This study presents a new Maximum Power Point Tracking (MPPT) model developed with MATLAB/SIMULINK based on P&O algorithm. This MPPT model takes into account the activation of bypass diodes since it will be used for the simulation of photovoltaic (PV) power plants equipped with flat reflectors. In order to validate the proposed simulation tool, we have compared our model to existing models, on one hand, and to experimental measurements realized without and with flat reflectors, on the other hand. The resulting absolute error can be lower than 3.6% for single days either with or without reflectors under stable sky conditions, whereas during one full month (November 2017), for the installation without reflectors, the absolute error was about 5.4%. In addition to these low errors found, the proposed MPPT model allows simulation for long periods of time, months to years, with a simulation time faster than that for the existing models (almost 20 times faster). REMARKS: We chose SUBTOPIC 6.2 because we present here a new method to model a PV power plant equipped with flat reflectors. This study focuses on MPPT.