Battery-buffered Fast-charging systems (BBFCSs) enable high-power Electric Vehicle (EV) charging at sites where the grid

connection alone cannot supply the required power, by buffering energy in a local battery energy storage system (BESS) and,

where available, in local renewable generation. Interest in such systems is growing, but the methodologies used to evaluate them

remain fragmented, which makes it difficult to compare control strategies or pricing schemes across installations.

This paper presents the Danish BBFCS demonstration developed within the European project AHEAD, combining a 150 kW

fast charging station, a 325 kWh BESS, and local renewable generation behind a grid connection limited to 43 kW. On this basis,

it proposes a framework of Key performance indicators (KPIs) that assesses the system from four complementary perspectives:

system level, charging service, battery operation, and economics. Self-consumption and self-sufficiency indicators are adapted to

the BBFCS case, and energy allocation indicators are introduced to quantify the contribution of renewable generation, storage,

and grid supply to the charging service.