This paper applies different methodologies through measurement and simulation for the partial shading analysis of SPV arrays. A two-diode photovoltaic solar cell model evaluates SPV arrays under shading conditions. Experimental data from two identical 1.5 kWp PV generators was used as a study case. One is subjected to shading caused by the branches of a tree, resulting in its electricity production being affected for several days, and the other is shadow-free. The authors use a methodology based on short-circuit of the solar cells to determine the different irradiance levels. It was considered because it avoids using several irradiance sensors to map the shaded and unshaded regions in a shadow SPV array. The two-diode photovoltaic solar cell model used was developed in MATLAB/Simulink. The applied model and the map irradiance methodology can be used to represent IV curves in complex shading. For example, what could help identify if a given SPV array is working on a Global Maximum Power Point or a Local Maximum Power Point. Furthermore, the experimental results demonstrated that the model and methodology are useful in understanding what happens with SPV arrays in very complex shadow situations.