The paper deals with concentrator photovoltaic dense-arrays under non-uniform solar irradiance. For given measured I-V characteristic of InGaP/GaAs/Ge multi-junction solar cells, estimated cell parameters connected to bypass diodes were obtained by using the Newton-Raphson method. Based on the cell parameters, the I-V characteristics of arrays were constructed and their performances under non-uniform irradiance were investigated. With the arrays performances analysis, the function of bypass diodes was also analyzed. Under non-uniform irradiance, the photo-generated currents of the cells are different and as a result, the I-V characteristic of the array contains steps. The steps may indicate the mismatched cells in the array operating in the negative voltage range and forcing the bypass diodes to conduct. For low dispersion of the non-uniformity of the solar flux, the inclusion of bypass diodes has no effect on the output power of the array; however for high dispersion, the output power decreases because the mismatched cells become reverse biased and dissipate power. (C) 2013 Elsevier B.V. All rights reserved.