How often does Grid update?

Grid refreshes every hour. Oil and gas prices refresh every 6 hours. Physical gas data is updated hourly. Missing metrics stay null, never zero. The site is not a second-by-second feed.

What is the market index versus the system price?

The headline £/MWh figure is Elexon's Market Index (APXMIDP), the short-term wholesale price. The system price is the imbalance (cash-out) price. Neither is the day-ahead auction.

What do records on Grid mean?

Records are highest or lowest half-hours since Grid's records began, from NESO historic generation mix (2009). They are shown next to NESO's official records and are not claimed as national records on their own.

How should I cite Grid?

Grid (grid.vahaah.com), data from Elexon BMRS and NESO, {date, time BST}. Derived data is CC BY 4.0 with the upstream attributions on this page.

How Grid's numbers are made

Grid compiles half-hourly Great Britain electricity figures from Elexon BMRS, NESO, the Carbon Intensity API and Sheffield Solar PV Live, plus slower oil and gas series from EIA, World Bank and National Gas. Every number carries its source, unit and time. Coverage starts 18 Mar 2025.

Sources

Grid data sources, licences and refresh
Source	Used for	Licence	Refresh
Elexon BMRS / Insights	Market Index (APXMIDP), system (imbalance) price, ITSDO demand, FUELINST generation and interconnectors, WINDFOR, and NDF. Interconnector pages attach the warmed FUELINST series by the exact INT fuel-type code. The map draws a straight schematic line between landing points, not the cable route, and reads the warmed interconnector envelope from Blob. The storage page reads pumped-storage and battery charging and discharge from the warmed FUELINST envelope.	Elexon BMRS Data Licence. Read on 20 Oct 2026.	Hourly
NESO Data Portal	Embedded wind, embedded wind and solar forecasts, and historic generation mix used for Year, All time, and records. Weekly constraint breakdown and weekday day-ahead boundary flows and limits, published to Blob. The transmission entry capacity register, including the Gate column, is fetched twice a week and published to Blob. NESO states that aggregated capacity may duplicate entries. The interconnector register supplies current import and export capacity in MW for the map. A duplicate stage at one connection site is not summed.	NESO Open Data Licence. Read on 20 Oct 2026. The previous licence path returned 404; this URL is the NESO Open Licence v1.0.	Hourly
Carbon Intensity API	National carbon intensity (actual half-hours) and a derived cleanest-window look-ahead.	CC BY 4.0	Hourly
Sheffield Solar PV_Live	National GB solar including estimated embedded / rooftop generation.	Open access. UKERC records that PV Live data may be freely used for any purpose.	Hourly
U.S. Energy Information Administration	Daily Brent, WTI, and Henry Hub prices.	U.S. government work. Public domain; attribution requested.	Every 6 hours
World Bank Pink Sheet	Monthly Europe natural gas and Japan LNG prices.	CC BY 4.0	Every 6 hours
National Gas	Operational National Transmission System flows and the Great Britain System Average Price (PUBOB603) in p/kWh. The hourly job also reads the instantaneous per-site flow API, without a login, and publishes terminal readings to Blob for the map. Theddlethorpe is omitted. Moffat is included because the portal publishes that exit. Physical NTS flows and completed gas-day totals are published to Blob and listed on data health.	National Gas Transmission confirmed in writing on 14 Oct 2026 that Grid may reuse Gas Data Portal and API data. Published as open operational data under the National Gas System Operator licence.	Hourly
DESNZ Renewable Energy Planning Database	Operational renewable power stations of 150 kW and above, with OSGB36 coordinates transformed to WGS84. The storage inventory also lists pumped storage and batteries, including projects that are not operating. The projects register reads planning, construction and operational status for England, Scotland and Wales from this extract, including projects that are not operating. The pipeline page counts renewable and storage projects in England, Scotland and Wales that are under construction, consented, or in planning. Data: DESNZ REPD via Grid.	Open Government Licence v3.0	Quarterly
DESNZ Digest of UK Energy Statistics	DUKES 5.11 power stations, including conventional plant, matched against REPD so the same site is not counted twice. Operating pumped storage on the storage page uses the counted DUKES megawatts. DUKES 2026 table 1.1 is the UK annual energy balance, in TWh. The DESNZ energy flow chart 2025 is that same edition.	Open Government Licence v3.0	Annual
NESO DNO licence areas	GB distribution network operator licence-area boundaries on the map. The boundaries in this dataset were originally shared by Western Power Distribution, now National Grid Electricity Distribution (the DNO responsible for 4 of the 14 Licence Areas) and come with the disclaimer that they are probably a little outdated and not 100% accurate.	Open Government Licence v3.0	Daily
OS Open Zoomstack	Vector basemap for the asset map. Edition 2026-06, zooms 0 to 13.	Open Government Licence v3.0	Twice a year
EirGrid Group	Northern Ireland, Ireland, and all-island electricity from the Smart Grid Dashboard. SONI system figures and SEMO imbalance prices in euro. Northern Ireland stays outside Grid's GB totals.	EirGrid Group Open Data Licence. Worldwide, royalty-free, and perpetual. Covers SONI, the Smart Grid Dashboard, SEMO, and SEMOpx. EirGrid Group may revise the licence. First read 15 Oct 2026. Read again on 20 Oct 2026.	Hourly
GeoNames	Schematic landing points for the ten electricity interconnectors, and approximate sites for NTS gas terminals including Moffat. Each pin cites a GeoNames feature id. These are not surveyed cable routes or terminal centroids.	CC BY 4.0	Curated
Elexon Industry Standing Data	Organisation names, MPIDs, BM Unit IDs, GSP group labels, and role dates for the directory lookup. The raw extract is not stored. Grid does not offer a download of the extract.	The ISD Data Store is publicly available. The BSC Open Data Licence covers only information Elexon identifies as open data. The ISD page, read on 20 Oct 2026, does not make that identification. Lookup display stays. Redistribution of an extract is not permitted.	Weekly
ONS National Statistics Postcode Lookup	Postcode to local authority, stored separately from the DNO licence area and the Carbon Intensity region. Local authority comes from the National Statistics Postcode Lookup. DNO and Carbon Intensity come from their own boundary layers and are not inferred from the authority. The lookup is published to Blob. Northern Ireland postcodes are not included. Grid does not offer a download of the ONS file.	Open Government Licence v3.0. Read on 20 Oct 2026. Postcode products are derived from Code-Point Open. Northern Ireland postcodes are excluded.	Quarterly

Attribution text required by each licence is on Data sources.

Definitions

Market index: Elexon APXMIDP, the short-term wholesale price in £/MWh. System price: imbalance / cash-out. Day-ahead auction prices are not republished.

Embedded wind: NESO's estimate of wind that is not metered on the transmission system, joined to Elexon FUELINST. Solar is Sheffield Solar PV Live, including estimated embedded panels.

Carbon intensity: national actual half-hour from the NESO Carbon Intensity API (CC BY 4.0). Forecasts are used for look-ahead only and are not treated as actuals.

Look-ahead uses the NESO Carbon Intensity 48-hour forecast, Elexon WINDFOR, Elexon NDF, and the NESO embedded wind and solar forecast, fetched by Grid and cached for 30 minutes. Year, All time and records use NESO historic generation mix.

Data checks

Snapshot integrity tests drop rows with impossible fuel shares, wind above 25.5 GW, or solar above 16.5 GW, and flag half-hours where the sum of generation exceeds 1.15× demand plus net exports. Missing metrics stay null. Coverage gaps are not filled with zeroes. Records stay blocked on any series that still fails those checks.

Records

A Grid record is the highest or lowest valid half-hour since Grid's records began (NESO historic data from 2009). Each card is paired with NESO's official record. Solar is hidden while Grid's peak disagrees with NESO. See /records.

Questions

How often does Grid update?: Grid refreshes every hour. Oil and gas prices refresh every 6 hours. Physical gas data is updated hourly. Missing metrics stay null, never zero. The site is not a second-by-second feed.
What is the market index versus the system price?: The headline £/MWh figure is Elexon's Market Index (APXMIDP), the short-term wholesale price. The system price is the imbalance (cash-out) price. Neither is the day-ahead auction.
What do records on Grid mean?: Records are highest or lowest half-hours since Grid's records began, from NESO historic generation mix (2009). They are shown next to NESO's official records and are not claimed as national records on their own.
How should I cite Grid?: Grid (grid.vahaah.com), data from Elexon BMRS and NESO, {date, time BST}. Derived data is CC BY 4.0 with the upstream attributions on this page.