Battery storage increases flexibility in power systems, enabling an optimal use of variable electricity sources like photovoltaic and wind. Batteries can provide services for system operation, defer investments in peak generation and grid reinforcement. Utility-scale battery storage systems have a typical storage capacity ranging from few to hundreds of MWh. Different battery storage technologies, such as lithium-ion (Li-ion), sodium sulphur and lead acid batteries, can be used for grid applications.

For system operators, battery storage systems can provide grid services such as frequency response, regulation reserves and ramp rate control. It can also defer investments in peak generation and grid reinforcements. Utility-scale battery storage systems can enable greater penetration of variable renewable energy into the grid by storing the excess generation and by firming the renewable energy output.