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Maximum power point tracking of partial shaded photovoltaic array using an evolutionary algorithm: A particle swarm optimization technique J. Renewable Sustainable Energy 6, 023102 (2014); 10.1063/1.4868025Performance evaluation of a solar photovoltaic thermal air collector using energy and exergy analysis J. Renewable Sustainable Energy 3, 043115 (2011); 10.1063/1.3624760Energy and exergy analysis of hybrid photovoltaic/thermal solar water heater considering with and without withdrawal from tankIn this paper, a mathematical model is used to determine the solar radiation incident on an inclined surface and the optimum slope angles for each month, season, and year are calculated for solar hybrid collectors. We recommend on how the collected energy can be increased by varying the tilt angle. First, we esteem the global solar radiation on a horizontal surface of a thermal photovoltaic hybrid collector (PVT) for a clear sky. The data set of the solar radiation at Gharda€ ıa (Algeria) measured during 2013 was used to analyze the models of global solar radiation estimation. The models of performance are evaluated by using the coefficient of correlation (R 2 ), the absolute average error skew (mean absolute error, MABE), average quadratic error (mean square error RMSE), the percentage of the average error (MPE), and the percentage of average absolute error. Then the anisotropic and isotropic models that provide the most accurate estimation of the total solar radiation has been used to determine the optimum collector slope. Particle swarm optimization method was applied to obtain the tilt angle setting of the tilt angle of PVT collector. The objective was to improve the efficiency of PVT collector. The results show that these models used are very well designed. The coefficient of correlation (R 2 ) varies from 0. 90 to 0. 99. For the percentage of errors of prediction (MABE and RMSE) lowered by 0.1, it is observed also that the angle of inclination of PVT collector takes different values during the year and that the collector received more solar energy compared to collector without optimal angle. V C 2014 AIP Publishing LLC. [http://dx.

Solar energy can be used for substitution of the depleting fossil fuels in thermal applications and electricity generation through thermal route. For medium and high temperature applications, a system for collecting solar energy at high temperatures was developed and built in this research work. The system, built at the center of development of renewable energy of the Algiers, consists of a 2θ m = 60° included angle, R 0 = 0.90 m diameter spherical reflector with a cylindrical receiver filled with water, tracking reflector which moves into the focus following the sun's movement. The system is capable of heating water or other fluids to temperatures above 350°C, thus making it possible to obtain process heat for domestic use and to store solar energy in a compact and economical way. An analysis of the system's optical characteristics was performed to aid in the design of the spherical reflector and cylindrical receiver. The thermal performance of the system was analyzed. The effects of mirror reflection, concentration ratio, heat transfer to the fluid (water), incidence angle, size and form of the cylindrical receiver, environmental conditions (wind, ambient temperature), have been studied by means of thermal model. The performance of the spherical reflector was tested by the temperature of the water. Total efficiencies (solar to thermal) of η th = 60% -70% were obtained for a wide range of temperatures up to 350°C. The results of the present study show that it is possible to use the spherical reflector for systems requiring process heat and make possible substantial utilization of solar energy and considerable savings relative to fossil energy in the sunny countries of the world.

In order to ensure thermal comfort and reduce energy consumption, a new composite based on Portland cement and date palm fiber was studied in this work. Our main objective is to study the possibility of integrating and using this new material as a thermal insulation material in the exterior coatings of buildings. Several composites were prepared for different weight concentrations (from 0% to 5%) of date palm fibers. The studied materials were analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). In addition, the hot wire method was used to measure thermo-physical properties. The results show that the addition of fibers has no effect on the chemical composition of the matrix, as shown by FTIR and XRD analyzes which proves the chemical stability. The results of the TGA analysis indicate that the inclusion of date palm fibers has an effect on the thermal characteristics of the matrix. The SEM analysis shows that there is good adhesion between the Portland cement and the plant fibers used and that the date palm fibers are well incorporated into the matrix, the SEM images also showed that the inclusion of the fibers increases the porosity. In addition, the results showed that the addition of the fibers of date palm a marked decrease in thermal conductivity, which makes the material insulating. Thus, the use of fibers in cement seems to be a promising option that allows it to be applied as a thermal coating material in buildings.