SSEN Transmission has delivered nearly £300 million in savings for energy consumers, a figure officially confirmed by the National Energy System Operator (NESO). The substantial saving is a direct result of the company's efforts under the System Operator: Transmission Owner (SO:TO) Optimisation incentive, which promotes innovative measures to lower constraint costs while ensuring a secure, reliable network.

Constraint costs arise when the electricity grid lacks the capacity to transport all available power. Consequently, some generation—frequently renewable energy like wind—must be curtailed or turned off. This happens when electricity generation exceeds grid capacity, or during planned outages for crucial maintenance and upgrade works, with the resulting expenses ultimately passed on to consumer bills.

Expanding grid investment is vital to resolving this issue by eliminating bottlenecks and generating capacity for increased clean power. Boosting network capacity ensures a greater flow of renewable energy from generation sites to areas of high demand, reducing the necessity for generators to dial down output and helping eliminate long-term constraint costs. By executing targeted engineering solutions, SSEN Transmission is lowering current constraint requirements while simultaneously investing in infrastructure upgrades to reduce them down the line.

A recent example of this strategy is at Fetteresso substation in Aberdeenshire, where temporary bypass infrastructure has been deployed to facilitate a major upgrade of the facility and its connecting overhead power lines. The Fetteresso 400kV upgrade project involves raising the operating level of the existing substation from 275kV to 400kV, which increases overall network capacity to transport more renewable electricity. Building works are currently restricted to the existing site boundary.

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Preserving network capacity during these upgrades is critical to preventing elevated constraint costs. Left unmanaged, extended outages on principal transmission circuits would restrict electricity movement across the grid, leading to higher volumes of constrained generation. To counter this, engineers installed temporary bypasses that keep key 275kV circuits between Kintore, Fetteresso, and Alyth fully operational while the upgrade works progress. This methodology minimises disruption and averts substantial generation constraint expenses.

David McKay, Network Director at SSEN Transmission, said: "Reducing constraint costs is an important part of delivering a fair and efficient electricity system for consumers. The National Energy System Operator estimates that our interventions have delivered almost £300m of savings for consumers in the last financial year. This reflects the practical steps we are taking, in collaboration with NESO, to manage the network more efficiently whilst building the infrastructure necessary for the future.

"By working closely with NESO and taking an innovative approach to how we plan and deliver network upgrades, we are reducing constraint costs today while helping to unlock more clean power over time. Through continued investment in the network, we are removing bottlenecks, enabling more low-carbon generation to connect, and supporting energy security, reliability and affordability for consumers.

"The work at Fetteresso is one example of how the SO:TO Optimisation incentive supports collaboration between transmission owners and NESO, enabling changes that deliver clear benefits to consumers while protecting value through strict regulatory oversight. As further solutions are identified and delivered, additional savings for consumers are expected in future years."

SSEN Transmission is currently moving forward with its £29 billion investment strategy to deliver new and upgraded infrastructure across the north of Scotland. Through rapid, large-scale grid expansion, the development programme aims to boost capacity, ease transmission constraints, and unlock homegrown renewable energy, thereby lowering dependency on volatile international fuel markets and reinforcing energy security across Great Britain.