Explore grid history

Use the range buttons to choose a period and the metric buttons to change the measure. “Last 24 hours” is a rolling window, rather than the period since midnight. The other ranges look back 7 days, 30 days or 366 days. Available records may cover only part of the selected window.

What each measure means

• Demand (GW): the recorded rate of electricity demand. Compare similar times of day before interpreting a rise or fall; daily routines, weather and the day of the week can all affect consumption.
• CCGT (Gas) (GW): output from combined-cycle gas turbines, which use a gas turbine and recovered heat to generate electricity. This category should not be treated as a measure of every gas-fired technology.
• Wind generation (GW): the wind output recorded in the dataset. Output is different from installed capacity: a wind fleet’s maximum rated power does not describe what it produces at every moment.
• Generation comparison (GW): wind, CCGT, nuclear and solar plotted together. These four series are a selection of sources, not a complete electricity balance. “Largest now” identifies the largest of those available values in the last stored row; it may differ from the current live reading.
• Carbon intensity (gCO₂/kWh): carbon dioxide emissions per unit of electricity. A lower reading means less CO₂ per kilowatt-hour on the reported basis, rather than a direct measurement of total emissions or a complete lifecycle assessment.
• Grid frequency (Hz): the alternating-current system’s frequency, centred on a nominal 50 Hz. Small changes reflect the system’s ongoing supply-and-demand balancing. This chart alone cannot diagnose a fault or predict an interruption.
• Market Index Price (£/MWh): a short-term wholesale electricity price indicator. It is not a household tariff or the full cost of delivering electricity. For unit comparison only, £100/MWh equals 10p/kWh before other charges; that conversion does not predict a bill.

What the summary numbers tell you

Low and High are the smallest and largest available sample values. Average is the arithmetic mean of those samples: each stored observation has equal weight. It is not a time-weighted average, an energy total or a volume-weighted market price. Missing records and uneven sampling can change its meaning. Latest means the last available value in the series, which may be older than the time you opened the page.

Resolution, missing records and chart scales

The Last 24 hours view uses the full-resolution local history for non-price metrics. Longer views use a compact archive intended for hourly records, so short-lived peaks may be absent. Price is requested from Elexon’s Market Index endpoint with the APXMIDP provider filter for windows of up to 31 days; longer price windows use locally archived values. Differences between views can reflect both the time period and the records used.

Points use actual elapsed time. Missing readings break the line; gaps longer than five minutes in full-resolution data, two hours in the compact archive or 90 minutes in price data are not joined. Tap or drag the chart, use its keyboard-accessible slider, or open the paginated table for exact values. CSV exports include the selected records without replacing missing readings with zero.

Most single-metric charts adjust their vertical scale to the available values, while frequency uses a fixed scale and the generation comparison starts at zero. Similar-looking slopes on separate charts need not represent similar-sized changes. An empty view means there are too few usable records to draw a chart; it does not establish that demand, output or prices were zero.

Try a careful comparison

Choose 7 days and inspect wind, then CCGT and demand over that same range. If wind falls while gas output rises, that is consistent with a change in the supply mix, but it does not establish the reason on its own. Demand, imports, storage and plant availability may also matter. For longer comparisons, consider seasonal differences and archive coverage before describing a trend.

These views concern Great Britain’s electricity system. For background and publisher definitions, see NESO’s generation and carbon-intensity information and Elexon’s Market Index overview. Read more about this independent project on the About page. Figures are for general information and education, not operational or trading decisions.