In order to meet the special application requirements of photovoltaic power system for contamination monitoring system in high voltage transmission line, this paper presents a charging system suitable for fast charging of supercapacitor with low-power solar cells. This design uses BUCK-BOOST circuit as the main charging circuit topology, uses a novel MPPT tracking method, Weighted Variable-Step Voltage-Hysteresis Perturbation & Observation MPPT(WVV P&O MPPT), and achieves control by FPGA. The system’s configuration and control strategy are theoretically verified by Matlab/Simulink, and the production and testing of the charging system are completed. Test results show that the charging system uses low-power solar cells and charges 2F and 5F super capacitors under normal weather conditions, and all of these charging works can be finished during a relatively short time. Compared with the previous research of our task force, this design effectively reduces the charging time and improves the utilization of solar energy.