The average cost of utility-scale battery storage in the US decreased by nearly 70% in the US between 2015 and 2018.

That’s according to the US Energy Information Administration (EIA), which found the average energy capacity cost rapidly decreased from $2,152 (£1,650)/kWh in 2015 to $625 (£479)/kWh three years later.

At the regional level, the 2013 to 2018 average utility-scale battery costs ranged from $1,946 (£1,492)/kWh in the PJM Interconnection, which manages the electric power grid in 13 eastern and midwestern states and the District of Columbia, to as low as $947 (£726)/kWh in Hawaii.

Most of the batteries installed in PJM are used for power applications, such as frequency regulation, which helps maintain the grid’s electric frequency on a second-to-second basis.

PJM prioritises power capabilities that use shorter durations over energy use cases that store large amounts of energy over time – the EIA says for this reason, the power capacity installed cost is a better indicator of price for value in PJM.

The US had 869MW of installed battery power capacity – the maximum amount of power a battery can provide at a given moment – and 1,236MWh of battery energy capacity – the total amount of energy that can be stored by a battery – at the end of 2018.

Around 152MW of battery storage capacity was installed in 2019 and 301MW in 2020 through to July.