International Journal of Photoenergy The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Optimal Design of a Secondary Optical Element for a Noncoplanar Two-Reflector Solar Concentrator Thu, 05 Mar 2015 13:11:01 +0000 This paper presents the results of a parametric design process used to achieve an optimal secondary optical element (SOE) in a noncoplanar solar concentrator composed of two reflectors. The noncoplanar solar concentrator comprises a primary parabolic mirror (M1) and a secondary hyperbolic mirror (M2). The optical performance (i.e., acceptance angle, optical efficiency, and irradiance distribution) of concentrators with various SOEs was compared using ray-tracing simulation. The parametric design process for the SOE was divided into two phases, and an optimal SOE was obtained. The sensitivity to assembly errors of the solar concentrator when using the optimal SOE was studied and the findings are discussed. Yi-Cheng Chen and Chia-Chi You Copyright © 2015 Yi-Cheng Chen and Chia-Chi You. All rights reserved. Photodegradation of Methylene Blue by TiO2-Fe3O4-Bentonite Magnetic Nanocomposite Mon, 02 Mar 2015 08:58:24 +0000 -bentonite nanoparticles have been prepared by a coprecipitation technique under a nitrogen atmosphere. An aqueous suspension of bentonite was first modified with FeCl2 and FeCl3. TiO2 was then loaded onto the surface of the -bentonite by a sol-gel method. After sufficient drying, the colloidal solution was placed in a muffle furnace at 773 K to obtain the -bentonite composite. The material has been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and vibrating sample magnetometry (VSM). Morphological observation showed that and TiO2 nanoparticles had been adsorbed on the surface of bentonite nanoneedles. The material was then applied for the photodegradation of the azo dye methylene blue (MB). It was found that the removal efficiency of MB exceeded 90% under UV illumination, and that only a 20% mass loss was incurred after six cycles. The composite material thus showed good photocatalytic performance and recycling properties. Wei Chen, Hongyao Xiao, Hang Xu, Tonggang Ding, and Yanmei Gu Copyright © 2015 Wei Chen et al. All rights reserved. Silver Nanoparticles in PEDOT:PSS Layer for Polymer Solar Cell Application Mon, 02 Mar 2015 07:50:05 +0000 We compare the performance of polymer solar cells based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) with silver nanoparticles (Ag NPs) incorporated in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The structure of constructed solar devices was ITO/PEDOT:PSS:Ag NPs/P3HT:PCBM/Al. Typical polyol chemistry was used to synthesize silver in water solution. Ag nanoparticles were investigated by UV-vis, atomic force microscopy (AFM), and dynamic light scattering (DLS) methods. We investigated influence of amount of silver in a hole transporting layer on the performance of bulk heterojunction polymer solar cells. The value of power conversion efficiency (PCE), equal to 2.16% under simulated 100 mW/cm2 AM 1.5G irradiation, was found for device created in air with 60 µL of Ag NPs added to 1 mL of PEDOT:PSS. Along with the increase amount of Ag NPs from 60 to 150 µL, the PCE decrease was found. Stability of solar cells with Ag was also investigated. The loss in value of PCE after 8 months was found in the range 13–47% depending on the device architecture. The solar cells were additionally measured with impedance spectroscopy. Agnieszka Iwan, Bartosz Boharewicz, Igor Tazbir, Andrzej Sikora, and Beata Zboromirska-Wnukiewicz Copyright © 2015 Agnieszka Iwan et al. All rights reserved. A Multicriteria Analysis of Photovoltaic Systems: Energetic, Environmental, and Economic Assessments Mon, 02 Mar 2015 06:44:50 +0000 The development of photovoltaic (PV) energy has led to rising efficiencies, better reliability, and falling prices. A multicriteria analysis (MCA) of PV systems is proposed in this paper in order to evaluate the sustainability of alternative projects. The investigations are presented using multiple indicators: Energy Payback Time (EPBT), Energy Return on Investment (EROI), Greenhouse Gas per kilowatt-hour (GHG/kWh), Greenhouse Gas Payback Time (GPBT), Greenhouse Gas Return on Investment (GROI), Net Present Value (NPV), Discounted Payback Time (DPBT), and Discounted Aggregate Cost Benefit (). PV energy is a relevant player in global electricity market and can have a key-role in sustainable growth. Federica Cucchiella and Idiano D’Adamo Copyright © 2015 Federica Cucchiella and Idiano D’Adamo. All rights reserved. Reliability Assessment of Transformerless PV Inverters considering Mission Profiles Sun, 01 Mar 2015 13:30:57 +0000 Due to the small volume and high efficiency, transformerless inverters have gained much popularity in grid-connected PV applications, where minimizing leakage current injection is mandatory. This can be achieved by either modifying the modulation schemes or adding extra power switching devices, resulting in an uneven distribution of the power losses on the switching devices. Consequently, the device thermal loading is redistributed and thus may alter the entire inverter reliability performance, especially under a long-term operation. In this consideration, this paper assesses the device reliability of three transformerless inverters under a yearly mission profile (i.e., solar irradiance and ambient temperature). The mission profile is translated to device thermal loading, which is used for lifetime prediction. Comparison results reveal the lifetime mismatches among the power switching devices operating under the same condition, which offers new thoughts for a robust design and a reliable operation of grid-connected transformerless PV inverters with high efficiency. Yongheng Yang, Huai Wang, and Frede Blaabjerg Copyright © 2015 Yongheng Yang et al. All rights reserved. Dynamics in Photoexcited DNA Bases and Related Molecules Sun, 01 Mar 2015 07:57:42 +0000 Yusheng Dou, Zhisong Wang, Fuli Li, and Roland E. Allen Copyright © 2015 Yusheng Dou et al. All rights reserved. Corrigendum to “Expanding Thermal Plasma Chemical Vapour Deposition of ZnO:Al Layers for CIGS Solar Cells” Wed, 25 Feb 2015 14:39:09 +0000 K. Sharma, B. L. Williams, A. Mittal, H. C. M. Knoops, B. J. Kniknie, N. J. Bakker, W. M. M. Kessels, R. E. I. Schropp, and M. Creatore Copyright © 2015 K. Sharma et al. All rights reserved. Analytical Modelling of High Concentrator Photovoltaic Modules Based on Atmospheric Parameters Mon, 23 Feb 2015 10:18:45 +0000 The goal of this paper is to introduce a model to predict the maximum power of a high concentrator photovoltaic module. The model is based on simple mathematical expressions and atmospheric parameters. The maximum power of a HCPV module is estimated as a function of direct normal irradiance, cell temperature, and two spectral corrections based on air mass and aerosol optical depth. In order to check the quality of the model, a HCPV module was measured during one year at a wide range of operating conditions. The new proposed model shows an adequate match between actual and estimated data with a root mean square error (RMSE) of 2.67%, a mean absolute error (MAE) of 4.23 W, a mean bias error (MBE) of around 0%, and a determination coefficient () of 0.99. Eduardo F. Fernández, F. Almonacid, T. K. Mallick, and P. Pérez-Higueras Copyright © 2015 Eduardo F. Fernández et al. All rights reserved. Functionalized Activated Carbon Derived from Biomass for Photocatalysis Applications Perspective Mon, 23 Feb 2015 06:33:34 +0000 This review highlighted the developments of safe, effective, economic, and environmental friendly catalytic technologies to transform lignocellulosic biomass into the activated carbon (AC). In the photocatalysis applications, this AC can further be used as a support material. The limits of AC productions raised by energy assumption and product selectivity have been uplifted to develop sustainable carbon of the synthesis process, where catalytic conversion is accounted. The catalytic treatment corresponding to mild condition provided a bulk, mesoporous, and nanostructure AC materials. These characteristics of AC materials are necessary for the low energy and efficient photocatalytic system. Due to the excellent oxidizing characteristics, cheapness, and long-term stability, semiconductor materials have been used immensely in photocatalytic reactors. However, in practical, such conductors lead to problems with the separation steps and loss of photocatalytic activity. Therefore, proper attention has been given to develop supported semiconductor catalysts and certain matrixes of carbon materials such as carbon nanotubes, carbon microspheres, carbon nanofibers, carbon black, and activated carbons have been recently considered and reported. AC has been reported as a potential support in photocatalytic systems because it improves the transfer rate of the interface charge and lowers the recombination rate of holes and electrons. Samira Bagheri, Nurhidayatullaili Muhd Julkapli, and Sharifah Bee Abd Hamid Copyright © 2015 Samira Bagheri et al. All rights reserved. Optical Properties of Spin-Coated TiO2 Antireflection Films on Textured Single-Crystalline Silicon Substrates Mon, 23 Feb 2015 06:32:31 +0000 Antireflection coating (ARC) prepared by a wet process is beneficial for low cost fabrication of photovoltaic cells. In this study, we investigated optical properties and morphologies of spin-coated TiO2 ARCs on alkaline textured single-crystalline silicon wafers. Reflectance spectra of the spin-coated ARCs on alkaline textured silicon wafers exhibit no interferences and low reflectance values in the entire visible range. We modeled the structures of the spin-coated films for ray tracing numerical calculation and compared numerically calculated reflectance spectra with the experimental results. This is the first report to clarify the novel optical properties experimentally and theoretically. Optical properties of the spin-coated ARCs without interference are due to the fractional nonuniformity of the thickness of the spin-coated ARCs that cancels out the interference of the incident light. Ryosuke Watanabe, Yohei Eguchi, Takuya Yamada, and Yoji Saito Copyright © 2015 Ryosuke Watanabe et al. All rights reserved. Bonded Excimer in Stacked Cytosines: A Semiclassical Simulation Study Sun, 22 Feb 2015 13:52:38 +0000 The formation of a covalent bond between two stacked cytosines, one of which is excited by an ultrafast laser pulse, was studied by semiclassical dynamics simulations. The results show that a bonded excimer is created, which sharply lowers the energy gap between the LUMO and HOMO and consequently facilitates the deactivation of the electronically excited molecule. This is different from the case of two stacked adenines, where the formation of a covalent bond alters the nonadiabatic deactivation mechanism in two opposite ways. It lowers the energy gap and consequently leads to the coupling between the HOMO and LUMO levels, thus enhancing the deactivation of the electronically excited molecule. On the other hand, it leads to restriction of the deformation vibration of the pyrimidine in the excited molecule, because of a steric effect, and this delays the deactivation process of the excited adenine molecule with return to the electronic ground state. Weifeng Wu, Shuai Yuan, Jiajie She, Yusheng Dou, and Roland E. Allen Copyright © 2015 Weifeng Wu et al. All rights reserved. Photocatalytic Based Degradation Processes of Lignin Derivatives Sun, 22 Feb 2015 11:09:41 +0000 Photocatalysis, belonging to the advanced oxidation processes (AOPs), is a potential new transformation technology for lignin derivatives to value added products (e.g., phenol, benzene, toluene, and xylene). Moreover, lignin represents the only viable source to produce aromatic compounds as fossil fuel alternative. This review covers recent advancement made in the photochemical transformation of industrial lignins. It starts with the photochemical reaction principle followed by results obtained by varying process parameters. In this context, influences of photocatalysts, metal ions, additives, lignin concentration, and illumination intensity and the influence of pH are presented and discussed. Furthermore, an overview is given on several used process analytical methods describing the results obtained from the degradation of lignin derivatives. Finally, a promising concept by coupling photocatalysis with a consecutive biocatalytic process was briefly reviewed. Colin Awungacha Lekelefac, Nadine Busse, Michael Herrenbauer, and Peter Czermak Copyright © 2015 Colin Awungacha Lekelefac et al. All rights reserved. Hybrid Neural Network Approach Based Tool for the Modelling of Photovoltaic Panels Sun, 22 Feb 2015 09:34:02 +0000 A hybrid neural network approach based tool for identifying the photovoltaic one-diode model is presented. The generalization capabilities of neural networks are used together with the robustness of the reduced form of one-diode model. Indeed, from the studies performed by the authors and the works present in the literature, it was found that a direct computation of the five parameters via multiple inputs and multiple outputs neural network is a very difficult task. The reduced form consists in a series of explicit formulae for the support to the neural network that, in our case, is aimed at predicting just two parameters among the five ones identifying the model: the other three parameters are computed by reduced form. The present hybrid approach is efficient from the computational cost point of view and accurate in the estimation of the five parameters. It constitutes a complete and extremely easy tool suitable to be implemented in a microcontroller based architecture. Validations are made on about 10000 PV panels belonging to the California Energy Commission database. Antonino Laudani, Gabriele Maria Lozito, Francesco Riganti Fulginei, and Alessandro Salvini Copyright © 2015 Antonino Laudani et al. All rights reserved. TiO2 Photocatalytic Materials 2014 Thu, 19 Feb 2015 09:40:40 +0000 Jiaguo Yu, Mietek Jaroniec, Wei Xiao, Christos Trapalis, and Hong Liu Copyright © 2015 Jiaguo Yu et al. All rights reserved. Water Soluble Aluminum Paste Using Polyvinyl Alcohol for Silicon Solar Cells Wed, 18 Feb 2015 13:25:21 +0000 Screen-printing aluminum is still dominantly used in the solar cell fabrication process. Ethyl cellulose is one of the main contents of screen-printing pastes that require dichloromethane for its cleaning process, a substance renowned for being extremely toxic and threatening to the human body. Developing environmental friendly aluminum pastes is essential in order to provide an alternative to the commercial pastes. In this work, new, nontoxic polyvinyl alcohol-based aluminum pastes are introduced. Polyvinyl alcohol was used as a soluble polymer that can be synthesized without saponification and that is also soluble in water. Three different pastes were developed using different recipes including many aluminum particle sizes varying from 3.0 to 45 μm, aluminum oxide with particle sizes between 35 and 50 μm, and acetic acid. Evaluation of the pastes was carried out by Scanning Electron Microscope (SEM) image analysis, sheet resistance measurements, and fabricating silicon solar cells using each paste. Solar cells with 15.6% efficiency were fabricated by nonvacuum processing on CZ-Si p-type wafers using developed aluminum pastes on the back side. Abdullah Uzum, Taiki Ashikaga, Takuma Noguchi, Hiroyuki Kanda, Toshifumi Matsuoka, Toru Nakanishi, Hidehito Fukui, Tomitaro Harada, and Seigo Ito Copyright © 2015 Abdullah Uzum et al. All rights reserved. Wet-Chemical Surface Texturing of Sputter-Deposited ZnO:Al Films as Front Electrode for Thin-Film Silicon Solar Cells Tue, 10 Feb 2015 09:45:27 +0000 Transparent conductive oxides (TCOs) play a major role as the front electrodes of thin-film silicon (Si) solar cells, as they can provide optical scattering and hence improved photon absorption inside the devices. In this paper we report on the surface texturing of aluminium-doped zinc oxide (ZnO:Al or AZO) films for improved light trapping in thin-film Si solar cells. The AZO films are deposited onto soda-lime glass sheets via pulsed DC magnetron sputtering. Several promising AZO texturing methods are investigated using diluted hydrochloric (HCl) and hydrofluoric acid (HF), through a two-step etching process. The developed texturing procedure combines the advantages of the HCl-induced craters and the smaller and jagged—but laterally more uniform—features created by HF etching. In the two-step process, the second etching step further enhances the optical haze, while simultaneously improving the uniformity of the texture features created by the HCl etch. The resulting AZO films show large haze values of above 40%, good scattering into large angles, and a surface angle distribution that is centred at around 30°, which is known from the literature to provide efficient light trapping for thin-film Si solar cells. Xia Yan, Selvaraj Venkataraj, and Armin G. Aberle Copyright © 2015 Xia Yan et al. All rights reserved. Structural Dependence of Electronic Properties in A-A-D-A-A-Type Organic Solar Cell Material Tue, 10 Feb 2015 08:58:51 +0000 Small conjugated molecules (SCMs) are promising candidates for organic photovoltaic (OPV) devices because of their structural simplicity, well control over synthetic reproducibility, and low purification cost. However, industrial development of SCM-based OPV devices requires improving their performance, which in turn relies on the fundamental understanding of structural dependence of electronic properties of SCMs. Herein, we report the structural and electronic properties of the BCNDTS molecule as a model system for acceptor-acceptor-donor-acceptor-acceptor (A-A-D-A-A) type SCMs, using density functional theory (DFT) and time-dependent DFT methods. Systematic calculations of two-dimensional potential energy surfaces, molecular electrostatic potential surfaces, ground state frontier molecular orbital energies, and the vertical excitation energies are performed. We found that the lowest energy conformation of the BCNDTS molecule is planar. The planar conformation favors the lowest ground state and the excited state energies as well as the strongest oscillator strength. The present results suggest that SCMs containing central dithienosilole cores connected with 2,1,3-benzothiadiazole groups have potential to be an efficient electron donor for OPV devices. Ram S. Bhatta and Mesfin Tsige Copyright © 2015 Ram S. Bhatta and Mesfin Tsige. All rights reserved. LED Lighting System Reliability Modeling and Inference via Random Effects Gamma Process and Copula Function Thu, 05 Feb 2015 06:04:09 +0000 Light emitting diode (LED) lamp has attracted increasing interest in the field of lighting systems due to its low energy and long lifetime. For different functions (i.e., illumination and color), it may have two or more performance characteristics. When the multiple performance characteristics are dependent, it creates a challenging problem to accurately analyze the system reliability. In this paper, we assume that the system has two performance characteristics, and each performance characteristic is governed by a random effects Gamma process where the random effects can capture the unit to unit differences. The dependency of performance characteristics is described by a Frank copula function. Via the copula function, the reliability assessment model is proposed. Considering the model is so complicated and analytically intractable, the Markov chain Monte Carlo (MCMC) method is used to estimate the unknown parameters. A numerical example about actual LED lamps data is given to demonstrate the usefulness and validity of the proposed model and method. Huibing Hao, Chun Su, and Chunping Li Copyright © 2015 Huibing Hao et al. All rights reserved. Solar CPC Pilot Plant Photocatalytic Degradation of Indigo Carmine Dye in Waters and Wastewaters Using Supported-TiO2: Influence of Photodegradation Parameters Thu, 05 Feb 2015 05:59:46 +0000 The photocatalytic degradation of indigo carmine (IC) dye in the presence of titanium dioxide under different conditions was reported. Several factors which interfere with the photodegradation efficiency as catalyst concentration, pH, initial concentration of dye, presence of inorganic anions, temperature, and the addition of hydrogen peroxide were studied under artificial irradiation with a 125 W mercury vapor lamp. Additionally, the catalyst supported on glass spheres was used for the photocatalytic degradation of the dye present in several types of waters in a CPC solar pilot plant. The photocatalytic products, carboxylic acids, and and were followed during IC mineralization. Formate, acetate, and oxalate were detected in real MWWTP secondary effluent. The mineralization efficiency was of 42 and 21% using in suspension and supported TiO2, respectively. In order to evaluate biological effects, Eisenia andrei earthworms were used as a model organism. No significant difference () of weight was observed in the earthworm submitted to different concentrations of IC and its photoproducts. The photocatalytic degradation of IC on TiO2 supported on glass spheres suffered strong influence of the water matrix; nevertheless the method has the enormous advantage that it eliminates the need for the final catalyst removal step, reducing therefore the cost of treatment. Enrico Mendes Saggioro, Anabela Sousa Oliveira, Thelma Pavesi, Margarita Jiménez Tototzintle, Manuel Ignacio Maldonado, Fábio Verissimo Correia, and Josino Costa Moreira Copyright © 2015 Enrico Mendes Saggioro et al. All rights reserved. Characteristics of DSSC Panels with Silicone Encapsulant Wed, 04 Feb 2015 14:39:41 +0000 Dye-sensitized solar cells (DSSC) allow light transmission and the application of various colors that make them especially suitable for building-integrated PV (BIPV) application. In order to apply DSSC modules to windows, the module has to be panelized: a DSSC module should be protected with toughened glass on the entire surface. Up to the present, it seems to be common to use double glazing with DSSC modules, with air gaps between the glass pane and the DSSC modules. Few studies have been conducted on the characteristics of various glazing methods with DSSC modules. This paper proposes a paneling method that uses silicone encapsulant, analyzing the performance through experimentation. Compared to a multilayered DSSC panel with an air gap, the encapsulant-applied panel showed 6% higher light transmittance and 7% higher electrical efficiency. The encapsulant also prevented electrolyte leakage by strengthening the seals in the DSSC module. Jun-Gu Kang, Jin-Hee Kim, Han-Bin Jang, and Jun-Tae Kim Copyright © 2015 Jun-Gu Kang et al. All rights reserved. Comparative Study of Maximum Power Point Tracking Techniques for Photovoltaic Systems Wed, 04 Feb 2015 13:02:45 +0000 The generation of electricity from photovoltaic (PV) arrays has been increasingly considered as a prominent alternative to fossil fuels. However, the conversion efficiency is typically low and the initial cost is still appreciable. A required feature of a PV system is the ability to track the maximum power point (MPP) of the PV array. Besides, MPP tracking (MPPT) is desirable in both grid-connected and stand-alone photovoltaic systems because the solar irradiance and temperature change throughout the day, as well as along seasons and geographical conditions, also leading to the modification of the (current versus voltage) and (power versus voltage) curves of the PV module. MPPT is also justified by the relatively high cost of the energy generated by PV systems if compared with other sources. Since there are various MPPT approaches available in the literature, this work presents a comparative study among four popular techniques, which are the fixed duty cycle method, constant voltage (CV), perturb and observe (P&O), and incremental conductance (IC). It considers different operational climatic conditions (i.e., irradiance and temperature), since the MPP is nonlinear with the environment status. PSIM software is used to validate the assumptions, while relevant results are discussed in detail. Fernando Lessa Tofoli, Dênis de Castro Pereira, and Wesley Josias de Paula Copyright © 2015 Fernando Lessa Tofoli et al. All rights reserved. Accurate Maximum Power Tracking in Photovoltaic Systems Affected by Partial Shading Tue, 03 Feb 2015 14:17:01 +0000 A maximum power tracking algorithm exploiting operating point information gained on individual solar panels is presented. The proposed algorithm recognizes the presence of multiple local maxima in the power voltage curve of a shaded solar field and evaluates the coordinated of the absolute maximum. The effectiveness of the proposed approach is evidenced by means of circuit level simulation and experimental results. Experiments evidenced that, in comparison with a standard perturb and observe algorithm, we achieve faster convergence in normal operating conditions (when the solar field is uniformly illuminated) and we accurately locate the absolute maximum power point in partial shading conditions, thus avoiding the convergence on local maxima. Pierluigi Guerriero, Fabio Di Napoli, Vincenzo d’Alessandro, and Santolo Daliento Copyright © 2015 Pierluigi Guerriero et al. All rights reserved. The Cortinarius Fungi Dyes as Sensitizers in Dye-Sensitized Solar Cells Sun, 01 Feb 2015 11:41:15 +0000 The dye-sensitized solar cells have been for the first time prepared using Cortinarius fungi extracts as a source of sensitizing dyes. The seven species of Cortinarius group, collected in the East Poland, have been used to obtain crude extracts of natural dyes used as sensitizing solutions to prepare DSSCs working electrodes. Extracts and sensitized electrodes have been well characterized by UV-Vis spectroscopy measurements. The device sensitized by Cortinarius sanguineus extract has been found the most active in photon-to-current conversion process with efficiency %, fill factor %, photocurrent density  mA/cm2, and photovoltage  mV. Maciej Zalas, Błażej Gierczyk, Hubert Bogacki, and Grzegorz Schroeder Copyright © 2015 Maciej Zalas et al. All rights reserved. Water-Solubilization of P(V) and Sb(V) Porphyrins and Their Photobiological Application Sun, 01 Feb 2015 08:15:48 +0000 Porphyrins have been widely utilized as biochemical and biological functional chromophores which can operate under visible-light irradiation. Water-soluble porphyrins have been used as the drug for photodynamic therapy (PDT) and photodynamic inactivation (PDI). Although usual water-solubilization of porphyrins has been achieved by an introduction of an ionic group such as ammonium, pyridinium, sulfonate, phosphonium, or carboxyl to porphyrin ring, we proposed the preparation of water-soluble P and Sb porphyrins by modification of axial ligands. Alkyl (type A), ethylenedioxy (type E), pyridinium (type P), and glucosyl groups (type G) were introduced to axial ligands of Sb and P porphyrins to achieve water-solubilization of Sb porphyrin and P porphyrins. Here, we review their water-soluble P and Sb porphyrins from the standpoints of preparation, bioaffinity, and photosensitized inactivation. Jin Matsumoto, Tsutomu Shiragami, Kazutaka Hirakawa, and Masahide Yasuda Copyright © 2015 Jin Matsumoto et al. All rights reserved. Investigating the Effect of Thermal Annealing Process on the Photovoltaic Performance of the Graphene-Silicon Solar Cell Wed, 28 Jan 2015 14:16:42 +0000 Graphene-silicon (Gr-Si) Schottky solar cell has attracted much attention recently as promising candidate for low-cost photovoltaic application. For the fabrication of Gr-Si solar cell, the Gr film is usually transferred onto the Si substrate by wet transfer process. However, the impurities induced by this process at the graphene/silicon (Gr/Si) interface, such as H2O and O2, degrade the photovoltaic performance of the Gr-Si solar cell. We found that the thermal annealing process can effectively improve the photovoltaic performance of the Gr-Si solar cell by removing these impurities at the Gr/Si interface. More interestingly, the photovoltaic performance of the Gr-Si solar cell can be improved, furthermore, when exposed to air environment after the thermal annealing process. Through investigating the characteristics of the Gr-Si solar cell and the properties of the Gr film (carrier density and sheet resistance), we point out that this phenomenon is caused by the natural doping effect of the Gr film. Lifei Yang, Xiaolei Wu, Xin Shen, Xuegong Yu, and Deren Yang Copyright © 2015 Lifei Yang et al. All rights reserved. Solar Energy and Clean Energy: Trends and Developments 2014 Wed, 28 Jan 2015 08:09:08 +0000 Ching-Song Jwo, Ho Chang, Chao-Rong Chen, Yen-Lin Chen, and Mohammad Yusri Hassan Copyright © 2015 Ching-Song Jwo et al. All rights reserved. Enhanced Light Trapping in Thin Film Solar Cells Using a Plasmonic Fishnet Structure Wed, 28 Jan 2015 07:43:51 +0000 Incorporating plasmonic structures into the back spacer layer of thin film solar cells (TFSCs) is an efficient way to improve their performance. The fishnet structure is used to enhance light trapping. Unlike other previously suggested discrete plasmonic particles, the fishnet is an electrically connected wire mesh that does not result in light field localization, which leads to high absorption losses. The design was verified experimentally. A silver fishnet structure was fabricated using electron beam lithography (EBL) and thermal evaporation. The final fabricated structure optically resembles a TFSC. The results predicted by numerical simulations were reproduced experimentally on a fabricated sample. We show that light absorption in the a-Si absorber layer is enhanced by a factor of 10.6 at the design wavelength of 690 nm due to the presence of the fishnet structure. Furthermore, the total absorption over all wavelengths was increased by a factor of 3.2. The short-circuit current of the TFSC was increased by 30% as a result of including the fishnet. Sayan Seal, Vinay Budhraja, Liming Ji, and Vasundara V. Varadan Copyright © 2015 Sayan Seal et al. All rights reserved. The Application Study in Solar Energy Technology for Highway Service Area: A Case Study of West Lushan Highway Low-Carbon Service Area in China Tue, 27 Jan 2015 08:39:03 +0000 A lot of research works have been made concerning highway service area or solar technology and acquired great achievements. However, unfortunately, few works have been made combining the two topics together of highway service areas and solar energy saving to make a systemic research on solar technology application for highway service area. In this paper, taking West Lushan highway low-carbon service area in Jiangxi Province of China as the case study, the advantages, technical principles, and application methods of solar energy technology for highway service area including solar photoelectric technology and solar water heating technology were discussed based on the analysis of characteristics of highway low-carbon service area; the system types, operation mode, and installing tilt angle of the two kinds of solar systems suitable for highway service areas were confirmed. It was proved that the reduction of the cost by electricity savings of solar system was huge. Taking the investment of the solar systems into account, the payback period of solar photoelectric systems and solar water heating systems was calculated. The economic effect of the solar systems in West Lushan highway service area during the effective operation periods was also calculated and proved very considerable. Xiaochun Qin, Yi Shen, and Shegang Shao Copyright © 2015 Xiaochun Qin et al. All rights reserved. Solubility Characteristics and Slow-Release Mechanism of Nitrogen from Organic-Inorganic Compound Coated Urea Thu, 22 Jan 2015 12:13:37 +0000 A soil incubation method was used to investigate the solubility characteristics and slow-release mechanism of organic-inorganic compound coated urea at temperature of 10, 20, and 30°C. The membrane microstructure with and without incubation was tested via scanning electron microscopy (SEM). Slow release of nitrogen (N) from different inorganic minerals was analysed by the activation energy from the nutrient solubility system. The rate of nitrogen solubility increased with temperature increasing. The first-order reaction kinetic equation described the solubility process of coated urea. The rate constant also increased with temperature increasing. Moreover, the SEM images showed that the microstructure of the coating layer changed into a flocculent structure and the number of tiny pores and holes on the membrane surface increased significantly with temperature increasing, which increased N solubility rate. The Arrhenius equation indicated that activation energy was closely related to during the solubility process; the activation energy was reduced with rising, which resulted in N solubility rate increasing. Overall, the N solubility rate of coated urea was affected by temperature. Hongtao Zou, Yao Ling, Xiuli Dang, Na Yu, YuLing Zhang, YuLong Zhang, and Jianghui Dong Copyright © 2015 Hongtao Zou et al. All rights reserved. Ultraviolet Radiation Emissions and Illuminance in Different Brands of Compact Fluorescent Lamps Thu, 22 Jan 2015 11:23:06 +0000 Introduction. Replacing incandescent lamps with compact fluorescent lamps (CFLs), which are three to six times more efficient, is one of the easiest methods to achieve energy efficiency. The present study aimed to evaluate relationships between UV emissions radiated and illuminance CFLs. Material and Methods. This pilot study was conducted on 16 single envelope CFLs. The illuminance and UV irradiance of various types of CFLs are measured on a three-meter long optical bench, using a calibrated lux meter and UV meter, and measurement was done in 10, 25, 50, 100, 150, and 200 cm, in three angles, including 0°, 45°, and 90°, at the ages of 0, 100, and 2000 hours. Result. UVC irradiance was not observed at the distance of 10 cm in all of lamps. The lowest value of UVB irradiance was recorded in Pars Khazar lamp, while the highest value was recorded in Etehad lamps. UVR values measured at different times showed negligible differences; the highest asset value was detected in zero times. One way ANOVA indicated that relationships between UVA irradiance and illuminance were significant (). Conclusion. UVB irradiance in most of the lamp in 10 and 25 cm was more than occupational exposure and UVA except for the fact that Pars Khazar 60 watts and Nama Noor 60 watts were less than occupational exposure. Shahram Safari, Sina Eshraghi Dehkordy, Meghdad Kazemi, Habibollah Dehghan, and Behzad Mahaki Copyright © 2015 Shahram Safari et al. All rights reserved.