Table of Contents
ISRN Renewable Energy
Volume 2013, Article ID 573919, 10 pages
http://dx.doi.org/10.1155/2013/573919
Research Article

A High-Performance Stand-Alone Solar PV Power System for LED Lighting

1Escola Superior de Tecnologia de Castelo Branco, Unidade Técnico Cientifica de Engenharia Electrotécnica e Industrial, Avenida Empresário, 6000 Castelo Branco, Portugal
2Departamento de Electrónica Telecomunicações e Informática, Universidade de Aveiro, 3810 Aveiro, Portugal

Received 19 April 2013; Accepted 11 June 2013

Academic Editors: O. Badran and M. Beccali

Copyright © 2013 José António Barros Vieira and Alexandre Manuel Mota. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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.