Current Issue : January - March Volume : 2017 Issue Number : 1 Articles : 5 Articles
A sun-tracking system for parabolic trough solar concentrators (PTCs) is a control system used to orient the\nconcentrator toward the sun always, so that the maximum energy can be collected. The work presented here is a\ndesign and development of PLC based sun tracking control system for PTC. Sun tracking control system consists of a\nProgrammable Logic Controller (PLC) and a single axis hydraulic drives tracking control system. Hydraulic drives\nand the necessary tracking angle algorithm have been designed and developed to perform the technical tasks. A PLC\nunit was employed to control and monitor the mechanical movement of the PTC and to collect and store data related\nto the tracking angle of PTC. It is found that the tracking error of the system is less than 0.6 �°. Field experience shows\nthat tracking algorithm act stable and reliable and suit for PTCs....
The tilt angle with the horizon (with respect to the ground) of the solar energy system\naffects the amount of solar radiation received. This paper suggests a simple and universal method to\nobtain the optimum tilt angles by estimating the monthly mean daily global solar radiation on tilted\nsurfaces facing directly towards the equator, which is based on monthly average daily global solar\nradiation data produced from Typical Meteorological Year (TMY) data. The monthly, seasonal, and\nyearly optimum tilt angles for photovoltaic panels are calculated at six stations of different climatic\ntypes (Tropical Zone (TZ), Subtropical Zone (SZ), Warm Temperate Zone (WTZ), Mid Temperate\nZone (MTZ), Cold Temperate Zone (CTZ) and Tibetan Plateau Zone (TPZ)). The results indicate that\nchanging the monthly, seasonal, and yearly optimum tilt angles causes a significant yearly gain in the\nsolar radiation for the region. In addition, general correlations are generated to estimate the optimum\ntilt angle of solar collectors at six typical climatic stations of China. The performances of the proposed\nmodels are compared using statistical error tests such as the mean absolute bias error (MABE), the\nroot mean square error (RMSE) and the correlation coefficients (R)....
This paper aims to address both the sustainability and environmental issues for cellular\nbase stations in off-grid sites. For cellular network operators, decreasing the operational expenditures\nof the network and maintaining profitability are important issues. Hence, this study addresses\nthe feasibility of a solar power system based on the characteristics of South Korean solar radiation\nexposure to supply the required energy to a remote cellular base station. The HOMER is used to\ndetermine the optimum size of the system components, to perform an energy production analysis,\nand to analyse the cost details of the project. The simulation results show that the proposed solar\npower system can achieve total operational expenditure savings of up to 48.6% by using sustainable\nand clean energy. This result means a significant long-term benefit can be achieved for cellular\nnetwork operators....
In this work, n-type silicon based solar cells with WO3/Ag/WO3 multilayer films\nas emitter (WAW/n-Si solar cells) were presented via simple physical vapor deposition\n(PVD). Microstructure and composition of WAW/n-Si solar cells were studied\nby TEM and XPS, respectively. Furthermore, the dependence of the solar cells\nperformances on each WO3 layer thickness was investigated. The results indicated\nthat the bottom WO3 layer mainly induced band bending and facilitated\ncharge-carriers separation, while the top WO3 layer degraded open-circuit voltage\nbut actually improved optical absorption of the solar cells. The WAW/n-Si solar\ncells, with optimized bottom and top WO3 layer thicknesses, exhibited 5.21%\nefficiency on polished wafer with area of 4 cm2 under AM 1.5 condition (25 ââ??¦C\nand 100 mW/cm2). Compared with WO3 single-layer film, WAW multilayer films\ndemonstrated better surface passivation quality but more optical loss, while the\noptical loss could be effectively reduced by implementing light-trapping structures.\nThese results pave a new way for dopant-free solar cells in terms of low-cost\nand facile process flow....
Energy is considered as a main influence on urban configurations. However, there is\na difficulty on translating the city models based on theoretical renewable energy concepts into\npractical applications. This study considers the possibility of understanding this future model as\na transformation of the existing urban centres. With this objective, a methodology to intervene\nin existing cities based on the study of solar access is developed. Therefore, an analysis of solar\npotential in relation with urban morphology is carried on through a simulation software in l�Eixample,\na neighbourhood of Barcelona. The distribution of the sun factor in the different areas of the\nbuilding blocks envelope displays possible morphological modifications that would facilitate solar\nenergy collection. Consequently, the analytical method presented could be applied to regulate urban\ninterventions with the aim of obtaining more solar energy based cities....
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