Data Centres in London: Capacity, Clusters and Grid Limits
How many there are, where the clusters sit, why the grid queue is 7 to 13 years, and what a rooftop array can and cannot do.
London had 99 operational data centres and 26 in the planning pipeline in November 2025, about 1 GW of operational capacity, according to an evidence report that Buro Happold wrote for the Greater London Authority in December 2025. Clusters sit on the Isle of Dogs, at Park Royal and at Hayes, and growth is spreading to Hillingdon and Barking and Dagenham. New grid connections for data centres in London may take 7 to 13 years.
How many data centres are there in London?
The GLA report counts 99 operational sites and 26 in the planning pipeline as of November 2025, mostly north of the Thames, with roughly 1 GW operational in 2025. Grid connection requests point to growth of up to tenfold by 2050 if every request were built, which the report treats as a ceiling rather than a forecast. These are not the same numbers as commercial trackers, which draw the "London" market much wider: DC Byte's 1,478 MW figure covers most of southern England. See data centres in Slough for that wider market.
Where are London's data centre clusters?
| Cluster | Boroughs | What the report says |
|---|---|---|
| Isle of Dogs / Docklands | Tower Hamlets (Newham emerging) | Established financial-sector cluster, facilities above 10 MW; key for latency-sensitive workloads such as trading |
| Park Royal / A40 / Heathrow corridor | Brent, Ealing, Hillingdon | About 26 of the 33 hectares (78%) of mapped data centre land in London; Hillingdon alone holds 16 hectares, the most of any borough |
| Hayes | Hillingdon | Campus-style developments close to National Grid and SSEN substations |
| Outer boroughs | Enfield, Barking and Dagenham | Emerging growth as land scarcity pushes development outwards |
The same source says remaining developable plots in the West London corridor are over 90% occupied and land values run 20% to 30% above comparable east and south-east boroughs, because data centres compete with logistics for sites.
The grid is the limit
- Timelines: new data centre connections in London may take 7 to 13 years, against 3 to 7 years in other European markets.
- Queue growth: UKPN's updated data shows requested capacity in Enfield rising by 450 MW between August 2025 and April 2026, with further increases in Brent (+190 MW), Newham (+150 MW) and Tower Hamlets (+110 MW).
- Reform: Ofgem's connections reform shifts the queue from "first come, first served" to "first ready and needed, first connected", favouring projects that meet readiness and national-need tests.
- Designation: the UK Government designated data centres Critical National Infrastructure in 2024, which the report says directs local plans to allocate sites and speeds large approvals.
The distribution networks are UKPN across most of London and SSEN in the west, with National Grid Electricity Transmission above them. More on how the queue interacts with on-site generation is in West London's data centre grid constraint and on-site solar.
London Plan expectations that affect a roof
For new data centre projects above 1 hectare, Buro Happold summarises the London Plan and Environment Act expectations as: at least 10% biodiversity net gain, 50% green or brown roof coverage, 30% permeable surfacing, and a waste-heat target of 25% reuse by 2030 for district heating. Roof area is therefore contested between green roofs, plant and solar. Projects that need both usually combine planted roof layers with raised arrays or put panels on the plant-free portion; this is a design question to settle at planning stage, not after.
What London means for on-site solar
Modelled rooftop yield at Docklands is 929 kWh per kWp a year for a flat roof tilted 10 degrees facing south with 14% losses (PVGIS 5.2 (EU Joint Research Centre)), essentially the same as Slough (928). Roof area is the limit: a 1 MWp array produces about 929 MWh a year, around 2% of the energy a hall averaging 5 MW uses (illustrative arithmetic). Solar cuts imported electricity and carbon at the margin and, with a flat load, almost all of it is self-consumed, but it does not shorten a connection queue.
Where it helps is reducing the new capacity a site must ask for and giving customers on-site, metered, time-matched renewable evidence for Scope 2 reporting. Practical steps are in data centre solar PV systems, G99 for data centres and the London solar guide at solar panels for data centres in London. For all UK clusters see the UK data centre map.
Frequently asked questions
How many data centres are there in London?
A December 2025 report by Buro Happold for the Greater London Authority counts 99 operational data centre sites and 26 in the planning pipeline as of November 2025, with roughly 1 GW of operational capacity. Commercial trackers draw the London market wider, so their totals are higher.
Where are London's main data centre clusters?
The established clusters are the Isle of Dogs in Tower Hamlets, Park Royal and Hayes in west London, with emerging activity in Hillingdon and Barking and Dagenham. The Park Royal, A40 and Heathrow corridor holds about 78% of mapped data centre land, and Hillingdon alone 16 hectares.
How long does a data centre grid connection take in London?
The GLA's consultants report that new connection timelines for data centres in London may range from 7 to 13 years, against 3 to 7 years in other European markets, with West London the tightest.
Does the London Plan require green roofs on data centres?
Buro Happold summarises the expectations for new data centre projects above 1 hectare as at least 10% biodiversity net gain, 50% green or brown roof coverage and 30% permeable surfacing. Check the current London Plan policy and your borough's requirements; the requirement competes with rooftop solar for roof area.
How much does solar produce on a London data centre roof?
PVGIS 5.2 models 929 kWh per kWp a year for a south-facing flat roof tilted 10 degrees with 14% losses at the Docklands. A 1 MWp array would cover roughly 2% of the energy used by a hall that averages 5 MW.
Pricing solar for a London data centre?
Four short steps. Your details go to installers who work on critical-power sites; they quote, you compare, no obligation. This site is a publisher, not an installer.