PV-Powered LED Street Lights Optimization Using the Zeta-Sepic converter and Photo-Electro-Thermal Theory

Nowadays, using photovoltaic-powered Light Emitting Diode (LED) street lights is spreading owing to their higher efficiency and longer lifetime. In this paper, the Zeta-Sepic converter is used to manage an LED light, a PV panel, and a battery storage in these systems since it offers compact and single-stage power conversion. The PV panel and LED light are connected to the converter input port using a simple relay, while the battery source is put at the converter output port. During the day, the PV panel energy is saved in the battery through the converter forward direction power flow. Besides, by the converter reverse direction power flow the battery supplies the LED light with the required power during night. For these operation cases, voltage regulation is realizable at both converter input and output ports. This performance provides MPPT to the PV panel, State of Charge (SOC) control for the battery and light control with the LED light. For the LED lights, there exist a relationship between light, electricity and thermal energy that is optimized to achieve the highest luminal flux to the input power ratio. As a result, this paper uses the photo-electro-thermal theory and heatsink characteristics and bidirectional Zeta-Sepic converter to drive the LED lights at the operating voltage, in which the LED light optimal luminous flux occurs. Finally, the proposed LED light system is analyzed and validated in different operational conditions using MATLAB/SIMULINK. As useful experimentation, a photo collector sphere was built in the laboratory to calculate and validate the optimal working point of the light by measuring the LED light intensity through sensors installed on it.