12 May 2025

Ofgem has today made its decision on another important aspect of the ongoing transmission connection reform programme in Great Britain.

What's changing now?

The change in approach applies to electricity generation projects seeking a connection to an electricity distribution network in England and Wales. Previously, any generation project with a capacity of 1 MW or more needed to be referred for a transmission impact assessment.

That threshold is now being increased to 5 MW - although a fault-level exception still applies, as outlined in our article below.

Background to the connection reform programme

The programme of reform has dominated the GB power sector for the past 2 years. The package of reforms is designed to speed up grid connections. The general principle of the reforms is to move away from an approach of ' first come, first served' towards an approach of 'first ready and needed, first connected' - prioritising connections based on their readiness and on strategic alignment.

Ofgem made its decision on the main package of reforms last month.

The current change in more detail

The change in approach applies to electricity generation projects seeking a connection to an electricity distribution network in England and Wales.

The change does not affect electricity demand sites, or generators seeking a connection in Scotland.

For electricity generation projects seeking a connection to a distribution network in Great Britain, each distributor must generally refer the connection to the National Energy System Operator (NESO) to review the impact which the project will have on the transmission network - a transmission impact assessment (TIA).

However, this process does not apply to projects which are sufficiently small not to be considered relevant. The threshold for England & Wales has been increased to 5 MW. The threshold remains 200 kW in mainland Scotland and 50 kW for the Scottish islands.

The 5 MW threshold for England & Wales applies to export capacity. It is, however, subject to a caveat linked to the fault level headroom within the distributor's Grid Supply Point.

What's next for the grid connection reform programme?

NESO has indicated that it will conduct a further review of the TIA thresholds in Scotland.

Meanwhile, the broader connection reform programme continues to evolve, aiming to create a more efficient and strategically aligned electricity grid across Great Britain.

For further information on the connection reform programme, contact Gus Wood, James Stanier or George Nixon from our Energy team.