This paper proposes an effective algorithm for simulating a large mismatched photovoltaic array. The technique allows to reproduce the array behavior at a cell level, including both the direct and the reverse operating mode, thus making the analysis of the hot-spot phenomenon possible. The algorithm is also able to manage the electrical variables related to the bypass diodes, which are usually connected in anti-parallel with a number of series connected cells. The non-linear system of equations describing the array is solved by using a suitable algorithm, introduced herein, for the inversion of the Jacobian matrix. The proposed procedure guarantees a high accuracy at a low computational burden. Some simulation examples allow to show the features of the technique on practical cases and to confirm its outstanding performances. (C) 2014 Elsevier Ltd. All rights reserved.