scholarly journals Photovoltaic Cell and Module I-V Characteristic Approximation Using Bézier Curves

Author(s):  
Roland Szabo ◽  
Aurel Gontean

The aim of this work is to introduce new ways to model the I-V characteristic of a PV cell or PV module using straight lines and Bézier curves. This is a complete novel approach, Bézier curves being previously used mainly for computer graphics. The I-V characteristic is divided in three sections, modeled with lines and a quadratic Bézier curve in the first case and with three cubic Bézier curves in the second case. The result proves to be accurate and relies on the fundamental points usually present in the PV cell datasheets: Voc (the open circuit voltage), Isc (the short circuit current), Vmp (the maximum power corresponding voltage) and Imp (the maximum power corresponding current) and the parasitic resistances Rsh0 (shunt resistance at Isc) and Rs0 (series resistance at Voc). The proposed algorithm completely defines all the implied control points and the error is analyzed. The temperature and irradiance influence is also analyzed. The model is also compared using the least squares fitting method. The final validation shows how to use Bézier cubic curves to accurately represent the I-V curves of an extensive range of PV cells and arrays.

Author(s):  
Roland Szabo ◽  
Aurel Gontean

The aim of this work is to introduce new ways to model the I-V characteristic of a PV cell or PV module using straight lines and Bézier curves. This is a complete novel approach, Bézier curves being previously used mainly for computer graphics. The I-V characteristic is divided in three sections, modeled with lines and a quadratic Bézier curve in the first case and with three cubic Bézier curves in the second case. The result proves to be accurate and relies on the fundamental points usually present in the PV cell datasheets: Voc (the open circuit voltage), Isc (the short circuit current), Vmp (the maximum power corresponding voltage) and Imp (the maximum power corresponding current) and the parasitic resistances Rsh0 (shunt resistance at Isc) and Rs0 (series resistance at Voc). The proposed algorithm completely defines all the implied control points and the error is analyzed. The proposed method is validated for different temperatures and irradiances. The model is finally compared and validated using the least squares fitting method.


2019 ◽  
Author(s):  
Saad Motahhir ◽  
Abdelaziz El Ghzizal ◽  
Aziz Derouich

The objective of this work is to make a model of photovoltaic cells (PV) dedicated to teaching renewable energy using PSIM software. This model is based on ratings provided by the manufacturer as: open circuit voltage, short circuit current, voltage and current corresponding to the maximum power point. So the resulting model has a better approach and takes into account the influence of different physical parameters including temperature, irradiation, series resistance, shunt resistance and saturation current of the diode. After a general presentation of the photovoltaic conversion chain, the article details, at first, the modeling of a photovoltaic panel. Secondly, we focus on the implementation of a MPPT command for controlling the DC / DC to operate the PV array at maximum power (MPP).


This paper presents an analysis of parameter variations of a single-diode solar cell model. The parameters analyzed are the series resistance, shunt resistance, temperature and radiation change. Model equations are derived and simulated. All simulations were performed in MatLab using looping iterative method. Results obtained show that an increase in series resistance causes a decrease in short-circuit current and output power. A decrease in shunt resistance also causes a decrease in short circuit current and output power. An increase in temperature above the nominal value of 25oC causes a significant decrease in the open circuit voltage. An increase in irradiance above a nominal value of 1000 W/m2 causes the short circuit current to increase from 8.21A at 1000 W/m2 to 10.67A at 1300W/m2. It can be seen that parameter variations have a net effect on the current-voltage (I-V) and power-voltage (P – V) characteristics.


Existing empirical solar cell models use one or two diodes. As the number of diodes in a model increases, the mathematical complexity in deriving model equations also increases. In this paper, a photovoltaic cell is modeled using three diodes. Non-linear mathematical equations governing the I-V and P-V characteristics are summarized and simulated using Matlab looping iterative method. All simulations were performed in Matlab. Comparison is made between all models (one, two and three-diode) for design verification. Results obtained show that as the number of diodes increases in a PV cell model, the open circuit voltage and maximum power decreases for a given set of PV cell parameters. The short circuit current remained at a fixed value irrespective of the number of diodes.


Author(s):  
Darrell Cheu ◽  
Thomas Adams ◽  
Shripad Revankar

There is an increasing need for devices that can be powered for extended periods of time where it is difficult or impossible to maintain or replace, such as pacemakers, long term space flight or undisturbed sensors for military use. Presently, most portable devices run off a Lithium-Iodide battery, which gives a high amount of power but could only last approximately 2 to 5 years, requiring frequent replacement. However, replacement is unnecessary for betavoltaic cells as they can last at least 20 years. City Labs Inc. received a general license for commercially available tritium betavoltaic cells that were validated at extreme temperatures without permanent degradation. To fully determine the effectiveness of a betavoltaic cell, the electrical performance (I-V curves) of three betavoltaics were evaluated while temperatures were ramped up and down from −30°C to 70°C. Short circuit current, open circuit voltage, maximum power and fill factor were used to compare electrical performance. Results indicated that the open-circuit voltage and maximum power decreased as temperature increased, suggesting that betavoltaic cells are suited for cold environments below 0°C, such as during nightfall when a photovoltaic cell may not be used.


2012 ◽  
Vol 550-553 ◽  
pp. 476-479
Author(s):  
Ai Fen Wang

The three photovoltaic cells with two different anode buffer layer on the basis of Pentacene/C60 as active layer was fabicated, the effect and mechanism of anode buffer layer on performance of organic photovoltaic cell are explored. The experimental result shows transition metal oxide inserted between organic active layer and ITO could increase short circuit current and open-circuit voltage,power conversion efficiency is increased to 107%,so it is effective anode buffer material.


Author(s):  
T. T. Kovaliuk ◽  
M. N. Solovan ◽  
P. D. Maryanchuk

Due to the physical properties of MoN and ITO thin films, it was decided to create MoN/p-CdTe and MoN/n-CdTe heterostructures and investigate their electrical and photoelectric properties. The method of reactive magnetron sputtering was used to create thin MoN and ITO films on single crystal CdTe substrates with different conductivity types. To manufacture test heterostructures, the following CdTe crystal substrates were used: 1) p-type conductivity, grown by Bridgman technique at low cadmium vapor pressures; 2) n-type conductivity, grown by Bridgman technique at high cadmium vapor pressures. During the deposition process, the argon pressure in the vacuum chamber was 0.4 Pa. The power of the magnetron was 30 W, the sputtering process continued 5 min at a substrate temperature of 150°C. I-V characteristics of the heterostructures at different temperatures were measured, the height of the potential barrier, the values of the series and shunt resistance were determined. Electrical and photoelectric properties of the heterostructures were studied, and the dominant mechanisms of current transfer at forward displacements was established. The tunnel-recombination mechanism was found to be the dominant mechanism of current transfer in the MoN/p-CdTe and MoN/n-CdTe heterostructures. It was shown that the photoelectric parameters for the MoN/p-CdTe heterostructure are higher than those for MoN/n-CdTe. MoN/p-CdTe heterojunctions have the following photoelectric parameters: open-circuit voltage Voc = 0.4 V, short-circuit current Isc = 24.6 mA/cm2 at an illumination intensity of 80 mW/cm2. This makes them a promising material for the manufacture of detectors of various radiation types.


Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 43
Author(s):  
Rachid Herbazi ◽  
Youssef Kharchouf ◽  
Khalid Amechnoue ◽  
Ahmed Khouya ◽  
Adil Chahboun

This work presents a method for extracting parameters from photovoltaic (PV) solar cells, based on the three critical points of the current-voltage (I-V) characteristic, i.e., the short-circuit current, the open circuit voltage and the maximum power point (MPP). The method is developed in the Python programming language using differential evolution (DE) and a three-point curve fitting approach. It shows a good precision with root mean square error (RMSE), for different solar cells, lower than to those cited in the literature. In addition, the method is tested based on the measurements of a solar cell in the Faculty of Science and Technology of Tangier (FSTT) laboratory, thus giving a good agreement between the measured data and those calculated (i.e., RMSE = 7.26 × 10−4) with fewer iterations for convergence.


1979 ◽  
Vol 237 (1) ◽  
pp. R74-R79 ◽  
Author(s):  
T. C. Cox ◽  
R. H. Alvarado

Carefully dissected, mounted, and bathed with Ringer solution, the larval bullfrog skin has a resistance of about 9,000 omega.cm2 and a stable transepithelial electrical potential of about 20 mV (inside +). A short-circuit current of about 2 microA.cm-2 is generated that is comparable in magnitude to the net inward flux of Na+. At open circuit the flux ratio equation for Na+ is not satisfied. Larval skin is less sensitive to ouabain, amiloride, and ADH than adult skin. The current-voltage (C-V) relationship across the preparation is not linear; there are distinct breaks in both the hyperpolarizing and hypopolarizing regions. The former break, at about +130 mV, corresponds with a break observed in adult skin that corresponds with ENa. The shunt resistance (RS) and active pathway resistance (RA) were estimated by C-V curve analysis and by ion substitution. The two methods yielded comparable values with RS about 11 k omega.cm2 and RA about 62 k omega.cm2. It is suggested that transport is limited by the number of entry sites for sodium at the apical border of transport cells.


Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1029 ◽  
Author(s):  
Ivan Tolić ◽  
Mario Primorac ◽  
Kruno Miličević

This paper presents measurement uncertainty propagation through four basic photovoltaic cell models: One-diode model without resistances, with one resistance and with two resistances and two-diode model with two resistances. The expressions for the output current of all photovoltaic cell models is presented as a function of global irradiance G and temperature T. Next, the expressions for all fill factor parameters: short-circuit current, open-circuit voltage, current and voltage at the maximum power point, depending on the global irradiance G and temperature T are derived as well. For each parameter, Monte Carlo simulations to calculate the measurement uncertainty of the parameter are performed and the results were used as input values for the calculation of measurement uncertainty of fill factor. Practical calculations are performed in laboratory for renewable energy sources located on 45°32′ N and 18°44′ E. Final fill factor calculations are compared for three different module technologies.


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