Current-voltage Characteristics Of Photovoltaic Modules Research Articles

Online extraction of physical parameters of photovoltaic modules in a building-integrated photovoltaic system

Building-integrated photovoltaic systems are solar photovoltaic modules that are used to replace traditional building construction materials to generate electrical energy. Photovoltaic modules are generally installed on the roofs or facades of buildings and cannot be monitored by conventional methods. This work presents a new online technique for analysing the current-voltage characteristics of photovoltaic modules installed on the facades of building-integrated photovoltaic systems. The proposed method, which is based on the modified double-diode model, can extract six physical parameters of the photovoltaic module that rely on the current and voltage at the short-circuit and open-circuit points and at the maximum power point. Unlike the approaches from existing studies, the method proposed in this paper requires only the current at the maximum power point. By measuring the solar irradiance, wind speed and average temperature of the photovoltaic module, the current and voltage at the short-circuit and open-circuit points can be calculated. To study the accuracy of the proposed models, the absolute error and root mean square error of individual photovoltaic modules are examined. The results indicate that the minimum absolute error of the current appears near the maximum power point. Moreover, the proposed simulation of the current-voltage characteristic curves achieves a lower root mean square error value and exhibits a better ability to represent the current-voltage characteristics of the photovoltaic modules. In addition, methods are used to extract the six parameters of the photovoltaic module, which operates in the building-integrated photovoltaic system. The experimental results show that the prediction of the current-voltage characteristic curves achieves the lowest root mean square error values at the short-circuit and open-circuit points and at the maximum power point. Furthermore, regardless of whether operating in the building-integrated photovoltaic system, the six parameters of the photovoltaic modules with the same initial characteristics extracted via the proposed methods have similar numerical ranges under standard test conditions. Based on these conclusions, the six parameters based on the modified double-diode model are useful and practical for the simulation and evaluation of the current-voltage characteristics of the photovoltaic module in the building-integrated photovoltaic system.

ANFIS-Based Modeling for Photovoltaic Characteristics Estimation

Due to the high cost of photovoltaic (PV) modules, an accurate performance estimation method is significantly valuable for studying the electrical characteristics of PV generation systems. Conventional analytical PV models are usually composed by nonlinear exponential functions and a good number of unknown parameters must be identified before using. In this paper, an adaptive-network-based fuzzy inference system (ANFIS) based modeling method is proposed to predict the current-voltage characteristics of PV modules. The effectiveness of the proposed modeling method is evaluated through comparison with Villalva’s model, radial basis function neural networks (RBFNN) based model and support vector regression (SVR) based model. Simulation and experimental results confirm both the feasibility and the effectiveness of the proposed method.