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Journal of Energy in Southern Africa

On-line version ISSN 2413-3051
Print version ISSN 1021-447X

J. energy South. Afr. vol.22 n.1 Cape Town  2011


Development of a universal DC power supply using solar photovoltaic, utility and battery power sources



Joe Oladosu OniI; Bukola Olalekan BolajiII

IDepartment of Electrical/ Electronics Engineering, Olabisi Onabanjo University, Ibogun Campus, Ogun State, Nigeria
IIDepartment of Mechanical Engineering, University of Agriculture, Abeokuta, Nigeria




In this paper, a universal direct current (DC) power supply system was developed and tested in order to provide uninterrupted power for DC appliances. The system employs simple Diode OR logic for the three power sources (mains from utility power supply, the solar photovoltaic and battery). The parallel combination of the three diodes at the output functions like a comparator circuit and compares the outputs voltage of the three sources, so that the highest voltage at a particular time feeds the DC output and supplies the charging current to the battery. The universal DC power supply system was tested under various operating conditions and the results obtained showed a good performance of the system. The system outputs, when all the power sources were available, during utility power failure and when only the stored energy in the back-up battery was available were 13.8, 13.1 and 12.2V, respectively. The system guarantees an uninterrupted power supply, which can be used to power telecommunication equipment, audiovisual materials, computers, DC motor driven devices and other DC appliances. A typical day solar radiation varied from 547 W/m2 to 865 W/m2 while the generated voltage from PV varied from 11.8 V to 13.7 V. The generated voltage from solar power source increases with the increase in solar radiation.

Keywords: battery, direct current, photovoltaic, power, solar, universal



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Received 15 July 2009
Revised 13 August 2010

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