gb_ssen_ltds_heatmap

SSEN Distribution LTDS Capacity Heatmap

Published by SSEN Distribution · GB · Twice a year

Grantedcommercial_use_with_attributionHealthy

Demand, generation and reverse-power-flow headroom (MVA) at SSEN's GSPs, BSPs and primary substations in central southern England (SEPD) and the north of Scotland (SHEPD), with firm capacity, connected and contracted demand, generation and storage, constraints and past-year connection activity, in the Ofgem LTDS Capacity Heatmap format.

What is withheld, and why

Nothing is withheld. Values are served with the attribution the licence asks for: SSEN Distribution; SEPD and SHEPD Long Term Development Statement Capacity Heatmap; https://data.ssen.co.uk/@ssen-distribution/sepd_long_term_development_statement, https://data.ssen.co.uk/@ssen-distribution/shepd_long_term_development_statement; CC BY 4.0. Keep it with any figure you show.

SSEN's attribution format is "Publisher; Data Asset Title; Data Asset Identifier; Date": serve the date from freshness.source_effective_at. The SSEN Distribution logo may not be used.

Licence and rights evidence

Licence: CC BY 4.0 (opens the operator’s site)
Attribution: SSEN Distribution; SEPD and SHEPD Long Term Development Statement Capacity Heatmap; https://data.ssen.co.uk/@ssen-distribution/sepd_long_term_development_statement, https://data.ssen.co.uk/@ssen-distribution/shepd_long_term_development_statement; CC BY 4.0required
Technical access: Yes
Commercial use: Yes
May be cached: Yes
May be redistributed: Yes
Derived data allowed: Yes

Evidence

"license_title": "Creative Commons Attribution 4.0"data-api.ssen.co.uk/api/3/action/package_show?id=sepd_long_term_devel… (opens the operator’s site) · read 25 Sep 2026
SSEN Distribution uses the Creative Common’s Attribution 4.0 International Licence for the publishing of it’s open data.data.ssen.co.uk/terms-and-conditions (opens the operator’s site) · read 25 Sep 2026
Publisher; Data Asset Title; Data Asset Identifier; Datedata.ssen.co.uk/terms-and-conditions (opens the operator’s site) · read 25 Sep 2026

Methodology

2 version(s)

SSEN LTDS Capacity Heatmap

gb_ssen_ltds_heatmap_2026 · v2026-05 (LTDS May 2026)

SSEN's implementation of the Ofgem LTDS Capacity Heatmap: firm, available and reverse-power-flow capacity per substation in MVA, with aggregate connected and contracted demand, generation and storage per substation. SSEN publishes no method statement beyond the standard's definition (available capacity calculated from firm capacity, demand, connected, contracted and quoted capacity and other constraints), so firmness of the headroom and what it nets off are not stated.

Capacity basis: operator calculated
Network state: unknown
Binding: No
Additive across assets: No — do not sum these figures
The method accounts for: reserved: not stated · allocated: not stated · pre-reserved: not stated · pending requests: not stated
Comparability class: gb_ssen_ltds_heatmap
Documentation: Operator’s method (opens the operator’s site)

The operator’s own caveats

"You should make your own checks and considerations before relying on the use of this information and data." (SSEN Distribution Data Portal terms)

SSEN past connection activity (LTDS Capacity Heatmap)

gb_ssen_ltds_heatmap_activity_2026 · v2026-05

Number and total MVA of budget estimates provided, connection offers made and connection offers accepted per substation and proposed connection voltage, 1 April 2025 to 31 March 2026 (periodStart / periodEnd in the file). A flow over a period, not capacity available now: budget estimates and offers made are `requested`, accepted offers `contracted`, each under its own variant.

Capacity basis: operator published
Network state: unknown
Binding: No
Additive across assets: No — do not sum these figures
The method accounts for: reserved: not stated · allocated: not stated · pre-reserved: not stated · pending requests: not stated
Comparability class: gb_ssen_connection_activity
Documentation: Operator’s method (opens the operator’s site)

How the publication maps to the model

availability types: ["available","total","connected","contracted","requested"]
binding: false
directions: ["offtake","injection"]
firmness: ["firm","unknown"]
geometry precision: exact
includes reserved projects: null
non additive: true
notes: ["GSP, BSP and primary substations are all records (SEPD 21 / 80 / 445; SHEPD 75 GSP / 360 primary — Scotland has no BSPs). Each BSP and primary is linked to the GSP or BSP it names (parent_source_asset_id). The GSP ⊃ BSP ⊃ primary hierarchy shares upstream capacity: never add values across levels.","Every GSP, and one SEPD BSP (Acton Lane), publishes null firm, available and reverse-power-flow capacity. The standard requires them, so each such substation counts as one rejected row (97 today); its connected/contracted children and connection activity are still served.","Demand / Generator / Storage children are one aggregate per substation (`aggregate: true`) with connected and contracted MVA; they are their own records (the child mRID, `<substation>_Demand` etc.) and subsets of the substation, never to be added to it. Storage appears once per direction; SSEN does not say which storage technology, so it is `storage_other`, not battery.","Amersham (GSP) and Loudwater (BSP) publish negative contracted generation (−38.95 MVA each): kept as published and flagged `negative`.","SEPD lists Ratfyn (_3a2e53d9-…) twice, identically: used once, the copy counted as rejected. Woodhill (SHEPD) has null connected generation and storage: those child records are rejected.","Available generation exceeds generation firm capacity at 49 SEPD and 42 SHEPD sites, and available demand exceeds demand firm capacity at 69 SHEPD sites, so SSEN's headroom is not read as firm.","RAG status and limiting factors are published as free text (\"Upstream Thermal Capacity & Upstream Fault Level Constraint\"), kept verbatim in details and attributes; `demandConstraintLimitingFactor` is null wherever demand is Green. `Constraint` entries (type Other, e.g. \"This substation is fed from a single transformer\") are attributes.","Connection activity has explicit periods (periodStart / periodEnd, 2025-04-01 to 2026-03-31), carried in details; SSEN writes every figure, zeros included.","mRIDs are CIM rdf:IDs (`_<uuid>`), offered as identifier `gb_ltds_cim_mrid` for matching with other CIM-based publications."]
spatial scope: substation
technologies: ["generic_load","generic_generation","storage_other"]
units: ["MVA","count"]

Query this source

$ curl "https://api.gridcapacityapi.com/v1/capacity/search?source=gb_ssen_ltds_heatmap&limit=20" \  -H "Authorization: Bearer gc_live_..."