This paper discusses a low power Maximum Power Point Tracker (MPPT) circuit specifically designed for wireless sensor node (hence effective, flexible, low cost and power-aware), that requires a power transferring circuit for conveying solar energy into rechargeable batteries even if it is not in optimal weather or orientation conditions. Depending on the operating conditions of the solar cell, the instantaneous generated power significantly changes requiring the adjustment not only of the working point of the solar panel but also of some other parameters and/or operating conditions of the converter itself in order to increase the conversion efficiency at different power level conditions. In this paper a two-dimensional MPPT algorithm that continuously changes both the converter switching frequency and the voltage on the solar panel is proposed, analyzed and experimentally verified.
