SIMULATION OF THE INFLUENCE OF IRRADIATION INHOMOGENEITY ALONG THE RECEIVING SURFACE ON PHOTOELECTRIC PANEL PARAMETERS

Abstract

When evaluating the photovoltaic systems energy yield, it is important to take into account the inhomogeneity in distribution of the light along the solar panels receiving surface. Specialized software used today is capable of correctly simulating the solar power plant energy performance in a typical year, taking into account the shading of the solar field by surrounding macro-objects. At the same time, local shading caused by the presence of extraneous objects or contaminations on the receiving surface of the panel are not taken into account. In this paper a block model of a photovoltaic panel which allows taking into account the influence of local shading on the panel generation is presented. The influence of inhomogeneity of the solar radiation flux along the receiving surface on the solar panel electrical parameters is simulated using MATLAB/Simulink environment. It is shown that in the case of panel with serial connected solar cells the solar radiation inhomogeneity can significantly reduce the output electric power, since the shaded solar cells block the current in the electric circuit, and bypass diodes must be used to avoid such blocking. In contrast to the series connection, in the case of solar panel with mixed series-parallel wiring of solar cells complete shading of a cell in one of the parallel lines does not cause critical fall in the electrical energy generation. Thus, if the panel contains two parallel lines, the complete shading of a cell in one of the lines reduces the generated power by half compared to the unshaded case. As the solar cell shading decreases, the current in the shaded line grows that leads to increases of the total current of panel, and electricity generation of panel rises. Obtained results are correlated with general theoretical concepts and regularities described in literary sources.