Implementation of Modified SEPIC Converter for Renewable Energy Built DC MicrogridsRead the full article
International Journal of Photoenergy publishes original research and review articles focused on all areas of photoenergy, including photochemistry and solar energy utilization.
Chief Editor, Giulia Grancini, is based at the University of Pavia, Italy. Her current research work aims at solving the stability and toxicity issues of developing multi-dimensional hybrid interfaces as lego-bricks for a new efficient, stable, and environmentally-friendly solar technology.
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Stochastic Optimal Selection and Analysis of Allowable Photovoltaic Penetration Level for Grid-Connected Systems Using a Hybrid NSGAII-MOPSO and Monte Carlo Method
Generally, the main focus of the grid-linked photovoltaic systems is to scale up the photovoltaic penetration level to ensure full electricity consumption coverage. However, due to the stochasticity and nondispatchable nature of its generation, significant adverse impacts such as power overloading, voltage, harmonics, current, and frequency instabilities on the utility grid arise. These impacts vary in severity as a function of the degree of penetration level of the photovoltaic system. Thus, the design problem involves optimizing the two conflicting objectives in the presence of uncertainty without violating the grid’s operational limitations. Nevertheless, existing studies avoid the technical impact and scalarize the conflicting stochastic objectives into a single stochastic objective to lessen the degree of complexity of the problem. This study proposes a stochastic multiobjective methodology to decide on the optimum allowable photovoltaic penetration level for an electricity grid system at an optimum cost without violating the system’s operational constraints. Five cutting-edge multiobjective optimization algorithms were implemented and compared using hypervolume metric, execution time, and nonparametric statistical analysis to obtain a quality solution. The results indicated that a Hybrid NSGAII-MOPSO had better convergence, diversity, and execution time capacity to handle the complex problem. The analysis of the obtained optimal solution shows that a practical design methodology could accurately decide the maximum allowable photovoltaic penetration level to match up the energy demand of any grid-linked system at a minimum cost without collapsing the grid’s operational limitations even under fluctuating weather conditions. Comparatively, the stochastic approach enables the development of a more sustainable and affordable grid-connected system.
Performance Analysis of Solar Still by Using Octagonal-Pyramid Shape in the Solar Desalination Techniques
This research work explored and compared the experimental performance of a solar still having novel octagonal-pyramid shape with a single slope solar still. It is found that the novel still provides twice distillation compared with conventional still. The experiments also evaluated the desalination productivity of octagonal-pyramid solar still by varying the depth of saline water inside the basin and angle of inclination of glass cover. It is observed that the optimum condition for high distillation is obtained when depth of water inside the basin is 5 cm with angle of inclination of glass cover which is 30°. Four types of water, i.e., underground borewell water, sea water, leather industry effluent, and plastic industry effluent were also used to see the effect on distillation. Results showed that underground borewell water provides high distillation due to low density. Furthermore, the performance of the octagonal-pyramid solar still is enhanced by adding different latent heat and sensible heat materials in the octagonal-pyramid solar still. Hence, the addition of brick to the octagonal-pyramid still yields the highest productivity compared to incorporation of paraffin wax. Hence, it can be concluded that the octagonal design of the solar still has shown an increased productivity when compared to a single slope solar still (conventional still) under all the conditions.
Effect of Molybdenum Disulphide Thin Films on Enhancing the Performance of Polycrystalline Silicon Solar Cells
This research work focuses on augmenting the power conversion efficiency of the polycrystalline silicon solar cell with the aid of antireflection coating (ARC) of synthesized molybdenum disulphide (MoS2). The sol-gel technique and electrospraying method were preferred for synthesizing and depositing MoS2 as transparent thin films on the surface of the solar cells. The optical, electrical, structural, and thermal properties of the coated solar cells were analyzed for understanding the influence of the MoS2 coating. Five different samples (A-II, A-III, A-IV, A-V, and A-VI) were coated with varying coating time. Among them, 120 min coated sample experienced a maximum power conversion efficiency (PCE) of 17.96% and 18.82% under direct sunlight and neodymium light with resistivity as low as . The investigation of optical properties of the coated solar cells revealed a maximum transmittance of 93.6% and minimum reflectance of 6.3%, achieved for A-IV sample in the visible UV spectrum. Sample A-IV showed prominent results in the temperature analysis with temperatures as low as 38.9°C in uncontrolled and 43.2°C in controlled source environments. The results from various analyses proved that MoS2 was an appropriate material for an antireflection coating to enhance the performance of polycrystalline solar cell.
A New Hybrid MPPT Based on Incremental Conductance-Integral Backstepping Controller Applied to a PV System under Fast-Changing Operating Conditions
Maximum power point tracking (MPPT) is becoming more and more important in the optimization of photovoltaic systems. Several MPPT algorithms and nonlinear controllers have been developed for improving the energy yield of PV systems. On the one hand, most of the conventional algorithms such as the incremental conductance (INC) demonstrate a good affinity for the maximum power point (MPP) but often fail to ensure acceptable stability and robustness of the PV system against fast-changing operating conditions. On the other hand, the MPPT nonlinear controllers can palliate the robust limitations of the algorithms. However, most of these controllers rely on expensive solar irradiance measurement systems or complex and relatively less accurate methods to seek the maximum power voltage. In this paper, we propose a new hybrid MPPT based on the incremental conductance algorithm and the integral backstepping controller. The hybrid scheme exploits the benefits of the INC algorithm in seeking the maximum power voltage and feeds a nonlinear integral backstepping controller whose stability was ensured by the Lyapunov theory. Therefore, in terms of characteristics, the overall system is a blend of the MPP-seeking potential of the INC and the nonlinear and robust potentials of the integral backstepping controller (IBSC). It was noted that the hybrid system successfully palliates the conventional limitations of the isolated INC and relieves the PV system from the expensive burden of solar irradiance measurement. The proposed hybrid system increased the operational efficiency of the PV system to 99.94% and was found better than the INC MPPT algorithm and 8 other recently published MPPT methods. An extended validation under experimental environmental conditions showed that the hybrid system is approximately four times faster than the INC in tracking the maximum power with better energy yield than the latter.
Thermal and Electrical Performance of Uncooled, Nature-Cooled, and Photovoltaic Thermal Module
The experimental study is aimed at analyzing photovoltaic module’s thermal and electrical performance (PV) with back surface cooling under Malaysian tropical climate conditions. The performance of a passively cooled PV module integrated with biomaterial (moist coconut fiber) was compared with a photovoltaic thermal (PVT) system with water circulation at the rate of 0.02 kg s-1 and a reference PV module. The study observed that the passively cooled PV module succeeded in reducing the module surface temperature by more than 20%. However, the PVT system reduced the temperature only by less than 17%. The electrical energy efficiency was improved remarkably in the passively cooled PV module by almost 11%, but the PVT system managed to increase the electrical efficiency by 9%, approximately. It can be concluded that nature-inspired coconut fiber-based cooling can be one of the potential alternatives to active cooling methods.
Novel Algorithm for Improving Tracking Accuracy of Open-Loop Mobile Sun-Tracking System via Different Timing Control Scheme
This paper proposes a mobile sun-tracking (MST) system to track the sun on the moving vehicle. We have developed a novel MST algorithm using general sun-tracking formulas associated with simple-moving average linear regression (SMALR) to smoothen sun-tracking activity. Furthermore, two different timing control schemes to activate sun tracking are investigated: time lapse (TL) mode and azimuth actuation (AA) mode. For experimental validation, a prototype of MST has been constructed on a small truck moving at constant speed of 30 km/h for field measurements. For the result, AA mode has average pointing error of 110 mrad for the open-loop tracking design (13% better than that of TL mode), which is still far below the half acceptance angle of compound parabolic concentrator at 659 mrad. Since there is no feedback sensor to be implemented in this prototype, optical encoders and CCD camera can be employed in the future work to further reduce the pointing error of MST system.