Impacto do sombreamento na potência de saída de uma matriz fotovoltaica com diodos de bypass

Abstract

It is true that the partial shading of a photovoltaic matrix reduces the capacity power generation. It is believed that the maximum power of a photovoltaic matrix partially shading is inversely proportional to the percentage of shading. With everything, it appears in the literature that this may not be the case. The maximum power of a matrix can be rendered insensitive to the percentage of shading if a critical point is reached and, this critical point depends on the size, number of shaded modules and the configuration of the matrix. It is constantly reported in the literature that in a photovoltaic matrix under conditions shading, the least impact condition occurs when the shaded modules are located in the same column or distributed over a limited number of columns. In fact, this observation is 100% true in photovoltaic arrays without using the bypass diode. As demonstrated in this dissertation, the condition with the least impact can also occur when the shaded modules are distributed in different columns if the bypass diodes are used in the configuration. Thus, this dissertation presents the relationship between the and the number of shaded modules versus the energy generated by a photovoltaic matrix partially shaded parallel series and establishes a set of analytical equations for estimate the voltage, current and power at each point of maximum local power, using only information from the data sheet, in the simplest and most direct way, without resorting to modeling complex, completely avoiding the iterative procedure, eliminating the calculation uncertainty and significantly reducing execution time. Derived expressions are validated by simulations. It was found that the loss of output power is directly and mainly related to the position of the shaded modules in the photovoltaic matrix.