A smart meter is a digital gas and/or electricity meter that records how much energy you use in near real time and sends those readings automatically to your supplier over a dedicated national network, replacing estimated bills and manual meter readings. In Great Britain, over 39 million domestic smart meters were in place by the end of Q1 2026 — 72% of all domestic meters — under the government-backed rollout run through suppliers. Installation is free, and you can decline one without losing your tariff. The main practical differences from an old meter are automatic billing, a handheld in-home display showing live cost and usage, and the option to feed that data into apps or a Home Assistant instance for room-by-room energy tracking. The main drawbacks are patchy signal in some rural or thick-walled properties and older SMETS1 meters that occasionally lose their "smart" functions after a supplier switch.
How does a smart meter actually work?
A smart meter records your gas and electricity consumption at least every 30 minutes and transmits those readings automatically to your energy supplier over a secure national communications network, rather than requiring a manual read or an estimate. Two generations exist in the UK: first-generation SMETS1 meters, which originally relied on each supplier's own communication system and could lose smart functionality if you switched supplier, and second-generation SMETS2 meters, which connect from the outset to the national Data Communications Company (DCC) network and stay smart regardless of who you're with. A communications hub links the meter and the in-home display to this national network, and by 31 May 2026 over 11.1 million SMETS1 meters had been migrated onto the DCC so they behave like SMETS2. If your meter went "dumb" after switching supplier, it's almost always an un-migrated SMETS1 unit rather than a fault.
What does the in-home display show you?
The in-home display (IHD) is a small handheld screen, provided free with installation, that shows your electricity use updating in near real time and your gas use updating roughly every 30 minutes, alongside a running cost estimate in pounds and pence. It's designed to make consumption visible enough that you notice when a kettle, tumble dryer, or immersion heater switches on, which is the single biggest lever most households have for cutting bills without buying anything. The IHD works independently of your broadband — it talks to the meter and the national network directly — so it keeps working through a Wi-Fi outage, though some suppliers also offer an app-based equivalent. For a much more granular view, including per-device usage and automation triggers, that same data can be pulled into a smart home system; see our Home Assistant energy monitoring UK guide for the hardware and integrations that make that possible.
Does installing a smart meter cost anything?
No — installation is free, funded through suppliers' operating costs rather than charged directly to the household, and there's no separate fee for the in-home display. Your supplier is legally obliged to offer you a smart meter and to make reasonable attempts to install one, but domestic customers are not legally required to accept, and you can decline without it affecting your tariff, pricing or service. If you refuse, your supplier can typically still fit the physical meter but leave it running in "dumb" mode with the communications switched off, so it behaves like a traditional meter until you change your mind. The one exception the government has floated is where energy theft is suspected, in which case the right to refuse may not apply.
Are smart meters safe — what about the radio signal?
Yes. The UK Health Security Agency (formerly Public Health England) reviewed the radio frequency emissions from smart meters and concluded that exposure is well below international guideline levels set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP), typically around a million times lower than those limits, and lower than exposure from a mobile phone or a home Wi-Fi router. Smart meters sold in Britain have to pass UK and EU safety and electromagnetic compatibility standards before installation, and there is no established evidence linking them to health effects. The communications hub only transmits in short bursts to relay meter readings, not continuously.
SMETS1 vs SMETS2: does the generation matter?
For most households the practical difference has narrowed as the DCC migration programme has progressed, but it still matters if your meter hasn't been migrated yet. A SMETS2 meter is connected to the national DCC network from day one, so smart functions — remote readings, tariff updates, in-home display data — survive a supplier switch automatically. An un-migrated SMETS1 meter only talks reliably to the supplier that installed it; switch away and it can revert to manual-read mode until it's enrolled onto the DCC or replaced. If you're on an older SMETS1 meter and it's misbehaving after a switch, ask your current supplier whether it's DCC-enrolled before requesting a swap — enrolment is free and often resolves the issue without a new installation visit.
| Feature | SMETS1 (unmigrated) | SMETS2 / migrated SMETS1 |
|---|---|---|
| Works after switching supplier | Often reverts to manual mode | Stays smart automatically |
| National DCC network | Not connected (pre-migration) | Connected from day one |
| In-home display data | May stop updating after a switch | Continues working |
| Remote/automatic readings | Only with original supplier | Available to any supplier |
| Fix if not working | Request DCC enrolment (free) | N/A |
Can you get your smart meter's data into Home Assistant?
Yes, and it's one of the most useful energy add-ons for a UK Home Assistant setup because it turns billing-cycle guesswork into a live feed you can graph, alert on, and automate against. The two common routes are Hildebrand Glow, which pulls SMETS2 data via the DCC (or locally via MQTT if you have a Glow CAD/display), and the unofficial Octopus Energy integration, which layers in tariff rates for households on time-of-use plans like Agile. Both plug into Home Assistant's built-in Energy Dashboard, which has tracked grid consumption, gas and solar since it shipped in 2021.8 and now handles real-time power alongside historical trends. If your tariff bills you by half-hourly rate, our Octopus Energy smart tariffs UK guide covers which plans actually reward this kind of live monitoring. For a broader look at hardware options — smart plugs, clamp meters, and meter bridges — beyond the meter feed itself, see the best home energy monitors UK roundup.
Is a smart meter worth having?
For most UK households, yes — it removes estimated billing, shows you where money is actually going, and is a prerequisite for time-of-use tariffs that can meaningfully cut electricity costs if you can shift some usage off-peak. The trade-offs are minor: a small minority of properties get poor signal (thick walls, rural areas with weak mobile coverage for the communications hub) and older SMETS1 installs occasionally need a free DCC enrolment fix after switching supplier. If you're already running Home Assistant, the meter becomes more than a billing tool — it's a free, always-on data source for automations, cost tracking and appliance-level insight that would otherwise need separate hardware.
