UKGRIDWATCH

Data and methodology

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Data and methodology

UKGRIDWATCH presents observations from its configured collector and public price data. It is an educational view of Great Britain’s electricity system, covering England, Scotland and Wales. It is not a control-room tool or a prediction of supply interruptions.

Sources and attribution

The dashboard’s demand, frequency, generation, carbon-intensity and interconnector readings come from the site’s local grid collector. The upstream publisher for each electricity feed is being verified. Until verification is complete, this page distinguishes the local collector from reference resources and avoids assigning an unconfirmed publisher. Reference links to NESO are background information and do not establish that a particular displayed reading was supplied by NESO.

Verified publisher names, dataset links and publication intervals will be added here as the feed documentation is completed. Do not infer one common publication schedule from the page refresh timer.

  • Market Index Price: Elexon’s Market Index API, using the APXMIDP provider filter. Elexon’s index overview explains its purpose.
  • Gas storage: the separate local gas-storage file, identified by the existing collector as National Gas. Its observation date and daily cadence are separate from electricity readings.
  • Further reading: NESO historic generation mix and NESO’s frequency explanation. Publisher definitions may differ from a collector’s stored fields.

Observation time and freshness

Electricity labels show the collector sample timestamp. They cannot establish the age of an individual upstream feed unless that feed’s own timestamp is stored. The dashboard normally checks for updated readings in the background on its two-minute schedule and warns after five minutes without a complete fresh grid observation. Price and gas labels use their own record timestamps. Dates are displayed in Europe/London time, including GMT or BST.

Freshness labels show the record’s age and configured cadence separately. Date-only records are displayed as data dates without inventing an observation hour; publication time may be unavailable. Expected update intervals describe the configured feed cadence, not a promise that every scheduled reading will arrive. The shared electricity timestamp describes the stored sample. While the feed documentation is being completed, its default two-minute interval reflects the dashboard schedule and should be checked against the collector.

Live readings update without a scheduled page reload. If an update request fails, the page retains the last displayed readings, shows a connection warning and retries. Read the observation timestamps to judge their age. Selecting a chart sample or opening its table keeps that chart in place while live readings continue updating; choose Resume live chart to return to the latest records.

Gauge comparisons use the stored observation nearest 15 minutes before the current sample, with a tolerance of three minutes. Sparklines show up to 30 minutes of available history, use independent vertical scales and break across gaps over five minutes. They show direction and variation; their heights should not be compared between metrics.

Missing or invalid observations

The live dashboard requires a timestamped observation with numeric values for all its expected fields. An empty, corrupt or incomplete current record shows Data unavailable; it is not replaced with a simulated live sample. A complete older record may remain visible with a delay warning. Historical views retain missing values rather than converting them to zero.

Generation shares and units

GW measures power: the rate of generation or use. GWh measures energy over time. The expanded generation breakdown uses the sum of the recorded generation categories. The stacked mix bar uses positive output only, excludes imports and does not count a negative storage-charging value as generation. If storage is charging, its bar denominator can therefore differ from the signed sum used by the detailed cards. The bar legend makes this distinction explicit.

Demand, generation and interconnector flows need not sum to a complete balance because definitions, reporting scope, storage, losses and timestamps can differ. National carbon intensity in gCO₂/kWh is emissions per unit of electricity, not total emissions or an individual home’s measured footprint.

History, charts and comparison

Last 24 hours is a rolling window covering the preceding 24 hours. The standard longer windows look back 7, 30 or 366 days. Custom dates use local midnight at the start and include the end day up to the current time, with a maximum of 366 calendar days. The available-since label reports the earliest local observation for the selected metric; it does not promise uninterrupted coverage or the same start date for Elexon’s API.

Full-resolution views use stored collector history; longer views use the compact archive intended for hourly observations. Prices for windows up to 31 days are requested from Elexon; longer price views use local records. Charts position records by actual elapsed time. Missing readings and gaps over five minutes in full-resolution data, two hours in the compact archive, or 90 minutes in price data break the line.

Record coverage compares occupied time slots with expected slots at the configured or intended collection cadence. Full-resolution cadence may be estimated from median timestamp spacing and is labelled accordingly. Duplicate timestamps do not improve coverage; a valid zero remains a reading and a missing value does not. Low and High describe available samples. Average is an arithmetic sample mean, not a time-weighted or volume-weighted mean. The previous-period comparison uses an immediately preceding window of equal elapsed duration, with sample counts shown for both windows. Daylight-saving transitions and incomplete coverage can affect calendar-day comparisons. Different charts may use different vertical scales; compare the numerical values as well as the shapes.

Tap or drag a chart, use its sample slider and arrow keys, or open its paginated table for exact readings. Chart zoom controls select shorter windows and allow movement earlier or later without leaving the page. Axis labels remain readable HTML text on small screens. Chart tables and shown-window CSV exports follow the zoom window; the separate History period export includes the full selected period. CSV exports use UTC timestamps and leave absent values blank. Period exports include both selected and previous records when comparison is enabled.

Frequency and other gauge alerts

The nominal frequency is 50 Hz. Frequency outside 49.8–50.2 Hz flashes amber; outside 49.5–50.5 Hz flashes red. Alarm flashing remains active. Generation labels describe output rather than declaring system health. Other gauge thresholds are dashboard display settings: high demand is not a calculation of spare capacity, and high nuclear or renewable output is not evidence of a fault. These labels do not predict blackouts.

Wholesale prices and caching

Market Index Price is a short-term wholesale indicator in £/MWh. Zero and negative values are valid. A unit conversion to p/kWh does not include network charges, supplier costs, taxes or a household tariff. The dashboard price cache normally refreshes after two minutes and delays retries after failures. Cached records are dated and marked if refresh is delayed; they are not guaranteed current prices.

Corrections and contact

If a figure or explanation appears wrong, email [email protected] with the page, metric and observation time. See Contact and corrections for details.