This paper introduces the P&O based Lock-On Mechanism (LOM) MPPT algorithm where the aim is to eliminate the commonly known steady state oscillations that are encountered in conventional P&O algorithms. The purpose of the LOM algorithm is to scale the perturbation size of the control parameter appropriately based on whether or not the maximum power point (MPP) has been located. Essentially, the LOM component is imposed on the reference input voltage and thus the P&O-LOM algorithm, is introduced. Indeed, a separate controller involving a simple PI controller is then used to drive the circuit dynamics to achieve the desired reference. To verify the functionality of the proposed P&O-LOM algorithm, a Simulink simulation and an experiment involving the non-inverting Buck-Boost (NIBB) converter is conducted. By comparing the performance of the P&O-LOM algorithm with that of the conventional P&O algorithm and the hill climbing LOM (HC-LOM) algorithm, it is shown that, the P&O-LOM algorithm can eliminate steady state errors and is also very robust to noise effects. (C) 2017 Elsevier Ltd. All rights reserved.