ABSTRACT:

Stand-alone photovoltaic (SAPV) system is more favourable than grid connected photovoltaic (PV) system in areas where extension of power grid is impracticable. However, the high set up cost of a SAPV system requires cost efficient solar energy harvesting methods. To improve the energy harvesting efficiency of a PV system, a large, centrally controlled PV array can be rearranged into smaller PV modules that are individually controlled to operate at its respective maximum power point (MPP), thus forming a modular SAPV system. However, the implementation cost of the modular SAPV system is higher due to the increase in component count. We propose to reduce the component count of a modular SAPV system by utilizing a single-inductor multiple-input-dual-output converter. In this paper, a single inductor quad-input-dual-output DC/DC buck converter (QIDO) is proposed. Simulation results verified that a QIDO could regulate three PV modules independently, so that each PV module could operate at its MPP. Results also proved that a QIDO could regulate the power delivered to the load by diverting excess PV power to recharge the battery and drawing supplementary battery power when PV power was inadequate. In summary, the cost efficiency of a modular SAPV system, comprising of three PV modules, a battery and a load can be improve replacing four DC/DC converters by a single QIDO, which results in a 56.25% reduction in the components required.