International Journal of Photoenergy The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Mapping and Estimation of Monthly Global Solar Irradiation in Different Zones in Souss-Massa Area, Morocco, Using Artificial Neural Networks Thu, 12 Oct 2017 04:26:59 +0000 Solar radiation data play an important role in solar energy research. However, in regions where the meteorological stations providing these data are unavailable, strong mapping and estimation models are needed. For this reason, we have developed a model based on artificial neural network (ANN) with a multilayer perceptron (MLP) technique to estimate the monthly average global solar irradiation of the Souss-Massa area (located in the southwest of Morocco). In this study, we have used a large database provided by NASA geosatellite database during the period from 1996 to 2005. After testing several models, we concluded that the best model has 25 nodes in the hidden layer and results in a minimum root mean square error (RMSE) equal to 0.234. Furthermore, almost a perfect correlation coefficient was found between measured and estimated values. This developed model was used to map the monthly solar energy potential of the Souss-Massa area during a year as estimated by the ANN and designed with the Kriging interpolation technique. By comparing the annual average solar irradiation between three selected sites in Souss-Massa, as estimated by our model, and six European locations where large solar PV plants are deployed, it is apparent that the Souss-Massa area is blessed with higher solar potential. O. Nait Mensour, S. Bouaddi, B. Abnay, B. Hlimi, and A. Ihlal Copyright © 2017 O. Nait Mensour et al. All rights reserved. Learning Processes to Predict the Hourly Global, Direct, and Diffuse Solar Irradiance from Daily Global Radiation with Artificial Neural Networks Wed, 11 Oct 2017 00:00:00 +0000 This paper presents three different topologies of feed forward neural network (FFNN) models for generating global, direct, and diffuse hourly solar irradiance in the city of Fez (Morocco). Results from this analysis are crucial for the conception of any solar energy system. Especially, for the concentrating ones, as direct component is seldom measured. For the three models, the main input was the daily global irradiation with other radiometric and meteorological parameters. Three years of hourly data were available for this study. For each solar component’s prediction, different combinations of inputs as well as different numbers of hidden neurons were considered. To evaluate these models, the regression coefficient (R2) and normalized root mean square error (nRMSE) were used. The test of these models over unseen data showed a good accuracy and proved their generalization capability (nRMSE = 13.1%, 9.5%, and 8.05% and R = 0.98, 0.98, and 0.99) for hourly global, hourly direct, and daily direct radiation, respectively. Different comparison analyses confirmed that (FFNN) models surpass other methods of estimation. As such, the proposed models showed a good ability to generate different solar components from daily global radiation which is registered in most radiometric stations. Hanae Loutfi, Ahmed Bernatchou, Younès Raoui, and Rachid Tadili Copyright © 2017 Hanae Loutfi et al. All rights reserved. Efficiency Enhancement of Multicrystalline Silicon Solar Cells by Inserting Two-Step Growth Thermal Oxide to the Surface Passivation Layer Sun, 08 Oct 2017 00:00:00 +0000 In this study, the efficiency of the multicrystalline was improved by inserting a two-step growth thermal oxide layer as the surface passivation layer. Two-step thermal oxidation process can reduce carrier recombination at the surface and improve cell efficiency. The first oxidation step had a growth temperature of 780°C, a growth time of 5 min, and with N2/O2 gas flow ratio 12 : 1. The second oxidation had a growth temperature of 750°C, growth time of 20 min, and under pure N2 gas environment. Carrier lifetime was increased to 15.45 μs, and reflectance was reduced 0.52% using the two-step growth method as compared to the conventional one-step growth oxide passivation method. Consequently, internal quantum efficiency of the solar cell increased 4.1%, and conversion efficiency increased 0.37%. These results demonstrate that the two-step thermal oxidation process is an efficient way to increase the efficiency of the multicrystalline silicon solar cells. Shun Sing Liao, Yueh Chin Lin, Chuan Lung Chuang, and Edward Yi Chang Copyright © 2017 Shun Sing Liao et al. All rights reserved. Effects of Ambient Parameters on the Performance of a Direct-Expansion Solar-Assisted Heat Pump with Bare Plate Evaporators for Space Heating Sun, 01 Oct 2017 00:00:00 +0000 Research on the direct-expansion solar-assisted heat pump (DX-SAHP) system with bare plate evaporators for space heating is meaningful but insufficient. In this paper, experiments on a DX-SAHP system applying bare plate evaporators for space heating are conducted in the enthalpy difference lab with a solar simulator, with the ambient conditions stable. The independent effects of ambient temperature, solar irradiation, and relative humidity on the system performance are investigated. When ambient temperature changes as 5°C, 10°C, and 15°C, COP increases as 2.12, 2.18, and 2.26. When solar irradiance changes as 0 W m−2, 100 W m−2, 200 W m−2, 300 W m−2, and 500 W m−2, COP of the system changes as 2.07, 2.09, 2.14, 2.26, and 2.36. With ambient temperature of 5°C and solar irradiance of 0 W m−2, when relative humidity is 50%, no frost formed. Whereas with relative humidity of 70% and 90%, frost formed but not seriously frosted after 120 min of operating. Frost did not deteriorate but improved the heating performance of the DX-SAHP system. The change of relative humidity from 70% to 90% improves the evaporating heat exchange rate by 35.0% and increases COP by 16.3%, from 1.78 to 2.07. Wenzhu Huang, Jie Ji, Mawufemo Modjinou, and Jing Qin Copyright © 2017 Wenzhu Huang et al. All rights reserved. Predictive Power of Machine Learning for Optimizing Solar Water Heater Performance: The Potential Application of High-Throughput Screening Sun, 24 Sep 2017 00:00:00 +0000 Predicting the performance of solar water heater (SWH) is challenging due to the complexity of the system. Fortunately, knowledge-based machine learning can provide a fast and precise prediction method for SWH performance. With the predictive power of machine learning models, we can further solve a more challenging question: how to cost-effectively design a high-performance SWH? Here, we summarize our recent studies and propose a general framework of SWH design using a machine learning-based high-throughput screening (HTS) method. Design of water-in-glass evacuated tube solar water heater (WGET-SWH) is selected as a case study to show the potential application of machine learning-based HTS to the design and optimization of solar energy systems. Hao Li, Zhijian Liu, Kejun Liu, and Zhien Zhang Copyright © 2017 Hao Li et al. All rights reserved. Investigation on Parameters Affecting the Effectiveness of Photocatalytic Functional Coatings to Degrade NO: TiO2 Amount on Surface, Illumination, and Substrate Roughness Sun, 24 Sep 2017 00:00:00 +0000 This paper deals with the degradation of NO by photocatalytic oxidation using TiO2-based coatings. Tests are conducted at a laboratory scale through an experimental setup inspired from ISO 22197-1 standard. Various parameters are explored to evaluate their influence on photocatalysis efficiency: TiO2 dry matter content applied to the surface, nature of the substrate, and illumination conditions (UV and visible light). This article points out the different behaviors between three kinds of substrates which are common building materials: normalized mortar, denser mortar, and commercial wood. The illumination conditions are of great importance in the photocatalytic process with experiments under UV light showing the best results. However, a significant decrease in NO concentration under visible light is also observed provided that the TiO2 dry matter content on the surface is high enough. The nature of the substrate plays an important role in the photocatalytic activity with rougher substrates being more efficient to degrade NO. However, limiting the roughness of the substrate seems to be of utmost interest to obtain the highest exposed surface area and thus the optimal photocatalytic efficiency. A higher roughness promotes the surface contact between TiO2 and NO but does not necessarily increase the photochemical oxidation. J. Hot, J. Topalov, E. Ringot, and A. Bertron Copyright © 2017 J. Hot et al. All rights reserved. Transformation of a University Lecture Hall in Valladolid (Spain) into a NZEB: LCA of a BIPV System Integrated in Its Façade Tue, 19 Sep 2017 07:37:58 +0000 The EU Energy Performance of Buildings Directive (Directive 2010/31/EU) poses a major challenge, as it promotes the transformation of existing buildings into nearly zero-energy buildings (NZEB). In this work, we present the case of study of a lecture hall building, owned by the University of Valladolid (Spain), that is currently being refurbished into a NZEB by integration of renewable energy sources (RES), also in line with the requirements from Directive 2009/28/EC. As part of its major renovation, not only Trombe walls and geothermal energy are to be incorporated but also a building-integrated solar photovoltaic (BIPV) system to address the electricity needs and reduce the building’s energy use and GHGs in a cost-effective manner. The environmental profile of this BIPV system has been investigated using life cycle impact assessment (LCIA), assessing the net emissions of CO2 and the damages caused in a comparative context with conventional electricity-generation pathways. In spite of the small power installed in this first stage (designed to cover only an annual energy consumption of about 13,000 kWh, around 6% of the total demand), it can be concluded that significant environmental benefits are gained using this system. Gloria Y. Palacios-Jaimes, Pablo Martín-Ramos, Francisco J. Rey-Martínez, and Ignacio A. Fernández-Coppel Copyright © 2017 Gloria Y. Palacios-Jaimes et al. All rights reserved. Effect of the Mg/Al Ratio on Activated Sol-Gel Hydrotalcites for Photocatalytic Degradation of 2,4,6-Trichlorophenol Tue, 19 Sep 2017 00:00:00 +0000 Currently, interest has grown in finding effective solutions for the treatment of water pollution by toxic compounds. Some of the latter that have acquired importance are phenols and chlorophenols, due to their employment in the manufacture of pesticides, insecticides, cords of wood, paper industry, among others. The problem is rooted in that these compounds are very persistent in the environment because they are partially biodegradable and cannot be photodegraded directly by sunlight. Chlorophenols are extremely toxic, especially 2,4,6-trichlorophenol, which is potentially carcinogenic. In this work, Mg/Al-mixed oxide catalysts were obtained from the thermal treatment of hydrotalcite-type materials, synthesized by sol-gel method with different Mg/Al ratios. Hydrotalcites and Mg/Al-mixed oxides were physicochemically characterized by X-ray diffraction, thermal analysis (DTA and TGA), and N2 physisorption. The results were obtained on having proven the photocatalytic degradation of 2,4,6-trichlorophenol as a pollutant model by water. The catalysts obtained present the hydrotalcite phase with thermal evolution until achieving Mg/Al-mixed oxides at 500°C. The catalysts are of mesoporous materials and exhibiting large surface areas. The catalysts demonstrated good photocatalytic activity with good efficiency, reaching degradation percentages with Mg/Al = 1, 2, 4, 5, and 7 ratios of 94.2, 92.5, 86.2, 84.2, and 63.9%, respectively, until achieving mineralization. Esthela Ramos-Ramírez, Norma L. Gutiérrez-Ortega, Francisco Tzompantzi-Morales, Gloria A. Del Ángel, Claudia Martínez-Gómez, and Elizabeth Pabón-Gelves Copyright © 2017 Esthela Ramos-Ramírez et al. All rights reserved. Functional Nanohybrid Materials from Photosynthetic Reaction Center Proteins Sun, 17 Sep 2017 00:00:00 +0000 Application of technical developments in biology and vice versa or biological samples in technology led to the development of new types of functional, so-called “biohybrid” materials. These types of materials can be created at any level of the biological organization from molecules through tissues and organs to the individuals. Macromolecules and/or molecular complexes, membranes in biology, are inherently good representatives of nanosystems since they fall in the range usually called “nano.” Nanohybrid materials provide the possibility to create functional bionanohybrid complexes which also led to new discipline called “nanobionics” in the literature and are considered as materials for the future. In this publication, the special characteristics of photosynthetic reaction center proteins, which are “nature’s solar batteries,” will be discussed in terms of their possible applications for creating functional molecular biohybrid materials. Kata Hajdu, Tibor Szabó, Abd Elaziz Sarrai, László Rinyu, and László Nagy Copyright © 2017 Kata Hajdu et al. All rights reserved. Optical Tests on a Curve Fresnel Lens as Secondary Optics for Solar Troughs Tue, 12 Sep 2017 00:00:00 +0000 A curve Fresnel lens is developed as secondary concentrator for solar parabolic troughs to reduce the number of photovoltaic cells. Specific measurements and optical tests are used to evaluate the optical features of manufactured samples. The cylindrical Fresnel lens transforms the focal line, produced by the primary mirror, into a series of focal points. The execution of special laboratory tests on some secondary concentrator samples is discussed in detail, illustrating the methodologies tailored to the specific case. Focusing tests are performed, illuminating different areas of the lens with solar divergence light and acquiring images on the plane of the photocell using a CMOS camera. Concentration measurements are carried out to select the best performing samples of curve Fresnel lens. The insertion of the secondary optics within the concentrating photovoltaic (CPV) trough doubles the solar concentration of the system. The mean concentration ratio is 1.73, 2.13, and 2.09 for the three tested lenses. The concentration ratio of the solar trough is 140 and approaches 300 after the introduction of the secondary lens. D. Fontani, P. Sansoni, F. Francini, M. DeLucia, G. Pierucci, and D. Jafrancesco Copyright © 2017 D. Fontani et al. All rights reserved. Application of DC-AC Hybrid Grid and Solar Photovoltaic Generation with Battery Storage Using Smart Grid Tue, 05 Sep 2017 00:00:00 +0000 Smart grid for the past few years has been the prime focus of research in power systems. The aim is to eliminate load shedding and problematic blackout conditions, further offering cheap and continuous supply of electricity for both large and small consumers. Another benefit is to integrate renewable energy resources with existing dump grid in more efficient and cost-effective manner. In past few years, growing demand for sustainable energy increases the consumption of solar PV. Since generation from solar PV is in DC and most of the appliances at home could be operated on DC, AC-DC hybrid distribution system with energy management system is proposed in this paper. EMS helps to shift or control the auxiliary load and compel the users to operate specific load at certain time slots. These techniques further help to manage the excessive load during peak and off peak hours. It demonstrates the practical implementation of DC-AC network with integration of solar PV and battery storage with existing infrastructure. The results show a remarkable improvement using hybrid AC-DC framework in terms of reliability and efficiency. All this functioning together enhances the overall efficiency; hence, a secure, economical, reliable, and intelligent system leads to a smart grid. Shoaib Rauf and Nasrullah Khan Copyright © 2017 Shoaib Rauf and Nasrullah Khan. All rights reserved. Cyanidin-Based Novel Organic Sensitizer for Efficient Dye-Sensitized Solar Cells: DFT/TDDFT Study Wed, 30 Aug 2017 06:15:52 +0000 Cyanidin is widely considered as a potential natural sensitizer in dye-sensitized solar cells due to its promising electron-donating and electron-accepting abilities and cheap availability. We consider modifications of cyanidin structure in order to obtain broader UV-Vis absorption and hence to achieve better performance in DSSC. The modified molecule consists of cyanidin and the benzothiadiazolylbenzoic acid group, where the benzothiadiazolylbenzoic acid group is attached to the cyanidin molecule by replacing one hydroxyl group. The resulting structure was then computationally simulated by using the Spartan’10 software package. The molecular geometries, electronic structures, absorption spectra, and electron injections of the newly designed organic sensitizer were investigated in this work through density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations using the Gaussian’09W software package. Furthermore, TDDFT computational calculations were performed on cyanadin and benzothiadiazolylbenzoic acid separately, as reference. The computational studies on the new sensitizer have shown a reduced HOMO-LUMO gap; bathochromic and hyperchromic shifts of absorption spectra range up to near-infrared region revealing its enhanced ability to sensitize DSSCs. Kalpana Galappaththi, Andery Lim, Piyasiri Ekanayake, and Mohammad Iskandar Petra Copyright © 2017 Kalpana Galappaththi et al. All rights reserved. Chelated Nitrogen-Sulphur-Codoped TiO2: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies Thu, 17 Aug 2017 08:57:09 +0000 This study presents in detail the physicochemical, photoluminescent, and photocatalytic properties of carboxylic acid chelated nitrogen-sulphur-codoped TiO2. From the Fourier transform infrared spectroscopic study, it was revealed that the formate group formed bidentate bridging linkage while the acetate group coordinated in a bidentate chelating mode with a titanium precursor. In compliance with X-ray diffraction data, the anatase to rutile transformation temperature was extended due to carboxylic acid chelation and NS codoping. Raman analysis indicated four Raman peaks at 146, 392, 512, and 632 cm−1 for the precalcined chelated TiO2; on incorporation with NS dopants, an increase in Raman intensity for these peaks was recorded, indicating the structure stability of the anatase phase. Furthermore, X-ray photoelectron spectroscopic study revealed the presence of anionic doping of nitrogen and cationic doping of sulphur in the lattice of TiO2. When evaluating the UV-visible photodegradation rate of 4-chlorophenol, the modified TiO2 (NS0.06-TFA) showed the highest photocatalytic activity. In connection with the activity tests, several scavenger agents were employed to elucidate the significance of the different reactive oxidizing species during the photocatalytic process. Moreover, the transfer pathways of photogenerated carriers and the photocatalytic reaction mechanism of modified TiO2 were also explained in detail. Hayat Khan, Imran Khan Swati, Mohammad Younas, and Asmat Ullah Copyright © 2017 Hayat Khan et al. All rights reserved. Photophysical Behavior of Modified Xanthenic Dyes Embedded into Silsesquioxane Hybrid Films: Application in Photooxidation of Organic Molecules Wed, 16 Aug 2017 07:11:24 +0000 Polymeric materials based on a bridged silsesquioxane with pendant dodecyl chains were synthesized and modified with different xanthenic dyes with the aim of developing a material with potential application in photooxidation of organic compounds. The employed dyes constitute a family of novel xanthenic chromophores with outstanding properties as singlet oxygen photosensitizers. The hybrid matrix was chosen for its enhanced properties such as flexibility and chemical resistance. The employed dyes were easily incorporated into the hybrid polymer obtaining homogeneous, transparent, and low-refractive-index materials. The polymeric films were characterized using UV-Vis absorption, fluorescence, and laser flash photolysis techniques. The ability of these materials to produce singlet oxygen was tested following the photooxidation of 9,10-dimethylanthracene which is a well-known chemical trap for singlet oxygen. High photooxidation efficiencies were observed for these materials, which present the advantage of being easily removed/collected from the solution where photooxidation takes place. While photobleaching of the incorporated dyes is commonly observed in the solution, it takes place very slowly when dyes are embedded in the hybrid matrix. These properties bode well for the potential use of these materials in novel wastewater purification strategies. Carolina V. Waiman, Rodrigo E. Palacios, Hernán A. Montejano, Carlos A. Chesta, and María Lorena Gómez Copyright © 2017 Carolina V. Waiman et al. All rights reserved. Experimental Analysis of the Potential Induced Degradation Effect on Organic Solar Cells Sun, 13 Aug 2017 00:00:00 +0000 Renewable energy applications are increasing daily, and solar electricity, in the form of photovoltaics, is getting more and more important worldwide. As photovoltaics are connected both in series and in parallel, the panels are exposed to high potentials compared to the ground; thus, high voltage stress (HVS) occurs. The scope of this paper is to analyze experimentally the potential induced degradation (PID) in organic solar cells. To that end, organic solar cells are manufactured and are then undergone a series of voltage-dependent degradation and time-dependent voltage degradation tests. In addition to that, they are also exposed to gaseous oxygen, oxygen plasma, air degradation, and annealing, and the degradation effects are compared with PID results. From the analysis, it is apparent that annealing, air, gaseous oxygen, and oxygen plasma degradation have similar effects with PID, while due to simple diode characteristics, organic cells proved to be relatively durable to potential induced degradation. At low voltages (10 V), the organic cells withstood degradation adequately, with a drop of 23% in their initial efficiency. As voltage increased, the degradation rate increased considerably reaching a 93% efficiency drop when 30 V was applied for 20 minutes. S. C. Akcaoğlu, G. Martinopoulos, and C. Zafer Copyright © 2017 S. C. Akcaoğlu et al. All rights reserved. Accurate Maximum Power Point Tracking Algorithm Based on a Photovoltaic Device Model Thu, 10 Aug 2017 00:00:00 +0000 An accurate method is proposed to track the maximum power point of a photovoltaic module. The method is based on the analytical value of the maximum power point voltage, determined from a mathematical model of the photovoltaic panel. The method has the advantage of accuracy without any oscillations, as with certain conventional methods. The algorithm has also the ability to track accurately the maximum power point under variable atmospheric conditions and load changes. Experimental results are presented to show the effectiveness of the method. The implementation of the method needs an online measurement of irradiance, panel temperature, and panel current and voltage. Lhoussain El Bahir and Touria Hassboun Copyright © 2017 Lhoussain El Bahir and Touria Hassboun. All rights reserved. Effect of Fe Loading Condition and Reductants on CO2 Reduction Performance with Fe/TiO2 Photocatalyst Wed, 09 Aug 2017 00:00:00 +0000 Fe-doped TiO2 (Fe/TiO2) film photocatalyst was prepared by sol-gel and dip-coating process and pulse arc plasma method. The effect of pulse number on the CO2 reduction performance with the Fe/TiO2 was investigated in this study. In addition, the effect of reductants such as H2O, H2, and NH3/H2O on the CO2 reduction performance with the Fe/TiO2 photocatalyst was also investigated. The characteristics of the prepared Fe/TiO2 film coated on a netlike glass fiber which is a base material were analyzed by SEM, EPMA, EDX, and EPMA. Furthermore, the CO2 reduction performance of the Fe/TiO2 film was tested under a Xe lamp with or without ultraviolet (UV) light. The results show that the CO2 reduction performance with the pulse number of 100 is the best with H2O and/or H2 as reductant under UV light illumination, while that with the pulse number of 500 is the best when NH3/H2O is used as reductant. On the other hand, the CO2 reduction performance with the pulse number of 500 is the best under every reductant condition without UV light illumination. The highest CO2 reduction performance with the Fe/TiO2 is obtained under H2 + H2O/CO2 condition, and the best moral ratio of total reductants to CO2 is 1.5 : 1. Akira Nishimura, Noriaki Ishida, Daichi Tatematsu, Masafumi Hirota, Akira Koshio, Fumio Kokai, and Eric Hu Copyright © 2017 Akira Nishimura et al. All rights reserved. Tandem Solar Cells Based on Cu2O and c-Si Subcells in Parallel Configuration: Numerical Simulation Tue, 08 Aug 2017 06:52:22 +0000 A tandem solar cell consisting of a bottom c-Si high-efficiency subcell and a top low-cost Cu2O subcell in parallel configuration is evaluated for the first time by a use of an electrical model. A numerical simulation based on the single-diode model of the solar cell is performed. The numerical method determines both the model parameters and the parameters of the subcells and tandem from the maximization of output power. The simulations indicate a theoretical limit value of the tandem power conversion efficiency of 31.23% at 298 K. The influence of temperature on the maximum output power is analyzed. This tandem configuration allows a great potential for the development of a new generation of low-cost high-efficiency solar cells. Mihai Răzvan Mitroi, Valerică Ninulescu, and Laurenţiu Fara Copyright © 2017 Mihai Răzvan Mitroi et al. All rights reserved. Determination of Performance Measuring Parameters of an Improved Dual Paraboloid Solar Cooker Mon, 07 Aug 2017 05:51:30 +0000 An experimental investigation into the performance evaluation of an improved dual reflector foldable paraboloid solar cooker has been reported, along with its energy and exergy analysis. The best attribute of this lightweight and low-cost solar cooker is its high performance coupled with the ease of handling. The cooker utilizes two paraboloid reflectors made out of Mylar-coated fiberglass dishes, each having a diameter of 90 cm and focal length of 105 cm. The total intercepted radiation energy is 1.08 kW under standard test conditions. Stagnation temperatures of up to 330°C and cooking temperatures of up to 290°C have been attained with load. Altogether, 9 experiments have been performed with and without load. Loaded tests have been conducted with water and vegetable oil. Results indicate an average cooking power of 485 W, peak exergy gain of 60.53 W, quality factor of 0.077, and a high product of temperature difference gap at half peak power to peak power of 4364.33 W·K. The maximum exergy output power attained was 70 W, while maximum exergy efficiency was 8–10%. All performance measuring parameters indicate that it is a high performance solar cooker for rural and urban communities and is suitable for all types of oil- and water-based cooking. Suhail Zaki Farooqui Copyright © 2017 Suhail Zaki Farooqui. All rights reserved. Small-Scale Flat Plate Collectors for Solar Thermal Scavenging in Low Conductivity Environments Thu, 03 Aug 2017 00:00:00 +0000 There is great opportunity to develop power supplies for autonomous application on the small scale. For example, remote environmental sensors may be powered through the harvesting of ambient thermal energy and heating of a thermoelectric generator. This work investigates a small-scale (centimeters) solar thermal collector designed for this application. The absorber is coated with a unique selective coating and then studied in a low pressure environment to increase performance. A numerical model that is used to predict the performance of the collector plate is developed. This is validated based on benchtop testing of a fabricated collector plate in a low-pressure enclosure. Model results indicate that simulated solar input of about 800 W/m2 results in a collector plate temperature of 298 K in ambient conditions and up to 388 K in vacuum. The model also predicts the various losses in W/m2 K from the plate to the surroundings. Plate temperature is validated through the experimental work showing that the model is useful to the future design of these small-scale solar thermal energy collectors. Emmanuel Ogbonnaya and Leland Weiss Copyright © 2017 Emmanuel Ogbonnaya and Leland Weiss. All rights reserved. Hybrid Power Forecasting Model for Photovoltaic Plants Based on Neural Network with Air Quality Index Tue, 01 Aug 2017 06:01:16 +0000 High concentration of greenhouse gases in the atmosphere has increased dependency on photovoltaic (PV) power, but its random nature poses a challenge for system operators to precisely predict and forecast PV power. The conventional forecasting methods were accurate for clean weather. But when the PV plants worked under heavy haze, the radiation is negatively impacted and thus reducing PV power; therefore, to deal with haze weather, Air Quality Index (AQI) is introduced as a parameter to predict PV power. AQI, which is an indication of how polluted the air is, has been known to have a strong correlation with power generated by the PV panels. In this paper, a hybrid method based on the model of conventional back propagation (BP) neural network for clear weather and BP AQI model for haze weather is used to forecast PV power with conventional parameters like temperature, wind speed, humidity, solar radiation, and an extra parameter of AQI as input. The results show that the proposed method has less error under haze condition as compared to conventional model of neural network. Idris Khan, Honglu Zhu, Jianxi Yao, Danish Khan, and Tahir Iqbal Copyright © 2017 Idris Khan et al. All rights reserved. Experimental Study of the Slit Spacing and Bed Height on the Thermal Performance of Slit-Glazed Solar Air Heater Sun, 30 Jul 2017 00:00:00 +0000 The thermal performances of three slit-glazed solar air heaters (SGSAHs) were investigated experimentally. Three SGSAHs with different bed heights (7 cm, 5 cm, and 3 cm) were fabricated with multiple glass panes used for glazing. The length, width, and thickness of each pane were 154 cm, 6 cm, and 0.4 cm, respectively. Ambient air was continuously withdrawn through the gaps between the glass panes by fans. The experiments were conducted for four different gap distances between the glass panes (0.5 mm, 1 mm, 2 mm, and 3 mm) and the air mass flow rate was varied between 0.014 kg/s and 0.057 kg/s. The effects of air mass flux on the outlet temperature and thermal efficiency were studied. For the SGSAH with bed height of 7 cm and glass pane gap distance of 0.5 mm, the highest efficiency was obtained as 82% at a mass flow rate of 0.057 kg/s and the air temperature difference between the inlet and the outlet (∆T) was maximum (27°C) when the mass flow rate was least. The results demonstrate that for lower mass flow rates and larger gaps, the performance of SGSAH with a bed height of 3 cm was better compared to that of others. However, for higher mass flow rates, the SGSAH with 7 cm bed height performed better. Seyyed Mahdi Taheri Mousavi and Fuat Egelioglu Copyright © 2017 Seyyed Mahdi Taheri Mousavi and Fuat Egelioglu. All rights reserved. Modeling and Modulation of NNPC Four-Level Inverter for Solar Photovoltaic Power Plant Sun, 30 Jul 2017 00:00:00 +0000 Photovoltaic (PV) power plant is an attractive way of utilizing the solar energy. For high-power PV power plant, the multilevel inverter is of potential interest. In contrast to the neutral-point clamped (NPC) or flying capacitor (FC) multilevel inverter, the nested neutral point clamped (NNPC) four-level inverter has better features for solar photovoltaic power plant. In practical applications, the common mode voltage reduction of the NNPC four-level is one of the important issues. In order to solve the problem, a new modulation strategy is proposed to minimize the common mode voltage. Compared with the conventional solution, our proposal can reduce the common mode voltage to 1/18 of the DC bus voltage. Moreover, it has the capability to balance the capacitor voltages. Finally, we carried out time-domain simulations to test the performance of the NNPC four-level inverter. Xiaoqiang Guo, Xuehui Wang, Ran He, and Mehdi Narimani Copyright © 2017 Xiaoqiang Guo et al. All rights reserved. An Analysis of ZnS:Cu Phosphor Layer Thickness Influence on Electroluminescence Device Performances Mon, 24 Jul 2017 00:00:00 +0000 Electroluminescence (EL) device is a new technology; its thickness is within micrometer range which can bend more easily and emit light. However, the thickness of ZnS:Cu phosphor layer may affect the light intensity, so we have analyzed the thickness of ZnS:Cu phosphor layer on EL device. The EL devices consist of ITO:PET/ZnS:Cu phosphor/insulator (BaTiO3)/Ag electrode. The EL devices were fabricated in changing thickness 10 μm, 30 μm, and 50 μm. At 100 V 400 Hz, the luminance of EL devices was 51.22 cd/m2 for thickness 30 μm more than that of 45.78 cd/m2 (thickness: 10 μm) and 42.58 cd/m2 (thickness: 50 μm). However, the peak light intensity was achieved at wavelength of 507 nm which was not influenced by the thickness of the ZnS:Cu phosphor. The use of the ZnS:Cu phosphor layer at thickness 30 μm in the EL device significantly improves the luminescence performance. Pakpoom Chansri, Somchai Arunrungrusmi, Toshifumi Yuji, and Narong Mungkung Copyright © 2017 Pakpoom Chansri et al. All rights reserved. Enhancement of UV Radiation by Cloud Effect in NE of Brazil Mon, 24 Jul 2017 00:00:00 +0000 This paper reports a detailed analysis of ground-based measurements of cloud-enhanced global solar and UV radiation in NE Brazil in the city of Recife. It was found that (a) the phenomenon of UV enhancement, above clear sky model, is not uncommon and that it occurs on at least eight months; (b) the cumulative duration can reach 13 minutes; (c) there is a clear seasonal effect, and the probability of occurrence on a monthly basis shows two peaks, one in March and another in October; and (d) the most extreme UV radiation was 70.4 W/m2, approximately 6 W/m2 higher than the clear sky UV radiation. The extreme values should be taken into account in the study of effects related to the UV index and biological effects. Two statistical models also were elaborated, to estimate the UV solar radiation, in which the first is for all sky conditions and the second exclusively for situations where the global solar radiation is equal to or higher than 1367 W/m2, resulting from the enhancement effect caused by a particular configuration of the clouds. The statistical indicatives for both models presented, respectively, MBE% of 3.09 and 0.48% and RMSE% of 15.80 and 3.90%. Chigueru Tiba and Sérgio da Silva Leal Copyright © 2017 Chigueru Tiba and Sérgio da Silva Leal. All rights reserved. Selective Adsorption and Photocatalytic Degradation of Dyes Using Polyoxometalate Hybrid Supported on Magnetic Activated Carbon Nanoparticles under Sunlight, Visible, and UV Irradiation Mon, 24 Jul 2017 00:00:00 +0000 In this study, magnetic activated carbon (MAC) nanoparticles were coated with an organic hybrid of silicotungstic acid that makes MAC suitable for adsorption and photocatalytic degradation of dyes. The prepared composite was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermal analyses, scanning electron microscopy, vibrating sample magnetometer, and N2 adsorption-desorption isotherms. Dye adsorption and photocatalytic properties of composite were examined by studying the decolorization of model dyes methylene blue (MB), methyl orange (MO), rhodamine B (RhB), and their mixture solutions. The results show that the composite can selectively adsorb MB molecules from binary mixtures of MB/MO or MB/RhB, and its adsorption capacity is enhanced as compared with the MAC. The composite is also, unlike MAC, a good photocatalyst in the degradation of dyes under sunlight, visible, and UV irradiation and can be separated by magnet, recovered and reused. Removal is via combination of adsorption and then photocatalytic degradation through direct oxidation by composite or indirect oxidation by •OH radicals. While the sunlight is not able to degrade alone MO and RhB solution in the presence of composite, it degrades the MO and RhB mixed with MB solution. Mehdi Taghdiri Copyright © 2017 Mehdi Taghdiri. All rights reserved. A Solar Heating and Cooling System in a Nearly Zero-Energy Building: A Case Study in China Tue, 18 Jul 2017 03:37:13 +0000 The building sector accounts for more than 40% of the global energy consumption. This consumption may be lowered by reducing building energy requirements and using renewable energy in building energy supply systems. Therefore, a nearly zero-energy building, incorporating a solar heating and cooling system, was designed and built in Beijing, China. The system included a 35.17 kW cooling (10-RT) absorption chiller, an evacuated tube solar collector with an aperture area of 320.6 m2, two hot-water storage tanks (with capacities of 10 m3 and 30 m3, respectively), two cold-water storage tanks (both with a capacity of 10 m3), and a 281 kW cooling tower. Heat pump systems were used as a backup. At a value of 25.2%, the obtained solar fraction associated with the cooling load was close to the design target of 30%. In addition, the daily solar collector efficiency and the chiller coefficient of performance (COP) varied from 0.327 to 0.507 and 0.49 to 0.70, respectively. Zhifeng Sun, Yaohua Zhao, Wei Xu, Xinyu Zhang, Huai Li, Min Wang, Tao He, and Dongxu Wang Copyright © 2017 Zhifeng Sun et al. All rights reserved. Solar Energy and PV Systems in Smart Cities Sun, 09 Jul 2017 08:04:06 +0000 Daniele Menniti, Angel A. Bayod-Rújula, Alessandro Burgio, Diego A. L. García, and Zbigniew Leonowicz Copyright © 2017 Daniele Menniti et al. All rights reserved. Modulation above Pump Beam Energy in Photoreflectance Sun, 09 Jul 2017 00:00:00 +0000 Photoreflectance is used for the characterisation of semiconductor samples, usually by sweeping the monochromatized probe beam within the energy range comprised between the highest value set up by the pump beam and the lowest absorption threshold of the sample. There is, however, no fundamental upper limit for the probe beam other than the limited spectral content of the source and the responsivity of the detector. As long as the modulation mechanism behind photoreflectance does affect the complete electronic structure of the material under study, sweeping the probe beam towards higher energies from that of the pump source is equally effective in order to probe high-energy critical points. This fact, up to now largely overseen, is shown experimentally in this work. E1 and E0 + Δ0 critical points of bulk GaAs are unambiguously resolved using pump light of lower energy. This type of upstream modulation may widen further applications of the technique. D. Fuertes Marrón Copyright © 2017 D. Fuertes Marrón. All rights reserved. Recent Overview of Solar Photocatalysis and Solar Photo-Fenton Processes for Wastewater Treatment Sun, 09 Jul 2017 00:00:00 +0000 This literature research, although not exhaustive, gives perspective to solar-driven photocatalysis, such as solar photo-Fenton and solar photocatalysis, reported in the literature for the degradation of aqueous organic pollutants. Parameters that influence the degradation and mineralization of organics like catalyst preparation, type and load of catalyst, catalyst phase, pH, applied potential, and type of organic pollutant are addressed. Such parameters may also affect the photoactivity of the catalysts used in the studied solar processes. Solar irradiation is a renewable, abundant, and pollution-free energy source for low-cost commercial applications. Therefore, these solar processes represent an environmentally friendly alternative mainly because the use of electricity can be decreased/avoided. A. G. Gutierrez-Mata, S. Velazquez-Martínez, Alberto Álvarez-Gallegos, M. Ahmadi, José Alfredo Hernández-Pérez, F. Ghanbari, and S. Silva-Martínez Copyright © 2017 A. G. Gutierrez-Mata et al. All rights reserved.