Gridcog for data centres

Large UK data centres now wait into the 2030s for a grid connection

Britain's demand connection queue grew from 41 GW to 125 GW in seven months, and data centres account for about 73 GW of it. Gridcog models how a battery, on-site generation and a flexible connection change your connection date and your returns, before you commit capital.

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  • 125GW

    Contracted demand in the GB connection queue by June 2025, up from 41 GW

  • 73GW

    Data centre demand in that queue, across about 315 projects

  • 2037+

    Connection dates offered to some data centre developers

  • £47m

    NPV lost when a 100 MW data centre connects three years late

Sources: Ofgem, Proposed data centre connection reforms, July 2026; Bryan Cave Leighton Paisner, June 2026; Ofgem 100 MW case study, NPV at 31 December 2026.

Why the queue is so long

Demand applications tripled in seven months

Contracted demand in the GB connection queue rose from 41 GW in November 2024 to 125 GW in June 2025. Almost all of the growth was at transmission level, which went from 17 GW to 97 GW.

Ofgem counts about 73 GW of data centres in the queue, more than GB's 45 GW peak demand. At its assumed £9.5m per MW, that implies £693bn of investment, about 23% of UK GDP, so much of it will never be built.

Britain's demand connection queuetripled to 125 GW in seven monthsContracted demand in the GB connections queue, GWContracted demand (GW)Notes: June 2025 segments sum to 126 GW because of rounding.GB peak demand was 45 GW on 11 February 2026.Sources: Ofgem, Proposed data centre connection reforms, July 2026Transmission-connected demandDistribution-connected demand0306090120150November 2024June 2025November 2024 (transmission-connected): 17 GWJune 2025 (transmission-connected): 97 GWNovember 2024 (distribution-connected): 24 GWJune 2025 (distribution-connected): 29 GW17972429GB peak demand, 45 GW
A three-year delay costs a 100 MW datacentre £47m, over twice the top feeNPV lost against a 2029 connection with no fee, £mNPV lost (£m)Notes: Ofgem's 100 MW case study, NPV at 31 December 2026.Sources: Gridcog analysis of Ofgem, Proposed data centre connection reforms,July 2026Commitment feeConnection delay, no fee£0£20m£40m£60m£80m£100m2.5% fee7.5% feeThree-yeardelay (2032)Six-yeardelay (2035)2.5% commitment fee: £5m of NPV lost7.5% commitment fee: £18m of NPV lostThree-year delay (2032): £47m of NPV lostSix-year delay (2035): £83m of NPV lost£5m£18m£47m£83m

What a delay costs

A three-year delay costs more than the top fee

In Ofgem's case study of a 100 MW data centre, connecting in 2032 rather than 2029 cuts net present value (NPV) from £210m to £163m. The highest proposed commitment fee takes £18m off the same project.

Large transmission-connected sites applying now face dates in the 2030s, and some developers have been offered 2037 or later. Even after energisation, NESO puts the average ramp to full demand at about seven years.

What's changing

The rules that now set your connection date

NESO connections reform

Readiness sets your place in the queue

Since Ofgem approved the reform package (TMO4+) on 15 April 2025, a firm offer needs a project to be ready and needed. Data centres are deemed needed, so secured land rights or a Development Consent Order application decide it.

Ofgem proposal

A commitment fee of up to £712,500 per MW

Proposed for data centres of 40 MW and above: £237,500 to £712,500 per MW, refunded at energisation and forfeited on an early exit. Ofgem consulted until 16 September 2026 and expects to decide later in 2026.

AI Growth Zones

Five zones with priority for capacity

Oxfordshire, North East England, North Wales, South Wales and Scotland. Zones get priority network capacity, a Connections Accelerator service and, from April 2027 subject to legislation, a possible electricity price discount.

The proposed 40 MW threshold covers 99% of the data centre capacity in the queue, because most of it sits in projects of 100 MW and above.
Projects of 100 MW and abovehold 93% of the data centre queueData centre demand in the GB queue by project size, GWContracted demand (GW)Notes: About 315 projects; number of projects in brackets. Values rounded.Sources: Ofgem, Proposed data centre connection reforms, July 2026, Table 1Projects under 100 MWProjects of 100 MW and above0102030400–10 MW(11)10–50 MW(47)50–100 MW(51)100–500 MW(166)500 MW +(40)0–10 MW (11 projects): 0.08 GW10–50 MW (47 projects): 1.4 GW50–100 MW (51 projects): 3.5 GW100–500 MW (166 projects): 37 GW500 MW and above (40 projects): 31 GW0.081.43.53731

Ways to connect sooner

Four ways to get power sooner

Each one trades years in the queue against capital cost, curtailment or running cost, and the right mix depends on the site.

Connection

Non-firm or phased connection

Connect earlier and accept curtailment until the network is reinforced, or ramp your import in stages. Ofgem is developing both under its Connect workstream.

Flexible connections

Storage

Co-located battery

Covers the gap between your import limit and peak load, and earns wholesale and balancing revenue the rest of the time. Developers say AI inference peaks can cut battery life from eight years to five.

Battery modelling

Generation

On-site generation

Gas engines or fuel cells as baseload or backup. New gas demand connections typically take six to 24 months, against electricity dates that can run past 2037.

SOFC or gas genset?

Load

Flexible workloads

AI training and high-performance computing can shift in time more easily than services that run around the clock, which makes curtailment easier to live with.

Flexible loads

Test it before you commit

Model your data centre's route to power

Put the grid connection, a battery, on-site generation and the data centre's own loads in one model, behind one meter. Gridcog simulates how they run together, interval by interval, so your team can compare options side by side with every assumption visible.

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UK data centre grid connections, answered

Figures from Ofgem and NESO cover Great Britain and are current at 2 November 2026. Northern Ireland has a separate system, run by SONI and NIE Networks.

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Large transmission-connected data centres applying now can expect connection dates in the 2030s, and some have been offered 2037 or later. Distribution-connected sites are often quicker: National Grid DSO models its accepted pipeline connecting by 2032 at the latest.

The demand queue tripled from 41 GW to 125 GW between November 2024 and June 2025, mostly because of data centre applications. Ofgem counts about 73 GW of data centres in the queue, more than GB's 45 GW peak demand, and much of it is speculative.

NESO's reform, approved by Ofgem on 15 April 2025, reorders the queue so that projects which are ready and needed get firm offers first. Data centres are deemed needed, so they have to show readiness: secured land rights or a Development Consent Order application.

A proposed refundable fee of £237,500 to £712,500 per MW for data centre projects of 40 MW and above. It is paid on accepting a connection offer and forfeited if the project leaves the queue early. Ofgem expects to decide later in 2026.

A government-designated site for large AI data centres, expected to support at least 500 MW. Zones get priority for network capacity, a Connections Accelerator service and, from April 2027 subject to legislation, a possible electricity price discount.

The average UK data centre in 2025 was about 12 MW, NESO says, but projects in the connection queue range from 1 MW to 1,500 MW. NESO forecasts that UK data centres will use just over 20 TWh a year by 2030.

Often, yes. A non-firm or phased connection can come years earlier if the site can handle curtailment. A co-located battery, on-site gas generation or flexible workloads can cover the gap until the network is reinforced.

Sources

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The team behind Gridcog

Fabian Le Gay Brereton, Chief Executive Officer and Co-Founder of Gridcog

Fabian Le Gay Brereton

Chief Executive Officer & Co-Founder

Previously co-founded Greensense, acquired by ERM Power (now Shell Energy).

Pete Tickler, Chief Product Officer and Co-Founder of Gridcog

Pete Tickler

Chief Product Officer & Co-Founder

Co-founded Greensense and led digital innovation at ERM Power (now Shell Energy).

Genna Boyle, Chief Commercial Officer and Head of EMEA at Gridcog

Genna Boyle

Chief Commercial Officer & Head of EMEA

More than 10 years in energy strategy, trading and renewables, with senior roles at Battery Optimiser and Limejump.