Maximum Power Point Tracking Condition Research Articles

Synergistic Effect of Sodium Cyanoborohydride in Pb‐Sn Perovskite Solar Cells

AbstractPb‐Sn mixed perovskite has received extensive attention because of its high research value in environmental protection and theoretical prospects. However, the film defects brought on by the quick crystallization of Pb‐Sn mixed perovskites and the facile oxidation of Sn2+ to Sn4+ are detrimental to the performance of Pb‐Sn perovskite solar cells (PSCs). Here, aiming at the interface of Pb‐Sn PSCs, which has been less studied, a reducing agent is first introduced on the top of Pb‐Sn mixed perovskite interface. The results show that in NaBH3CN(SC), B─H can suppress the oxidation of Sn2+ and C≡N can enhance the perovskite crystallinity and passivate the surface defects. Benefitting from this synergistic effect, a champion power conversion efficiency of 21.3% is obtained for Pb‐Sn PSCs. In addition, the encapsulated device can maintain good stability under maximum power point tracking conditions.

Lattice Strain Regulation Enables High-Performance Formamidinium Perovskite Photovoltaics.

Formamidinium lead iodide (FAPbI3 ) perovskite possesses an ideal optical bandgap and is a potential material for fabricating the most efficient single-junction perovskite solar cells (PSCs). Nevertheless, large formamidinium (FA) cations result in residual lattice strain, which reduces the power conversion efficiency (PCE) and operational stability of PSCs. Herein, the modulation of lattice strain in FAPbI3 crystals via a π-conjugated organic amine, i.e., 4-pyrene oxy butylamine (PYBA), is proposed. PYBA pairs at the grain boundary serve as a template for the crystallization of FAPbI3 perovskite, thereby inducing a highly oriented crystal and a pure α-phase film. The PYBA pairs with strong π-π interactions provide a solid fulcrum for external compression strain, thus compensating for the inherent tension strain of FAPbI3 crystals. The strain release elevates the valence band of the perovskite crystals, thereby decreasing the bandgap and trap density. Consequently, the PYBA-regulated FAPbI3 PSC achieves an excellent PCE of 24.76%. Moreover, the resulting device exhibits improves operational stability and maintains over 80% of its initial PCE after 1500h under maximum power point tracking conditions.

Bifunctional hole-shuttle molecule for improved interfacial energy level alignment and defect passivation in perovskite solar cells

Perovskite solar cells have reached a power conversion efficiency over 25%, and the engineering of the interface between the perovskite and hole transport layer (HTL) has been crucial to achieve high performance. Here we design a bifunctional molecule CBz-PAI with carbazole-triphenylamine and phenylammonium iodide units to passivate defects at the perovskite/HTL interface. Owing to a favourable energy level alignment with the perovskite, the CBz-PAI acts as a hole shuttle between the perovskite layer and the HTL. This minimizes the difference between the quasi-Fermi level splitting of the perovskite, or ‘internal’ Voc, and the external device Voc, thus reducing voltage losses. As a result, solar cells incorporating CBz-PAI reach a stabilized power conversion efficiency of 24.7% and maintain 92.3% of the initial efficiency after 1,000 h under damp heat test (85 °C and 85% relative humidity) and 94.6% after 1,100 h under maximum power point-tracking conditions.

Highly Stable n–i–p Structured Formamidinium Tin Triiodide Solar Cells through the Stabilization of Surface Sn2+ Cations

AbstractImproving the performance, reproducibility, and stability of Sn‐based perovskite solar cells (PSCs) with n–i–p structures is an important challenge. Spiro‐OMeTAD [2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)9,9′‐spirobifluorene], a hole transporting material (HTM) with n–i–p structure, requires the oxygen exposure after addition of Li‐TFSI [Lithium bis(trifluoromethanesulfonyl)imide] as a dopant to increase the hole concentration. In Sn‐based PSC, Sn2+ is easily oxidized to Sn4+ under such a condition, resulting in a sharp decrease in efficiency. Herein, a formamidinium tin triiodide (FASnI3)‐based PSCs fabricated using DPI‐TPFB [4‐Isopropyl‐4′‐methyldiphenyliodonium tetrakis(pentafluorophenyl)borate] instead of Li‐TFSI are reported as a dopant in Spiro‐OMeTAD. The DPI‐TPFB enables the fabrication of PSCs with an efficiency of up to 10.9%, the highest among FASnI3‐based PSCs with n–i–p structures. Moreover, ≈80% of the initial efficiency is maintained even after 1,597 h under maximum power point tracking conditions. In particular, the encapsulated device does not show any decrease in efficiency even after holding for 50 h in the 85 °C/85% RH condition. The high efficiency and excellent stability of PSCs prepared by doping with DPI‐TPFB are attributed to not only increasing electrical conductivity by acting as a Lewis acid, but also stabilizing Sn2+ through coordination with Sn2+ on the surface of FASnI3.

Optimal control strategies-based maximum power point tracking for photovoltaic systems under variable environmental conditions

To increase the efficiency of photovoltaic (PV) array output under variable environmental conditions, maximum power point tracking (MPPT) of the solar arrays is needed. This paper proposes fuzzy logic controller (FLC)-based MPPT, artificial neural network (ANN)-based MPPT, neuro-fuzzy (NF)-based MPPT, particle swarm optimisation (PSO)-based MPPT, and cuckoo search (CS) algorithm-based MPPT to combine an adaptive controller and an optimisation, to guarantee global stability and a constant settling time for all operation conditions. This combination enables an increase in the power generated in comparison with conventional MPPT techniques. Simulation results show that the proposed photovoltaic/storage generator is able to supply the suggested dynamic loads under different conditions, and achieve good performance. It is also noticed that operating the photovoltaic array based on maximum power point tracking conditions gives about 43% extra power generation than in the case of normal operation.

Unveiling the key factor affecting the illumination deterioration and response measures for lead halide perovskite solar cells

So far, it’s been widely acknowledged that the PbI2 decomposition under illumination mainly accounts for the degradation of perovskite solar cells (PSCs) under maximum power point (MPP) tracking condition. However, PSCs without excess PbI2 were also reported to deteriorate rapidly under the same condition. Here, we demonstrate that the key to enhance PSCs stability under MPP tracking condition is not to have fascinating surface morphology with effective suppression of nonradiative recombination traps but to prevent the migration of iodine ion (I−) under light illumination. By partially substituting methylammonium chloride (MACl) with methylammonium iodide (MAI) and simutaneouly introducing I2 during the sequential deposition, the iodine vacancies in perovskite films are substantially suppressed, thereby limiting the pathways for I− migration. As a consequence, PSCs with efficiency of 24.28% are fabricated with remarkably enhanced working stability.

An efficient hybrid tunicate swarm algorithm and radial basis function searching technique for maximum power point tracking in wind energy conversion system

Purpose The purpose of this paper is to track the maximal power of wind energy conversion system (WECS) and enhance the search capability for WECS maximum power point tracking (MPPT). Design/methodology/approach The hybrid technique is the combination of tunicate swarm algorithm (TSA) and radial basis function neural network. Findings TSA gets input parameters from the rectifier outputs such as rectifier direct current (DC) voltage, DC current and time. From the input parameters, it enhances the reduced fault power of rectifier and generates training data set based on the MPPT conditions. The training data set is used in radial basis function. During the execution time, it produces the rectifier reference DC side voltage that is converted to control pulses of inverter switches. Originality/value Finally, the proposed method is executed in MATLAB/Simulink site, and the performance is compared with different existing methods like particle swarm optimization algorithm and hill climb searching technique. Then the output illustrates the performance of the proposed method and confirms its capability to solve issues.

Fault diagnosis for photovoltaic array based on convolutional neural network and electrical time series graph

Fault diagnosis of photovoltaic array plays an important role in operation and maintenance of PV power plant. The nonlinear characteristics of photovoltaic array and the Maximum Power Point Tracking technology in the inverter prevent conventional protection devices to trip under certain faults which reduces the system’s efficiency and increases the risks of fire hazards. In order to better diagnose photovoltaic array faults under Maximum Power Point Tracking conditions, the sequential data of transient in time domain under faults are analyzed and then applied as the input fault features in this work. Firstly, the sequential current and voltage of the photovoltaic array are transformed into a 2-Dimension electrical time series graph to visually represent the characteristics of sequential data. Secondly, a Convolutional Neural Network structure comprising nine convolutional layers, nine max-pooling layers, and a fully connected layer is proposed for the photovoltaic array fault diagnosis. The proposed model for photovoltaic array fault diagnosis integrates two main parts, namely the feature extraction and the classification. Thirdly, this model automatically extracts suitable features representation from raw electrical time series graph, which eliminates the need of using artificially established features of data and then employs for photovoltaic fault diagnosis. Moreover, the proposed Convolutional Neural Network based photovoltaic array fault diagnosis method only takes the array of voltage and current of the photovoltaic array as the input features and the reference panels used for normalization. The proposed approach of photovoltaic array fault diagnosis achieved over 99% average accuracy when applied to the case studies. The comparisons of the experimental results demonstrate that the proposed method is both effective and reliable.

An H5 Transformerless Inverter for Grid Connected PV Systems with Improved Utilization Factor and a Simple Maximum Power Point Algorithm

Due to their small size, minimum cost, and great efficiency, photovoltaic (PV) grid-connected transformerless inverters have been developed and become famous around the world in distributed PV generators systems. One of the most efficient topologies of the transformerless inverter family is H5 topology. This inverter extracts a discontinuous current from the PV panel, which conflicts with the operation at maximum power point tracking (MPPT) conditions while the utilization factor of the PV degrades. This paper proposes improved H5 topology featuring a boost converter inserted in the middle between the PV panels and the H5 inverter. The design of the boost converter is planned to operate at continuous conduction mode to guarantee MPPT conditions of the PV. A new and simple off line MPPT algorithm is introduced and performance factors like efficiency and utilization factors of the proposed and convention H5 topology are compared. The simulation results indicate that the proposed system provides a preferable utilization factor and a simpler MPPT algorithm.

Solvent engineering for efficient inverted perovskite solar cells based on inorganic CsPbI2Br light absorber

Inorganic cesium lead halide perovskites, as alternative light absorbers for organic−inorganic hybrid perovskites, have attracted more and more attentions due to their superb thermal stability for photovoltaic applications. However, the device performance, as reported to date, is dispirited as it is still a challenge to prepare inorganic perovskite films with both sufficient absorbance and high quality. Here, solvent engineering is conducted, and solvent composition is found largely influence the crystallization progress and film morphology. Combined with anti-solvent-extraction technology, homogenous and pinhole-free CsPbI2Br films have been prepared with optimized solvent of DMF/DMSO mixture with the volume ratio of 3:2. The inverted planar device with a 410 nm-thick CsPbI2Br absorber achieves a power conversion efficiency of 9.14%. Furthermore, the as-prepared perovskite and its based device exhibit good stability under high temperature stress and continuous light soaking at maximum power point tracking conditions (100 mW cm−2, 500 h).

A Fuzzy Logic Based Mppt Controller For Wind-Driven Three-Phase Self-Excited Induction Generators Supplying Dc Microgrid

<p class="Default"><span lang="EN-US">In this paper, a straightforward strategy for tracking the maximum power (MP) accessible in the wind energy conversion system for dc microgrid is proposed. A three-phase diode bridge rectifier alongside a dc-dc converter has been utilized between the terminals of wind-driven induction generator and dc microgrid. Induction generator is being worked in self-energized mode with excitation capacitor at stator. The output current i.e., dc grid current act as a control variable to track the MP in the proposed WECS. In this manner, the proposed calculation for maximum power point tracking (MPPT) is autonomous of the machine and wind-turbine parameters. Further, a technique has been created for deciding the obligation proportion of the dc-dc converter for working the proposed system in MPPT condition utilizing wind turbine qualities, relentless state proportionate circuit of prompting generator and power balance in power converters. Circuit straightforwardness and basic control calculation are the significant points of interest of the proposed setup for supplying energy to the dc microgrid from WECS. The fruitful working of the proposed calculation for Fuzzy logic based MPPT has been shown with broad exploratory results alongside the simulated values.</span></p>

NiO x Hole Transport Layer for Perovskite Solar Cells with Improved Stability and Reproducibility.

In this study, highly stable, low-temperature-processed planar lead halide perovskite (MAPbI3–xClx) solar cells with NiOx interfaces have been developed. Our solar cells maintain over 85% of the initial efficiency for more than 670 h, at the maximum power point tracking (MPPT) under 1 sun illumination (no UV-light filtering) at 30 °C, and over 73% of the initial efficiency for more than 1000 h, at the accelerating aging test (85 °C) under the same MPPT condition. Storing the encapsulated devices at 85 °C in dark over 1000 h revealed no performance degradation. The key factor for the prolonged lifetime of the devices was the sputter-deposited polycrystalline NiOx hole transport layer (HTL). We observed that the properties of NiOx are dependent on its composition. At a higher Ni3+/Ni2+ ratio, the conductivity of NiOx is higher, but at the expense of optical transmittance. We obtained the highest power conversion efficiency of 15.2% at the optimized NiOx condition. The sputtered NiOx films were used to fabricate solar cells without annealing or any other treatments. The device stability enhanced significantly compared to that of the devices with PEDOT:PSS HTL. We clearly demonstrated that the illumination-induced degradation depends heavily on the nature of the HTL in the inverted perovskite solar cells (PVSCs). The sputtered NiOx HTL can be a good candidate to solve stability problems in the lead halide PVSCs.

A Single-Sensor-Based MPPT Controller for Wind-Driven Induction Generators Supplying DC Microgrid

In this paper, a simple method of tracking the maximum power (MP) available in the wind energy conversion system (WECS) for dc microgrid application is proposed. A three-phase diode bridge rectifier along with a dc–dc converter has been employed between the terminals of a wind-driven induction generator and dc microgrid. Induction generator is being operated in self-excited mode with excitation capacitor at stator. The output current of the dc–dc converter, i.e., dc-grid current is considered as a control variable to track the MP in the proposed WECS. Thus, the proposed algorithm for maximum power point tracking (MPPT) is independent of the machine and wind-turbine parameters. This algorithm has been implemented using dsPIC30F4011 controller. Furthermore, a method has been developed for determining the duty ratio of the dc–dc converter for operating the proposed system in MPPT condition using wind-turbine characteristics, steady-state equivalent circuit of a induction generator, and power balance in power converters. Circuit simplicity and simple control algorithm are the major advantages of the proposed configuration for supplying power to the dc microgrid from the proposed small-scale WECS. The successful working of the proposed algorithm for MPPT has been demonstrated with extensive experimental results along with the simulated values.

OPTIMAL PHOTOVOLTAIC WATER PUMPING SYSTEM PERFORMANCE UNDER DIFFERENT OPERATING CONDITIONS

This paper presents dc photovoltaic pumping system. The system consists of photovoltaic (PV) generator, boost converter and permanent magnet (PM) dc motor-pump set. Each part of the system is modelled. Photovoltaic generator parameters are extracted based on data-sheet parameters. Boost converter is designed to operate in continuous conduction mode (CCM) and controlled using incremental conductance (IC) algorithm for maximum power point tracking (MPPT).The system is simulated using Matlab/Simulink .The proposed system is studied under direct coupling and maximum power point tracking conditions. The results show a very good performance MPPT compared with direct coupling. The system is tested under varying conditions of temperature and radiation.

Direct Connection of Supercapacitors to Photovoltaic Panels With On–Off Maximum Power Point Tracking

A system dedicated to energy storage is presented. It allows energy storage from photovoltaic panels to a compressed air accumulator. This accumulator is controlled to enable compression and expansion modes under Maximum Efficiency Point Tracking (MEPT). A Maximum Power Point Tracking (MPPT) power converter is as usual connected to the solar cells. An intermediary storage tank consisting of supercapacitors and its associated power converter are inserted as a buffer. They adapt the power extracted from the solar cells under the MPPT condition to the power injected into the hydro-pneumatic system under the MEPT condition. Energy transfer from the solar cells to the hydro-pneumatic system is sequentially operated. The number of cascaded power converters decreases the global efficiency of this hybrid accumulator. This paper introduces a solution that consists of the reduction of the number of power converters. It is obtained by a direct connection of the supercapacitors on the solar panels to lower losses. Taking advantage of the sequential energy transfer, the MPPT mode is kept for the solar panels, as well as the MEPT mode for the hydro-pneumatic accumulator. The general topologies, sizing criteria, and control are presented, as well as considerations on efficiency.

A novel maximum power fuzzy logic controller for photovoltaic solar energy systems

The maximum power tracking problem and efficient energy utilization of a stand-alone photovoltaic array (PVA) feeding voltage controlled linear and nonlinear loads is studied. A novel and simple on-line fuzzy logic-based dynamic search, detection and tracking controller is developed to ensure maximum power point (MPP) operation under excursions in solar insolation, ambient temperature and electric load variations. A computer simulation model of the PVA renewable utilization scheme including the effects of temperature and solar irradiation changes was developed and fully simulated. The load voltage is controlled by a DC chopper and kept constant at the required rated voltage. A permanent magnet DC motor (PMDC) driving a fan-type load was connected in parallel to an RL passive load. A speed control scheme is also used for the PMDC motor drive so that the drive can be operated at specified speeds. Different controllers have been employed in the unified PVA scheme to control three separate loads at MPP tracking condition namely voltage at load bus and speed of the PMDC motor. The main objective of the paper is to present a novel enhanced, cost-effective MPP detector (MPPD) and dynamic MPP tracking (MPPT) controller for a hybrid mix of electric loads.