Journal of Solar Energy http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. About the Relation between Sunshine Duration and Cloudiness on the Basis of Data from Hamburg Thu, 10 Apr 2014 17:31:15 +0000 http://www.hindawi.com/journals/jse/2014/306871/ The aim of this paper is to relate the two meteorological parameters known as relative (bright) sunshine duration and cloudiness using the data from two stations of the city of Hamburg, Germany. We test the classic linear relationship, as well as newer polynomial extensions suggested in the literature. The results of regression are interpreted against a theoretical background recently put forward by Badescu. The suggested relations can be borne out, but we also point out difficulties due to data quality and insufficiency. Stefanie Neske Copyright © 2014 Stefanie Neske. All rights reserved. Hybrid TiO2 Solar Cells Produced from Aerosolized Nanoparticles of Water-Soluble Polythiophene Electron Donor Layer Thu, 27 Feb 2014 12:55:25 +0000 http://www.hindawi.com/journals/jse/2014/192812/ Hybrid solar cells (HSCs) with water soluble polythiophene sodium poly[2-(3-thienyl)-ethyloxy-4-butylsulfonate] (PTEBS) thin films produced using electrospray deposition (ESD) were fabricated, tested, and modeled and compared to devices produced using conventional spin coating. A single device structure of FTO/TiO2/PTEBS/Au was used to study the effects of ESD of the PTEBS layer on device performance. ESD was found to increase the short circuit current density () by a factor of 2 while decreasing the open circuit voltage () by half compared to spin coated PTEBS films. Comparable efficiencies of 0.009% were achieved from both device construction types. Current-voltage curves were modeled using the characteristic solar cell equation and showed a similar increase in generated photocurrent with an increase by two orders of magnitude in the saturation current in devices from ESD films. Increases in are attributed to an increase in the interfacial contact area between the TiO2 and PTEBS layers, while decreases in are attributed to incomplete film formation from ESD. Marshall L. Sweet, Joshua G. Clarke, Dmitry Pestov, Gary C. Tepper, and James T. McLeskey Jr. Copyright © 2014 Marshall L. Sweet et al. All rights reserved. Empirical Models for Estimating Global Solar Radiation over the Ashanti Region of Ghana Thu, 16 Jan 2014 13:05:38 +0000 http://www.hindawi.com/journals/jse/2014/897970/ The performances of both sunshine and air temperature dependent models for the estimation of global solar radiation (GSR) over Ghana and other tropical regions were evaluated and a comparison assessment of the models was carried out using measured GSR at Owabi (6°45′0′′N, 1°43′0′′W) in the Ashanti region of Ghana. Furthermore, an empirical model which also uses sunshine hours and air temperature measurements from the study site and its environs was proposed. The results showed that all the models could predict very well the pattern of the measured monthly daily mean GSR for the entire period of the study. However, most of the selected models overestimated the measured GSR, except in April and November, where the empirical model using air temperature measurements underestimated the measured GSR. Nevertheless, a very good agreement was found between the measured radiations and the proposed models with a coefficient of determination within the range 0.88–0.96. The results revealed that the proposed models using sunshine hours and air temperature had the smallest values of MBE, MPE, and RMSE of −0.0102, 0.0585, and 0.0338 and −0.2973, 1.7075, and 0.9859, respectively. Emmanuel Quansah, Leonard K. Amekudzi, Kwasi Preko, Jeffrey Aryee, Osei R. Boakye, Dziewornu Boli, and Mubarick R. Salifu Copyright © 2014 Emmanuel Quansah et al. All rights reserved. Optimum Tilt Angle for Photovoltaic Solar Panels in Zomba District, Malawi Thu, 09 Jan 2014 13:41:18 +0000 http://www.hindawi.com/journals/jse/2014/132950/ A study to determine the optimum tilt angle for installing photovoltaic solar panels in Zomba district, Malawi, has been conducted. The study determined the optimum monthly tilt angles of PV solar panels and the seasonal adjustments needed for the panels in order to collect maximum solar radiation throughout the year. In this study, global solar radiation (GSR) on four tilted surfaces was measured. The north-facing surfaces were titled at angles of 0°, 15°, 20°, and 25°. The GSR data was used to determine the daily and monthly optimum tilt angles for the PV panels. The optimum tilt angles were found to be 0° or 25° depending on the time of the year. From October to February, the optimum tilt angle has been determined to be 0° and, from March to September, the optimum tilt angle is observed to be 25°. There are only two seasonal adjustments that are needed for PV solar panels in Zomba district and these should be carried out at the end of February and at the end of September. For fixed solar panels with no seasonal adjustments, the optimum tilt angle for the PV solar panels that are northfacing has been determined to be 25°. B. Kamanga, J. S. P. Mlatho, C. Mikeka, and C. Kamunda Copyright © 2014 B. Kamanga et al. All rights reserved. Experimental Study of Thermal Performance of One-Ended Evacuated Tubes for Producing Hot Air Sun, 08 Dec 2013 13:25:35 +0000 http://www.hindawi.com/journals/jse/2013/524715/ The thermal performance of an evacuated tube solar air collector is experimentally investigated at different air flow rates. Air is used as a working fluid in experimental setup and tested in Indian climatic conditions. The evacuated tube solar air collector consists of fifteen evacuated tubes and manifold channel. The manifold channel consists of a hollow pipe (square pipe) in centre through which air flows. The temperature difference and efficiency are studied with different air flow rates. The reflectors are used to enhance the performance of evacuated tubes solar air collector. It is observed that in case of reflector evacuated tube solar air collector gives higher outlet temperature and temperature difference and has better thermal performance as compared to the case without reflector. The maximum outlet temperature and temperature difference of air are found to be 97.4°C and 74.4°C at a flow rate of 6.70 kg/hr. Ashish Kumar, Sanjeev Kumar, Utkarsh Nagar, and Avadhesh Yadav Copyright © 2013 Ashish Kumar et al. All rights reserved. Review of Ni-Cu Based Front Side Metallization for c-Si Solar Cells Thu, 21 Nov 2013 14:14:26 +0000 http://www.hindawi.com/journals/jse/2013/183812/ Given the high percentage of metal cost in cell processing and concerns due to increasing Ag prices, alternative metallization schemes are being considered. Ni-Cu based front side metallization offers potential advantages of finer grid lines, lower series resistance, and reduced costs. A brief overview of various front side patterning techniques is presented. Subsequently, working principle of various plating techniques is discussed. For electroless plated Ni seed layer, fill factor values nearing 80% and efficiencies close to 17.5% have been demonstrated, while for Light Induced Plating deposited layers, an efficiency of 19.2% has been reported. Various methods for qualifying adhesion and long term stability of metal stack are discussed. Adhesion strengths in the range of 1–2.7 N/mm have been obtained for Ni-Cu contacts tabbed with conventional soldering process. Given the significance of metallization properties, different methods for characterization are outlined. The problem of background plating for Ni-Cu based metallization along with the various methods for characterization is summarized. An economic evaluation of front side metallization indicates process cost saving of more than 50% with Ni-Cu-Sn based layers. Recent successful commercialization and demonstration of Ni-Cu based metallization on industrial scale indicate a potential major role of Ni-Cu based contacts in near future. Mehul C. Raval and Chetan S. Solanki Copyright © 2013 Mehul C. Raval and Chetan S. Solanki. All rights reserved. Nanostructured CuO Thin Films Prepared through Sputtering for Solar Selective Absorbers Tue, 01 Oct 2013 11:47:07 +0000 http://www.hindawi.com/journals/jse/2013/147270/ Nanostructured cupric oxide (CuO) thin films have been deposited on copper (Cu) substrates at different substrate temperatures and oxygen to argon gas ratios through direct current (DC) reactive magnetron sputtering. The deposited CuO thin films are characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), profilometry, and spectrophotometry techniques. The crystalline phases, morphology, optical properties, and photothermal conversion efficiency of the CuO thin films are found to be significantly influenced by the change in substrate temperature and oxygen to argon gas ratio. The variations in the substrate temperature and oxygen to argon gas ratio have induced changes in Cu+ and Cu2+ concentrations of the CuO thin films that result in corresponding changes in their optical properties. The CuO thin film prepared at a substrate temperature of 30°C and O2 to Ar gas ratio of 1 : 1 has exhibited high absorptance and low emittance; thus, it could be used as a solar selective absorber in solar thermal gadgets. Senthuran Karthick Kumar, Sepperumal Murugesan, Santhanakrishnan Suresh, and Samuel Paul Raj Copyright © 2013 Senthuran Karthick Kumar et al. All rights reserved. Performance of Photovoltaic Modules of Different Solar Cells Thu, 05 Sep 2013 15:51:54 +0000 http://www.hindawi.com/journals/jse/2013/734581/ In this paper, an attempt of performance evaluation of semitransparent and opaque photovoltaic (PV) modules of different generation solar cells, having the maximum efficiencies reported in the literature at standard test conditions (STC), has been carried out particularly for the months of January and June. The outdoor performance is also evaluated for the commercially available semitransparent and opaque PV modules. Annual electrical energy, capitalized cost, annualized uniform cost (unacost), and cost per unit electrical energy for both types of solar modules, namely, semitransparent and opaque have also been computed along with their characteristics curves. Semitransparent PV modules have shown higher efficiencies compared to the opaque ones. Calculations show that for the PV modules made in laboratory, CdTe exhibits the maximum annual electrical energy generation resulting into minimum cost per unit electrical energy, whereas a-Si/nc-Si possesses the maximum annual electrical energy generation giving minimum cost per unit electrical energy when commercially available solar modules are concerned. CIGS has shown the lowest capitalized cost over all other PV technologies. Ankita Gaur and G. N. Tiwari Copyright © 2013 Ankita Gaur and G. N. Tiwari. All rights reserved. Study of Photovoltaic Energy Storage by Supercapacitors through Both Experimental and Modelling Approaches Wed, 04 Sep 2013 11:11:45 +0000 http://www.hindawi.com/journals/jse/2013/659014/ The storage of photovoltaic energy by supercapacitors is studied by using two approaches. An overview on the integration of supercapacitors in solar energy conversion systems is previously provided. First, a realized experimental setup of charge/discharge of supercapacitors fed by a photovoltaic array has been operated with fine data acquisition. The second approach consists in simulating photovoltaic energy storage by supercapacitors with a faithful and accessible model composed of solar irradiance evaluation, equivalent electrical circuit for photovoltaic conversion, and a multibranch circuit for supercapacitor. Both the experimental and calculated results are confronted, and an error of 1% on the stored energy is found with a correction largely within % of the transmission line capacitance according to temperature. Pierre-Olivier Logerais, Olivier Riou, Mohamed Ansoumane Camara, and Jean-Félix Durastanti Copyright © 2013 Pierre-Olivier Logerais et al. All rights reserved. Design and Optimization of a Monoaxial Tracking System for Photovoltaic Modules Sun, 28 Jul 2013 08:16:14 +0000 http://www.hindawi.com/journals/jse/2013/586302/ This paper presents researches on increasing the energetic efficiency of a photovoltaic (PV) string by designing and optimizing a tracking mechanism that simultaneously changes the daily position of the modules using a single driving source (there are modules with individual supports). The motion is transmitted from the driving source, which is a linear actuator, with a parallelogram mechanism. The main task in optimizing the tracking system is to maximize the energetic gain by increasing the solar input and minimizing the energy demand for tracking. The study is performed by developing the virtual prototype of the tracking system, which integrates the mechanical device and the control system, in mechatronic concept. Virtual prototyping software solutions (ADAMS, EASY5, and MAT) are used in this study. Cătălin Alexandru Copyright © 2013 Cătălin Alexandru. All rights reserved. Localized Surface Plasmons Enhanced Light Transmission into c-Silicon Solar Cells Wed, 24 Jul 2013 08:27:51 +0000 http://www.hindawi.com/journals/jse/2013/584283/ The paper investigates the light incoupling into c-Si solar cells due to the excitation of localized surface plasmon resonances in periodic metallic nanoparticles by finite-difference time-domain (FDTD) technique. A significant enhancement of AM1.5G solar radiation transmission has been demonstrated by depositing nanoparticles of various metals on the upper surface of a semi-infinite Si substrate. Plasmonic nanostructures located close to the cell surface can scatter incident light efficiently into the cell. Al nanoparticles were found to be superior to Ag, Cu, and Au nanoparticles due to the improved transmission of light over almost the entire solar spectrum and, thus, can be a potential low-cost plasmonic metal for large-scale implementation of solar cells. Y. Premkumar Singh, Amit Jain, and Avinashi Kapoor Copyright © 2013 Y. Premkumar Singh et al. All rights reserved. Solar Cells Efficiency Increase Using Thin Metal Island Films Wed, 26 Jun 2013 13:25:52 +0000 http://www.hindawi.com/journals/jse/2013/478219/ Metal nanodimension structures have multiple applications in modern technology. Noncontinuous thin island metal films of several types of metals deposited on dielectric or semiconductor surface introduce a unique behavior. In response to light exposure in certain range, the metal islands present a resonant absorption of light accompanied with a collective behavior of free electrons in these islands. In this paper, we present one of the possible ways to increase the efficiency of solar cells with metal islands imbedded in a semiconductor junction. Rough calculation was performed for a silicon solar cell and showed an increase of 17.5% in the overall efficiency of the cell. Alexander Axelevitch and Gady Golan Copyright © 2013 Alexander Axelevitch and Gady Golan. All rights reserved. Performance Evaluation Criterion at Equal Pumping Power for Enhanced Performance Heat Transfer Surfaces Mon, 10 Jun 2013 09:45:16 +0000 http://www.hindawi.com/journals/jse/2013/370823/ The existing equations for the thermal performance evaluation, at equal pumping power for the artificially roughened and smooth surfaced multitube and rectangular duct heat exchangers, have been critically reviewed because the literature survey indicates that a large number of researchers have not interpreted these equations correctly. Three of the most widely used equations have been restated with clearly defined constraints and conditions for their application. Two new equations have been developed for the design constraints not covered earlier. Rajendra Karwa, Chandresh Sharma, and Nitin Karwa Copyright © 2013 Rajendra Karwa et al. All rights reserved. Development of Solar Electricity Supply System in India: An Overview Thu, 09 May 2013 14:56:40 +0000 http://www.hindawi.com/journals/jse/2013/632364/ Solar electricity supply system has grown at very rapid pace in India during the last few years. A total of 1047.84 MW of grid connected photovoltaic projects and 160.8 MW of off-grid systems have been commissioned under different policy mechanisms between January 2010 and November 2012. It is observed that solar capacity development has achieved a greater height under state policies (689.81 MW) than others. A study is made in this paper of various national and state level schemes, incentives, packages, instruments, and different mechanisms to promote solar photovoltaics and its effectiveness. Sandeep Kumar Gupta and Raghubir Singh Anand Copyright © 2013 Sandeep Kumar Gupta and Raghubir Singh Anand. All rights reserved.