A photovoltaic (PV) array having multiple cells in series with bypass diodes may exhibit multiple power peaks under uneven irradiation, therefore an algorithm is required to reach the global maximum power point (GMPP). While a lot of methods have been proposed in the literature, they are usually quite complex and does not fully utilize the characteristics of the PV array. This paper first highlights a rapid and optimized mathematical simulation of the PV array using MATLAB to find the probability distribution of voltage at GMPP under multiple irradiation conditions and temperatures. The resulting GMPP distribution in 22E6 irradiation and temperature conditions checked for an array of 4 PV modules in series with bypass diodes is presented, as well as the optimizations in MATLAB necessary to keep simulation time in check. From the obtained result, we propose a simple and efficient probability-based algorithm capable of reaching GMPP up to 93.64% of the time.