Development of photovoltaic hybrid LED street lighting system

Renewable energy exploitation becomes more and more important as consumption type energies are being exhausted. This paper presents the utilization of photovoltaic power applied in LED street lighting and an intelligent street lighting system is developed. The system consists of photovoltaic panels (12V, 60W), a lithium iron phosphate battery(12V, 40Ah), a LED array, a photovoltaic charge controller(CN3722), a LED driving circuit, an AC/DC circuit, a power switching circuit, a wireless communication module and a 16-bit microcontroller. The MCU controls the power switching circuit to select either the battery or output of AC/DC to illumine LEDs according to the output voltage of the photovoltaic panels and battery. Dimming function of LEDs can be remotely operated through the wireless communication module. The characteristics of the photovoltaic panels are tested and output voltage of ~17.5V corresponding to maximum output power is found. MPPT of the photovoltaic panel is achieved by CN3722 and the charging efficiency reaches above 85%.