Series resonant-based ballast for off-grid photovoltaic supply systems

In this paper, electronic ballast design criteria for an off-grid photovoltaic (PV) lighting system are discussed. A photovoltaic system is undoubtedly the most reliable source of electrical energy available for remote locations, especially for rural areas where grid supply has not yet reached. The system is composed of PV array, intelligent charge controller unit (ICCU), battery, electronic ballast and the lighting loads such as fluorescent lamp or compact fluorescent lamp (CFL). Electronic ballast provides the required high frequency power supply for a CFL. The criticality of the ballast design is based on a saturable ferrite core relaxation oscillator and the design of a capacitor-based harmonic filter circuit. To verify the resonant ballast design, five ballasts were designed and tested for three different applications; one for a 6 W CFL-based portable lantern, two for lighting two small rooms with 6 W CFLs and the other two for lighting two 18 W fluorescent lamps.