A Dual-Battery Storage Bank Configuration for Isolated Microgrids Based on Renewable Sources

In isolated microgrids, storage systems play a crucial role in maintaining the instantaneous power balance between generation and consumption. Lead-acid batteries are now widely used as storage elements in such systems, and their useful life depends heavily on the operation strategy. This is a serious problem that up to now has limited the sustainability of this type of systems. This article proposes a new philosophy of battery storage energy management for isolated systems based on photovoltaic energy. A dual-battery bank is proposed: the first one is responsible for storing energy when renewable sources are available to meet the load demand. The second bank has smaller size and is calculated to meet the needs of daily snapshot balancing and network voltage regulation. The proposed configuration significantly increases the life of the largest bank, reducing the operating and maintenance costs of isolated systems by more than 19%. Results are reported using data from an isolated microgrid based on photovoltaic solar energy located in Humberto de Campos, Maranhão, Brazil.