Reliable power supply is a necessary requirement for remote telecommunication systems, generally utilizing DC microgrid setup. Standard operating assets consist of diesel generator, battery energy storage systems (BESS), and photovoltaic (PV) array. Owing to the replenishable BESS storage, a mode switching is required to charge and discharge the battery units. In this paper, a control algorithm is presented which combines the standard operation with a bumpless transfer control strategy for the BESS controller, by a suitable modification of the proportional-integrator (PI) cascaded control used. The proposed control method is verified using simulations and provides a negligible variation in the voltage and power profile of the system.