What is NESO’s Transmission Entry Capacity (TEC)?

What is NESO’s Transmission Entry Capacity (TEC)?

Your energy asset will connect to the National Electricity Transmission System (NETS), where the Transmission Entry Capacity (TEC) determines its contribution. We explore TEC and NESO's crucial role in its management.

Your asset will output into what’s known as the National Electricity Transmission System (NETS). We take a look at the Transmission Entry Capacity (TEC) as well as NESO’s role in management.

Understanding Transmission Entry Capacity (TEC)

The TEC is the amount of energy a generator’s asset will output into the NETS. The maximum output is set by the Connection Entry Capacity (CEC). The CEC of a project tends to be set higher than the TEC, as this allows for a project to mature and grow without changing the infrastructure it connects to.

TEC is crucial in energy transmission as it helps accelerate the scale and pace of generation and connection to a high-voltage network of the future.

What is NESO's role in TEC management?

Created in 2023 as part of the UK’s 2023 Energy Act, the impartial energy planner NESO is crucial in ensuring Great Britain has an energy source that matches consumer demand.

Who is NESO (National Electricity System Operator)? 

NESO, previously known as Electricity System Operator (ESO), helps to balance the demand for and supply of electricity. It advised the British government on the Clean Energy 2030 plan and made its data on Great Britain’s power mix - including renewable sources - available to the public. It also leads the Transmission Entry Capacity (TEC) Register, a list of contract-holding projects for TEC.  

NESO's Responsibilities in Managing TEC

A big part of NESO’s responsibility is managing the TEC Register, which helps connect new-generation projects to the national grid. It’s responsible for both current projects and projects that will be connected to the grid in the future. NESO manages:

• National Electricity Transmission System (NETS)-connected projects, which are directly connected.

• Bilateral Embedded Generator Agreement (BEGA)-connected projects, which are distributor-connected.

How does transmission entry capacity impact energy systems?

The TEC’s influence on electricity generation and distribution is significant. It is an influential force on Britain’s energy supply as it allows the true balance of generation and demand and allows renewable energy to become a real part of the energy offering. We take a look at the effect TEC has on Britain’s energy supply: 

1.Transmission entry capacity enables localised renewable energy sources

Renewable energy tends to be localised—for example, wind power is generated in specific locations with high wind availability. TEC allows these localised sources to connect to the national grid, making them a realistic alternative to fossil fuels.

2. TEC Delivers energy to remote areas

In the same way that TEC connects localised energy sources, it also enables more remote areas to be supplied with renewable energy sources.

3. TEC driving the energy transition

The energy transition is moving away from traditional fuel sources like fossil fuels towards renewable sources. TEC is aiding the energy transition by connecting new renewable generation sources to the grid.  

TEC case study - Balance Mechanism Units (BMU) issues in Combined Cycle Gas Turbines (CCGTs) 

Location can be an issue for TEC. Combined Cycle Gas Turbines (CCGTs) are a flexible renewable energy source in Britain, but a constraint boundary between Scotland and England placed pressure on the balancing of energy within the two areas.  

• The SSE-SP boundary separates Northern Scotland from the rest of Britain.

• The CCGT facility in Peterhead, Scotland, has a 1.2GW capacity and competes with renewable wind power when it sends energy into England.

• South Humber CCGT facility has a 0.8GW capacity and is the closest CCGT provider to Peterhead.

On January 26, 2022, the SSE-SP boundary was operating at 99% capacity due to high Scottish wind output. NESO (then ESO) spent £7.5m in constraint costs to balance across the boundary. 

The process for applying for TEC 

The process for applying for connection is a complex one, with various stages that will affect the timescale of a project connection: 

Steps involved in obtaining a TEC allocation 

1. Application - Applications to apply for the TEC are sent to NESO for approval via NGET, who will carry out the required checks.  

2. Connection capacity - A project's connection capacity will be determined via TEC (the actual amount exported) and CEC (which is often set slightly higher to allow for the project's growth). 

3. Connection registers - Connection registers, such as the Interconnector Register and the Transmission Entry Capacity Register will give you an idea of connection time for your project type. Timeline expectations can be requested from National Grid.  

Common challenges and solutions in TEC applications 

A key issue with the TEC queue is that it is currently bloated with a number of ‘phantom projects’, which refer to projects that haven’t yet been approved for connection. This could be due to reasons such as lack of planning approval or lack of land for the projects—currently, one-fifth of the queue is stagnated with these phantom projects. In an effort to help clear this backlog, if these projects miss crucial project milestones, they will be removed from the TEC Register.  

Future of Transmission Entry Capacity and grid development 

Developing trends and innovations in TEC will see design take centre stage in the future, with network design treated separately from the design of the connections process, rather than designing the network specifically to service individual connections.  

Physical connection points will also receive attention, with connection points being built before projects require connection, allowing investment decisions of project owners to take place ahead of time. 

and strengthen their investment decisions. We can also expect to see more flexible connection options, with new types of standardised modular connection points for new projects to be connected to the network. 

To make more room for viable new projects, NESO will implement a ‘connect or move’ model, pushing projects out of the TEC queue that do not meet certain connection milestones on time.  

Transmission Entry Capacity (TEC) plays a crucial role in connecting energy generation to the national grid, supporting Britain's transition to a renewable energy future.