More than stored electricity: Scotland’s grid-forming battery example

On 11 March 2025, Britain’s National Energy System Operator, NESO, announced the first live Stability Phase 2 Pathfinder projects, including the country’s first grid-forming battery. The complete programme included five such batteries and five synchronous condensers.

Approximately GBP 500 million in savings was projected across the programme’s ten-year contracts. This is an expected programme-wide benefit, not one battery’s revenue or money already saved. It gives a sense of the procurement’s significance, but does not establish the investment return earned by an individual asset owner.

Grid-forming describes specialised inverter control. It helps support grid voltage and frequency and provides stability characteristics traditionally associated with synchronous generators. NESO’s explanation highlights a direct response to sudden frequency changes and synthetic inertia: resistance to that change created through control behaviour.

That is a different task from deciding which hour is best for buying electricity. One question concerns the system’s behaviour during a disturbance; the other concerns using stored energy over time. The word battery can appear in both discussions, but describing the service requires more than a general equipment label. The intended function needs to be specified.

NESO’s stability service description explains short circuit level as the current flowing during a fault. This property is central to the programme’s task in Scotland. As connected equipment changes, the operator seeks new providers of these characteristics. Synchronous condensers support stability without generating active electricity in the manner of a conventional power station.

The programme’s varied composition helps explain why stored megawatt-hours alone are not the right comparison. When a stability characteristic is being purchased, the relevant question is the ability to supply it. A buyer can choose different technical approaches to the same problem. Defining the task this way explains why batteries and quite different-looking equipment can appear in the same service portfolio.

In its April 2026 Summer Outlook, NESO reported seven Phase 2 units already operating. At that point it expected the remaining Phase 2 projects to be operational by year-end. This updates the programme’s progress; it does not confirm that the entire contracted portfolio, or all projected benefits, had already been delivered.

For someone considering battery ownership, the case suggests a specific question: does the proposal identify the control function, how it will be verified and the service it is intended to provide? We do not automatically assign these capabilities to the battery selected for the Silver BESS park under development; they require confirmation in its equipment specification. Scotland’s experience is useful because it shows clearly that an electricity system can purchase more than a quantity of energy.