The average energy capacity cost of utility-scale battery storage in the United States has rapidly decreased from $2,152 per kilowatthour (kWh) in 2015 to $625/kWh in 2018. Battery storage systems store electricity produced by generators or pulled directly from the electric power grid and redistribute the power later as needed. At the end of 2018, the United States had 869 megawatts (MW) of installed battery power capacity (the maximum amount of power a battery can provide at a given moment) and 1,236 megawatthours (MWh) of battery energy capacity (the total amount of energy that can be stored by a battery).