Methodology

Geographic coverage

Most live electricity-grid data covers Great Britain: England, Scotland and Wales. Northern Ireland is part of the UK but operates in a separate electricity market. EnergyMix.info uses “UK electricity mix” where that matches public search language, but clarifies the Great Britain coverage wherever precision matters.

Metric definitions used by the atlas

Domestic generation excludes imports and pumped storage. Renewable share is wind, solar, hydro and biomass divided by domestic generation; low-carbon share additionally includes nuclear. Biomass is reported explicitly, not treated as zero-emission.

Estimated supply-balance demand is domestic generation plus signed net imports plus pumped-storage transfer. It is not a direct measure of national consumption and is not substituted for transmission demand based on a tolerance. Mixed source intervals and losses limit reconciliation.

Historical measured-generation reports retain their original definitions: archived renewable-share figures can exclude biomass and historical hydro can include pumped storage. They are not directly comparable to the atlas’s domestic-generation share. Corrections to archived evidence must be explicit.

Map connections are schematic country aggregates, not cable telemetry. Regional carbon markers are forecasts at approximate region centres. Northern Ireland is shown for geographic context but is outside Great Britain’s headline totals.

Forecast windows must consist of contiguous future intervals. The source retrieval time is not the forecast issue time. A timestamp ahead of the current time is never used as the last observation. Source age and operating mode are separate.

Primary data sources

• Elexon BMRS / FUELINST: transmission-connected generation, balancing and related electricity market data.
• NESO / National Grid ESO sources: grid demand, embedded generation context and system-level data where available.
• Carbon Intensity API: official national, regional and postcode carbon-intensity estimates and forecasts for electricity consumption.
• ENTSO-E and BMRS fallbacks: interconnector flow context where the dashboard can retrieve reliable data.
• Sheffield Solar PV Live: embedded solar generation estimates used to avoid undercounting distributed solar.
• Elexon Market Index Price: latest wholesale market index price, shown as grid-market context rather than a household tariff.
• Elexon FREQ: GB system frequency, used as a simple grid-health signal around the 50 Hz target.

For source links and licensing notes, see the data sources page.

Update frequency

Fast-changing generation data is refreshed more often than slower settlement-period or historical data. The live dashboard is designed to feel current while avoiding unnecessary load on public APIs. Individual charts and source freshness labels may show the latest available upstream timestamp.

Known limitations

• Live data can lag the physical grid and may be revised after publication.
• Fuel categories can differ between source systems, especially storage, biomass, embedded generation and interconnectors.
• Storage and pumped storage are sign-sensitive: positive PS is shown as generation, negative PS as charging/pumping. EnergyMix surfaces the state separately instead of folding it into renewable output.
• Wholesale price is shown as market context only. It is not the same as a retail tariff, export tariff, Agile/Tracker price or final household cost.
• Interconnector imports and exports affect domestic generation mix and carbon intensity in different ways.
• Carbon intensity estimates are modelled and should be interpreted as best available public estimates, not exact metering.

How percentages are calculated

Percentage shares are calculated from the generation values available to the dashboard at the time of refresh. Where imports, exports, storage or embedded generation are shown separately, explanatory labels are used to avoid implying false precision.