%0 Journal Article
%T A High-Performance Stand-Alone Solar PV Power System for LED Lighting
%A Jos¨¦ Ant¨®nio Barros Vieira
%A Alexandre Manuel Mota
%J ISRN Renewable Energy
%D 2013
%R 10.1155/2013/573919
%X This paper presents new improvements and real result of a stand-alone photovoltaic power system for LED lighting that was developed previously. The actual system, during day, charges a lead acid battery using MPPT algorithm for power transfer optimization, and, during night, it supervises battery discharge and controls the current in the power LED array. The improvements are in hardware and software. The hardware was simplified using only one DC/DC converter and only one microcontroller making it more efficient. The system board uses an ATMEL ATTINY861V microcontroller, a single-ended primary inductance converter (SEPIC), and sensors to read input and output voltages and currents to control all system. The software improvements are made in the battery charging algorithm, battery discharging algorithm, and in current control of the power LED array adjusting the light intensity. Moreover, results are presented showing the balance of energy in a period of 24 hours: first results of the MPPT algorithm in bulk battery charge phase and then the over battery charge phase, both in a sunny day. The power LED current control results are also presented showing a very small error. It turns off at 00£¿:£¿00 at each day to reduce the waste of energy. Finally, the balance of energy is studied and presented to help the right projection of the PV power panel needed and the necessary battery capacity. 1. Introduction The use of stand-alone photovoltaic lighting system has increased in remote rural areas and in towns. Conventional street lighting is energy intensive and can represent a high cost to local governments, which creates an impetus to investigate more efficient light sources such as photovoltaic-(PV-) powered light emitting diodes (PLEDs) lighting systems. Photovoltaic system is gaining increased importance as a renewable source due to its advantages such as little maintenance and no noise and wear due to its absence of moving parts. But there are still two principal barriers to the generalization use of photovoltaic systems: the high installation cost and the low energy conversion efficiency. To increase the ratio output power/cost of installation it is important that PV panel operates in its maximum power point (MPP) to absorb the maximum power possible. The combination of PV panels with power LEDs makes the called new green light sources. Battery is the energy store element in this system. State measure and energy management are critical issues for the battery in PV LED lighting system, such as the state of charge (SOC) [1].(1)The fast charging capability may
%U http://www.hindawi.com/journals/isrn.renewable.energy/2013/573919/