BESS (battery energy storage system)
Grid-scale battery storage — an asset that buys, stores and resells electricity, and provides flexibility services to the system.
A battery energy storage system charges when power is cheap or abundant and discharges when it is scarce or expensive. GB grid-scale batteries are characterised by their power rating (MW) and duration (how long they can sustain full output), with fleet durations lengthening as the market matures.
BESS revenues are inherently stacked: frequency response services, wholesale arbitrage, Balancing Mechanism actions and Capacity Market agreements each contribute, with the optimal mix shifting as individual markets saturate.
Because merchant battery revenue is volatile, contract structures — tolling agreements, revenue floors, optimisation agreements with revenue share — have developed to allocate risk between asset owners and the traders or optimisers operating them.
Structuring against this in a live deal?
ETC prices and executes PPAs across GB — founder-led, from indicative quote to signed contract.