Building Grid: a GB Electricity Dashboard from Public Data

Grid is a public dashboard of Great Britain's electricity system. I built it as a side project, and it uses only public data. It shows where GB power is coming from, how much is being drawn from the transmission network, how much carbon each kilowatt-hour carries, how power is flowing through the interconnectors, and the imbalance price, with a year of history.

I'm Alex Vakhitov, an AI and software architect in London. I've spent more than a decade on software for the energy market. In 2015 I co-founded Cloud KB and was its CTO; we built software for energy-market participants and supported SMETS2 installations from the early stages of the national roll-out. Correla acquired Cloud KB in 2022, and I stayed on as Product Architect.

This post describes what Grid shows, where each series comes from and one design choice the page itself doesn't explain yet.

What Grid shows

The page opens with a few plain sentences that summarise the selected window: how carbon intensity compares with its average, which source is leading supply, and whether Great Britain is importing or exporting. Below that summary sit the details:

Carbon intensity, in grams of CO₂ per kilowatt-hour, benchmarked against the average for the window, with forecast context.
Transmission demand, compared with the window's peak and low.
The generation mix, source by source, with a chart of how the mix shifts over the window. Embedded wind and solar (PV Live estimate) appear as their own series.
Interconnector flows, link by link, with the net import or export position. Positive values are imports into Great Britain.
The imbalance price across the window.

The window runs from the last 24 hours up to a year. The selected view is recorded in the URL, so a link opens the same view for someone else. The page also shows the time its data is from.

Where each series comes from

Grid combines four public sources. Each series comes from one of them:

Generation by fuel type comes from Elexon, the body that administers balancing and settlement in the GB electricity market. It publishes this data through BMRS, the Balancing Mechanism Reporting Service (the FUELINST dataset). This is metered output from plant connected to the transmission network.
Interconnector flows come from the same Elexon data, which reports each interconnector alongside the fuel types.
Demand comes from Elexon's transmission system demand figures (ITSDO). It's the demand met through the transmission network, which is not the same as total electricity consumption in Great Britain.
The imbalance price comes from Elexon's system prices.
National carbon intensity, and the summary generation mix at the top of the generation section, come from the Carbon Intensity API.
Embedded wind comes from NESO, the National Energy System Operator, which publishes estimates of it in its demand data.
Solar (PV Live estimate) comes from Sheffield Solar PV Live, which estimates total solar generation across Great Britain.

All of this data, including the imbalance price, refreshes every hour. Grid keeps a year of history.

Counting what the transmission system can't see

This is the one design choice I want to explain, because the page doesn't yet.

A large share of Britain's solar panels and many of its wind turbines are connected to local distribution networks rather than the transmission network. The transmission system doesn't meter them, so Elexon's generation data doesn't include them. On a sunny afternoon, rooftop solar reduces what homes and businesses take from the wider network, and transmission demand falls even though consumption hasn't.

A picture built only from transmission metering would therefore understate how much of Britain's power comes from wind and solar. Grid fills that gap with estimates: embedded wind from NESO and solar from PV Live. It shows them as separate series, next to metered wind, rather than folding them into it, and it counts them in the domestic supply total. Metered and estimated figures stay distinguishable, and the total reflects generation the transmission data alone would miss.

The PV Live figure is an estimate of total GB solar, not strictly the embedded part. Most solar capacity in Great Britain is connected to distribution networks, but I call the series "solar (PV Live estimate)" here rather than embedded solar, because that describes the number accurately.

Imbalance prices, not wholesale prices

The price on Grid is the imbalance price, sometimes called the cash-out price. The page states that it is not the day-ahead wholesale price, and the difference is worth understanding.

The GB market settles in half-hour periods. For each one, generators and suppliers are expected to match what they have contracted with what they actually produce or consume. When they don't, they are charged or paid for the difference at the imbalance price, which Elexon calculates for each settlement period. It reflects the cost of balancing the system in that half-hour.

The day-ahead wholesale price is agreed before delivery, and it is what most people mean by "the price of electricity". The two are related, but the imbalance price moves much more, and it can go negative when there is more generation than the system needs. Grid's price chart notes that negative prices are real.

How the page is organised

A few choices shape how Grid reads:

Summary first. The opening sentences give the main points in words, and the charts underneath show the working.
Clear labels. The price is labelled as the imbalance price, with a note that it isn't the day-ahead wholesale price. Transmission demand is labelled as such, and the estimated wind and solar series sit in their own rows rather than inside the metered figures.
Shareable views. Because the view is recorded in the URL, a link points to a specific range and section rather than to "the dashboard" in general.
Separate clocks. Further down, a short section shows oil and gas benchmark prices (Brent, WTI, Henry Hub, TTF and JKM) as wider market context. They refresh every six hours and have their own range control, because, as the page's methodology puts it, intraday grid behaviour and commodity settlement move on different clocks.

It isn't a control-room screen. It's a sourced view of how Great Britain's electricity system has been behaving, over a day or over a year.

Grid is at grid.vahaah.com.