Journal of Solar Energy Research
Volume:4 Issue: 3, Summer 2019

The electrical energy produced by photovoltaic (PV) process is inexhaustible, developable everywhere and clean. Whatever the conditions, it is desirable to extract the biggest amount of power from the solar panel. This is achieved with the use of a Maximum Power Point Tracking (MPPT) algorithm. Fluctuations in weather conditions (irradiation and temperature) strongly degrade the performance of the photovoltaic module's energy conversion and therefore all the power cannot be transferred to the load. The objective is to study and compare different approaches of MPPT algorithms to evaluate the power extracted under the standard test conditions and varying weather conditions. Results of the performance with all these algorithms are compared under different operating conditions. The results show that the Fuzzy Logic Controller (FLC) is the fastest in terms of stabilization and is followed respectively by Fractional Short-Circuit Current (FSCC), Fractional Open-Circuit Voltage (FOCV), Perturb and Observe (P&O), Incremental Conductance (INC) and Hill Climbing (HC) algorithms. The FLC also gives the best results in extracting, followed by P&O INC, HC, FSCC and FOCV algorithms.

DC-DC converters have found wide application in daily life due to considerable industrial requirements. However, high output gain in these converters is not achieved due to parasitic elements and other circuit restrictions. This shortcoming is very important for certain applications such as solar systems that need to boost considerably the low voltage output of PV panels. This paper proposes a new topology based on the PSOL converter that can increase output gain beyond a conventional PSOL converter. This topology benefits from clamp circuits and voltage multipliers that are efficiently added to a Luo converter to increase its output voltage gain. Circuit analysis both in continuous and discontinuous conduction mode is performed together with operational waveforms obtained by the simulation to show the performance of the proposed circuit. In addition, the proposed converter is compared against some of the conventional converters to show the superiority of the converter over other ones. The results show that the proposed converter can achieve higher gains in comparison with other methods. Meanwhile, the proposed topology utilizes a single switch to increase the output voltage. Finally, simulation results for 1 kW load are included in the paper to show the performance of the converter.

Albedo is the fraction of solar energy reflected from a surface back to the atmosphere; it is controlled by the characteristics of the surface, specially land cover type. Here, we examined the effects of five types of tree species (maple, poplar, chestnut-leaved oak, cypress and alder) in the mono-cultured plantations at Hyrcanian temprature forests (in the north of Iran). The field data were collected during the summer and the winter. Albedo was estimated by an albedometer set-up that was installed on a movable mast in each stand. In this study, two analytical methods were used to estimate the reaction of forest trees to the summer and winter albedo. One way ANOVA was used to determine the significance difference between tree species considering the summer and winter albedo. The analysis of variance indicated that, there was a significant difference among tree species albedo in two seasons (p˂ 0.01). In the summer alder and cypress had the highest and lowest albedo (0.34 and 0.16 respectively) and in the winter chestnut-leaved oak and alder had the highest albedo (0.19) and cypress had the lowest one (0.10). Our findings suggest that considering of these factors (summer and winter albedo), plantation with broadleaved trees is the most appropriate choice for forest regeneration in the temperate Iranian forests.

Due to the increasing penetration rate of solar systems in electrical power distribution networks, the technical studies are required on power quality standards of utility grid Caused by solar system effects. This paper investigates the solar system connected to the utility grid in the view of the harmonic effects. The effects of temperature and sunlight changes are discussed on the harmonics produced by solar cells and its effect on the distribution network and the performance of its various components. Furthermore, Analysis of the current THD is carried out for the two cases, using and without using sun tracker technology at the point of common coupling between the solar system and utility grid. Then, the results are compared with each other. The obtained harmonic distortion values are compared with the specified limits in the standard IEEE STD 519-1992. Finally, simulation results verify the environmental model of a photovoltaic system.

Light is one of the comfort factors in the environment, which unwittingly has a direct impact on the human beings. An environment without natural light can gradually cause illness. Light energy accounts for 25% of energy consumption, therefor it has a main rank in studies. As Shiraz is a southern city with considerable sunny days in a year, illuminance of this source can be studied more exactly equipment and convenient ways can be recognized in order to reach efficient use. First of all, the documents analyzed in an analytical-describtive method. Then, the studied issue had been observed in a sample place, and analyzed by the simulation. At last, a type of light guidance system had been used in order to offer the efficient light.Vertical light pipe has been analyzed, in order to provide the quality and quantity of office illuminance in medium depth plan building. Analysis Autodesk Ecotect 2010 version had been used for modeling and Radiance Control Panel for light analyze. The simulation results of the determined office room, had shown some issues such as, light dazzlement, light concentration and light reduction in the different hours of a day of the special months in a year. The findings suggest that, it’s possible to use sunlight for sufficient illumination by using DGS , such as a lightpipes if daylighting process would be revised in the glare and illumination distribution in the different times. It also, offers that the light pipes can be used in the other types of buildings.

A popular and common method to enhance the heat transfer in a flow passage is to artificially roughen the surfaces with ribs, grooves or combination of ribs and grooves (rib-grooved surface). The artificial roughness is often used in heat exchanger systems, such as solar air heaters, nuclear reactors, electronic cooling devices and gas turbine blades .Among the artificially roughen the surfaces, rib-grooved surfaces are one of the popular techniques that are extensively used in plate heat exchanger manufacturing. In fact, the ribs, grooves and their combination increase the fluid flow turbulence near the wall by breaking the laminar sub layer and create local wall turbulence due to flow separation and reattachment, which disrupt the thermal boundary layer and reduce the thermal resistance and greatly enhance the heat transfer. In this paper, heat transfer enhancement of optimized rib-grooved surfaces in channels is multi objectively optimized applying the NSGA II algorithm. The distance between rib and groove was set from 0 to 3w. The optimized distance between rib and groove was d=2.2w which computed by considering maximum heat transfer and minimum friction factor, simultaneously. The effects of Reynolds number of 5000 to 30000 are so investigated. when the velocity of flow increases the nusselt number and pressure drop increase .When the distance between rib and groove increases the nusselt number increased while the friction factor decreases in optimization with NSGAІІ algorithm point=2.2w is the most optimized than other points for Reynolds from 5000 to 30000.