A RISC-microcontroller based photovoltaic system for illumination applications

This work presents the development of a solar powered public illumination system used for a waste recycle campaign in the city of Sao Paulo (Brazil). A lighting pole is installed in a street for area illumination. It has a translucent sign vinyl which shines in the sun and glows at night with fluorescent lamps; there are stainless steel receptacles used as recycle trash bin collectors at the base of the pole. The intented use of such a photovoltaic array to power the glassy advertisement works as a way of bringing solar energy into daily use, and to encourage companies in funding local recycle awareness campaigns. Solar energy is captured by a photovoltaic solar panel and delivered into a lead-acid battery through a flyback converter. The converter also performs the function of tracking the maximum power operating conditions. At night, a resonant push-pull current-fed inverter drives a fluorescent lamp. The system is controlled by a RISC PIC16C74 microcontroller, which searches the maximum power point by commanding the flyback converter with a hill-climbing algorithm, monitors the battery energy level, and turns on the fluorescent inverter with a real-time internal clock. Serial communication is provided for connection to a portable computer, which is used for battery life management and time clock settings. The paper shows the implementation of the whole system and describes comprehensive field tests.