An investigation on partial shading of PV modules with different connection configurations of PV cells

Partial shading is a commonly encountered issue in a PV (photovoltaic) system. In this paper, five different connection configurations of PV cells are studied to compare their performance under the condition of partial shading. They are SS (simple series), SP (series-parallel), TCT (total-cross-tied), BL (bridge-linked) and HC (honey comb) configurations. The electric network of each connection configuration is analyzed, taking into account the nonlinear nature of PV cells, by writing the Kirchhoffs voltage and current equations. The analysis is followed by solving the simultaneous nonlinear equations using the Newton-Raphson algorithm, which allows the I-V (current-voltage) characteristic of the module with a specific configuration in response to different types and levels of partial shading to be evaluated. Comparison of the maximum power and fill factors of the five connection configurations is then carried out. Also studied is the reverse voltage across each PV cell. It is found that in most cases, the TCT configuration has a superior performance over the other four configurations in most comparison indices. (C) 2011 Elsevier Ltd. All rights reserved.