The lack of control in voltage overshoot, transient response, and steady state error are major issues that are frequently encountered in a grid-connected photovoltaic (PV) system, resulting in poor power quality performance and damages to the overall power system. This paper presents the performance of a control strategy for an inverter in a three-phase grid-connected PV system. The system consists of a PV panel, a boost converter, a DC link, an inverter, and a resistor-inductor (RL) filter and is connected to the utility grid through a voltage source inverter. The main objective of the proposed strategy is to improve the power quality performance of the three-phase grid-connected inverter system by optimising the proportional-integral (PI) controller. Such a strategy aims to reduce the DC link input voltage fluctuation, decrease the harmonics, and stabilise the output current, voltage, frequency, and power flow. The particle swarm optimisation (PSO) technique was implemented to tune the PI controller parameters by minimising the error of the voltage regulator and current controller schemes in the inverter system. The system model and control strategies were implemented using MATLAB/Simulink environment (Version 2020A) Simscape-Power system toolbox. Results show that the proposed strategy outperformed other reported research works with total harmonic distortion (THD) at a grid voltage and current of 0.29% and 2.72%, respectively, and a transient response time of 0.1853s. Compared to conventional systems, the PI controller with PSO-based optimization provides less voltage overshoot by 11.1% while reducing the time to reach equilibrium state by 32.6%. The consideration of additional input parameters and the optimization of input parameters were identified to be the two main factors that contribute to the significant improvements in power quality control. Therefore, the proposed strategy effectively enhances the power quality of the utility grid, and such an enhancement contributes to the efficient and smooth integration of the PV system.

The influence of Molybdenum diselenide (MoSe2) as an interfacial layer between Cu(In,Ga)Se2 (CIGS) absorber layer and Molybdenum (Mo) back contact in a conventional CIGS thin-film solar cell was investigated numerically using SCAPS-1D (a Solar Cell Capacitance Simulator). Using graded bandgap profile of the absorber layer that consist of both back grading (BG) and front grading (FG), which is defined as double grading (DG), attribution to the variation in Ga content was studied. The key focus of this study is to explore the combinatorial effects of MoSe2 contact layer and Ga grading of the absorber to suppress carrier losses due to back contact recombination and resistance that usually occur in case of standard Mo thin films. Thickness, bandgap energy, electron affinity and carrier concentration of the MoSe2 layer were all varied to determine the best configuration for incorporating into the CIGS solar cell structure. A bandgap grading profile that offers optimum functionality in the proposed configuration with additional MoSe2 layer has also been investigated. From the overall results, CIGS solar cells with thin MoSe2 layer and high acceptor doping concentration have been found to outperform the devices without MoSe2 layer, with an increase in efficiency from 20.19% to 23.30%. The introduction of bandgap grading in the front and back interfaces of the absorber layer further improves both open-circuit voltage (VOC) and short-circuit current density (JSC), most likely due to the additional quasi-electric field beneficial for carrier collection and reduced back surface and bulk recombination. A maximum power conversion efficiency (PCE) of 28.06%, fill factor (FF) of 81.89%, JSC of 39.45 mA/cm2, and VOC of 0.868 V were achieved by optimizing the properties of MoSe2 layer and bandgap grading configuration of the absorber layer. This study provides an insight into the different possibilities for designing higher efficiency CIGS solar cell structure through the manipulation of naturally formed MoSe2 layer and absorber bandgap engineering that can be experimentally replicated.

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Summary Safe and reliable operation is among the considerations when integrating lithium‐ion batteries as the energy storage system in microgrids. A lithium‐ion battery is very sensitive to temperature in which it is one of the critical factors affecting the performance and limiting the practical application of the battery. Furthermore, the adverse effects differ according to the temperature. The susceptibility of lithium‐ion battery to temperature imposes the need to deploy an efficient battery thermal management system to ensure the safe operation of the battery while at the same time maximizing its performance and life cycle. To design a good thermal management system, accurate temperature measurement is vital to assist the battery thermal management system in managing relevant states such as the stage‐of‐charge and state‐of‐health of the battery. This article outlines the effects of low and high temperatures on the performance of Li‐ion batteries. Next, a review of currently available internal temperature monitoring approaches is presented based on their feasibility and complexity. Then, an overview of battery thermal management systems based on different cooling mediums is presented. This includes air cooling, liquid cooling, phase change material (PCM) cooling, heat pipe cooling, boiling‐based cooling, and solid‐state cooling. The final section of this article discusses the practical implementation of the internal temperature measurement approach and battery thermal management system for microgrids. From the review, a suitable candidate is the flexible, low maintenance, and long lifetime hybrid battery thermal management system that combines heat pipe cooling and solid‐state cooling. It is capable of maintaining the maximum operating temperature of the battery within 45°C at up to 3C discharge rate while being a relatively simple system. Additionally, passive PCM with thermally conductive filler can also be employed to assist the hybrid battery thermal management system in improving the temperature uniformity well within 5°C.