Electricity generation from solar energy is gaining importance day by day. The solar panels used for this purpose are affected by environmental factors. Many maximum power point tracking techniques have been used in order to benefit from the solar panels in maximum efficiency. This paper presents a new maximum power extraction algorithm for a photovoltaic system under partial shading. The new algorithm has capability to reach global peak under nonuniform radiation conditions. The proposed technique is implemented using Matlab/Simulink to show effectiveness of symbiotic organisms search (SOS) based maximum power point tracking (MPPT). The results show that SOS-MPPT algorithm gives accurate and fast results in finding maximum power point of PV systems.