommodating physiological function for luminance change. Taken Huashuyan Tunnel of G109 Highway located in Hohhot of Inner Mongolia in China as the case study, the system design of solar optical fiber lighting for enhanced lighting in threshold zone of highway tunnel was made. It was indicated through calculation that the design length of solar optical fiber enhanced lighting was related to the design speed, longitudinal slope, and overhead clearance of the tunnel, and the design luminance of solar optical fiber enhanced lighting was related to the luminance outside the tunnel, the design speed, and the design traffic flow of the tunnel. Luminance analysis of the solar optical fiber lighting system of Huashuyan Tunnel was made based on the on-site experiment. Also, the 3D illuminance simulation results by DIALux software were made to indicate that the solar optical fiber lighting system in Huashuyan Tunnel still well met the enhanced lighting demand even not considering the contribution of LED lighting. Xiaochun Qin, Xuefeng Zhang, Shuai Qi, and Hao Han Copyright © 2015 Xiaochun Qin et al. All rights reserved. Probabilistic Modeling of Partial Shading of Photovoltaic Arrays Mon, 07 Dec 2015 13:35:24 +0000 The probabilistic modeling technique is used in this paper to ascertain the performance of energy conversion of a photovoltaic (PV) array under the influence of partial shading. Three cases of increasing complexity are studied in this paper. The first case is to find the probability density function (pdf) of the maximum power output (MPO) of a single PV module exposed to a random level of solar irradiance. Given that the probability distribution of solar irradiance is known a priori, the pdf of the MPO of the PV module is derived analytically. A Monte Carlo simulation is then conducted to validate the analysis. This is followed in the second case by studying the MPO of an array composed of two series PV modules, each exposed to a random and independent level of irradiance. The third case further involves the effects of bypass diodes which are commonly installed to reduce partial shading losses. Yaw-Juen Wang and Ruey-Long Sheu Copyright © 2015 Yaw-Juen Wang and Ruey-Long Sheu. All rights reserved. Synthesis of CuO/Co3O4 Coaxial Heterostructures for Efficient and Recycling Photodegradation Mon, 30 Nov 2015 13:35:50 +0000 The highly efficient CuO/Co3O4 composite photocatalyst with different morphologies has been synthesized directly on Cu wire mesh by controlling the composition of cobalt-containing solid precursors via a simple hydrothermal method. The structure morphology and composition of the composite photocatalyst have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance spectra. The photocatalytic result shows that the CuO/Co3O4 coaxial heterostructure is easy to recycle and exhibit enhanced photodegradation activity for methylene blue compared to single CuO nanorod arrays under full spectrum solar light irradiation. The enhanced photocatalytic efficiency of the composite could be ascribed to the synergistic effect of CuO and Co3O4. This study provides a general and effective method in the fabrication of 1D composition NRs with sound heterojunctions that show enhancement of photocatalytic performance and facility of recycling. R. X. Chen, S. L. Zhu, J. Mao, Z. D. Cui, X. J. Yang, Y. Q. Liang, and Z. Y. Li Copyright © 2015 R. X. Chen et al. All rights reserved. Parameter Optimization of Single-Diode Model of Photovoltaic Cell Using Memetic Algorithm Thu, 26 Nov 2015 07:21:33 +0000 This study proposes a memetic approach for optimally determining the parameter values of single-diode-equivalent solar cell model. The memetic algorithm, which combines metaheuristic and gradient-based techniques, has the merit of good performance in both global and local searches. First, 10 single algorithms were considered including genetic algorithm, simulated annealing, particle swarm optimization, harmony search, differential evolution, cuckoo search, least squares method, and pattern search; then their final solutions were used as initial vectors for generalized reduced gradient technique. From this memetic approach, we could further improve the accuracy of the estimated solar cell parameters when compared with single algorithm approaches. Yourim Yoon and Zong Woo Geem Copyright © 2015 Yourim Yoon and Zong Woo Geem. All rights reserved. New 1,3,4-Oxadiazole Based Photosensitizers for Dye Sensitized Solar Cells (DSSCs) Thu, 26 Nov 2015 06:05:33 +0000 1,3,4-Oxadiazole based photosensitizers with biphenyl, naphthalene, anthracene, and triphenylamine as the electron-donating moiety were synthesized for solar cell applications. In these photosensitizers, cyano groups were introduced as the electron acceptor and the anchor group because of their high electron-withdrawing ability and strong bonding to the semiconductor. Oxadiazole isomers were used as the π-conjugation system, which bridges the donor-acceptor systems. The electrochemical and optical properties of the sensitizers were investigated both in their native form and upon incorporation into dye sensitized solar cells. The results of UV-visible absorption spectroscopy, electrochemical impedance spectroscopic measurements, and photocurrent voltage characteristics indicate that 1,3,4-oxadiazole pi-spacer with the anthracene moiety has the highest efficiency of 2.58%. Density functional theory was employed to optimize the structures of the sensitizers and the TiO2 cluster. Umer Mehmood, Ibnelwaleed A. Hussein, and Muhammad Daud Copyright © 2015 Umer Mehmood et al. All rights reserved. Evaluation of La-Doped Mesoporous Bioactive Glass as Adsorbent and Photocatalyst for Removal of Methylene Blue from Aqueous Solution Thu, 19 Nov 2015 10:07:04 +0000 A series of La-doped mesoporous bioactive glass (BG-La) materials with excellent biosafety and hypotoxicity have been prepared and tested as adsorbent. The study was aimed to evaluate the possibility of utilizing BG-La for the adsorptive removal of methylene blue (MB) from aqueous solution and test the adsorption and desorption behavior of this new material. The process parameters affecting adsorption behaviors such as pH, contact time, and initial concentration and the photocatalytic degradation of MB were systematically investigated. The result showed that BG-La had excellent removal rate (R) of MB, and BG-La showed better photocatalytic effect than undoped mesoporous bioactive glass (BG). Furthermore, the MB loaded BG-La was easily desorbed with acid solution due to its electronegativity and mesoporous structure. The result indicated that these materials can be employed as candidates for removal of dye pollutant owing to their high removal rate, excellent photocatalytic effect, desorption performance, and their reusability. Liying Li, Huanrui Shi, Lu Chen, Qianxuan Yuan, Xi Chen, and Weijian Lin Copyright © 2015 Liying Li et al. All rights reserved. Improved Photocatalytic Performance of a Novel Fe3O4@SiO2/Bi2SiO5 Hierarchical Nanostructure with Magnetic Recoverability Tue, 17 Nov 2015 14:21:21 +0000 Magnetic Fe3O4@SiO2/Bi2SiO5 composites with a novel hierarchical nanostructure were synthesized by sol-gel and hydrothermal methods and were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). It was found that the introduction of Fe3O4@SiO2 could turn the morphology of Bi2SiO5 from close-grained slab to hollow hierarchical architecture with fabric-structure. The Fe3O4@SiO2/Bi2SiO5 composite showed enhanced photodegradation efficiency for the degradation of reactive brilliant red dye (X-3B) in aqueous solution under simulated sunlight irradiation, as compared with that of commercial P25. In addition, the Fe3O4@SiO2/Bi2SiO5 composite exhibited good magnetic recoverability and excellent photocatalytic stability (no obvious activity loss after recycling tests). Xinxin Zhang, Xiaoli Dong, Baiyu Leng, Hongchao Ma, and Xiufang Zhang Copyright © 2015 Xinxin Zhang et al. All rights reserved. Theoretical and Experimental Optical Evaluation and Comparison of Symmetric 2D CPC and V-Trough Collector for Photovoltaic Applications Tue, 17 Nov 2015 13:32:28 +0000 This paper presents theoretical and experimental optical evaluation and comparison of symmetric Compound Parabolic Concentrator (CPC) and V-trough collector. For direct optical properties comparison, both concentrators were deliberately designed to have the same geometrical concentration ratio (1.96), aperture area, absorber area, and maximum concentrator length. The theoretical optical evaluation of the CPC and V-trough collector was carried out using a ray-trace technique while the experimental optical efficiency and solar energy flux distributions were analysed using an isolated cell PV module method. Results by simulation analysis showed that for the CPC, the highest optical efficiency was 95% achieved in the interval range of 0° to ±20° whereas the highest outdoor experimental optical efficiency was 94% in the interval range of 0° to ±20°. For the V-tough collector, the highest optical efficiency for simulation and outdoor experiments was about 96% and 93%, respectively, both in the interval range of 0° to ±5°. Simulation results also showed that the CPC and V-trough exhibit higher variation in non-illumination intensity distributions over the PV module surface for larger incidence angles than lower incidence angles. On the other hand, the maximum power output for the cells with concentrators varied depending on the location of the cell in the PV module. Damasen Ikwaba Paul Copyright © 2015 Damasen Ikwaba Paul. All rights reserved. TiO2/Halloysite Composites Codoped with Carbon and Nitrogen from Melamine and Their Enhanced Solar-Light-Driven Photocatalytic Performance Mon, 16 Nov 2015 16:23:16 +0000 Carbon (C) and nitrogen (N) codoped anatase TiO2/amorphous halloysite nanotubes (C+N-TiO2/HNTs) were fabricated using melamine as C and N source. The samples prepared by different weight ratios of melamine and TiO2 were investigated by X-ray diffraction (XRD) and UV-vis diffuse reflectance spectrometer. It is shown that the doping amounts of C and N could influence the photocatalytic performance of as-prepared composites. When the weight ratio of melamine/TiO2 is 4.5, the C+N-TiO2/HNTs exhibited the best photocatalytic degradation efficiency of methyl blue (MB) under solar light irradiation. The obtained C+N-TiO2/HNTs were characterized by transmission electron microscopy (TEM), N2 adsorption-desorption isotherm (BET), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectrum (FT-IR). The results showed that the aggregation was effectively reduced, and TiO2 nanoparticles could be uniformly deposited on the surface of HNTs. This leads to an increase of their specific surface area. XPS and FT-IR analyses indicated TiO2 particles were doped successfully with C and N via the linkage of the Ti–O–N, O–Ti–N, and Ti–O–C. Photocatalytic experiments showed that C+N-TiO2/HNTs had higher degradation efficiency of MB than TiO2/HNTs. This makes the composite a potential candidate for the photocatalytic wastewater treatment. Pengcheng Yao, Shuhui Zhong, and Zhurui Shen Copyright © 2015 Pengcheng Yao et al. All rights reserved. Improving Performance of CIGS Solar Cells by Annealing ITO Thin Films Electrodes Mon, 16 Nov 2015 12:50:19 +0000 Indium tin oxide (ITO) thin films were grown on glass substrates by direct current (DC) reactive magnetron sputtering at room temperature. Annealing at the optimal temperature can considerably improve the composition, structure, optical properties, and electrical properties of the ITO film. An ITO sample with a favorable crystalline structure was obtained by annealing in fixed oxygen/argon ratio of 0.03 at 400°C for 30 min. The carrier concentration, mobility, resistivity, band gap, transmission in the visible-light region, and transmission in the near-IR regions of the ITO sample were  cm−3,  cm2/Vs,  Ohm-cm, 3.2 eV, 89.1%, and 94.7%, respectively. Thus, annealing improved the average transmissions (400–1200 nm) of the ITO film by 16.36%. Moreover, annealing a copper-indium-gallium-diselenide (CIGS) solar cell at 400°C for 30 min in air improved its efficiency by 18.75%. The characteristics of annealing ITO films importantly affect the structural, morphological, electrical, and optical properties of ITO films that are used in solar cells. Chuan Lung Chuang, Ming Wei Chang, Nien Po Chen, Chung Chiang Pan, and Chung Ping Liu Copyright © 2015 Chuan Lung Chuang et al. All rights reserved. Substrate Temperature Effect on Charge Transport Performance of ZnO Electron Transport Layer Prepared by a Facile Ultrasonic Spray Pyrolysis in Polymer Solar Cells Mon, 16 Nov 2015 08:19:36 +0000 A novel ultrasonic spray pyrolysis for high-quality ZnO films based on zinc-ammonia solution was achieved in air. To investigate the structural and optical properties as well as the performance of polymer solar cells (PSCs), ZnO films at different substrate temperatures and thicknesses were prepared. The performance of poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) based PSC was found to be improved due to the ZnO films. The crystal structure and roughness of the ZnO films fabricated at different temperatures were found to affect the performance of PSCs. The optimized power conversion efficiency was found to be maximum for PSCs with ZnO films prepared at 200°C. The growth process of these ZnO films is very simple, cost-effective, and compatible for larger-scale PSC preparation. The precursor used for spray pyrolysis is environmentally friendly and helps to achieve ZnO film preparation at a relative low temperature. Jiang Cheng, Rong Hu, Qi Wang, Chengxi Zhang, Zhou Xie, Zhangwen Long, Xin Yang, and Lu Li Copyright © 2015 Jiang Cheng et al. All rights reserved. Highlighting Photocatalytic H2-Production from Natural Seawater and the Utilization of Quasi-Photosynthetic Absorption as Two Ultimate Solutions for CO2 Mitigation Wed, 11 Nov 2015 11:55:35 +0000 This paper reviews five potential solutions for CO2 mitigation and theoretically analyzes related outstanding questions. Emission trading under the global mitigation objectives and policies is in dilemma because reducing emission while utilizing fossil fuels is a difficult balance. CO2 capture and sequestration (CCS) technique offers a comprehensive solution, but it is risky and expensive. Analyses of the 100% renewable energy plan suggest hydrogen as a fuel of zero CO2 emission. Photocatalytic splitting of natural seawater can be an ultimate scheme for the hydrogen production, providing that the associated technological constraints would be overcome. Soil CO2 absorption in the arid regions (terms such absorption “quasi-photosynthetic absorption”) implies a potential solution, but the kinetics and overall importance are undetermined. Further investigations of these unresolved issues are strongly needed to realize the global CO2 mitigation target. Comparing the five potential solutions, photocatalytic H2-production from natural seawater and the utilization of quasi-photosynthetic absorption are highlighted as two ultimate solutions. Wenfeng Wang, Xi Chen, Heng Zhang, Changqing Jing, Yifan Zhang, and Bo Yan Copyright © 2015 Wenfeng Wang et al. All rights reserved. Method to Calculate the Electricity Generated by a Photovoltaic Cell, Based on Its Mathematical Model Simulations in MATLAB Tue, 10 Nov 2015 13:36:13 +0000 This paper presents a practical method for calculating the electrical energy generated by a PV panel (kWhr) through MATLAB simulations based on the mathematical model of the cell, which obtains the “Mean Maximum Power Point” (MMPP) in the characteristic - curve, in response to evaluating historical climate data at specific location. This five-step method calculates through MMPP per day, per month, or per year, the power yield by unit area, then electrical energy generated by PV panel, and its real conversion efficiency. To validate the method, it was applied to Sewage Treatment Plant for a Group of Drinking Water and Sewerage of Yucatan (JAPAY), México, testing 250 Wp photovoltaic panels of five different manufacturers. As a result, the performance, the real conversion efficiency, and the electricity generated by five different PV panels in evaluation were obtained and show the best technical-economic option to develop the PV generation project. Carlos Morcillo-Herrera, Fernando Hernández-Sánchez, and Manuel Flota-Bañuelos Copyright © 2015 Carlos Morcillo-Herrera et al. All rights reserved.