Maximum Power Point Condition Research Articles

All-perovskite tandem solar cells achieving >29% efficiency with improved (100) orientation in wide-bandgap perovskites.

Monolithic all-perovskite tandem solar cells present a promising approach for exceeding the efficiency limit of single-junction solar cells. However, the substantial open-circuit voltage loss in the wide-bandgap perovskite subcell hinders further improvements in power-conversion efficiency. Here we develop wide-bandgap perovskite films with improved (100) crystal orientation that suppress non-radiative recombination. We show that using two-dimensional perovskite as an intermediate phase on the film surface promotes heterogeneous nucleation along the (100) three-dimensional perovskite facets during crystallization. Preferred (100) orientations can be realized by augmenting the quantity of two-dimensional phases through surface composition engineering, without the need for excessive two-dimensional ligands that otherwise impede carrier transport. We demonstrate an open-circuit voltage of 1.373 V for 1.78 eV wide-bandgap perovskite solar cells, along with a high fill factor of 84.7%. This yields an open-circuit voltage of 2.21 V and a certified power-conversion efficiency of 29.1% for all-perovskite tandem solar cells, measured under the maximum power-point conditions.

Review of Grid-Connected Solar PV Systems With Decoupled Control

This paper presents a decoupled control for grid-connected solar photovoltaic (PV) system. The control framework used in this paper aims not to track the changing maximum power point (MPP) for extracting power at MPP, hence blocking the MPP tracking issue against the effect of solar radiation and temperature. Real power is produced by tracking the control voltage with a zero-dynamics-based controller. A cascaded loop controller with inner loop to regulate the control voltage is incorporated to ensure the produced real power follows the reference power in the presence of power disturbance. The proposed control scheme with the consideration of the inverter's rated voltage shows improved system dynamics. Simulations in various conditions are conducted to prove the effectiveness of the proposed control strategies. CIGRE 13-node benchmark system is used as the case study to evaluate the results of the PV system connected to a more complex power system. It has been shown that the proposed controller allows the total production of the energy under maximum power point conditions and also improves the overall stability of distributed generation connected to the grid. Therefore, it can be implemented to increase the capacity of renewable inverter-based power generation and the power system quality.

Performance evaluation and parametric analysis of nighttime electricity generation system integrating thermogalvanic cells with radiative sky cooling

Performance evaluation and parametric analysis of nighttime electricity generation system integrating thermogalvanic cells with radiative sky cooling

Modeling and Quantifying Optimal Dynamics of Extraction of Charge Carriers in the Operation of Perovskite Solar Cells

AbstractIn this paper, a mathematical model and the relevant computer code are developed to quantify the extraction probability rate of charge carriers (EPRCC) in a perovskite solar cell of the structure: Glass/ITO/PEDOT: PSS/CH3NH3PbI3/PC60BM/Al to investigate the influence of interfaces and grain boundaries. It is found that, without passivation, the probability of an electron generated near the anode reaches to the cathode is only 35%, while by passivating the interfaces and grain boundaries, this probability increases to about 60% at maximum power point condition. Likewise, without passivation, the probability of a hole generated near the electron transport layer‐active layer interface reaches to the hole transport layer is only 15%, while by passivating the interfaces and grain boundaries, this probability increases to about 45% at maximum power point condition. The same calculation has been done at the short‐circuit current condition, and it is found that at the maximum power point condition, passivation works better for increasing the EPRCC than at the short circuit current condition. The authors have also investigated the influence of grain boundary sizes on the EPRCC, and the results show that the EPRCC is almost grain boundary size independent.

PV Panel Model Parameter Estimation by Using Neural Network

Photovoltaic (PV) panels have been widely used as one of the solutions for green energy sources. Performance monitoring, fault diagnosis, and Control of Operation at Maximum Power Point (MPP) of PV panels became one of the popular research topics in the past. Model parameters could reflect the health conditions of a PV panel, and model parameter estimation can be applied to PV panel fault diagnosis. In this paper, we will propose a new algorithm for PV panel model parameters estimation by using a Neural Network (ANN) with a Numerical Current Prediction (NCP) layer. Output voltage and current signals (VI) after load perturbation are observed. An ANN is trained to estimate the PV panel model parameters, which is then fined tuned by the NCP to improve the accuracy to about 6%. During the testing stage, VI signals are input into the proposed ANN-NCP system. PV panel model parameters can then be estimated by the proposed algorithms, and the estimated model parameters can be then used for fault detection, health monitoring, and tracking operating points for MPP conditions.

Intelligent voltage controller based on firefly algorithm for DC-DC boost converter

DC-DC boost converter is one of the important tools of photovoltaic (PV) power plant. DC-DC boost converter can be used to adjust the voltage output of photovoltaic before going to the inverter. In addition, DC-DC boost converter can be used as additional devices to make the PV plant operated in maximum power point condition. To get the optimal voltage adjusment, an appropriate controller is essential. Generally, PI controller is commonly used to control the switching procedure of the boost converter. However, with uncertainty of the source (uncertainty of the PV output), PI controller is out off dated. Hence designing PI controller based on the metaheuristic algorithm such as firefly algorithm is essential. This paper is proposed an intelligent voltage controller for DC-DC boost converter based on firefly algorithm (FA). From the simulation results it is noticeable that the PI based on FA could provide better control signal (indicated by the fastest settling time of the boost converter).

Take it to the Carnot limit: Perspectives and thermodynamics of dual-cell electrochemical heat engines

• Transport of heat and charge is fully decoupled. • New expression for the thermoelectric figure-of-merit for dual cell electrochemical heat engines. • Dual cell electrochemical heat engines can be optimized to Carnot limit. • Heat exchangers increases conversion efficiency. In electrochemical dual-cell heat engines, the conduction of heat and electricity are fully decoupled, allowing their independent optimisation to maximise the conversion efficiency. Despite this advantage, the dual-cell electrochemical heat engine has only been explored superficially in previous studies. Here we address the in-depth thermodynamic aspects of the heat engines integrated with two electrochemical flow cells and assess the route to achieve a high heat-to-electricity conversion efficiency and system's power output. Our theoretical analysis revealed for the first time that in the dual-cell electrochemical system, the flow rate must be controlled as a response to the electrical current, and conversion efficiency no longer depend on the conventional thermoelectric figure-of-merit. Based on established principles and considering tremendous advancements for the past 10 years within thermogalavic materials and flow battery systems, our analysis presents that it is realistic to develop dual-cell electrochemical heat engines that can be operated at conversion efficiencies approaching the Carnot limit, reaching 10.1 % and 19.3 % at maximum power point and maximum conversion efficiency conditions, respectively, under the temperature gradient of 80 °C.

Maximizing energy tracking in photovoltaic grid-connected system through modified tunicate swarm algorithm – control on environmental effect of irradiance conditions

ABSTRACT Photovoltaic (PV) systems are mostly utilized in all fields of applications, especially for remote electrification purpose. Irradiance change during the day, and the conditions are more dynamic at cloudy days. Environmental conditions are a challenge/dynamic task and require individual control methods for maximum tracking of the available power. Maximum Power Point Tracking (MPPT) methods are designed through power electronic converters, which supply the PV systems to the load. Maximum Power Point (MPP) conditions of PV system with proposed Modified Tunicate Swarm Algorithm (md-TSA) effectively tunes the controller parameters by the help of voltage and current control. Power control with I/V control is almost improved up to 3.2% as compared with existing methods. Testing of md-TSA has been validated during uniform irradiance and different partial shading conditions. Proposed md-TSA tracking control vector is validated with Positive Conductance Region (PCR) and Negative Conductance Region (NCR) in all maximum energy tracking cases. In a propped work, Gravity force of will be modified and determined modified gravity force. Hence control of md-TSA will to meet and ( on both PCR and NCR for validating MPP. Proposed md-TSA has been validated for 50% loading and 100% loading conditions with the control vector. Quantitative data according to variations of loading, the voltage control vector can able improves the performance up to 6–8%. Also quantitative data according to variations of irradiance levels, the control vector of module current will improve the performance 5–10% and explored in test condition-1, 2 of results. By the proposed md-TSA, islanding has been tested with added control to voltage thresholds and hence proper switching pulses of converter are initiated. Here islanding switching has been considered either ‘0’ or ‘1’ for test event validation. Switching time signal have determined for switching instants , and validated based on quantitative data variations on PCR and on NCR of MPPT. Proposed md-TSA verified over a PSO, fuzzy and conventional MPP methods and control taken as per 2–6%effective control of energy extraction estimated during quantitative data of load and irradiance level.

Maximum power point tracking based on modified firefly scheme for PV system

Solar photovoltaic (PV) cells play a major role as natural, renewable energy sources. It is characterized by having nonlinear photoelectric voltage and current characteristics. These properties depend on the amount of solar radiation and temperature. PV can be used as an electrical charge circuit. But due to the low efficiency of the resulting photoelectric power, it should operate in conditions of maximum power point. There are several algorithms for achieving this maximum power point condition. In this paper, a PV system is proposed to obtain the maximum power point using a modified firefly algorithm. The modifications have been made both in fireflies’ locations and their random movement. Several simulations are implemented using MATLAB to verify the performance of the proposed system. From the simulation results, the proposed algorithm outperforms all traditional algorithms such as firefly and perturbation and observation technique. Moreover, the impacts of some variants of the proposed technique are studied. The variants are the number of the fireflies, the randomness, the maximum iterations, and the effect of changing the sampling time. A proposed modified firefly is presented with an MPPT controller in the PV system to ensure operating the PV at the MPP. Additionally, the mathematical expressions are explained. Moreover, MATLAB simulation programs are done to compare the performance of the proposed scheme with other related ones.

Sources of Thermal Power Generation and Their Influence on the Operating Temperature of Organic Solar Cells.

Thermal stability, closely associated with the operating temperature, is one of the desired properties for practical applications of organic solar cells (OSCs). In this paper, an OSC of the structure of ITO/PEDOT:PSS/P3HT:PCBM/ZnO/Ag was fabricated, and its current-voltage (J-V) characteristics and operating temperature were measured. The operating temperature of the same OSC was simulated using an analytical model, taking into consideration the heat transfer, charge carrier drift-diffusion and different thermal generation processes. The simulated results agreed well with the experimental ones. It was found that the thermalization of charge carriers above the band gap had the highest influence on the operating temperature of the OSCs. The energy off-set at the donor/acceptor interface in the bulk heterojunction (BHJ) was shown to have a negligible impact on the thermal stability of the OSCs. However, the energy off-sets at the electrode/charge-transporting layer and BHJ/charge-transporting layer interfaces had greater impacts on the operating temperature of OSCs at the short circuit current and maximum power point conditions. Our results revealed that a variation over the energy off-set range from 0.1 to 0.9 eV would induce an almost 10-time increase in the corresponding thermal power generation, e.g., from 0.001 to 0.01 W, in the cells operated at the short circuit current condition, contributing to about 16.7% of the total solar power absorbed in the OSC.

Improved Operational Stability of Perovskite Solar Cells via Au Barrier Layer Incorporation

Metal electrode corrosion by halogen species from perovskites causes severe degradation in perovskite solar cells (PSCs). By employing the Au–Ag bilayer top electrode, we show improved operational stability for PSCs compared to devices with a single metal electrode. The optoelectronic property of bilayer electrodes and their influence on device parameters and operational stability are characterized and discussed. Significantly enhanced operational stability (T80 > 200 h) is demonstrated compared to pure Ag metal electrode devices (T40 ≈ 200 h), under maximum power point conditions. The applicability of this strategy is further confirmed by the Au–Al bilayer electrode system. The work not only demonstrates an effective method to prevent metal electrode corrosion and perovskite decomposition but also provides insights into the working principle and degradation of PSCs.

One‐Step Slot‐Die Coating Deposition of Wide‐Bandgap Perovskite Absorber for Highly Efficient Solar Cells

Slot‐die coating is a promising technique paving the way for large‐area perovskite deposition and commercially relevant solar device fabrication with sharp control over the thickness and material composition. However, before transferring perovskite solar cells technology to commercial applications, it is required to develop ink formulations, guaranteeing high homogeneity over a wide surface and leading to large, defect‐free, and well‐crystallized perovskite grains to maximize the device performances. A one‐step slot‐die deposition route, combining ink tailoring and vacuum aspiration solvent extraction, affording the deposition of a high‐bandgap multication perovskite, is reported. One important key is the introduction of methylammonium chloride in the ink formulation, which substantially enhances the film quality over a large area. Although the efficacy of antisolvent dripping is demonstrated on a small area, it is not compatible with larger areas. This work compares the latter with a vacuum quench protocol, allowing efficient extraction of the solvents. Considering both ink formulation engineering and vacuum solvent extraction, a stabilized power conversion efficiency of up to 17.5% is reached. This constitutes, to the best of our knowledge, the highest reported value for a high‐bandgap absorber deposited by slot‐die coating. Moreover, stability over 180 h under maximum power point conditions is herein demonstrated.

Advanced method for electrical characterization of carrier-selective passivating contacts using transfer-length-method measurements under variable illumination

Carrier-selective passivating contacts have been demonstrated to be crucial to reach the practical efficiency limit of single junction, crystalline silicon (c-Si) based solar cells. Yet, the electrical transport losses affecting the collection of photogenerated carriers remain to be addressed. To this aim, different methodologies and characterization techniques are currently used. In this contribution, we propose the concept of shell as a new terminology to describe carrier-selective passivating contacts. Then, we present a novel characterization methodology using transfer length method (TLM) measurement under variable illumination to investigate the charge-carrier transport in amorphous/crystalline silicon heterojunction (SHJ) n-type contact stacks. We use technology computer-aided design simulation to model a TLM structure and to identify the physical phenomena and the key parameters affecting the contact resistivity (ρc) and the charge carrier accumulation of such contact stacks. Then, the simulation results are compared with experimental data by performing variable-illumination TLM measurements of actual SHJ n-type contact stacks. Specifically, we demonstrate that illumination has a strong impact on the measured ρc value, highlighting the importance of measuring ρc under maximum power point conditions for a relevant characterization of solar cell transport losses. In addition, we investigate the dependence of ρc to a change in the injected carrier density within the c-Si bulk to compare the illumination responses of different SHJ n-type contact stacks. In the quest for maximal efficiency, this method may insightfully complete other characterization techniques to further understand and study the electrical transport in solar cells.

Maximum Power Point Tracking for a PV System Using Tuned Support Vector Regression by Particle Swarm Optimization

The photovoltaic (PV) system is always operated at the maximum power point (MPP) condition irrespective of the fluctuations in PV voltage. The maximum power point tracking (MPPT) employed in PV system is not effective during the presence of current ripple as normal tracking becomes increasingly complex during fluctuation in solar irradiation or due to change in MPP condition. This paper proposes a high-efficiency power point tracking algorithm to minimize the current ripple and power oscillation around the maximum power point. The developed algorithm is based on particle swarm optimization-support vector regression (PSO-SVR) technique. The proposed algorithm is implemented to select and tune the Support Vector Regression (SVR) parameters such as kernel parameters, variance, and the penalty factor for predicting the irradiation level as well as to determine the PV voltage corresponding of maximum power point. The PSO method is used to accelerate the process of optimizing the SVR parameters at different conditions and get knowledge about the corresponding global optimum. From the experimental results,the efficiency of maximum power point tracking is found to be 99.8%. The proposed algorithm PSO-SVR shows a better performance than using SVR alone. The stability and accuracy of MPPT have been validated during the rapid fluctuation of solar irradiation in the range of 25% to 100%.

Two-Level Islanding Detection Method for Grid-Connected Photovoltaic System-Based Microgrid With Small Non-Detection Zone

This article proposes a fast and reliable two-level islanding detection method (IDM) for grid-connected photovoltaic system (GCPVS)-based microgrid. In the first level of the proposed IDM, the magnitude of the rate of change of output voltage (ROCOV) is computed. If this variable exceeds a predefined threshold, a disturbance is injected into the duty cycle of DC/DC converter after a given time delay to deviate the system operating point away of its maximum power point (MPP) condition. This leads to a substantial active power output and voltage reduction in an islanded mode. Therefore, the ROCOV and the rate of change of active power output (ROCOP) indices, measured in the second stage, pose great negative sets at the same time in islanding states. However, the variation of at least one of these variables is near-zero in non-islanding switching events. The assessment of the presented algorithm has been conducted under extensive islanding and non-islanding scenarios for a case study system with two PV power plants using hardware-in-the-loop (HiL) simulation tests. The provided results remark precise islanding classification with an eminently small non-detection zone (NDZ) within 510 ms. The presented IDM has the advantages of self-standing thresholds determination, no improper effect on the output power quality, and simple and inexpensive structure. Moreover, the fast MPP restoration of the proposed scheme after islanding identification boosts the chance of seamless reconnection and DG autonomous operation in microgrid.

Stable and Highly Flexible Perovskite Solar Cells with Power Conversion Efficiency Approaching 20% by Elastic Grain Boundary Encapsulation

Here, we show that flexible perovskite solar cells (PSCs) with high operational stability and power conversion efficiency (PCE) approaching 20% were achieved by elastic grain boundary (GB) encapsul...

Maximum Power Point Tracking Injection Method for Islanding Detection of Grid-Connected Photovoltaic Systems in Microgrid

This paper proposes a novel islanding detection method (IDM) for grid-connected photovoltaic systems (GCPVSs) through a disturbance injection in the maximum power point tracking (MPPT) algorithm. When an absolute deviation of the output voltage exceeds a threshold, the applied disturbance shifts system operating point from its maximum power point (MPP) condition. This leads to a sharp active power output reduction and consequently, a significant voltage drop in islanded mode beyond the standard voltage limit. The proposed algorithm is defined in a way that the distributed generator (DG) can be restored to MPP after islanding classification. It is thereby effective in microgrid in where the power injection at maximum level to cater the critical loads and maintain the stability of the isolated area are pursued. An intentional time delay has also been considered to avoid nuisance tripping in short-circuit faults which do not require tripping. The assessment of the proposed technique has been conducted for a sample network containing two GCPVSs in a real-time platform including actual relays in hardware-in-the-loop (HiL). The provided results under extensive islanding scenarios defined in islanding standards endorse timely and accurately detection with negligible non-detection zone (NDZ) as well as no false tripping in non-islanding disturbances. The comparative analysis of the presented scheme with a few recent IDMs for GCPVS highlights its overall superiorities, including very small NDZ, fast detection, thresholds self-standing determination, no adverse effect on power quality, and simple and inexpensive integration.

An improved methodology for reactive power management in grid integrated solar PV system with maximum power point condition

Abstract The grid-integrated solar photovoltaic (PV) inverter is generally used to provide active power (P) support to the distribution grid operated at maximum power point (MPP) condition. Moreover, it should also be capable of providing reactive power support (Q) to the distribution grid. Therefore, an appropriate range of reactive power should be known at MPP condition to ensure satisfactory operation of the grid-integrated PV system (GIPV). In this work, an improved mathematical methodology is proposed to derive the P-Q capability curve of GIPV for managing the reactive power injection into the grid at MPP condition for various environmental conditions. By evaluating all the possible set of working point within the stable region of operation, this methodology is used to obtain reactive power limits of a utility-scale single-stage three-phase PV system connected to the IEEE 33 bus distribution grid. The considered PV system is simulated using software-in-the-loop (SIL) environment based on OPAL-RT OP4510 real-time digital simulator with coordinated closed-loop control of dc-link voltage controller, maximum power point tracking (MPPT) controller, and active and reactive power controller. To validate the effectiveness of the improved mathematical methodology, the reactive power injection to the grid is changed, and the corresponding active power injection to the grid are measured, which are compared with the P-Q values obtained from the improved mathematical methodology.

Evaluation and Comparison of DC-DC Power Converter Variations in Solar Panel Systems Using Maximum Power Point Tracking (MPPT) Flower Pollination Algorithm (FPA) Control

Maximum Power Point Tracking (MPPT) is a method that can be used to optimize the electrical power output from solar panels. The performance of the MPPT method on solar panel systems can be influenced by many variables. One of them is the selection of a DC-DC power converter. DC-DC-DC Converter is a component that is used to optimize the performance of solar panels. Several types of DC-DC Converter are Buck, Buck-Boost, Single Ended Primary Inductance Converter (SEPIC), and CUK. Each converter has a different effect on solar panels output power. In order to observe and make a comprehensive analysis, simulations are performed through PSIM (Power Simulator) software on the performance of several DC-DC Converters that use Flower Pollination Algorithm (FPA) as the MPPT algorithm. Variables that observed are the output power characteristic, the response of the voltage-current ripple signal, and the accuracy of the converter in the process of reaching the maximum power point condition. As a result, CUK converter can obtain the highest value of solar panel output power, 145.02 W. A low ripple level with a stable power value response is entirely generated by CUK and SEPIC Converter. Overall, for this system, the CUK converter has better performance than the other converters.

V/F based Multi-Phase Induction Motor Drive For PV Powered Boat Applications

This paper presents a detailed discussion about single stage inverter to drive the multi-phase V/F induction motor to propel boat fed from stand-alone photovoltaic (PV) system, increases compactness, reliability and economical features to the entire system. To drive the boat using non-linear multi-phase induction motor from a non-linear PV source, under maximum power point condition is a tedious task. Though, single stage systems seem to simple, obtaining various control functionalities such as MPPT operation, model reference speed estimation, V/F speed control methods along with controller design and modulator functions from only one power electronics converter increases the design complexity to the designer. While performing MPPT and speed estimation operations in closed loop, re-checking ability is integrated to the inverter fed V/F control induction motor initiative for superior exactness results improves the dynamic performance, and also energy saving to end-user. Closed-loop (CL) boat sailing operation with load torque and model reference adaptive based speed estimation using multi-phase induction motor model along with the MPPT P&O algorithm, is used to generate reference command to the controller, and designed controller ensure to track this reference by producing controller voltage to modulator. Simple Sine PWM is adopted for the generation PWM pulses to the inverter in this drive to enhance the design simplicity. Proposed method is simulated using MATLAB/SIMULINK and closed loop solution at both different irradiations and load torque conditions presented. The simulation marks illustration that planned method is inexpensive, efficient, performance is reliable and superior.