GridTelemetry FAQ

GridTelemetry uses five live public feeds plus published project-register snapshots. The Carbon Intensity API provides carbon emissions, regional mix and forecasts. Elexon BMRS supplies generation, demand, interconnectors, frequency, prices, balancing, margin and outages. NESO Open Data provides renewable forecasts, network-constraint forecasts, balancing economics and the Transmission Entry Capacity register. Sheffield Solar PVLive supplies embedded-solar outturn estimates. Octopus Energy supplies Agile tariff rates for regional price windows. The DESNZ Renewable Energy Planning Database supplies the future-project map.

GridTelemetry combines these sources and calculates some comparisons, records and outlooks. Derived figures and interpretive labels are identified where they appear; the future-project registers are dated snapshots rather than live operational feeds.

The scenario explorer uses the mapped projects of 10 MW or more retained from the DESNZ Renewable Energy Planning Database. Visitors can compare status, technology, region, minimum-capacity, storage and recorded-stage-date filters. Totals are gross published project capacity; they are not delivery forecasts, and GridTelemetry does not assign completion probabilities. When a date horizon is active, records without the relevant current-stage date are excluded and counted rather than assumed to be inside the horizon.

The connection outlook is a separate view of NESO’s Transmission Entry Capacity register. Its effective-year horizon applies to the annual TEC aggregate, while the REPD technology, region and status filters do not. NESO warns that capacity may be split across technology or connection-stage rows, so GridTelemetry removes only exact duplicate rows and does not guess that similarly named projects are the same asset. Project counts are distinct within each year and can repeat across years.

Scenario choices use public filter identifiers in the URL so comparisons can be shared. They contain no postcode, account or private watchlist information.

The underlying feeds refresh at different rates: generation by fuel type roughly every five minutes, system frequency about every fifteen seconds, and carbon intensity and wholesale prices once per half-hourly settlement period.

Live operational pages re-poll once a minute, while the 1-day frequency view refreshes every 30 seconds. The “Live” badge shows how far through the latest measured period the data covers, rather than merely when the API was last called. Carbon intensity, generation and prices still move at their source publication cadence, so faster requests would usually return the same figures.

When you open the panel, GridTelemetry requests one representative dataset from each live provider. “Available” means that check succeeded at that moment; “Unavailable” means it failed or timed out.

This is a GridTelemetry connectivity check, not an official status for the provider as a whole. One dataset can fail while other data from the same provider continues to work.

No. It’s an independent project built on openly published data, and it isn’t affiliated with or endorsed by the electricity system operator, Elexon, or any energy company.

It’s built for general interest and education. Live data can lag, be revised later, or briefly drop out when an upstream source is unavailable, and some figures are estimated (see the drill-down question below). For operational or commercial use, always go to the primary sources directly.

Two reasons. First, they are genuinely different quantities: Great Britain also imports and exports power over interconnectors and loses a little in transmission, so generation and demand rarely line up to the megawatt.

Second, the raw feeds are “transmission-level”, which excludes smaller generators connected to local distribution networks — chiefly rooftop and field solar. GridTelemetry adds an estimate of that “embedded” generation back on, so both figures sit on a comparable national basis.

Transmission figures cover only what flows across the high-voltage grid the system operator meters directly. National figures also include “embedded” generation connected further down, in the distribution networks — mostly solar.

National is the more intuitive “what the country is producing and using” number, so that’s the basis the dashboard shows.

Most solar is embedded, so it doesn’t appear in the transmission generation feed at all. GridTelemetry uses Sheffield Solar PVLive’s national embedded-solar outturn estimate and adds it to the transmission figures. If PVLive is temporarily unavailable, the live grid can fall back to an estimate derived from the Carbon Intensity API’s fuel-mix percentage.

Historical Generation Mix charts use retained PVLive observations where available. Solar remains a modelled estimate rather than a meter reading, so it is labelled separately from transmission-connected generation.

Carbon intensity is the grams of CO₂ emitted per kilowatt-hour of electricity generated. The coloured band is a simple qualitative scale — very low, low, moderate, high, very high — matching the Carbon Intensity API’s own thresholds, so a glance tells you how clean the grid is right now without reading the exact number.

Interconnectors are the subsea and cross-border cables linking Great Britain to France, the Netherlands, Belgium, Norway, Denmark and Ireland. “Import” means power is flowing into GB over a link; “export” means it’s flowing out. The net figure sums simultaneous imports and exports across every link, so it is not the gross volume traded over all cables.

On the chart, positive values are net imports and negative values are net exports. The flow-pattern card summarises regularly spaced periods in the selected window; values within ±25 MW are treated as near balanced. Connected-market rows group parallel links to the same country, so opposing flows within that corridor offset.

It’s the half-hourly Great Britain wholesale reference price in pounds per megawatt-hour, taken from Elexon’s Market Index Data (the APX/EPEX index). It reflects the short-term market price of electricity — not a retail or household tariff.

The day-ahead price, or Market Index Price, is the volume-weighted price traded for each half-hour on Great Britain’s short-term electricity markets.

The imbalance price, also called the cash-out price, settles differences between the electricity generators and suppliers contracted and what they delivered or used. It is published later than the day-ahead price and may be revised by subsequent settlement runs.

The grid runs at a nominal 50 hertz. Frequency drifts slightly above 50 Hz when generation exceeds demand and below it when demand exceeds generation, so it acts as a real-time heartbeat of grid balance. The operator continuously works to hold it within a tight band around 50 Hz.

De-rated margin is NESO’s estimate of the generation available above forecast demand, adjusted for the likelihood that each source will be available. GridTelemetry shows the forecast for each half-hour over roughly the next two days.

Loss of load probability is the modelled chance that available generation will fall short of demand in a settlement period. It is not a blackout forecast: NESO can use reserves, imports and demand-side actions, and it issues formal Electricity Margin Notices when it needs a market response.

Labels such as “Comfortable” are GridTelemetry interpretations, not official NESO status labels. Any active official notices appear on the Live Grid and Grid Margin pages.

A network constraint occurs when the transmission system cannot safely carry every planned electricity flow, even when Great Britain has enough generation overall. NESO may pay generators or flexible demand to change output so a boundary stays within its operating limit.

The boundary chart is NESO’s day-ahead forecast of flow and limit, not measured outturn. The 1D view includes the next 48 hours; historical views compare the day-ahead snapshots GridTelemetry stored. Forecast utilisation is the absolute flow divided by the published limit.

NESO changed the calculation on 22 April 2024. Earlier published flows included expected mitigation and optimisation actions; later flows do not, so comparisons across that date need care. The balancing-cost figures are separate historical outturn datasets and may be revised after the event.

Balancing actions are instructions accepted by the system operator to change a Balancing Mechanism unit’s level. “Raise” and “lower” describe the direction of the instruction; the profile shown is an instruction, not metered output.

A system flag means the action may relate to a network constraint or another system-operating need. The published feed does not provide a plain-English reason for each flag. Historical balancing costs and volumes are separate datasets and may be revised.

The detailed 48-hour view combines actual wind and embedded solar with the latest available forecasts. The 14-day view uses daily summaries for a simpler look ahead. A gap means a component is not available; it is not treated as zero.

Forecast capacity factor is expected output as a share of the capacity NESO publishes for the same settlement period. It is context for the forecast, not a measurement of every renewable asset in Great Britain.

For most fuels, yes. Gas, coal, nuclear, biomass, wind, hydro, pumped storage and batteries all drill down to real named stations carrying their own output, taken from Elexon’s per-unit data. The imports drill-down likewise shows each interconnector’s real measured flow.

What “output” means there is worth being precise about: it is the operator’s own declaration for the current half-hour, not a meter reading. Metered per-station figures aren’t published until five working days later, so anything shown live is necessarily a declaration.

Solar is mostly embedded in distribution networks and “other” is a mixed national category, so neither has a trustworthy live per-station split. Their drill-down therefore shows one clearly labelled national estimate with installed-capacity context; it does not allocate output to named sites or infer a load factor.

Great Britain is divided into fourteen regions for the purpose of reporting carbon intensity, and Your Region shows you the one you live in: how clean your local electricity is right now, how that compares with the national average, and what is generating in your area.

You type only the outward half of your postcode — the part before the space — which is enough to identify a region and not a house. The postcode is not stored; only the resulting region number is remembered in your browser. See the privacy answer for details.

Because the regional generation mix is not an inventory of what stands nearby. It is a model of the electricity being supplied to your region, and it accounts for power flowing in from neighbouring regions and across the transmission network.

So a fuel can hold a large share in a region that contains no plant of that kind at all. Large gas stations in particular are connected to the national transmission network and serve the whole of GB rather than the patch of ground they sit on. Read the mix as “this is the character of the electricity arriving here”, never as “these are the power stations down the road”.

You can compare two to four of the fourteen distribution-network regions using current and forecast carbon intensity, the past day’s actual high, the next 48 hours’ forecast high, modelled regional supply mix, and the cleanest and cheapest complete three-hour windows. The GB difference is a GridTelemetry calculation against the national reading for the same snapshot.

The cheapest windows and displayed rates use Octopus Agile: one supplier’s regional retail tariff including VAT, not a wholesale price or a claim about every household tariff. Missing carbon, national or tariff data is shown as unavailable, never as zero.

A comparison link contains only public Carbon Intensity region IDs. It never contains the postcode originally used to find a region. The supply-mix comparison describes electricity supplied to each region and must not be read as a list of generation assets physically located there.

The opposite question, deliberately. That list is what physically sits inside your region — real named stations, with the output their operators have declared for the current half-hour. It answers “what is generating here”, while the mix above answers “what is powering here”. The two genuinely disagree, and that is the point of showing both.

Offshore wind farms are tagged as such: they are out at sea and connect to the grid in the region, rather than sitting in it. Some regions have no transmission-connected generation at all, which is a real answer rather than a failure.

They are the electricity distribution licence areas — the historic patches served by each regional network operator — not counties, postcodes or anything a map of England would show you. The Carbon Intensity API reports against them, so the site follows the same boundaries.

That produces occasional surprises which look like bugs and are not: Iron Acton in South Gloucestershire falls in the West Midlands area, and Coventry falls in the East Midlands one. The licence areas simply do not follow the names you would expect.

Almost. Roughly 99.6% of the transmission-connected fleet by capacity is placed in a region; a handful of small units are not yet located and are left out rather than being put in the wrong place. The fleet also grows on its own as new units connect, so a very new site may take a while to appear.

Embedded generation never appears here at all — rooftop solar, small wind and anything else connected to the local distribution network is invisible to the per-unit feed, however much of it there is.

It lists grid-scale batteries and pumped hydro, kept separate from the generation table because they are not generating: they return energy taken off the grid earlier, and spend a good part of their lives consuming it. A negative figure means the unit is charging.

Your Region compares complete three-hour windows across the rest of today and tomorrow. “Cleanest” uses the lowest average forecast carbon intensity, “Cheapest” uses the lowest average Octopus Agile rate, and “Best balance” combines the two. The single cleanest half-hour is shown separately.

Agile is one supplier’s regional retail tariff, including VAT, so it is a useful price signal rather than a forecast of every household’s bill. If a required forecast or price is missing, GridTelemetry does not fill the gap with zero.

Choose an appliance or custom load, its energy use, duration, time window and whether cost, carbon or a balance matters most. The planner ranks every complete half-hour window that fits, using regional Octopus Agile rates and regional carbon forecasts.

Costs and savings are estimates based on the energy figure you enter. You can share the plan settings in a link or export the result to a calendar; see the privacy answer for what stays on your device.

They switch the time window. “1D” is the live view of roughly the last 24 hours; the longer ranges show averages over a week, month, year, five years, or all stored history, each at a progressively coarser resolution.

On Generation Mix, the live snapshot remains fixed at the top and the range buttons apply only to the stacked historical chart. On supported analysis pages, range and comparison choices are retained in the page URL so the view can be shared.

Yes, where a page has selectable analysis state. Carbon Intensity, Frequency and Interconnectors retain range and comparison choices in the URL; Carbon Intensity also retains its regional table or map choice. Outage search and filters are shareable in the same way.

Download CSV exports the points or filtered notices behind the current view. Download chart exports the visible SVG where offered. These files are generated in your browser and do not upload the view or its data anywhere.

On the day view, the solid line is actual data and the dashed tail is a short forward forecast (for demand and carbon intensity), with a “now” marker separating them. The longer ranges are historical only and carry no forecast.

Explore can compare up to four measures, including demand, individual generation types such as wind, solar and nuclear, carbon intensity, price and net imports. Because their units differ, each line is indexed to 100 at its first available reading; hover or focus a point to see the original value. This shows relative movement, not equal physical quantities.

The daily-pattern heatmap is different: it shows the underlying daily averages by hour and date rather than an index.

Accuracy views compare forecasts made at fixed lead times with the later outturn. Mean absolute error shows the typical size of a miss; bias shows whether forecasts tended to be high or low. Results are only shown where both forecast and outturn exist.

Revision or “vintage” views compare forecasts published at different times. Their ranges describe how much retained forecasts changed, not a probability that the future value will fall inside them. Some long-range history only accumulates from the date GridTelemetry began retaining vintages because the upstream source does not publish a historical archive.

It places sourced warnings, outages, demand, wind and balancing facts on one chronology to make a period easier to investigate. Nearby events are context, not proof that one caused another; follow the source links before drawing an operational conclusion.

The Asset Explorer lets you save a browser-only watchlist, monitor it as a fleet and compare up to four assets across the available history. The fleet workspace combines current operator declarations, retained metered history and published REMIT outage notices. Missing readings stay blank rather than being counted as zero.

The saved list is not placed in the address bar automatically. “Share fleet” first shows every asset ID that would enter the URL and adds them only after you confirm. Opening that link displays a shared fleet without saving it to the recipient’s private watchlist. Renamed, retired or missing catalogue entries remain visible until you remove them.

The bell can check official NESO warnings and thresholds you choose for margin, frequency, wholesale price, watched-asset deratings and major unplanned outages. Official NESO warnings are labelled and styled separately; the other conditions are GridTelemetry interpretations of published data.

Your choices use a versioned browser-only setting and are not linked to an account or synced to another device. The first delivery is in-app only: it works while GridTelemetry is open and does not ask for browser notification permission. Reliable alerts while the site is closed would require a separate explicit opt-in, service worker and server-side push subscription, with a separate privacy and operational decision.

Carbon intensity reaches back to 2017; the Elexon-derived series (generation, demand, interconnectors and price) to around 2019; and the regional series — regional carbon intensity and regional generation mix — to 2018. Because those start dates differ, the far-left edge of a “Max” chart can look ragged where one series begins before another.

Each record is calculated from the half-hourly observations GridTelemetry holds for that series. The cards show when the available series begins, so these are records for the stated data period rather than claims about all time.

Implausible readings are excluded before records are calculated. Runs use consecutive half-hours, and any gap in the data ends a run rather than assuming the missing period continued it.

Dated milestones are sourced historical events rather than numerical records or a leaderboard. They are grouped separately so the two are not confused.

Grid frequency is excluded because only a rolling 60 days are retained, which is not enough history for a meaningful long-term record.

There are no accounts or sign-in, and GridTelemetry does not profile or sell your activity.

If you use Your Region, the outward half of your postcode — the part before the space — is sent to the Carbon Intensity API to find one of the fourteen regions. The full postcode is never requested and the outward code is not stored. Your resulting region, asset watchlist, alert settings and planner preferences are kept only in your browser so the site can remember them; clearing local browser data removes them.

Share links can include selected assets, a region number or planner settings so another browser can reproduce the view. A fleet share includes the exact watchlist asset IDs only after a confirmation panel shows them; ordinary Asset Explorer links do not include the private watchlist. Share links never contain a postcode.

The API also counts requests per IP address, so that one heavy caller cannot overwhelm the upstream feeds for everyone else. And when the server hits an error, the details are recorded by an error tracker running on the same machine as the site — never a third party. Query strings are stripped before anything is written down, specifically so that a postcode cannot end up in an error report.

The underlying data belongs to its providers and is published under their own terms. Check the relevant provider’s licence before reusing it, especially commercially.

Use the share button in the header to copy a link to the exact page you’re looking at, and send it along with a note about what you saw. A precise link makes issues much easier to reproduce. On this page it is more precise still: opening a question puts it in the address bar, so the link you copy points at that individual answer.