This paper proposes a maximum power point tracking (MPPT) method to seek the global maximum power point (MPP) in photovoltaic (PV) modules. The method infers partial shading—and hence the possibility of multiple maxima—by monitoring bypass-diode voltages and initiates a global search routine only if a bypass diode turns on. Under nominal conditions, conventional MPPT is implemented through a perturbation-based approach. This technique provides a significant advantage over existing methods to counter partial shading that periodically scan the entire PV power profile. Experimental results demonstrate the ability of the algorithm to track the global MPP for string and cell-level shading scenarios.