Ofgem proposes to widen transmission self-build beyond 2km

Ofgem is considering removing the 2km restriction that currently prevents most transmission customers from building their own connection infrastructure.

Self-build is already possible at transmission level, but only in limited circumstances. Ofgem says the existing arrangements largely restrict it to projects within 2km of the transmission system where the assets are not potentially shareable. That means the majority of connecting customers cannot currently take that route.

Now, under a new consultation, demand, generation and storage projects could build all of the dedicated, or ‘sole-use’, assets between their connection point and the existing transmission network before transferring them to the relevant Transmission Owner.

That could include the overhead line or project substation needed to connect a development to the grid.

For projects where the dedicated connection itself is holding up delivery, that could give developers considerably more control. They could appoint their own contractors and take responsibility for designing, consenting and constructing the connection assets, rather than relying on the Transmission Owner to deliver all of that work.

Of course, the Transmission Owner will still have some say over what gets built. It would still determine where the project connects to the existing network, set its technical standards and assess whether the completed assets meet the requirements for adoption.

According to Ofgem, there are already 36 demand projects in the connections queue that have expressed interest in self-build – meaning it could prove a popular route for developers if ultimately given the go-ahead.

It’s easy to see why it would be popular too. Stakeholders have told the regulator that self-build could cut costs by around 20% and shorten delivery by one to two years where reinforcement is not required.

Self-build cannot remove every connection delay

Of course, self-build won’t be the magic bullet that solves all connection delays. 

Reinforcement and other enabling work on the existing network would remain outside self-build. That could include upgrades needed before the system has enough capacity to accommodate a new large electricity user, generator or storage project.

For projects waiting on that work, building the final connection more quickly may make little difference.

Ofgem acknowledges that completing self-build assets earlier will not result in an earlier connection date for many projects because the timetable is instead determined by enabling or wider work elsewhere on the network.

The greatest benefit is therefore likely to be for projects where the dedicated connection assets are themselves the constraint, or where enough capacity is available to support a phased or ramped connection before all wider network work is finished.

That limitation was already apparent when the Government set out its Great British Grid plans, which included making it easier for businesses to build their own high-voltage connections. The Ofgem consultation now sets out how a wider self-build regime could operate in practice.

More control also means more delivery risk

For the developers who can take advantage, there is one thing that should give them pause. While it could speed up the connection – it also means taking on more responsibility. 

They would be responsible for securing the necessary permissions and consents, managing construction and meeting the Transmission Owner's requirements. If construction costs exceed the agreed price, the customer would bear the additional cost, while money already spent could also be lost if its connection agreement is terminated.

Ofgem is also proposing a five-year defect notification period covering problems arising from the self-build work after the assets have been transferred.

Transmission Owners would be required to publish their technical standards and produce standard adoption agreements, giving customers more visibility of the requirements before committing to construction.

Customers would therefore gain more control over contractors, costs and construction programmes, but they would also take on more of the risk involved in delivering the connection.

The consultation closes on November 13, 2026, and Ofgem expects to publish a decision or policy statement in Q1 2027.