International Journal of Photoenergy The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Advanced Oxidation Processes for Wastewater Treatment 2014 Thu, 27 Aug 2015 06:34:19 +0000 Muruganandham Manickavachagam, Mika Sillanpaa, Meenakshisundaram Swaminathan, and Bashir Ahmmad Copyright © 2015 Muruganandham Manickavachagam et al. All rights reserved. Ozonation of Indigo Carmine Enhanced by Fe/Pimenta dioica L. Merrill Particles Wed, 26 Aug 2015 13:34:42 +0000 Green synthesis of metallic particles has become an economic way to improve and protect the environment by decreasing the use of toxic chemicals and eliminating dyes. The synthesis of metal particles is gaining more importance due to its simplicity, rapid rate of synthesis of particles, and environmentally friendly. The present work aims to report a novel and environmentally friendly method for the synthesis of iron particles using deoiled Pimenta dioica L. Merrill husk as support. The indigo carmine removal efficiency by ozonation and catalyzed ozonation is also presented. Synthesized materials were characterized by N2 physisorption and scanning electron microscopy (SEM/EDS). By UV-Vis spectrophotometry the removal efficiency of indigo carmine was found to be nearly 100% after only 20 minutes of treatment under pH 3 and with a catalyst loading of 1000 mgL−1. Analytical techniques such as determination of the total organic carbon content (TOC) and chemical oxygen demand (COD) showed that iron particles supported on deoiled Pimenta dioica L. Merrill husk can be efficiently employed to degrade indigo carmine and achieved a partial mineralization (conversion to CO2 and H2O) of the molecule. From the results can be inferred that the prepared biocomposite increases the hydroxyl radicals generation. Teresa Torres-Blancas, Gabriela Roa-Morales, Carlos Barrera-Díaz, Fernando Ureña-Nuñez, Julian Cruz-Olivares, Patricia Balderas-Hernandez, and Reyna Natividad Copyright © 2015 Teresa Torres-Blancas et al. All rights reserved. Water and Wastewater Disinfection with Peracetic Acid and UV Radiation and Using Advanced Oxidative Process PAA/UV Wed, 26 Aug 2015 07:31:54 +0000 The individual methods of disinfection peracetic acid (PAA) and UV radiation and combined process PAA/UV in water (synthetic) and sanitary wastewater were employed to verify the individual and combined action of these advanced oxidative processes on the effectiveness of inactivation of microorganisms indicators of fecal contamination E. coli, total coliforms (in the case of sanitary wastewater), and coliphages (such as virus indicators). Under the experimental conditions investigated, doses of 2, 3, and 4 mg/L of PAA and contact time of 10 minutes and 60 and 90 s exposure to UV radiation, the results indicated that the combined method PAA/UV provided superior efficacy when compared to individual methods of disinfection. Jeanette Beber de Souza, Fernanda Queiroz Valdez, Rhuan Felipe Jeranoski, Carlos Magno de Sousa Vidal, and Grasiele Soares Cavallini Copyright © 2015 Jeanette Beber de Souza et al. All rights reserved. Novel Electrochemical Treatment of Spent Caustic from the Hydrocarbon Industry Using Ti/BDD Tue, 25 Aug 2015 13:56:34 +0000 During the crude oil refining process, NaOH solutions are used to remove H2S, H2, and sulfur compounds from different hydrocarbon streams. The residues obtained are called “spent caustics.” These residues can be mixed with those obtained in other processes, adding to its chemical composition naphthenic acids and phenolic compounds, resulting in one of the most dangerous industrial residues. In this study, the use of electrochemical technology (ET), using BDD with Ti as substrate (Ti/BDD), is evaluated in electrolysis of spent caustic mixtures, obtained through individual samples from different refineries. In this way, the Ti/BDD’s capability of carrying out the electrochemical destruction of spent caustics in an acidic medium is evaluated having as key process a chemical pretreatment phase. The potential production of •OHs, as the main reactive oxygen species electrogenerated over Ti/BDD surface, was evaluated in HCl and H2SO4 through fluorescence spectroscopy, demonstrating the reaction medium’s influence on its production. The results show that the hydrocarbon industry spent caustics can be mineralized to CO2 and water, driving the use of ET and of the Ti/BDD to solve a real problem, whose potential and negative impact on the environment and on human health is and has been the environmental agencies’ main focus. Alejandro Medel, Erika Méndez, José L. Hernández-López, José A. Ramírez, Jesús Cárdenas, Roberto F. Frausto, Luis A. Godínez, Erika Bustos, and Yunny Meas Copyright © 2015 Alejandro Medel et al. All rights reserved. Determination of Biological Treatability Processes of Textile Wastewater and Implementation of a Fuzzy Logic Model Tue, 25 Aug 2015 13:36:28 +0000 This study investigated the biological treatability of textile wastewater. For this purpose, a membrane bioreactor (MBR) was utilized for biological treatment after the ozonation process. Due to the refractory organic contents of textile wastewater that has a low biodegradability capacity, ozonation was implemented as an advanced oxidation process prior to the MBR system to increase the biodegradability of the wastewater. Textile wastewater, oxidized by ozonation, was fed to the MBR at different hydraulic retention times (HRT). During the process, color, chemical oxygen demand (COD), and biochemical oxygen demand (BOD) removal efficiencies were monitored for 24-hour, 12-hour, 6-hour, and 3-hour retention times. Under these conditions, 94% color, 65% COD, and 55% BOD removal efficiencies were obtained in the MBR system. The experimental outputs were modeled with multiple linear regressions (MLR) and fuzzy logic. MLR results suggested that color removal is more related to COD removal relative to BOD removal. A surface map of this issue was prepared with a fuzzy logic model. Furthermore, fuzzy logic was employed to the whole modeling of the biological system treatment. Determination coefficients for COD, BOD, and color removal efficiencies were 0.96, 0.97, and 0.92, respectively. Harun Akif Kabuk, Yasar Avsar, S. Levent Kuzu, Fatih Ilhan, and Kubra Ulucan Copyright © 2015 Harun Akif Kabuk et al. All rights reserved. Removal of Polyvinyl Alcohol in Aqueous Solutions Using an Innovative Paired Photoelectrochemical Oxidative System in a Divided Electrochemical Cell Tue, 25 Aug 2015 12:35:25 +0000 This study evaluates the performance of an innovative paired photoelectrochemical oxidative system fabricated in our laboratory to determine the removal efficiency of polyvinyl alcohol (PVA) in aqueous solutions. An innovative paired photoelectrochemical oxidative system employed metal redox mediators with high redox potential for anodic oxidation (MEO process) and UV assisted photoelectrochemical oxidation (PEO process) for cathodic oxidation in a divided electrochemical cell. Several parameters were investigated to characterize the removal efficiency of PVA, such as the current density, initial Ce(III) concentration, nitric acid concentration, oxygen flow rate, and UV irradiation intensity. The effects of these parameters on the specific energy consumption were also investigated. Additionally, the conversion yield of Ce(IV) concentration and the electrogeneration of H2O2 were calculated in this study. The optimum current density, initial Ce(III) concentration, nitric acid concentration, oxygen flow rate, and UV irradiation intensity were found to be 3 mA cm−2, 0.01 M, 0.3 M, 500 cm3 min−1, and 1.2 mW cm−2, respectively. The synergistic effect of combination process of MEO and PEO would be as a promising alternative for the removal efficiency of PVA. Kai-Yu Huang, Chih-Ta Wang, Wei-Lung Chou, and Chi-Min Shu Copyright © 2015 Kai-Yu Huang et al. All rights reserved. Design, Development, and Analysis of a Densely Packed 500x Concentrating Photovoltaic Cell Assembly on Insulated Metal Substrate Thu, 20 Aug 2015 11:53:09 +0000 The paper presents a novel densely packed assembly for high concentrating photovoltaic applications, designed to fit 125x primary and 4x secondary reflective optics. This assembly can accommodate 144 multijunction cells and is one of the most populated modules presented so far. Based on the thermal simulation results, an aluminum-based insulated metal substrate has been used as baseplate; this technology is commonly exploited for Light Emitting Diode applications, due to its optimal thermal management. The original outline of the conductive copper layer has been developed to minimize Joule losses by reducing the number of interconnections among the cells in series. Oversized Schottky diodes have been employed for bypassing purposes. The whole design fits the IPC-2221 requirements. The plate has been manufactured using standard electronic processes and then characterized through an indoor test and the results are here presented and commented on. The assembly achieves a fill factor above 80% and an efficiency of 29.4% at 500x, less than 2% lower than that of a single cell commercial receiver. The novel design of the conductive pattern is conceived to decrease the power losses and the deployment of an insulated metal substrate represents an improvement towards the awaited cost-cutting for high concentrating photovoltaic technologies. Leonardo Micheli, Nabin Sarmah, K. S. Reddy, Xichun Luo, and Tapas K. Mallick Copyright © 2015 Leonardo Micheli et al. All rights reserved. Thermal Analysis of Direct Liquid-Immersed Solar Receiver for High Concentrating Photovoltaic System Wed, 12 Aug 2015 06:40:16 +0000 Concentrator solar cells that operate at high solar concentration level must be cooled. In this paper, direct liquid immersion cooling of triple-junction solar cells (InGaP/InGaAs/Ge) is proposed as a heat dissipation solution for dense-array high concentrating photovoltaic (HCPV) systems. The advantages of triple-junction CPV cells immersed in a circulating dielectric liquid and dish HCPV technology are integrated into a CPV system to improve the system electrical conversion efficiency. An analytical model for the direct liquid-immersed solar receiver with triple-junction CPV cells is presented. The main outputs of the model are the components temperatures of the receiver and the system electrical efficiency. The influence of concentration factor, mass flow rate, and inlet liquid temperature on the operating temperature of the triple-junction CPV cells and the system electrical conversion efficiency are discussed. It is shown that the system electrical conversion efficiency is very high for a wide range of operating conditions. The three operating parameters have a major effect on the operating temperature of the triple-junction CPV cells and, by extension, system output power. The flow rate selection should match concentration factor to keep the triple-junction CPV cells temperature lower and increase the electrical conversion efficiency of the dense-array HCPV system. Xinyue Han, Qian Wang, Jun Zheng, and Jian Qu Copyright © 2015 Xinyue Han et al. All rights reserved. Construction and Optical Testing of Inflatable Membrane Mirror Using Structured Light Technique Sun, 09 Aug 2015 07:11:03 +0000 Construction and characterization of an inflatable mirror prototype made out of flexible polymeric membranes are being presented. Surfaces were curved by imposing a slight excess of air pressure. Lightweighted, lowcost, and commercially available materials were selected in order to produce solar concentration elements at competitive prices. In this sense, large-area, image-forming mirrors with low optical acuity were achieved by concentration purposes. Optical characterization of the mirror’s shape at a given pressure or curvature radius was done by means of a structuredlight technique with a resolution of 0.1 mm finding a conical shape acquired by the inflated mirror as the best approximation. Concentration ratio achieved for a focal length of 5068 mm was of 25.1 suns, making a promising approach for lowering initial investment costs in applications such as hot-water, parabolic dish with Stirling engines, or concentrated photovoltaic electricity generation. Felipe Patiño-Jiménez, Yuri Nahmad-Molinari, Víctor Iván Moreno-Oliva, Fátima De Los Santos-García, and Agustin Santiago-Alvarado Copyright © 2015 Felipe Patiño-Jiménez et al. All rights reserved. Recent Research Progress in Solar Thermal Conversion Theory and Applications Tue, 04 Aug 2015 13:33:37 +0000 Gang Pei, Yuehong Su, Sauro Filippeschi, and Hongfei Zheng Copyright © 2015 Gang Pei et al. All rights reserved. Performance Investigation and Structure Optimization of a Flat Dual-Function Solar Collector Tue, 04 Aug 2015 11:37:55 +0000 The performance of a dual-function solar collector (DFSC) that can work as either water heater or air heater depending on seasonal requirement is investigated via both experimental and numerical approaches in this paper. The numerical results are well consistent with the experimental results. Daily efficiency of the thermosiphon system with DFSC is more than 55% in water heating mode and the instantaneous air heating efficiency of the collector reaches 60%. The effects of inner parameters on the thermal efficiency of the collector are analyzed by numerical simulations of the operation of DFSC in two working modes. It is found that the depths of the two air channels in DFSC have an optimal range suitable for both working modes. The thickness of back insulation should be no less than 0.06 m to prevent heat loss via backboard, and the diameter and number of copper tubes show notable effect on the efficiency of DFSC in water heating mode but slight effect in air heating mode. Jinwei Ma, Haitao Wang, Yanping Wang, Wei Sun, and Jie Ji Copyright © 2015 Jinwei Ma et al. All rights reserved. A Study on Thermal Performance of a Novel All-Glass Evacuated Tube Solar Collector Manifold Header with an Inserted Tube Tue, 04 Aug 2015 11:30:38 +0000 A novel all-glass evacuated tube collector manifold header with an inserted tube is proposed in this paper which makes water in all-glass evacuated solar collector tube be forced circulated to improve the performance of solar collector. And a dynamic numerical model was presented for the novel all-glass evacuated tube collector manifold header water heater system. Also, a test rig was built for model validation and comparison with traditional all-glass evacuated tube collector. The experiment results show that the efficiency of solar water heater with a novel collector manifold header is higher than traditional all-glass evacuated tube collector by about 5% and the heat transfer model of water heater system is valid. Based on the model, the relationship between the average temperature of water tank and inserted tube diameter (water mass flow) has been studied. The results show that the optimized diameter of inserted tube is 32 mm for the inner glass with the diameter of 47 mm and the water flow mass should be less than 1.6 Kg/s. Jichun Yang, Qingyang Jiang, Jingxin Hou, and Chenglong Luo Copyright © 2015 Jichun Yang et al. All rights reserved. Solar Lighting Technologies for Highway Green Rest Areas in China: Energy Saving Economic and Environmental Evaluation Tue, 04 Aug 2015 10:52:00 +0000 In this paper, taking Lushan West Sea highway green rest area in Jiangxi Province of China as the case study, the suitable types, applicability, advantages, and effective methods of solar lighting technologies for highway rest area were determined based on the analysis of characteristics of highway green rest area. It was proved that solar lighting technologies including the natural light guidance system, solar LED lighting, and maximizing natural light penetration were quite suitable for highway rest area in terms of lighting effects and energy and economic efficiency. The illuminance comparison of light guidance system with electrical lighting was made based on the on-site experiment. Also, the feasibility of natural light guidance system was well verified in terms of the lighting demand of the visitor centre in the rest area by the illuminance simulation analysis. The evaluation of the energy saving, economic benefits, and environmental effects of solar lighting technologies for highway rest area was, respectively, made in detail. It was proved that the application of solar technology for green lighting of highway rest facilities not only could have considerable energy saving capacity and achieve high economic benefits, but also make great contributions to the reduction of environment pollution. Xiaochun Qin, Qingchao Wei, Lianjun Wang, and Yi Shen Copyright © 2015 Xiaochun Qin et al. All rights reserved. Improved Optimization Study of Integration Strategies in Solar Aided Coal-Fired Power Generation System Mon, 03 Aug 2015 13:51:09 +0000 Solar aided coal-fired power generation system (SACFPGS) combines solar energy and traditional coal-fired units in a particular way. This study mainly improves the solar thermal storage system. Genetic algorithm is used to optimize the SACFPGS. The best integration approach of the system, the collector area, and the corresponding thermal storage capacity to replace each high-pressure extraction are obtained when the amount of coal saving in unit solar investment per hour is at its largest. System performance before and after the improvement is compared. Results show that the improvement of the thermal storage system effectively increases the economic benefit of the integrated system. Rongrong Zhai, Miaomiao Zhao, Chao Li, Pan Peng, and Yongping Yang Copyright © 2015 Rongrong Zhai et al. All rights reserved. Design and Testing of a Shell-Encapsulated Solar Collector with the Compound Surface Concentrators Mon, 03 Aug 2015 13:50:24 +0000 This paper presents design and testing of a shell-encapsulated solar collector which can be used in north area of China for wall-amounting installation. The designed solar collector is based on the combination of a novel compound curved surface concentrator and an aluminum concentric solar receiver, which is contained in a glass evacuated-tube. As there is no perforative joint between the double-skin glass evacuated-tube and the aluminum concentric solar receiver, the difficulty of vacuum keeping for a glass-metal joint is avoided. The cavity shell provides an additional thermal insulation to reduce heat loss of the designed solar collector. The working principle of the compound curved surface concentrator is described. The ray-tracing results are given to show the effect of deviation angle of the concentrator on its optical efficiency, hence determining its maximum acceptance angle. A prototype of the designed solar collector has been constructed and tested under the sunny winter weather condition. The experimental results indicate that the hot water temperature higher than 80°C with a daily average efficiency of about 45~50% has been achieved at the average ambient temperature below 0°C, so the designed solar collector can produce hot water at a useful temperature in winter. Hongfei Zheng, Gang Wu, Jing Dai, and Yanyan Ma Copyright © 2015 Hongfei Zheng et al. All rights reserved. Theoretical and Experimental Study of Spectral Selectivity Surface for Both Solar Heating and Radiative Cooling Mon, 03 Aug 2015 13:49:08 +0000 A spectral selectivity surface for both solar heating and radiative cooling was proposed. It has a high spectral absorptivity (emissivity) in the solar radiation band and atmospheric window band (i.e., 0.2~3 μm and 8~13 μm), as well as a low absorptivity (emissivity) in other bands aside from the solar radiation and atmospheric window wavelengths (i.e., 3~8 μm or above 13 μm). A type of composite surface sample was trial-manufactured combining titanium-based solar selective absorbing coating with polyethylene terephthalate (TPET). Sample tests showed that the TPET composite surface has clear spectral selectivity in the spectra of solar heating and radiation cooling wavelengths. The equilibrium temperatures of the TPET surface under different sky conditions or different inclination angles of surface were tested at both day and night. Numerical analysis and comparisons among the TPET composite surface and three other typical surfaces were also performed. These comparisons indicated that the TPET composite surface had a relative heat efficiency of 76.8% of that of the conventional solar heating surface and a relative temperature difference of 75.0% of that of the conventional radiative cooling surface, with little difference in cooling power. Mingke Hu, Gang Pei, Lei Li, Renchun Zheng, Junfei Li, and Jie Ji Copyright © 2015 Mingke Hu et al. All rights reserved. Photocorrosion Mechanism of TiO2-Coated Photoanodes Mon, 03 Aug 2015 13:09:43 +0000 Atomic layer deposition was used to coat CdS photoanodes with 7 nm thick TiO2 films to protect them from photocorrosion during photoelectrochemical water splitting. Photoelectrochemical measurements indicate that the TiO2 coating does not provide full protection against photocorrosion. The degradation of the film initiates from small pinholes and shows oscillatory behavior that can be explained by an Avrami-type model for photocorrosion that is halfway between 2D and 3D etching. XPS analysis of corroded films indicates that a thin layer of CdS remains present on the surface of the corroded photoanode that is more resilient towards photocorrosion. Arjen Didden, Philipp Hillebrand, Bernard Dam, and Roel van de Krol Copyright © 2015 Arjen Didden et al. All rights reserved. Study on a Mid-Temperature Trough Solar Collector with Multisurface Concentration Mon, 03 Aug 2015 12:59:44 +0000 A new trough solar concentrator which is composed of multiple reflection surfaces is developed in this paper. The concentrator was analyzed firstly by using optical software. The variation curves of the collecting efficiency affected by tracking error and the deviation angle were given out. It is found that the deviation tolerance for the collector tracking system is about 8 degrees when the receiver is a 90 mm flat. The trough solar concentrators were tested under real weather conditions. The experiment results indicate that, the new solar concentrator was validated to have relative good collecting efficiency, which can be more than 45 percent when it operated in more 145°C. It also has the characteristics of rdust, wind, and snow resistance and low tracking precision requirements. Zhengliang Li, Mingxian Chen, Husheng Meng, Zehui Chang, and Hongfei Zheng Copyright © 2015 Zhengliang Li et al. All rights reserved. Numerical and Experimental Study on Energy Performance of Photovoltaic-Heat Pipe Solar Collector in Northern China Mon, 03 Aug 2015 12:51:47 +0000 Several studies have found that the decrease of photovoltaic (PV) cell temperature would increase the solar-to-electricity conversion efficiency. Water type PV/thermal (PV/T) system was a good choice but it could become freezing in cold areas of Northern China. This paper proposed a simple combination of common-used PV panel and heat pipe, called PV-heat pipe (PV-HP) solar collector, for both electrical and thermal energy generation. A simplified one-dimensional steady state model was developed to study the electrical and thermal performance of the PV-HP solar collector under different solar radiations, water flow rates, and water temperatures at the inlet of manifold. A testing rig was conducted to verify the model and the testing data matched very well with the simulation values. The results indicated that the thermal efficiency could be minus in the afternoon. The thermal and electrical efficiencies decreased linearly as the inlet water temperature and water flow rate increased. The thermal efficiency increased while the electrical efficiency decreased linearly as the solar radiation increased. Hongbing Chen, Xilin Chen, Sai Chu, Lei Zhang, and Yaxuan Xiong Copyright © 2015 Hongbing Chen et al. All rights reserved. Design and Simulation of InGaN - Junction Solar Cell Thu, 30 Jul 2015 13:01:10 +0000 The tunability of the InGaN band gap energy over a wide range provides a good spectral match to sunlight, making it a suitable material for photovoltaic solar cells. The main objective of this work is to design and simulate the optimal InGaN single-junction solar cell. For more accurate results and best configuration, the optical properties and the physical models such as the Fermi-Dirac statistics, Auger and Shockley-Read-Hall recombination, and the doping and temperature-dependent mobility model were taken into account in simulations. The single-junction In0.622Ga0.378N (Eg = 1.39 eV) solar cell is the optimal structure found. It exhibits, under normalized conditions (AM1.5G, 0.1 W/cm2, and 300 K), the following electrical parameters:  mA/cm2, volts, FF = 86.2343%, and %. It was noticed that the minority carrier lifetime and the surface recombination velocity have an important effect on the solar cell performance. Furthermore, the investigation results show that the In0.622Ga0.378N solar cell efficiency was inversely proportional with the temperature. A. Mesrane, F. Rahmoune, A. Mahrane, and A. Oulebsir Copyright © 2015 A. Mesrane et al. All rights reserved. Control of the Gas Flow in an Industrial Directional Solidification Furnace for Production of High Purity Multicrystalline Silicon Ingots Sun, 26 Jul 2015 12:31:38 +0000 A crucible cover was designed as gas guidance to control the gas flow in an industrial directional solidification furnace for producing high purity multicrystalline silicon. Three cover designs were compared to investigate their effect on impurity transport in the furnace and contamination of the silicon melt. Global simulations of coupled oxygen (O) and carbon (C) transport were carried out to predict the SiO and CO gases in the furnace as well as the O and C distributions in the silicon melt. Cases with and without chemical reaction on the cover surfaces were investigated. It was found that the cover design has little effect on the O concentration in the silicon melt; however, it significantly influences CO gas transport in the furnace chamber and C contamination in the melt. For covers made of metal or with a coating on their surfaces, an optimal cover design can produce a silicon melt free of C contamination. Even for a graphite cover without a coating, the carbon concentration in the silicon melt can be reduced by one order of magnitude. The simulation results demonstrate a method to control the contamination of C impurities in an industrial directional solidification furnace by crucible cover design. Lijun Liu, Xiaofang Qi, Wencheng Ma, Zaoyang Li, and Yunfeng Zhang Copyright © 2015 Lijun Liu et al. All rights reserved. Conformational States of the Spiropyran Molecule Thu, 02 Jul 2015 12:37:27 +0000 The form of the potential surface of the ground state was investigated on the basis of indoline spiropyran. As a result of this work the rotamers of an open-ring form of the spiropyran molecule were discovered, and the existence of the most probable rotamers was justified. The 3D potential surface of the ground state of the spiropyran molecule was built. The route of the isomerization of the molecule was discovered and values of barriers for this reaction were found. The part of the isomerization route that is responsible for changing the hybridization of spiroatom from sp3 to sp2 was found. Olha Kovalenko, Petro Kondratenko, and Yuriy Lopatkin Copyright © 2015 Olha Kovalenko et al. All rights reserved. New Energy Materials and Device Application Mon, 29 Jun 2015 06:14:27 +0000 Sheng-Po Chang, Jun Zhu, Shyh-Jer Huang, Hsin-Chieh Yu, Ting-Jen Hsueh, and Hsin-Ying Lee Copyright © 2015 Sheng-Po Chang et al. All rights reserved. Power Quality Experimental Analysis on Rural Home Grid-Connected PV Systems Wed, 24 Jun 2015 11:28:32 +0000 Microgeneration is the small-scale generation of heat or electric power or both, by individuals or buildings to meet their own needs. Recently, microgeneration is being regarded as a means to decentralize the power production of renewable energies, reducing the impacts on the grid caused by unexpected energy demands. Given the increase in microgeneration facilities, determining the quantity of energy produced and the power quality assumes growing importance in low, medium, or high voltage facilities. This paper presents a power quality analysis of two different facilities with photovoltaic generation localized in a rural area of Portugal, describing the voltage and frequency behaviour, the harmonic contents, and the total harmonic distortion. Statistical data are presented regarding the number of voltage events and occurrence of dips and swells in both facilities as a percentage of rated voltage. We conclude that some PV systems can severely affect voltage quality, forcing the grid to work at and even above the maximum voltage standard limit. Rita Jorge Cerqueira Pinto, Sílvio José Pinto Simões Mariano, and Maria do Rosário Alves Calado Copyright © 2015 Rita Jorge Cerqueira Pinto et al. All rights reserved. Optimization of μc-Si1−xGex:H Single-Junction Solar Cells with Enhanced Spectral Response and Improved Film Quality Wed, 24 Jun 2015 07:14:42 +0000 Effects of RF power on optical, electrical, and structural properties of μc-Si1−xGex:H films was reported. Raman and FTIR spectra from μc-Si1−xGex:H films reflected the variation in microstructure and bonding configuration. Unlike increasing the germane concentration for Ge incorporation, low RF power enhanced Ge incorporation efficiency in μc-Si1−xGex:H alloy. By decreasing RF power from 100 to 50 W at a fixed reactant gas ratio, the optical bandgap of μc-Si1−xGex:H was reduced owing to the increase in Ge content from 11.2 to 23.8 at.%, while Ge-related defects and amorphous phase were increased. Consequently, photo conductivity of 1.62 × 10−5 S/cm was obtained for the μc-Si1−xGex:H film deposited at 60 W. By applying 0.9 μm thick μc-Si1−xGex:H absorber with of 48% and [Ge] of 16.4 at.% in the single-junction cell, efficiency of 6.18% was obtained. The long-wavelength response of μc-Si1−xGex:H cell was significantly enhanced compared with the μc-Si:H cell. In the case of tandem cells, 0.24 μm a-Si:H/0.9 μm μc-Si1−xGex:H tandem cell exhibited a comparable spectral response as 0.24 μm a-Si:H/1.4 μm μc-Si:H tandem cell and achieved an efficiency of 9.44%. Yen-Tang Huang, Pei-Ling Chen, Po-Wei Chen, Hung-Jung Hsu, Cheng-Hang Hsu, and Chuang-Chuang Tsai Copyright © 2015 Yen-Tang Huang et al. All rights reserved. Modeling and Maximum Power Point Tracking Techniques of Photovoltaic Systems Thu, 18 Jun 2015 06:35:06 +0000 Marcelo Cabral Cavalcanti, Francisco de Assis dos Santos Neves, Denizar Cruz Martins, Emilio José Bueno Peña, and Euzeli Cipriano dos Santos Júnior Copyright © 2015 Marcelo Cabral Cavalcanti et al. All rights reserved. Superior Photocurrent of Quantum Dot Sensitized Solar Cells Based on PbS : In/CdS Quantum Dots Wed, 17 Jun 2015 07:28:23 +0000 PbS : In and CdS quantum dots (QDs) are sequentially assembled onto a nanocrystalline TiO2 film to prepare a PbS : In/CdS cosensitized photoelectrode for QD sensitized solar cells (QDSCs). The results show that PbS : In/CdS QDs have exhibited a significant effect in the light harvest and performance of the QDSC. In the cascade structure of the electrode, the reorganization of energy levels between PbS and TiO2 forms a stepwise structure of band-edge levels which is advantageous to the electron injection into TiO2. Energy conversion efficiency of 2.3% is achieved with the doped electrode, under the illumination of one sun (AM1.5, 100 mW cm2). Besides, a remarkable short circuit current density (up to 23 mA·cm−2) is achieved in the resulting PbS : In/CdS quantum dot sensitized solar cell, and the related mechanism is discussed. Zongbo Huang and Xiaoping Zou Copyright © 2015 Zongbo Huang and Xiaoping Zou. All rights reserved. Maximum Power Point Tracking Based on Sliding Mode Control Tue, 16 Jun 2015 14:26:34 +0000 Solar panels, which have become a good choice, are used to generate and supply electricity in commercial and residential applications. This generated power starts with the solar cells, which have a complex relationship between solar irradiation, temperature, and output power. For this reason a tracking of the maximum power point is required. Traditionally, this has been made by considering just current and voltage conditions at the photovoltaic panel; however, temperature also influences the process. In this paper the voltage, current, and temperature in the PV system are considered to be a part of a sliding surface for the proposed maximum power point tracking; this means a sliding mode controller is applied. Obtained results gave a good dynamic response, as a difference from traditional schemes, which are only based on computational algorithms. A traditional algorithm based on MPPT was added in order to assure a low steady state error. Nimrod Vázquez, Yuz Azaf, Ilse Cervantes, Eslí Vázquez, and Claudia Hernández Copyright © 2015 Nimrod Vázquez et al. All rights reserved. MPPT Technique Based on Current and Temperature Measurements Tue, 16 Jun 2015 12:49:22 +0000 This paper presents a new maximum power point tracking (MPPT) method based on the measurement of temperature and short-circuit current, in a simple and efficient approach. These measurements, which can precisely define the maximum power point (MPP), have not been used together in other existing techniques. The temperature is measured with a low cost sensor and the solar irradiance is estimated through the relationship of the measured short-circuit current and its reference. Fast tracking speed and stable steady-state operation are advantages of this technique, which presents higher performance when compared to other well-known techniques. Eduardo Moreira Vicente, Robson Luiz Moreno, and Enio Roberto Ribeiro Copyright © 2015 Eduardo Moreira Vicente et al. All rights reserved. A New Fractional-Order Based Intelligent Maximum Power Point Tracking Control Algorithm for Photovoltaic Power Systems Tue, 16 Jun 2015 12:48:30 +0000 This paper proposes a new type of variable fractional-order incremental conductance algorithm (VFOINC), combined with extenics variable step size (EVSS) control into the maximum power point tracking (MPPT) design for photovoltaic power systems. At the beginning of maximum power tracking, the fractional-order number is selected as 1; the good transient tracking characteristic of traditional incremental conductance method is used. When the maximum power point is approached, the fractional-order number is selected as variable fractional order; the curve profile of in fractional order is used to approximate, so that the system has good tracking effect in transient and steady states. The experimental and simulation results show that, compared with traditional incremental conductance method (INC) and fractional-order incremental conductance method (FOINC), this method has better MPPT effect. Kuo-Nan Yu, Chih-Kang Liao, and Her-Terng Yau Copyright © 2015 Kuo-Nan Yu et al. All rights reserved.