Optimal Battery Size for Grid Connected Rooftop Solar Photovoltaic Systems in South Australia

Recent reduction in feed-in-tariff makes the installation of residential rooftop solar photovoltaic system unattractive without having suitable battery energy storage system. This paper describes a technique of determining the optimal size of battery storage for a typical residential home in South Australia with grid connected rooftop solar photovoltaic system. An optimization problem is carefully formulated to determine the optimal size of the battery while minimizing the total life cycle cost of the system. Hourly load data as well hourly solar output data for various ratings of the PV systems are used. The optimal size of battery is also determined for different retail prices of grid electricity. The results obtained are then carefully analyzed and discussed. It has been found that, with current retail price of electricity in South Australia, installation of battery storage is becoming more beneficial and crosses the economic breakeven point.