This paper introduces a method that allows estimating the incident solar irradiance on a photovoltaic (PV) panel by the mathematical model of the equivalent circuit, that characterizes its behavior and operation. The estimation includes the calculation of the variation of the internal resistances (series and parallel) that are dynamically influenced by changes in current, voltage, temperature and irradiance incident on the photovoltaic panel under operating conditions at the Maximum Power Point (MPP). The Maximum Power Point Tracking algorithm (MPPT) is used to control the input capacitor voltage of a Boost converter. This method is evaluated under different irradiance and temperature profiles using the Matlab®/Simulink simulation software, taking account a 30W photovoltaic panel parameters.