Modeling of series-connected photovoltaic cells

© 2016 IEEE. This paper proposes a new model for series-connected photovoltaic (PV) cells, using a modified one-diode equivalent-circuit model. The PV modules comprise many series-connected cells to generate more electrical power. This modified model starts with the conventional one-diode equivalent-circuit (parallel-connected current source with a diode and a shunt resistance which are connected in series with a series resistance and a load) of PV cells and then proposes a new way of connecting the aforementioned circuit elements. The advantage of the presented modified model, is that it can model the series-connected PV cells by a new representation of one-diode equivalent-circuit. To validate the results of the modified model, similar input variables are applied to the conventional and the presented models. The current/voltage (I/V) characteristics are then calculated from both models and compared. The results show that the difference between the calculated I/V characteristics using the two models is much less than 1 percent. The presented approach can thus, be very useful for researchers or engineers to quickly and easily determine the performance of PV modules

Photovoltaic Grid Integrated System Based on MPPT Technique By using MATLAB/SIMULINK

This paper provides an easy accurate method of modeling photovoltaic arrays. The methodis comfortable to obtain the parameters of the array model using information from the datasheet. The electric system consists of a photovoltaic module (PV) module, a DC/DC converter and a DC/AC converter to release the grid connection. A maximum-power point tracking (MPPT) technique is used to extract maximum amount of power from solar cells. The photovoltaic model is established using basic circuit equations of the Photovoltaic (P-V) cells including the effects of solar radiation and temperature changes. One-diode equivalent circuit is used in order to study I-V and P-V characteristics of a typical 36W solar module and draws results according to values changes of the temperature and solar irradiation which is observed in MATLABSIMULINK. Hence, the P-V module has nonlinear characteristics, and the Photovoltaic system characteristic curves such as current-voltage (I-V) and power-voltage (P-V) characteristics are drawn according to values change in temperature and solar radiation which is observed in MATLAB-SIMULINK

A NEW FIVE-PARAMETER MODEL FOR PV PANELS-EXPERIMENTAL VALIDATION ON A POLYCRYSTALLINE MODULE

A new five-parameters model to describe the relation between the electric current and the voltage for a photovoltaic module is experimentally validated on the field, with variable conditions of operative temperature and solar irradiance. The electrical parameters of the one diode equivalent circuit are found by solving an equations system based on the data commonly issued by manufacturers in standard test conditions. To verify the capability of the new model to fit PV panel characteristics, the model was tested on two different panels comparing the results both with the data issued by manufacturers and with the results obtained using the five- parameters model already proposed by other Authors. The comparison shows that the new model is able to reproduce with very good precision the I-V curve issued by manufactures. Furthermore, the reliability of the proposed model was assessed performing an experimental validation connecting a PV panel to several different electrical resistances. The simultaneous measurement of the silicon temperature, air temperature, wind speed and direction, solar irradiance and voltage drop across the load, has permitted to verify a very good correspondence between the measured and the calculated data

Series connected photovoltaic cells-modelling and analysis

As solar energy costs continue to drop, the number of large-scale deployment projects increases, and the need for different analysis models for photovoltaic (PV) modules in both academia and industry rises. This paper proposes a modified equivalent-circuit model for PV modules. A PV module comprises several series-connected PV cells, to generate more electrical power, where each PV cell has an internal shunt resistance. Our proposed model simplifies the standard one-diode equivalent-circuit (SEC) model by removing the shunt resistance and including its effect on the diode part of the circuit, while retaining the original model accuracy. Our proposed equivalent circuit, called here a modified SEC (MSEC), has less number of circuit elements. All of the PV cells are assumed operating under the same ambient conditions where they share the same electric voltage and current values. To ensure the simplification did not come at a reduction in the accuracy of the SEC model, we validate our MSEC model by simulating both under the same conditions, calculate, and compare their current/voltage (I/V) characteristics. Our results validate the accuracy of our model with the difference between the two models falling below 1%. Therefore, the proposed model can be adopted as an alternative representation of the equivalent circuit for PV cells and modules

Assessment of the Usability and Accuracy of the Simplified One-Diode Models for Photovoltaic Modules

Models for photovoltaic (PV) cells and panels, based on the diode equivalent circuit, have been widely used because they are effective tools for system design. Many authors have presented simplified one-diode models whose three or four parameters are calculated using the data extracted from the datasheets issued by PV panel manufactures and adopting some simplifying hypotheses and numerical solving techniques. Sometimes it may be difficult to make a choice among so many models. To help researchers and designers working in the area of photovoltaic systems in selecting the model that is fit for purpose, a criterion for rating both the usability and accuracy of simplified one-diode models is proposed in this paper. The paper minutely describes the adopted hypotheses, analytical procedures and operative steps to calculate the parameters of the most famous simplified one-diode equivalent circuits. To test the achievable accuracy of the models, a comparison between the characteristics of some commercial PV modules issued by PV panel manufacturers and the calculated current-voltage (I-V) curves, at constant solar irradiance and/or cell temperature, is carried out. The study shows that, even if different usability ratings and accuracies are observed, the simplified one-diode models can be considered very effective tools

Improved DC utilization using advanced modulation techniques with Z source Inverter

Generally, an inverter is required to convert DC power generated by PV cell into AC power. A multilevel inverter (MLI) can synthesizes a staircase waveform. In this paper, a comparative study is made on performance of 5-level Z Source H Bridge inverter by considering advanced pulse width Modulation (PWM) strategies. PWM strategies of proposed ZSI’s is quite similar to the traditional carried-based PWM control method, the only difference is that to turn null states into shoot through states and keep the active switching states unchanged, so that the reliability of the inverter is greatly improved because miss-gating can no longer destroy the circuit. Keywords: Z source Inverter; PWM Schemes; Shoot Through; Photo voltai

Electrical-thermal analysis of III–V triple-junction solar cells under variable spectra and ambient temperatures

AbstractThe influence of the incident spectral irradiance on the electrical and thermal behaviour of triple-junction solar cells has been investigated. A spectral dependent electrical model has been developed to calculate the electric characteristics and quantify the heat power of a multijunction solar cell. A three-dimensional finite element analysis is also used to predict the solar cell’s operating temperature and cooling requirements for a range of ambient temperatures. The combination of these models improves the prediction accuracy of the electrical and thermal behaviour of triple-junction solar cells. The convective heat transfer coefficient between the back-plate and ambient air was found to be the significant parameter in achieving high electrical efficiency. These data are important for the electrical and thermal optimisation of concentrating photovoltaic systems under real conditions. The objective of this work is to quantify the temperature and cooling requirements of multijunction solar cells under variable solar spectra and ambient temperatures. It is shown that single cell configurations with a solar cell area of 1cm2 can be cooled passively for concentration ratios of up to 500× with a heat sink thermal resistance below 1.63K/W, however for high ambient temperatures (greater than 40°C), a thermal resistance less than 1.4K/W is needed to keep the solar cell operating within safe operating conditions

Analysis of spatial fixed PV arrays configurations to maximize energy harvesting in BIPV applications

This paper presents a new approach for efficient utilization of building integrated photovoltaic (BIPV) systems under partial shading conditions in urban areas. The aim of this study is to find out the best electrical configuration by analyzing annual energy generation of the same BIPV system, in terms of nominal power, without changing physical locations of the PV modules in the PV arrays. For this purpose, the spatial structure of the PV system including the PV modules and the surrounding obstacles is taken into account on the basis of virtual reality environment. In this study, chimneys which are located on the residential roof-top area are considered to create the effect of shading over the PV array. The locations of PV modules are kept stationary, which is the main point of this paper, while comparing the performances of the configurations with the same surrounding obstacles that causes partial shading conditions. The same spatial structure with twelve distinct PV array configurations is considered. The same settling conditions on the roof-top area allow fair comparisons between PV array configurations. The payback time analysis is also performed with considering local and global maximum power points (MPPs) of PV arrays by comparing the annual energy yield of the different configurationsPeer ReviewedPostprint (author’s final draft

Maximizing solar photovoltaic system efficiency by multivariate linear regression based maximum power point tracking using machine learning

Introduction. In recent times, there has been a growing popularity of photovoltaic (PV) systems, primarily due to their numerous advantages in the field of renewable energy. One crucial and challenging task in PV systems is tracking the maximum power point (MPP), which is essential for enhancing their efficiency. Aim. PV systems face two main challenges. Firstly, they exhibit low efficiency in generating electric power, particularly in situations of low irradiation. Secondly, there is a strong connection between the power output of solar arrays and the constantly changing weather conditions. This interdependence can lead to load mismatch, where the maximum power is not effectively extracted and delivered to the load. This problem is commonly referred to as the maximum power point tracking (MPPT) problem various control methods for MPPT have been suggested to optimize the peak power output and overall generation efficiency of PV systems. Methodology. This article presents a novel approach to maximize the efficiency of solar PV systems by tracking the MPP and dynamic response of the system is investigated. Originality. The technique involves a multivariate linear regression (MLR) machine learning algorithm to predict the MPP for any value of irradiance level and temperature, based on data collected from the solar PV generator specifications. This information is then used to calculate the duty ratio for the boost converter. Results. MATLAB/Simulink simulations and experimental results demonstrate that this approach consistently achieves a mean efficiency of over 96 % in the steady-state operation of the PV system, even under variable irradiance level and temperature. Practical value. The improved efficiency of 96 % of the proposed MLR based MPP in the steady-state operation extracting maximum from PV system, adds more value. The same is evidently proved by the hardware results.Вступ. Останнім часом зростає популярність фотоелектричних (ФЕ) систем, насамперед через їх численні переваги в галузі відновлюваної енергетики. Однією з найважливіших і складних завдань у ФЕ системах є відстеження точки максимальної потужності (MPP), яка необхідна для підвищення їх ефективності. Мета. ФЕ системи стикаються із двома основними проблемами. По-перше, вони демонструють низьку ефективність вироблення електроенергії, особливо в умовах низького випромінювання. По-друге, існує сильний зв’язок між вихідною потужністю сонячних батарей і погодними умовами, що постійно змінюються. Ця взаємозалежність може призвести до невідповідності навантаження, коли максимальна потужність не ефективно відбиратиметься і передаватиметься в навантаження. Цю проблему зазвичай називають проблемою відстеження точки максимальної потужності (MPPT). Для оптимізації пікової вихідної потужності та загальної ефективності генерації ФЕ систем було запропоновано різні методи керування MPPT. Методологія. У цій статті представлено новий підхід до максимізації ефективності сонячних ФЕ систем шляхом відстеження MPP та дослідження динамічної реакції системи. Оригінальність. Цей метод включає алгоритм машинного навчання багатовимірної лінійної регресії (MLR) для прогнозування MPP для будь-якого рівня освітленості і температури на основі даних, зібраних зі специфікацій сонячних ФЕ генераторів. Ця інформація потім використовується для розрахунку коефіцієнта заповнення перетворювача, що підвищує. Результати. Моделювання MATLAB/Simulink та експериментальні результати показують, що цей підхід послідовно забезпечує середню ефективність понад 96 % в режимі роботи ФЕ системи, що встановився, навіть при змінних рівнях освітленості і температурі. Практична цінність. Підвищена ефективність 96 % пропонованого MPP на основі MLR в режимі роботи, що вистачає максимум з ФЕ системи, підвищує цінність. Те саме, очевидно, підтверджують і апаратні результати

Combining power electronic converters and automation to simulate solar PV systems

This paper presents a solar photovoltaic panel simulator system with the ability to perform automatic tests in different condition according to manufacture parameters. This simulator is based on three buck-boost DC-DC converters controlled by a microcontroller and supported by a Programmable Logic Controller which is responsible for the automatic tests. This solution will allow to achieve fast response, like suddenly changes in the irradiation, temperature, or load. To control the power converter, it will be used a fast and robust sliding mode controller. Therefore, with the proposed system is possible to perform the I-V curve simulation of a solar PV panel, evaluate different MPPT algorithms considering different meteorological and load variation. The main advantage of this work is the possibility to evaluate and test several MPPT algorithms and understand the operation and typical operation of solar PV panels in different conditions. Several simulations and experimental results from a laboratory prototype are presented to confirm the theoretical operation.info:eu-repo/semantics/publishedVersio