TSO (Transmission System Operator)
The entity responsible for operating the high-voltage electricity transmission network. TSOs maintain grid stability, procure frequency regulation and ancillary services from BESS plants, and define the grid code requirements all connected assets must meet. Examples: National Grid ESO (UK), Svenska kraftnät (Sweden), Fingrid (Finland).
In energy storage
The TSO is the primary counterparty for a transmission-connected BESS — issuing the grid connection offer, defining the grid code requirements, and procuring the ancillary services (FCR, aFRR, mFRR) that form a large share of BESS revenue. Pre-qualification testing with the TSO is required before the plant can participate in each ancillary service market.
Also available in: Svenska