Use of the Maximum Power Point Tracking Method in a Portable Lithium-Ion Solar Battery Charger

The use of solar panels in low-power applications is an increasingly developing topic. Various methods are currently used to obtain the highest possible solar panel power generation efficiency. The methods of determining the maximum power point (MPP) and its tracking are under constant development, resulting in the creation of new algorithms to accelerate the operational efficiency while maintaining good parameters. Typically, these methods are only used in high-power photovoltaic installations. Due to the problems resulting from the adjustment to MPP working conditions for low-power solar panels used to charge a Li-Ion battery, an attempt was made to check the feasibility of operating control based on a Pulse Width Modulation (PWM) method and a Maximum Power Point Tracking (MPPT) algorithm like the one used in high-power solar systems also for low-power systems. The article presents adaptation of PWM and MPPT methods for small chargers, including the stages of modelling a solar charger and the results of a computer simulation of the charger operation. The stages of building a real, physical device are also presented. From the analysis of the test results of the constructed charger in real- and laboratory conditions with the use of a device imitating sunlight, the so-called solar box, and comparisons with computer simulations show that the assumed goal was achieved. The results obtained with the PWM method were compared with the MPPT method. The optimization of the device operation parameters and improvement of the algorithms used in the MPPT method resulted in better optimalization of maximum point tracking, improving the efficiency of energy storage from solar cells.