Current figures — last updated 2026-06-25
- Went live1 October 2024
- OwnershipPublicly owned (UK government)
- ReplacesNational Grid ESO
- Grid frequency target50 Hz
- RegulatorOfgem
- Demand Flexibility sign-ups~2.46 million (last winter)
Source: NESO. Figures change; the Demand Flexibility sign-up total is for the most recent winter reported.
The belief to drop: "National Grid runs the grid"
For decades that was true. The company that owned the high-voltage wires also ran the system. But running the grid and owning the grid are two very different jobs, and giving both to one private company created an awkward conflict: the body deciding which projects connect and how big the network should grow was also the company that profits from owning that network.
So the system operator was carved out. On 1 October 2024 it became NESO, taken into public ownership and made independent of National Grid. National Grid still owns the transmission wires in England and Wales. It just no longer runs the show. When you hear "the grid", you are usually picturing the wires; when you hear about balancing, margins and connections, that is NESO.
What NESO actually does, in plain words
NESO has one impossible-sounding job split into four parts. The first is real-time; the rest shape the years ahead.
Balances the grid every second
Electricity cannot be stored cheaply at grid scale, so the amount made must equal the amount used at all times. NESO constantly nudges generators up and down to hold the balance and keep the frequency at 50 Hz.
Keeps the lights on tonight
It forecasts demand and checks there is enough generation. When spare capacity is tight it issues a public notice asking the market for more power, which usually fixes it long before any risk to homes.
Runs the connection queue
Every new wind farm, solar park or battery has to ask NESO to connect to the grid. A huge backlog built up, and reforming that queue, so ready projects are not stuck behind stalled ones, is one of NESO's biggest current jobs.
Plans the future network
NESO maps out how the whole energy system, electricity and gas, should develop to reach net zero, including where new transmission lines are needed. This whole-system planning role is new and is why it is the energy system operator, not just electricity.
Try it: balance the grid like NESO
NESO does not watch demand on its own. It watches the margin: the gap between the power available to generate and the power being used. A cold, still evening is risky because demand is high and wind is low, squeezing that gap. Set both sliders below and watch the headroom, and see what NESO does about it.
It is the margin that matters, not the demand
Demand
Available
Headroom
GW
Simplified for illustration. GB demand runs from roughly 20 GW on a summer night to the mid-40s GW on a cold winter evening; the headroom (margin) is what NESO acts on. NESO holds the frequency at 50 Hz throughout.
What NESO does at each margin (the headroom = available power minus demand), in plain text:
- Headroom of 0 GW or less (demand above available supply): shortfall; NESO maximises generation, calls a Demand Flexibility event, and only as a last resort uses brief rotating disconnections;
- Headroom up to about 3 GW: tight margin; NESO starts reserve plants and may issue an Electricity Margin Notice, and can call a Demand Flexibility event;
- Headroom of roughly 4 to 11 GW: comfortably balanced; NESO fine-tunes generation and holds the frequency at 50 Hz;
- Headroom of about 12 GW or more: big surplus; NESO may pay generators to turn down or reward people for using more electricity now.
Where this hits real life
Two NESO decisions reach ordinary people, even though most never hear the name.
Winter margin notices. When cold, still weather pushes demand up and wind output down, NESO publishes a notice that spare capacity is tight. Headlines call it a "blackout warning". It almost never is. It is NESO asking the market for more power, and the market nearly always answers. Knowing this saves a lot of needless worry every winter.
The connections queue. If you have ever wondered why a solar farm or battery sits built but not switched on, the answer is often the connections queue NESO manages. Reforming it, so projects that are ready are not stuck behind ones that are not, is one of the biggest levers on how fast Britain decarbonises and, eventually, on network costs in your bill.
The insider point: you can be paid by the system operator
Here is the part that surprises people. The system operator that feels remote and industrial has a direct, opt-in reward for households: the Demand Flexibility Service. On tight evenings NESO pays for electricity demand to move off the peak, and that money flows to you through your supplier or an aggregator as cash, points or prizes. Nearly 2.5 million homes and businesses signed up last winter. From 2026 the scheme also rewards using more electricity when there is a surplus, for example on windy nights, flipping the old "always use less" advice on its head.
The deeper insight: as Britain adds wind and solar, the value is shifting from how much energy you use to when you use it. The system operator is quietly building a market that pays flexible households for timing. People on fixed routines miss it; people who can shift a dishwasher or charge an EV at the right hour get paid for it.
For households: could you be paid for when you use power?
This is the part that actually puts money in your pocket. On a time-of-use tariff (such as Economy 7 or an EV tariff), electricity is far cheaper off-peak, usually overnight, than at the early-evening peak. Tick the things you could move to the cheap window, and the tool estimates what you might save in a year. It is the same idea NESO rewards nationally, scaled to one home.
What could you save by shifting usage to off-peak?
Tick what you could move to the cheap overnight window. We multiply the energy you shift by the gap between your peak and off-peak rates.
You could save roughly
£ / year
by shifting kWh a year to your p off-peak rate, a p saving on every unit moved.
Tick something on the left to see your saving.
Cheapest live off-peak rate: E.ON Next at 6.50p/kWh.
Estimate only. You need a time-of-use tariff to get an off-peak rate, and you must actually move the usage. Live rates from our comparison feed; default rates are illustrative, so check your own bill.
Example savings (at a typical 18p gap between a 28p peak and a 10p off-peak rate), in plain text:
| If you shift this off-peak | Typical energy / year | Rough saving / year |
|---|---|---|
| Electric car charging | ~2,500 kWh | ~£450 |
| Home battery (store cheap power) | ~1,800 kWh | ~£324 |
| Hot water / immersion | ~800 kWh | ~£144 |
| Tumble dryer | ~250 kWh | ~£45 |
| Dishwasher | ~200 kWh | ~£36 |
| Washing machine | ~150 kWh | ~£27 |
What you can actually do
- 1.Ask your supplier whether they offer the Demand Flexibility Service or a similar "saving sessions" scheme, and opt in if you can shift usage;
- 2.Treat winter "margin notice" headlines calmly: they are requests for more generation, not blackout alerts;
- 3.If you have an EV, battery or heat pump, look at a time-of-use tariff, the household version of what NESO rewards at national scale;
- 4.For a power cut, still call 105 and your distribution operator, not NESO. The system operator does not handle local faults.
NESO: frequently asked questions
NESO is the National Energy System Operator, the body that runs Great Britain's electricity grid in real time. It balances supply and demand every second, tells power stations when to run, keeps the system stable, and plans how the grid should grow. It began on 1 October 2024 and is publicly owned. It does not own cables, generate power or sell electricity.
They are the same role under new ownership. National Grid ESO was the electricity system operator while it was still part of National Grid. In October 2024 it was separated from National Grid and taken into public ownership, and renamed NESO. NESO also took on a wider job: planning the whole energy system, including gas, not just operating electricity.
NESO is owned by the UK government, through the Department for Energy Security and Net Zero. It was deliberately taken out of private hands so that the body planning the grid has no financial interest in who connects to it or how big it gets. It is still regulated by Ofgem, like the rest of the GB energy system.
Indirectly, yes, through the Demand Flexibility Service (DFS). NESO runs events, usually on tight winter evenings, where it rewards homes and businesses for shifting electricity use away from the busiest times. You sign up through a participating supplier or aggregator, who rewards you in money, points or prizes; NESO pays the provider. Nearly 2.5 million homes and businesses had signed up by last winter.
Usually neither, directly. Local power cuts are almost always a fault on the cables, which your distribution network operator fixes (call 105). NESO works at the national level: it issues notices when the country's spare capacity is tight, and in very rare emergencies it can instruct controlled, rotating disconnections. A margin notice is a request for more generation, not a blackout warning.