Optimal design of a PV-diesel hybrid system for electrification of an isolated island—Sandwip in Bangladesh using genetic algorithm

Abstract

It is not cost effective or feasible to extend a centralized power grid to islands and other isolated communities. Decentralized renewable energy sources are alternatives. Among these alternatives are hybrid photovoltaic systems which combine solar photovoltaic energy with other renewable energy sources like wind. A diesel backup system can be used when PV system fails to satisfy the load and when the battery storage is depleted. If the hybrid systems are optimized, these would be cost effective and more reliable. This paper presents an optimal design of a solar PV-diesel hybrid mini-grid system for a fishing community in an isolated island—Sandwip in Bangladesh. The electrical load is considered based on the local needs and the electrical load demand is 15 kWh. This load is based on 2 lights (compact florescent bulb, 230 V, 15 W), 1 fan (ceiling fan, 230 V, 40 W) and 1 television (TV, 230 V, 80 W) for each family of the rural settings of the island. The system is optimized using genetic algorithms. If the renewable energy source produces more than the one required by the loads, the excess energy can be used to charge the battery while if the amount of energy demand is higher than the one produced by the renewable energy source, the control strategy determines the most economical way to meet the energy deficit. The optimized system configurations are: 4s × 12p 50 W PV panels, 4s × 3p 200 Ah batteries, 230 V 1.9 kVA ac generator and 3300 VA inverter. The system supplies 48 V dc and 230 V ac. The major share of the energy (23,077 kWh) comes from solar while the contribution of diesel generation is very small (35 kWh).This study reveals that the major shares of the cost are for solar panels and batteries. Technological development in solar photovoltaic technology and economic production of batteries would make rural electrification in the isolated islands more promising and demanding. Finally, the sustainability of solar-diesel hybrid mini-grid for an isolated island—Sandwip is discussed.