Abstract

As the popularity of solar panels increases, significant research is being performed on maximizing the power extracted from photovoltaic systems. A phenomenon known as partial shading is a major source of power losses for photovoltaic plants. One way to reduce the effects of partial shading conditions is by using bypass-diodes. Typically any number of series and parallel-connected photovoltaic cells, known as photovoltaic cell arrays, are connected in anti-parallel with bypass-diodes. Due to this, it is advantageous to have an equivalent model for a photovoltaic cell array that is connected to bypass-diodes. In order to accurately develop this model, it is necessary to consider both series and parallel configurations of bypass-diodes, as well as the thermal behavior of bypass-diodes. The bypass-diode's temperature model must be comprised of the constantly changing dissipated power, the effects of wind speed and the ambient temperature. This paper constructs an electro-thermal modular model for any size photovoltaic system and includes the effects of both the photovoltaic cells and bypass-diodes. A detailed analysis of the proposed model is performed and is then validated in both PSCAD/EMTDC and Matlab-Simscape. The proposed model is then further validated by the use of real measurements of ambient temperature, cell temperature, wind speed and then finally by a performance analysis of several maximum-power-point-tracking algorithms.