Performance evaluation of analytical methods for parameters extraction of photovoltaic generators

© 2020 The Authors. Published by MDPI. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.3390/en13184825This paper presents a succinct exploration of several analytical methods for extracting the parameters of the single-diode model (SDM) of a photovoltaic (PV) module under standard test conditions (STC). The paper investigates six methods and presents the detailed mathematical analysis leading to the development of each method. To evaluate the performance of these methods, MATLAB-based software has been devised and deployed to generate the results of each method when used to extract the SDM parameters of various PV test modules of different PV technologies. Similar software has also been developed to extract the same parameters using well-established numerical and iterative techniques. A comparison is subsequently made between the synthesized results and those obtained using numerical and iterative methods. The comparison indicates that although analytical methods may involve a significant amount of approximations, their accuracy can be comparable to that of their numerical and iterative counterparts, with the added advantage of a significant reduction in computational complexity, and without the initialization and convergence difficulties, which are normally associated with numerical methods.Published onlin

Modeling and Simulation of the Photovoltaic Cells for Different Values of Physical and Environmental Parameters

Both research and technological development in the area of renewable energy sources are necessary to account for the increase in energy demand and environment problems in the world. The photovoltaic (PV) cell has been described by non-linear outputs characteristics in current-voltage and power-voltage. This outputs is affected by various effects such as; series resistance ( ), shunt resistance ( ), solar irradiance and temperature. In this paper the effect of variation of parameters has been studied such as series resistance ( ) and shunt resistance ( ) of the diode in the photovoltaic cell and these effects could be seen in the Current-Voltage (I-V) and Power-Voltage (P-V) characteristic curves. In this paper also has been studied the effect of variation of the environmental parameters such as solar irradiance and temperature. Results show that a higher temperature at constant solar irradiance produces a decrease power. So the voltage and the photovoltaic cell output power tend to decrease at higher temperatures, but there is no noticeable effect on the photovoltaic cell current. Thus, it is important to keep the cell temperature as low as possible, because higher temperatures have negative effect on output power of photovoltaic cell. On the other hand, the effect of solar irradiance on photovoltaic cell, it reveals that higher solar irradiance gives higher current and higher power. Shunt resistance has significant effect on the operating characteristic curves of PV cells as low power output is recorded if the value of shunt resistance varies from 0.07 ohms to 1700 ohms. Finally, I have presented power-voltage characteristic curves and current voltage characteristic curves of photovoltaic cell for different solar irradiance in Shkoder, Tirana and Vlore

Metaheuristic Algorithm for Photovoltaic Parameters: Comparative Study and Prediction with a Firefly Algorithm

In this paper, a Firefly algorithm is proposed for identification and comparative study of five, seven and eight parameters of a single and double diode solar cell and photovoltaic module under different solar irradiation and temperature. Further, a metaheuristic algorithm is proposed in order to predict the electrical parameters of three different solar cell technologies. The first is a commercial RTC mono-crystalline silicon solar cell with single and double diodes at 33 °C and 1000 W/m2. The second, is a flexible hydrogenated amorphous silicon a-Si:H solar cell single diode. The third is a commercial photovoltaic module (Photowatt-PWP 201) in which 36 polycrystalline silicon cells are connected in series, single diode, at 25 °C and 1000 W/m2 from experimental current-voltage. The proposed constrained objective function is adapted to minimize the absolute errors between experimental and predicted values of voltage and current in two zones. Finally, for performance validation, the parameters obtained through the Firefly algorithm are compared with recent research papers reporting metaheuristic optimization algorithms and analytical methods. The presented results confirm the validity and reliability of the Firefly algorithm in extracting the optimal parameters of the photovoltaic solar cell

Thermal modelling and experimental assessment of the dependence of PV module temperature on wind velocity and direction, module orientation and inclination

A theoretical and experimental analysis of PV module temperature under various environmental conditions is presented in relation to module inclination, wind velocity and direction. The present experimental study, makes use of hourly PV temperature data collected from a double-axis sun-tracking PV system and environmental parameters monitored for a period of one year. The f coefficient which relates the PV module temperature with the intensity of the global solar radiation on the PV plane and the ambient temperature, is assessed in relation to the angle of PV inclination, the wind velocity and the angle of incidence of the wind stream on the PV surface, either front or back. The f coefficient is evaluated both experimentally and theoretically through thermal modelling based on the energy balance equation. The simulation model developed in this study considers heat convection by natural and air forced flow, the flow pattern either laminar or turbulent, the relative geometry of the PV module with respect to the wind direction, and the radiated heat by the PV module. Various expressions for the forced heat convection coefficient available in the literature are tested within the thermal model with reference to the windward and leeward side of the PV module, and their applicability to PV thermal analysis is experimentally assessed in terms of the agreement shown with measured data. The values of the f coefficient provided by the simulation model lie very close to the experimental data for the entire range of PV inclination angles, wind velocities and wind directions tested

Variable parameters for a single exponential model of photovoltaic modules in crystalline-silicon

The correct approximation of parallel resistance (Rp) and series resistance (Rs) poses a major challenge for the single diode model of the photovoltaic module (PV). The bottleneck behind the limited accuracy of the model is the static estimation of resistive parameters. This means that Rp and Rs, once estimated, usually remain constant for the entire operating range of the same weather condition, as well as for other conditions. Another contributing factor is the availability of only standard test condition (STC) data in the manufacturer’s datasheet. This paper proposes a single-diode model with dynamic relations of Rp and Rs. The relations not only vary the resistive parameters for constant/distinct weather conditions but also provide a non-iterative solution. Initially, appropriate software is used to extract the data of current-voltage (I-V) curves from the manufacturer’s datasheet. By using these raw data and simple statistical concepts, the relations for Rp and Rs are designed. Finally, it is proved through root mean square error (RMSE) analysis that the proposed model holds a one-tenth advantage over numerous recently proposed models. Simultaneously, it is low complex, iteration-free (0 to voltage in maximum power point Vmpp range), and requires less computation time to trace the I-V curve

ALGORITHM TO EXTRACT MODEL PARAMETERS OF PARTIALLY SHADED PHOTOVOLTAIC MODULES

Uneven irradiation, due to partial shading, can produce hot spots in photovoltaic modules. A classical solution to avoid hot spot consists in using bypass diodes in antiparallel to series-connected cell groups. This solution brings a new problem: the presence of multiple local maximum power points. We present a simple algorithm for fast extraction of the model parameters of partially shaded photovoltaic panels with bypass diodes. An example of the application of the proposed algorithm is illustrated using the data from a real monocrystalline silicon technology photovoltaic module measured under uniform illumination and partial shading conditions. The possibility of using the algorithm as a practical approximate solution is also discussed. The simulations, using only four parameters, represent reasonably well the measured data

Quick and Accurate Strategy for Calculating the Solutions of the Photovoltaic Single-Diode Model Equation

The photovoltaic (PV) single-diode model is the most widely used to characterize the behavior of a PV panel because it combines high precision with moderate difficulty. Lots of methods to obtain the model parameters use optimization techniques that require the resolution of the characteristic equation thousands of times; therefore, it is essential to calculate its solutions accurately but also in the shortest possible time. The objective of this article is to describe a new numerical strategy to solve the characteristic equation in a simple, fast and precise way. The main idea is based on a reparameterization of the Lambert equation which is closely related with the infinite power tower, and some well-known bounds of this tower will be used as seeds of numerical methods. This strategy is powerful for certain “small” values of the Lambert W function argument, but it is combined with another re-expression of the Lambert equation for the remaining “large” values. The proposed numerical strategy is so precise in very few iterations that it can be suitably transformed into an explicit formula. The results obtained have been compared with some of the best options in the literature and expexperimental results prove the power of the proposed methodolog

Interpretation of MPPT Techniques in Grid Connected Solar PV Array System

Solar energy is one of the most used and readily available renewable energy sources among the other energy sources. The power generated by PV systems is dependent on solar irradiance and temperature parameters. In the literature, many researchers and studies are interested in estimating true maximum efficiency point for the PV systems. Due to that fact, MPPT applications and techniques become an important issue for PV systems under both uniform and non uniform conditions. Although, PV system under uniform environment has only one maxima point on P-V curve which is simple to estimate correctly by conventional MPPT techniques, it is not as simple as under non-uniform condition such as partial shading and mismatch effects. To overcome the drawbacks of the conventional MPPTs under non uniform condition, researchers has been investigated new soft computing MPPTs, PV array configurations, system architectures and topologies