International Journal of Photoenergy The latest articles from Hindawi © 2019 , Hindawi Limited . All rights reserved. Use of Nanofluids in Solar PV/Thermal Systems Sun, 16 Jun 2019 08:05:17 +0000 The continuous growth in the energy demand across the globe due to the booming population, in addition to the harmful effects of the fossil fuels on the environment, has made it essential to harness renewable energy via different technologies and convert it to electricity. The potential of solar energy still remains untapped although it has several advantages particularly that it is a clean source to generate both electricity and heat. Concentrating sunlight is an effective way to generate higher throughput per unit area of the absorber material used. The heat extraction mechanisms and the fluids used in solar thermal systems are key towards unlocking higher efficiencies of solar thermal systems. Nanofluids can play a crucial role in the development of these technologies. This review is aimed at presenting the recent studies dealing with cooling the photovoltaic thermal (PVT), concentrated photovoltaic thermal (CPVT), and other solar systems using nanofluids. In addition, the article considers the definition of nanofluids, nanoparticle types, nanofluid preparation methods, and thermophysical properties of the most common nanoparticles and base fluids. Moreover, the major factors which affect the nanofluid’s thermal conductivity according to the literature will be reviewed. Asmaa Ahmed, Hasan Baig, Senthilarasu Sundaram, and Tapas K. Mallick Copyright © 2019 Asmaa Ahmed et al. All rights reserved. Preparation of Nano-Ag-TiO2 Composites by Co-60 Gamma Irradiation to Enhance the Photocurrent of Dye-Sensitized Solar Cells Wed, 12 Jun 2019 09:05:23 +0000 Nano-silver-titanium dioxide (Ag-TiO2) composites were prepared from commercial TiO2 (P25, Degussa) and silver nitrate (AgNO3) by gamma Co-60 irradiation method with various initial concentrations of AgNO3. The nano-AgTiO2 composites are utilized as the photoanode for dye-sensitized solar cells (DSCs). Under full sunlight illumination (1000 W/m2, AM 1.5), the efficiency of DSCs has improved significantly despite the Ag content of below 1%. The DSC—assembled with 0.75 Ag-TiO2 (0.75% Ag) photoanode—showed that the photocurrent was significantly enhanced from 8.1−2 to 9.5−2 compared to the DSCs using bared TiO2 photoanode. The unchanged open-circuit voltage resulted in the overall energy conversion efficiency to be increased by 25% from 3.75% to 4.86%. Electrochemical impedance spectroscopy (EIS) analysis showed that the charge transfer resistance is reduced when increasing Ag content, demonstrating that the charge transfer at TiO2/dye interface was enhanced in the presence of silver nanoparticles. Le Thanh Nguyen Huynh, Viet Hai Le, Thanh Long Vo, Thi Kim Lan Nguyen, Quoc Hien Nguyen, and Thai Hoang Nguyen Copyright © 2019 Le Thanh Nguyen Huynh et al. All rights reserved. Recent Advances on Renewable and Biodegradable Cellulose Nanopaper Substrates for Transparent Light-Harvesting Devices: Interaction with Humid Environment Mon, 10 Jun 2019 09:05:10 +0000 Cellulose nanopaper (CNP) has attracted much interest during the last decade as a new fascinating renewable and biodegradable substrate for printed electronics and solar cells. Its outstanding optical and mechanical properties make CNP the ideal substrate for the preparation of photovoltaic devices, since its high transparency and haze favour the absorption of light from the active layer of the solar cell. However, some advances need to be done in the direction of increasing CNP stability in humid environment without compromising its remarkable advantages. This review critically points at these aspects, presenting an overview of state-of-art solutions to enhance nanopaper stability in a humid environment. Alessandra Operamolla Copyright © 2019 Alessandra Operamolla. All rights reserved. Performance Improvement of Dye-Sensitized Solar Cell- (DSSC-) Based Natural Dyes by Clathrin Protein Sun, 09 Jun 2019 00:00:00 +0000 Dye-Sensitized Solar Cell (DSSC) is a solar cell device that works using electrochemical principles in which sensitive dyes are absorbed in the TiO2 photoelectrode layer. The problem of DSSC-based natural dyes is the lower efficiency than silicon solar cells. This low efficiency is due to the barrier of electron transfer in the TiO2 semiconductor layer. In this study, the addition of clathrin protein to the TiO2 layer was used to increase electron transfer in the semiconductor layer resulting in improved DSSC performance. Clathrin is a protein that plays a role in the formation of transport vesicle membrane in eukaryotic cells. The method used in this study is clathrin protein with a concentration of 0%, 25%, 50%, and 75% added to TiO2 in DSSC structure. Photovoltaic characteristics of DSSC were measured using a data logger to determine the performance of DSSC, layer morphology was analyzed using Scanning Electron Microscopy (SEM), the element content in DSSC was analyzed using Energy-Dispersive X-ray Spectroscopy (EDS), and functional groups in DSSC layers were analyzed using Fourier-Transform Infrared Spectroscopy (FTIR). The result of this study is the addition of clathrin protein can improve DSSC performance, which resulted in the highest performance of DSSC on 75% clathrin protein addition with ,, and . From the results of SEM analysis, it appears that clathrin protein molecules fill the cavities in TiO2 molecules. EDS analysis shows an increase in carbon, oxygen, and phosphorus content in TiO2 layers with increasing clathrin protein concentration. FTIR analysis shows an increasingly sharp absorption in the FTIR spectrum of protein-forming functional groups by increasing clathrin protein concentration in DSSC. Prihanto Trihutomo, Sudjito Soeparman, Denny Widhiyanuriyawan, and Lilis Yuliati Copyright © 2019 Prihanto Trihutomo et al. All rights reserved. An Advanced Multicarrier Residential Energy Hub System Based on Mixed Integer Linear Programming Sun, 09 Jun 2019 00:00:00 +0000 This work proposes a multicarrier energy hub system with the objective of minimizing the economy cost and the CO2 emissions of a residential building without sacrificing the household comfort and increasing the exploitation of renewable energy in daily life. The energy hub combines the electrical grid and natural gas network, a gas boiler, a heat pump, a photovoltaic plant, and a photovoltaic/thermal (PV/T) system. In addition, to increase the overall performance of the system, a battery-based energy storage system is integrated. To evaluate the optimal capacity of each energy hub component, an optimization scheduling process and the optimization problem have been solved with the YALMIP platform in the MATLAB environment. The result showed that this advanced system not only can decrease the economic cost and CO2 emissions but also reduce the impact to electrical grid. Yue Yuan, Angel A. Bayod-Rújula, Huanxin Chen, Amaya Martínez-Gracia, Jiangyu Wang, and Anna Pinnarelli Copyright © 2019 Yue Yuan et al. All rights reserved. Adaptive Electromagnetic Field Optimization Algorithm for the Solar Cell Parameter Identification Problem Mon, 03 Jun 2019 16:05:00 +0000 Solar cell parameter identification problem (SCPIP) is one of the most studied optimization problems in the field of renewable energy since accurate estimation of model parameters plays an important role to increase their efficiency. The SCPIP is aimed at optimizing the performance of solar cells by estimating the best parameter values of the solar cells that produce an accurate approximation between the current vs. voltage () measurements. To solve the SCPIP efficiently, this paper introduces an adaptive variant of the electromagnetic field optimization (EFO) algorithm, named adaptive EFO (AEFO). The EFO simulates the attraction-repulsion mechanism between particles of electromagnets having different polarities. The main idea behind the EFO is to guide electromagnetic particles towards global optimum by the attraction-repulsion forces and the golden ratio. Distinct from the EFO, the AEFO searches the solution space with an adaptive search procedure. In the adaptive search strategy, the selection probability of a better solution is increased adaptively whereas the selection probability of worse solutions is reduced throughout the search progress. By employing the adaptive strategy, the AEFO is able to maintain the balance between exploration and exploitation more efficiently. Further, new boundary control and randomization procedures for the candidate electromagnets are presented. To identify the performance of the proposed algorithm, two different benchmark problems are taken into account in the computational studies. First, the AEFO is performed on global optimization benchmark functions and compared to the EFO. The efficiency of the AEFO is identified by statistical significance tests. Then, the AEFO is implemented on a well-known SCPIP benchmark problem set formed as a result of real-life physical experiments based on single- and double-diode models. To validate the performance of the AEFO on the SCPIP, extensive experiments are carried out, where the AEFO is tested against the original EFO, AEFO variants, and novel metaheuristic algorithms. Results of the computational studies reveal that the AEFO exhibits superior performance and outperforms other competitor algorithms. Ilker Kucukoglu Copyright © 2019 Ilker Kucukoglu. All rights reserved. Enhancement of the Antibacterial Efficiency of Silver Nanoparticles against Gram-Positive and Gram-Negative Bacteria Using Blue Laser Light Thu, 30 May 2019 08:05:28 +0000 Silver nanoparticles (Ag-NPs) possess excellent antibacterial properties and are considered to be an alternative material for treating antibiotic-resistant bacteria. The present study was aimed at enhancing the antibacterial efficiency of Ag-NPs using visible laser light against Escherichia coli and Staphylococcus aureus in vitro. Four concentrations of Ag-NPs (12.5, 25, 50, and 100 μg/ml), synthesized by the chemical reduction method, were utilized to conduct the antibacterial activity of prepared Ag-NPs. The antibacterial efficiencies of photoactivated Ag-NPs against both bacteria were determined by survival assay after exposure to laser irradiation. The mechanism of interactions between Ag-NPs and the bacterial cell membranes was then evaluated via scanning electron microscopy (SEM) and reactive oxygen species analysis to study the cytotoxic action of photoactivated Ag-NPs against both bacterial species. Results showed that the laser-activated Ag-NP treatment reduced the surviving population to 14% of the control in the E. coli population, while the survival in the S. aureus population was reduced to 28% of the control upon 10 min exposure time at the concentration of 50 μg/ml. However, S. aureus showed lower sensitivity after photoactivation compared to E. coli. Moreover, the effects depended on the concentration of Ag-NPs and exposure time to laser light. SEM images of treated bacterial cells indicated that substantial morphological changes occurred in cell membranes after treatment. The results suggested that Ag-NPs in the presence of visible light exhibit strong antibacterial activity which could be used to inactivate harmful and pathogenic microorganisms. Anes Al-Sharqi, Kasing Apun, Micky Vincent, Devagi Kanakaraju, and Lesley Maurice Bilung Copyright © 2019 Anes Al-Sharqi et al. All rights reserved. Sizing Control and Hardware Implementation of a Hybrid Wind-Solar Power System, Based on an ANN Approach, for Pumping Water Thu, 30 May 2019 08:05:26 +0000 In our day, solar energy and wind energy are becoming more and more used as renewable sources by various countries for different uses such as in an isolated home. These energies admit a unique limitation related to the characteristic of energy instability. For this, the objective of this manuscript is to command and synchronize the power flow of a hybrid system using two sources of energy (solar and wind). The first contribution of our work is the utilization of an artificial neural network controller to command, at fixed atmospheric conditions, the maximum power point. The second contribution is the optimization of the system respecting real-time constraints to increase a generating system performance. As a matter of fact, the proposed system and the controller are modeled using MATLAB/Simulink and a Xilinx System Generator is utilized for hardware implementation. The simulation results, compared with other works in the literature, present high performance, efficiency, and precision. The suggested system and its control strategy give the opportunity of optimizing the hybrid power system performance, which is utilized in rural pumping or other smart house applications. Ons Zarrad, Mohamed Ali Hajjaji, Aymen Jemaa, and Mohamed Nejib Mansouri Copyright © 2019 Ons Zarrad et al. All rights reserved. Development of a Daily Databank of Solar Radiation Components for Moroccan Territory Thu, 16 May 2019 12:05:26 +0000 The main objective of this work is to create a daily updated database that includes all components of solar radiation, either energetic or spectral radiation. This will lead us to quantify the Moroccan solar potential and to determine the dimensions of all types of solar thermal and photovoltaic systems. Consequently, the obtained database will be the fundamental support for engineers, designers, and all organizations interested in developing solar systems, in different regions throughout Morocco. It will also be a basic tool for researchers in modelling and simulating the new solar systems. Firstly, we used one year’s worth of measurements of the different components of the solar radiation, provided by the National Meteorological Department, to establish the extrapolation equations between the global radiation at the reference site and the global radiation of twenty-eight other sites. As well as with the same measurements, we developed the correlation equations between the global solar radiation and the other solar radiation components. Secondly, from ten years of Fez station’s daily global radiation measurements and through the extrapolation equations, we were able to estimate the global radiation of all Moroccan cities. Then, by using the obtained global radiation data and the correlation equations, we predicted the other components of solar radiation. Subsequently, with a new measurement campaign carried out on several sites, we validated the estimation models by using the usual statistical indicators. In addition, we compared our results with those obtained by other estimation models. The resulting differences for each solar component display the advantage of our model with errors under 6%. To facilitate the use of our results, we compiled them into maps representing the spread of solar radiation across Morocco. Mohammed Benchrifa, Hajar Essalhi, Rachid Tadili, Mohammed N. Bargach, and Abdellah Mechaqrane Copyright © 2019 Mohammed Benchrifa et al. All rights reserved. Comparison of Photoelectrochemical Current in Amorphous and Crystalline Anodized TiO2 Nanotube Electrodes Thu, 16 May 2019 12:05:24 +0000 The interest in TiO2 nanotubes has resulted in a lot of studies including the effects of various parameters on the properties and performance for different applications. This study investigated the effect of anodization at a low temperature on the properties and photoelectrochemical performance. The effects of varied anodization settings on morphology, crystallinity, and PEC response were studied. Low-temperature anodization resulted in smaller pore diameter and shorter tube length. Annealing temperature affected the presence of varied phases of TiO2 such as the prominence of anatase and amounts of rutile and amorphous TiO2 at 125°C. To observe photoelectrochemical response, annealing at 450°C is necessary. However, a cathodic response was observed for TiO2 nanotubes synthesized with low voltage at low temperature. Hence, amorphous titania nanotubes annealed at 125°C with thickness achieved in the anodization can be a potential material used for photocatalytic applications due to its determined cathodic photoelectrochemical response. Candy C. Mercado, Michael Eric L. Lubrin, Hazel Anne J. Hernandez, and Reynaldo A. Carubio Jr. Copyright © 2019 Candy C. Mercado et al. All rights reserved. Cascade Control of Grid-Connected PV Systems Using TLBO-Based Fractional-Order PID Thu, 16 May 2019 07:05:11 +0000 Cascade control is one of the most efficient systems for improving the performance of the conventional single-loop control, especially in the case of disturbances. Usually, controller parameters in the inner and the outer loops are identified in a strict sequence. This paper presents a novel cascade control strategy for grid-connected photovoltaic (PV) systems based on fractional-order PID (FOPID). Here, simultaneous tuning of the inner and the outer loop controllers is proposed. Teaching-learning-based optimization (TLBO) algorithm is employed to optimize the parameters of the FOPID controller. The superiority of the proposed TLBO-based FOPID controller has been demonstrated by comparing the results with recently published optimization techniques such as genetic algorithm (GA), particle swarm optimization (PSO), and ant colony optimization (ACO). Simulations are conducted using MATLAB/Simulink software under different operating conditions for the purpose of verifying the effectiveness of the proposed control strategy. Results show that the performance of the proposed approach provides better dynamic responses and it outperforms the other control techniques. Afef Badis, Mohamed Nejib Mansouri, and Mohamed Habib Boujmil Copyright © 2019 Afef Badis et al. All rights reserved. Atomic Layer Deposition of TiO2 Nanocoatings on ZnO Nanowires for Improved Photocatalytic Stability Thu, 09 May 2019 07:05:22 +0000 Photocatalytic water splitting represents an emerging technology well positioned to satisfy the growing need for low-energy, low CO2, economically viable hydrogen gas production. As such, stable, high-surface-area electrodes are increasingly being investigated as electrodes for the photochemical conversion of solar energy into hydrogen fuel. We present a titanium dioxide (TiO2)/zinc oxide (ZnO) nanowire array using a hybrid hydrothermal/atomic layer deposition (ALD) for use as a solar-powered photoelectrochemical device. The nanowire array consists of single crystalline, wurtzite ZnO nanowires with a 40 nm ALD TiO2 coating. By using a TiO2 nanocoating on the high surface area-ZnO array, three advancements have been accomplished in this work: (1) high aspect ratio nanowires with TiO2 for water splitting (over 8 μm), (2) improved stability over bare ZnO nanowires during photocatalysis, and (3) excellent onset voltage. As such, this process opens up new class of the micro/nanofabrication process for making efficient photocatalytic gas harvesting systems. Emmeline Kao, Hyun Sung Park, Xining Zang, and Liwei Lin Copyright © 2019 Emmeline Kao et al. All rights reserved. Endocrine Disruptor Degradation by UV/Chlorine and the Impact of Their Removal on Estrogenic Activity and Toxicity Wed, 08 May 2019 08:05:20 +0000 Recently, chlorination disinfection technology applying ultraviolet radiation (Cl/UV) has received attention as an advanced oxidative process (AOP) for the generation of highly oxidant species. Many studies have evaluated its effects on pathogen inactivation, contaminant removal, and formation of disinfection by-products (DBPs). However, the degradation of three endocrine disruptor chemicals (EDCs), 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and bisphenol-A (BPA), associated with simultaneous disinfection and estrogenic activity and ecotoxicity assessments has not yet been reported. Compound degradation increased with increasing chlorine concentrations (2 mg·L-1 chlorine), with pseudo-first-order kinetics s-1, s-1, and s-1 for BPA, E2, and EE2, respectively. The degradation kinetics in a WWTP effluent significantly decreased to min-1, min-1, and min-1, for BPA, E2, and EE2, respectively. However, 45% TOC removal and disinfection of E. coli and total coliform bacteria (TCB) were observed in 10 min of treatment. The yeast estrogen screen (YES) revealed that the treatment did not form by-products with estrogenic activity, demonstrating cleavage or mineralization in the phenolic group, common to all assessed compounds. High cell growth inhibition and mortality for Raphidocelis subcapitata and Ceriodaphnia dubia, respectively, were observed during the photodegradation process. Thus, the formed DBPs may be responsible for the observed toxicity and should be taken into account in WWTP treatments in order to monitor the formation of chlorinated by-products. Enrico M. Saggioro, Fernanda P. Chaves, Louise C. Felix, Giselle Gomes, and Daniele M. Bila Copyright © 2019 Enrico M. Saggioro et al. All rights reserved. Electrochemical Coprecipitation of Zinc and Aluminum in Aqueous Electrolytes for ZnO and AZO Coverage Deposition Tue, 07 May 2019 07:05:11 +0000 The aim of this study is to examine the technological challenge of the electrochemical formation of zinc oxide and Al-doped ZnO films (ZnO:Al, AZO) as transparent conductive oxide coatings with complex architectures for solar cell photoanode materials. A cathodic electrodeposition of AZO was performed using aqueous nitrate electrolytes at 25°C. A significant positive deviation in aluminum percentage in the films was demonstrated by the LAES, EDX, and XPS methods, which originates from aluminum hydroxide sedimentation. The photoluminescent characteristics of the ZnO films reveal low band intensities related to intrinsic defects, while the samples with 1 at.% of aluminum show a strong and wide PL band at and increase in conductivity. Natalia A. Martynova, Viktor N. Svishchev, Leonid S. Lepnev, Shakhnozabonu R. Alieva, Elena G. Chertorylskaya, Mikhail E. Vishnevskiy, Alexey D. Bozhko, and Anastasia V. Grigorieva Copyright © 2019 Natalia A. Martynova et al. All rights reserved. Concentrated Solar Power Plants with Molten Salt Storage: Economic Aspects and Perspectives in the European Union Tue, 30 Apr 2019 07:05:51 +0000 Concentrated solar power plants belong to the category of clean sources of renewable energy. The paper discusses the possibilities for the use of molten salts as storage in modern CSP plants. Besides increasing efficiency, it may also shift their area of application: thanks to increased controllability, they may now be used not only to cover baseload but also as more agile, dispatchable generators. Both technological and economic aspects are presented, with focus on the European energy sector and EU legislation. General characteristics for CSP plants, especially with molten salt storage, are discussed. Perspectives for their development, first of all in economic aspects, are considered. Andrzej Bielecki, Sebastian Ernst, Wioletta Skrodzka, and Igor Wojnicki Copyright © 2019 Andrzej Bielecki et al. All rights reserved. Design and Dynamic Modelling of a Hybrid Power System for a House in Nigeria Tue, 30 Apr 2019 07:05:49 +0000 This paper presents the design and dynamic modelling of a hybrid power system for a house in Nigeria. Thermal modelling of the house under consideration is carried out using BEopt software to accurately study the heat loss through the walls, windows, doors, and roof of the house. The analysis of this thermal model is used to determine hourly load data. Design of an optimum hybrid power system for the house is done with HOMER Pro software. The hybrid power system is made up of a diesel generator and a stand-alone PV system. The proposed PV system consists of PV arrays, DC–DC boost converter, MPPT controller, single-phase full-bridge inverter, inverter voltage mode controller (PI controller), and single-phase step-up transformer. Dynamic simulation of the proposed PV system component of the hybrid power system is carried out in MATLAB/Simulink environment to study the power quality, harmonics, load impact, voltage transients, etc. of the system, and the simulation results are presented in the paper. Lawrence O. Aghenta and M. Tariq Iqbal Copyright © 2019 Lawrence O. Aghenta and M. Tariq Iqbal. All rights reserved. Visible Light-Driven Gas-Phase Artificial Photosynthesis Reactions over Ruthenium Metal Nanoparticles Modified with Anatase TiO2 Tue, 30 Apr 2019 00:00:00 +0000 Ruthenium metal nanoparticles with a narrow size distribution have been synthesised via a solvothermal method. The solids were characterised using a range of analytical techniques (XRD, TEM, TPD, and XPS) and tested in the CO2+H2O reaction under simulated solar radiation, showing photocatalytic activity towards the production of CH4 and CO. The photocatalysis was promoted through a plasmonic excitation of the Ru. The addition of Ti to the preparation resulted in the formation of anatase TiO2. Notwithstanding the fact that the energy of the light used during the photocatalysis was insufficient to excite TiO2, its presence affects the catalysts’ optical and chemical properties and the product (CH4/CO) ratios, favouring the evolution of CO over that of CH4 (suggesting exciton transfer to TiO2 from plasmonically excited Ru). Eduardo Morais, Colin O’Modhrain, K. Ravindranathan Thampi, and James A. Sullivan Copyright © 2019 Eduardo Morais et al. All rights reserved. Flexible, Front-Facing Luminescent Solar Concentrators Fabricated from Lumogen F Red 305 and Polydimethylsiloxane Tue, 30 Apr 2019 00:00:00 +0000 Luminescent solar concentrators (LSCs) fabricated with transparent host materials and fluorescent organic dyes are cost effective and versatile tools for solar power production. In this study, the first flexible, front-facing LSCs utilizing Lumogen F Red 305 (LR305) and polydimethylsiloxane (PDMS) were demonstrated. Bulk-doped devices, fabricated with dye evenly distributed throughout the waveguide, were optimized for light gain with LR305 concentrations between 0.075 and 0.175 g/l. Thin-film devices, fabricated with a thin layer of luminescent material applied to the bottom side of the waveguide, were optimized between 0.5 and 0.75 g/l. The bulk-doped and thin-film devices produced light gains of 1.86 and 1.89, respectively, demonstrating that flexible designs can be developed without sacrificing power production. Bulk-doped devices proved to be less effective than thin-film devices at collecting direct light due to the placement of fluorescent dyes above the front-facing solar cell. Thin-film devices demonstrated less light collection than bulk-doped devices further from the device centers possibly due to quenching and self-absorption losses at higher dye concentrations. Light collection was minimally impacted by moderate bending in both LSC designs, suggesting that flexible, front-facing devices could be effectively deployed on curved and uneven surfaces. Finally, optical measurements of the LSC waveguides suggest that they could support plant growth underneath. Similar designs could be developed for applications in agricultural settings. Ian A. Carbone, Katelynn R. Frawley, and Melissa K. McCann Copyright © 2019 Ian A. Carbone et al. All rights reserved. Autoregressive Neural Network for Cloud Concentration Forecast from Hemispheric Sky Images Wed, 24 Apr 2019 09:05:35 +0000 We present here a new method to predict cloud concentration five minutes in advance from all-sky images using the Artificial Neural Networks (ANN). An autoregressive neural network with backpropagation (Ar-BP) was created and trained with four years of all-sky images as inputs. The pictures were taken with a hemispheric sky imager fixed on the roof at the Institute of Meteorology and Climatology (IMUK) of the Leibniz Universität Hannover, Hannover, Germany. Firstly, a statistical method is presented to obtain key information of the pictures. Secondly, a new image-processing algorithm is suggested to optimize the cloud detection process starting with the Haze Index. Finally, the cloud concentration five minutes in advance at the IMUK is forecasted using machine learning methods. A persistence model forecast to provide a reference for comparison was generated. The results are quantified in terms of the root mean square error (RMSE) and the mean absolute error (MAE). The new algorithm reduced both the RMSE and the MAE of the prediction by approximately 30% compared to the reference persistence model under diverse cloud conditions. The new algorithm could be used as a tool for the stable maintenance of the network for the transmission system operators, i.e., the primary control reserve (within 30 seconds) and the secondary control reserve (within 5 minutes). Cristian Crisosto Copyright © 2019 Cristian Crisosto. All rights reserved. Design and Analysis of a Stand-Alone PV System for a Rural House in Pakistan Tue, 23 Apr 2019 10:05:25 +0000 In this paper, thermal modeling of a typical rural house in Pakistan has been done using BEopt, to determine the hourly load profile. Using the load data, the design of a stand-alone PV system has been completed using HOMER Pro. The designed system consists of a 5.8 kW PV with eight batteries of 12 V, 255 Ah, and a 1.4 kW inverter. The system analyses show that such system can support mainly lighting and appliance load in a rural house. The dynamic model of the designed system has been simulated in MATLAB-Simulink. Perturbation and observation-based algorithm has been used for maximum power extraction from PV. Simulation results indicate that the system can provide a stable voltage and frequency for the domestic load. The method and analysis presented here can be used for the PV system design for other parts of the world. Amjad Iqbal and M. Tariq Iqbal Copyright © 2019 Amjad Iqbal and M. Tariq Iqbal. All rights reserved. Performance Modelling of Dual Air/Water Collector in Solar Water and Space Heating Application Thu, 18 Apr 2019 09:05:22 +0000 In the present work, the detailed mathematical model of a dual air/water solar collector (DAWC) has been developed and experimentally verified. To demonstrate the application of the DAWC, three buildings with different energy performance levels and three building locations were chosen in analyzed case studies. Four solar collector systems were compared with one another. The solar yield of the described systems was determined by simulation using the detailed theoretical model of DAWC. The results indicate that in the case of combining a domestic hot water preparation system and recirculating-air heating system based on DAWC, it is possible to achieve up to 30% higher solar energy yield compared to a conventional solar domestic hot water preparation system dependent on climate and building performance. Viacheslav Shemelin and Tomas Matuska Copyright © 2019 Viacheslav Shemelin and Tomas Matuska. All rights reserved. Form and Operation Mode Analysis of a Novel Solar-Driven Cogeneration System with Various Collector Types Thu, 11 Apr 2019 09:05:20 +0000 In this study, the form and operation modes of a novel solar-driven cogeneration system consisted of various solar collectors (flat plat collectors (FPC), evacuated tube collectors (ETC), and parabolic trough collectors (PTC)) and ORC (organic Rankine cycle) based on building heating load are analyzed. This paper mainly obtains the fitting formula of thermal efficiency of the ORC power generation device and determines the form and operation mode of the cogeneration system. The form is the same, but the operation modes are different for PTC and FPC or ETC. There are six operating modes, respectively, based on the size relationship between the heating load of buildings and the effective heat collection of the solar collector subsystem when the solar collectors are PTC or FPC and ETC. Haofei Zhang, Bo Lei, Tao Yu, and Zhida Zhao Copyright © 2019 Haofei Zhang et al. All rights reserved. Photovoltaic Panel Efficiency Estimation with Artificial Neural Networks: Samples of Adiyaman, Malatya, and Sanliurfa Wed, 10 Apr 2019 15:05:09 +0000 The amount of electric energy produced by photovoltaic panels depends on air temperature, humidity rate, wind velocity, photovoltaic module temperature, and particularly solar radiation. Being aware of the behaviour patterns of the panels to be used in project and planning works regarding photovoltaic applications will set forth a realistic expense form; therefore, erroneous investments will be avoided, and the country budget will benefit from added value. The power ratings obtained from the photovoltaic panels and the environmental factors were measured and recorded for a year by the measurement stations established in three diverse regions (Adiyaman-Malatya-Sanliurfa). In the developed artificial neural network models, the estimation accuracy was 99.94%. Furthermore, by taking the data of the General Directorate of Meteorology as a reference, models of artificial neural networks were developed using the data from Adiyaman province for training; by using Malatya and Sanliurfa as test data, 99.57% estimation accuracy was achieved. With the artificial neural network models developed as a result of the study, the energy efficiency for the photovoltaic energy systems desired to be established by using meteorological parameters such as temperature, humidity, wind, and solar radiation of various regions anywhere in the world can be estimated with high accuracy. Yasin Icel, Mehmet Salih Mamis, Abdulcelil Bugutekin, and Mehmet Ismail Gursoy Copyright © 2019 Yasin Icel et al. All rights reserved. Donor-π-Conjugated Spacer-Acceptor Dye-Sensitized Solid-State Solar Cell Using CuI as the Hole Collector Tue, 09 Apr 2019 07:05:08 +0000 Dye-sensitized solid-state solar cells (DSSCs) replacing the liquid electrolyte with a p-type semiconductor have been extensively examined to solve the practical problems associated with wet-type solar cells. Here, we report the fabrication of a solid-state solar cell using copper iodide (CuI) as the hole conductor and alkyl-functionalized carbazole dye (MK-2) as the sensitizer. A DSSC sensitized with MK-2 showed a solar-to-electrical power conversion efficiency of 3.33% with a of 496 mV and a of 16.14 mA cm-2 under AM 1.5 simulated sunlight. The long alkyl chains act as a barrier for charge recombination, and the strong accepting and donating abilities of the cyanoacrylic and carbazole groups, respectively, enhance the absorption of light at a longer wavelength, increasing the short-circuit current density. The efficiency recorded in this work is higher than similar DSSCs based on other hole collectors. D. N. Liyanage, K. D. M. S. P. K. Kumarasinghe, G. R. A. Kumara, A. C. A. Jayasundera, K. Tennakone, and B. Onwona-Agyeman Copyright © 2019 D. N. Liyanage et al. All rights reserved. Optimization of Helium Inflating on Heat Dissipation and Luminescence Properties of the A60 LED Filament Lamps Tue, 02 Apr 2019 13:05:21 +0000 LED filament lamp has the characteristics of nearly 360° lighting angle, high brightness, and low energy consumption, turning it gradually into the best substitute for traditional incandescent lamps. At present, due to the limitations of heat dissipation, the development of high-power LED filament lamp is restricted. Helium is a rare gas with small density and high heat transfer coefficient. It can be used as a cooling and protective gas for LED filament lamp. In this paper, we investigated the effects of helium on the heat dissipation and luminescence performance of the A60 LED filament lamps by detecting the changes of junction temperature, color temperature, and luminous flux of different ratios helium inflating in the different power A60 LED filament lamps. Through the experiment, we found the most cost-effective ratio of helium gas in the A60 LED filament lamps without improving the lamp size and the filament diameter. Yizhan Chen, Qingguang Zeng, Lite Zhao, Yuanxing Li, Guangyao Huang, and Bingqian Li Copyright © 2019 Yizhan Chen et al. All rights reserved. Photosynthetic Pigments with Potential for a Photosynthetic Antenna: A DFT Analysis Tue, 02 Apr 2019 08:05:09 +0000 Geometrical and electronic properties of the main photosynthetic pigments in higher plants such as chlorophylls and xanthophylls were studied to find potential candidates that were able to participate in an eventual zeolite-dye artificial antenna. CRDFT (chemical reactivity density functional theory) and TD-DFT (time-dependent DFT) methods were employed in ground-state and excited-state calculations, respectively. The evaluated electronic properties at the gas phase included (a) energies such as HOMO-LUMO band gap (-, ranging from 2.168 to 2.504 eV), adiabatic ionization potential (, ranging from 5.964 to 7.207 eV), and adiabatic electronic affinity (, ranging from 2.176 to 2.741 eV); (b) global chemical reactivity indexes such as electronegativity (, ranging from 4.121 to 4.974 eV), hardness (, ranging from 1.812 to 2.233 eV), electrophilicity index (, ranging from 4.365 to 5.541 eV), and electroaccepting-electrodonating powers (, ranging from 1.671 to 2.115 eV, and , ranging from 4.375 to 5.273 eV); (c) electron-hole reorganization energies (, ranging from 0.225 to 0.519 eV and ranging from 0.168 to 0.425 eV, respectively) and electron-hole extraction potentials (EEP, ranging from 2.570 to 2.966 eV, and HEP, ranging from 5.538 to 7.012 eV, respectively); and (d) local chemical reactivity indexes like condensed Fukui functions (), condensed dual descriptor (), and condensed local softness (). These electronic properties allowed the association between molecules and reactivity-selectivity criteria, under the context of charge transfer and electronic transitions. Also, the aforementioned electronic properties were determined for combinations made with the selected molecules (β-cryptoxanthin and zeaxanthin) and 5 solvents (n-hexane, diethyl ether, acetone, ethanol, and methanol) with upward dielectric constants (). From frequency calculations, IR spectra were obtained for combinations. Finally, excited-state computations were carried out to acquire UV-Vis spectra of the combinations. We conclude that the selection of dyes is controlled mainly by geometrical constraints rather than by electronic properties. Jesús Francisco Monzón-Bensojo, Manuel A. Flores-Hidalgo, and Diana Barraza-Jiménez Copyright © 2019 Jesús Francisco Monzón-Bensojo et al. All rights reserved. Multiple DGs for Reducing Total Power Losses in Radial Distribution Systems Using Hybrid WOA-SSA Algorithm Sun, 31 Mar 2019 09:05:29 +0000 Distributed generators (DGs) are currently extensively used to reduce power losses and voltage deviations in distribution networks. The optimal location and size of DGs achieve the best results. This study presents a novel hybridization of new metaheuristic optimizations in the last two years, namely, salp swarm algorithm (SSA) and whale optimization algorithm (WOA), for optimal placement and size of multi-DG units in radial distribution systems to minimize total real power losses (kW) and solve voltage deviation. This hybrid algorithm is implemented on IEEE 13- and 123-node radial distribution test systems. The OpenDSS engine is used to solve the power flow to find the power system parameters, such power losses, and the voltage profile through the MATLAB coding interface. Results describe the effectiveness of the proposed hybrid WOA-SSA algorithm compared with those of the IEEE standard case (without DG), repeated load flow method, and WOA and SSA algorithms applied independently. The analysis results via the proposed algorithm are more effective for reducing total active power losses and enhancing the voltage profile for various distribution networks and multi-DG units. Khalid Mohammed Saffer Alzaidi, Oguz Bayat, and Osman N. Uçan Copyright © 2019 Khalid Mohammed Saffer Alzaidi et al. All rights reserved. Recent Progress of Graphene-Based Photoelectrode Materials for Dye-Sensitized Solar Cells Tue, 26 Mar 2019 08:05:32 +0000 Graphite with a single atomic layer known as graphene shows great capability in energy conversion and storage devices. Dye-sensitized solar cells (DSSCs) have attracted intense interests due to offering high photo-to-electric conversion efficiencies. DSSCs are built from a photoelectrode (a dye-sensitized nanocrystalline semiconductor), an electrolyte with redox couples, and a counterelectrode. In this review article, we outline the strategies to enhance the efficiency and reduce the cost by introducing graphene into the DSSCs as the photoelectrode. First, the development of DSSCs and the properties of graphene are briefly described. Then, the applications of graphene-based materials for photoelectrodes (transparent electrode, semiconductor layer, and dye sensitizer) in DSSCs are deeply discussed. Finally, an outlook for graphene materials in DSSCs is provided. Kaustubh Patil, Soheil Rashidi, Hui Wang, and Wei Wei Copyright © 2019 Kaustubh Patil et al. All rights reserved. Development of Back and Front Contacts for CdTe Layer in Tandem Flexible Photoelectric Converters on Basis of CdTe/CuInSe2 Sun, 24 Mar 2019 13:05:19 +0000 By the method of nonreactive high-frequency magnetron sputtering on Upilex polyimide films, transparent and conductive layers of ITO were obtained. These layers, after high-temperature annealing, at temperatures typical for the solar cell formation, had a resistance of 11 ohm/ and a transmittance of up to 72%. The use of such an ITO layer with the addition of a 100 nm thick layer of undoped zinc oxide, as the front contact, and Cu/ITO composition, as the back contact, made it possible to obtain a flexible solar cell polyimide/ITO/CdS/CdTe/Cu/ITO with an efficiency of 10.4%. With a thickness of the base layer of cadmium telluride 2.5 μm, the average transmittance of the SC in the 850-1100 nm wavelength range is 46.8%. The developed design of a flexible solar cell based on cadmium telluride due to the use of a transparent back contact with a comb metal electrode is easily interfaced with existing designs of flexible solar cells based on copper and indium diselenide, which allow the formation of flexible tandem photoelectric converters CdTe/CuInSe2. M. G. Khrypunov, D. A. Kudii, N. A. Kovtun, M. M. Kharchenko, and I. V. Khrypunova Copyright © 2019 M. G. Khrypunov et al. All rights reserved. Line-End Voltage and Voltage Profile along Power Distribution Line with Large-Power Photovoltaic Generation System Sun, 24 Mar 2019 09:05:18 +0000 In recent years, the introduction of the photovoltaic generation system (PV system) has been increasing by promoting the use of renewable energy. It has been feared that the reverse current from the PV system may cause an unacceptable level of voltage rise at the interconnection node in the power distribution system. This paper discusses the effects of the reverse current on the voltage rise and fall characteristics of the interconnection node and the voltage profiles along the power distribution line. When the line current on the circuit is small, the voltage on the line monotonically increases from the sending end to the receiving end. When a relatively large current flows, it causes a voltage reduction near the distribution substation. Furthermore, on the basis of the voltage aspects in the power distribution system with a large PV system, the allowable limits of the line current and the output power from PV system are investigated. Toshiro Matsumura, Masumi Tsukamoto, Akihiro Tsusaka, Kazuto Yukita, Yasuyuki Goto, Yasunobu Yokomizu, Kento Tatewaki, Daisuke Iioka, Hirotaka Shimizu, Yuuki Kanazawa, Hiroyuki Ishikawa, Akimori Matsuo, and Hideki Iwatsuki Copyright © 2019 Toshiro Matsumura et al. All rights reserved.