SMETS1 and SMETS2 Smart Meters Explained

A smart meter automatically sends your electricity and gas meter readings to your supplier, so you get bills based on accurate readings rather than estimates¹. Alongside the meter itself, most installations include an in-home display, a small portable screen that shows your energy use as it happens, giving a level of transparency the old meter cupboard never could². The data it puts in front of you is what the whole system is for: it puts you in control of your energy usage, so you can see where energy is going and take steps to cut it, and cut your emissions with it³.

Behind the familiar screen on the kitchen table, though, there are two quite different generations of smart meter in British homes, and which one you have matters. A SMETS2 meter, the modern type, keeps working normally when you change energy supplier. A SMETS1 meter, the earlier type, could go "dumb" after a switch, leaving you reading the meter by hand again. The good news is that about 12 million SMETS1 meters have now been connected to the national network by over-the-air software updates⁴, so the problem is far smaller than it once was. This page explains both generations, how to tell them apart, and what each means for your household.

How a smart meter works in your house

Strip away the jargon and a smart meter does two jobs. First, it measures your electricity and gas use exactly as a traditional meter does, but instead of waiting for someone to read the dials, it sends those readings to your supplier automatically¹. Second, it feeds a separate in-home display unit, the portable screen most households put somewhere visible, which shows consumption in near real time².

The practical effect on billing is immediate. Because readings arrive automatically, bills are based on accurate meter readings and not estimates¹, which ends the familiar cycle of estimated bills followed by a large correcting bill. For prepayment customers the change is just as significant: credit information travels to and from the meter remotely, so topping up no longer depends on walking to a shop with a key or card.

The deeper value is informational. The data provided by your smart meter puts you in control of your energy usage, meaning you can take energy-saving steps to reduce your CO2 emissions³. Households that can see what the tumble dryer or the immersion heater actually cost tend to use that knowledge: the display turns an invisible monthly total into a visible, minute-by-minute number.

For a household working towards energy independence, that visibility is the foundation. You cannot sensibly size a solar array, a battery or a heat pump without knowing your consumption pattern, and a smart meter records it for you. What a smart meter does not do is reduce consumption by itself; it is a measuring instrument, and the savings come from what the measurements prompt you to change. How the meter talks to the outside world, and who controls that link, is where the two generations differ, and that is the subject of the rest of this page.

The two smart meter generations explained: SMETS1 and SMETS2

"SMETS" is the acronym for "Smart Metering Equipment Technical Specifications", the technical standard that smart meters in Great Britain are built to⁸. There have been two versions. First-generation meters, SMETS1, were installed from the start of the rollout. Second-generation meters, known as SMETS2, started being installed in 2018⁴, and every new smart meter installation now uses SMETS2⁹.

The difference between them is not the measuring, which both do to the same standard, but the communications. All first-generation smart meters use a third-party communications network to send metering information to the energy supplier⁹. Each supplier arranged its own communications for the meters it installed, which is why a SMETS1 meter's behaviour depended on who installed it and who supplies you now. SMETS2 meters use a bespoke secure smart data network called the DCC, the Data Communications Company, to communicate⁸.

There is also a hardware deadline built into the older generation. SMETS1 meters were designed with an integrated 2G Communications Hub, and any remaining SMETS1 meters which have not been upgraded to SMETS2 will need to be physically replaced prior to 2033, in line with the SMETS1 communication provider contracts⁷. The 2G network that carries their signals is being switched off, so the meters that still depend on it have a fixed end date.

For a householder trying to identify which generation is on the wall, the meter itself gives few clues by sight, since both look like a plain box with a small display. The reliable route is to ask your supplier, or use the checking tools available: Smart Energy GB and the DCC both offer ways to establish what you have, and the DCC has worked with Citizens Advice to provide a tool that allows you to check whether your meter has been migrated onto the DCC network¹⁰. If your meter was installed before 2018 it is SMETS1; from 2018 onwards it is increasingly likely to be SMETS2.

SMETS2 meters link straight to the DCC, so smart features survive a switch

The defining design decision of SMETS2 is that the meter was built to connect directly to the DCC's secure national network¹⁰, the same nationwide network for every supplier, rather than to a communications arrangement chosen by whichever supplier installed it. That single change is what fixed the biggest complaint of the first generation.

Because every supplier reads a SMETS2 meter through the same national network, SMETS2 meters allow consumers to switch supplier while retaining smart functionality, including automatic meter readings¹¹. The switch is described by the DCC as seamless: consumers can switch between energy suppliers because the meters are connected to a nationwide secure smart meter network⁴. In practice, a household with a SMETS2 meter can switch energy suppliers without any interruption to its energy readings or bill payments⁸.

This matters beyond convenience. When you have a smart meter installed, all the readings are automatically sent via the DCC's secure network to your energy supplier¹², and that flow continues regardless of which company's name is on the bill. The household's data relationship is with the metering system, not with one supplier's proprietary setup. Cross-compatibility, as the Energy Ombudsman puts it, means a smart meter will keep its smart functions across all energy suppliers, so if you switch supplier, your meter will continue to work as a smart meter⁹.

There is still a dependence to be honest about: the DCC network itself. A SMETS2 household does not depend on its supplier for the communications link, but it does depend on the national network operating, and on the DCC as an organisation. That is a far more durable dependency than a single supplier's system, since the DCC's network is regulated infrastructure serving the whole market, but it is a dependency all the same. If the network link fails, the meter keeps measuring; what stops is the automatic sending, and manual readings fill the gap.

SMETS1 limitations and the upgrade programme

The weakness of SMETS1 was structural. Because each meter spoke to a communications service arranged by its installing supplier, some SMETS1 meters could lose smart functionality when a consumer switched energy supplier¹⁰. In the language the industry settled on, the meters could temporarily go "dumb" and lose their ability to send automatic meter readings after a switch¹¹. First-generation smart gas and electricity meters don't always allow the consumer to change energy supplier without losing the ability to send meter readings automatically⁴.

The fix has been a large migration programme. SMETS1 meters need to be upgraded to work on the DCC's new unified system, and this software upgrade is managed remotely by DCC⁵, meaning no visit to your home. Through the SMETS1 migration programme, millions of first-generation smart meters were enrolled onto the DCC network, helping to restore smart functionality to these meters¹⁰. About 12 million of these first-generation smart meters have now been connected to the DCC's network via over-the-air software updates⁴. The scale of progress is visible in the figures: as of August 2023, there were over 11 million SMETS1 meters connected to the DCC network⁵, a count that has continued to rise since.

Not every meter can be migrated. In June 2023, the Department told the Public Accounts Committee it might not be possible to enrol 500,000 of these SMETS1 meters, in which case they might ultimately need to be replaced⁶. Where migration is not possible, an energy supplier may replace the meter with a SMETS2 meter¹¹. So a household with an old SMETS1 meter faces one of three outcomes:

1. The meter is enrolled over the air onto the DCC network and keeps working⁵.
2. It cannot be enrolled, and the supplier replaces it with a SMETS2 meter¹¹.
3. It still relies on its 2G Communications Hub, and will need to be physically replaced before 2033 in any case⁷.

Almost all SMETS1 meters that DCC can proactively identify and upgrade have now been migrated, restoring smart functionality¹¹. If you have a SMETS1 meter and it is behaving dumb, the first step is to check whether it has been migrated, using the Citizens Advice-backed tool¹⁰, and then to speak to your supplier, since the migration programme exists precisely to end this problem.

Switching energy supplier: the process

Putting the two generations together, the switching picture is straightforward. With a SMETS2 meter, the switch should be seamless: readings keep flowing to the new supplier automatically, with no interruption to your readings or bill payments⁸.

With a SMETS1 meter that has not been enrolled onto the DCC network, the position is different. SMETS1 meters can temporarily lose some of their functionality following a switch⁸. Your meter may not work in smart mode when you move to the new supplier, and you may need to take meter readings manually and submit them to your new supplier instead¹³. The meter keeps measuring accurately throughout; what is lost is the automatic sending, and with it the in-home display's live link in some cases.

There are two further wrinkles worth knowing:

• You can switch suppliers if you have a smart meter, but your new supplier might not offer all the smart meter services such as remote meter readings, and the meter may need replacing¹⁴.
• The same dumb-mode effect can appear for reasons other than switching: if you have an older first-generation SMETS1 meter and you have switched supplier following its installation, your smart meter may not be working in smart mode⁸, which is a common experience for solar households whose meter predates their panels.

The remedy in every case is the same: check whether the meter has been migrated onto the DCC network¹⁰, and if it has not, ask your supplier about enrolment or replacement. Manual readings remain available throughout, so you are never left without a way to be billed accurately. For a household that treats switching as a routine part of managing energy costs, a SMETS2 meter removes the one friction the first generation created.

Free of charge from your supplier

The cost position is unambiguous and consistent across every official source: a smart meter is free. Contact your supplier to get a smart meter for free¹. You can get a smart meter installed by your energy supplier at no extra cost¹⁶, and the same statement appears again from the DCC: installation is at no extra cost¹⁸.

There is no installation charge, no rental charge for the meter, and no fee for the in-home display. The costs of the national programme are recovered through energy bills generally rather than through a charge to the household that receives the meter, which is why the price a household pays is nothing at the point of installation. Smart meters are also free to use, and are available for payment-on-account or prepay customers alike¹¹.

For a household weighing up the value, the honest framing is this: the meter costs nothing, and in exchange the household gains accurate billing, an end to estimated bills, and the consumption data that underpins any later investment in solar, storage or heating changes. What it does not deliver is a saving by itself; the meter measures, and the household acts. The smart meter cost question is therefore less "what does it cost" than "what do I do with what it shows me".

How your readings reach your supplier, plus data and security

The meter automatically sends your energy usage data to your supplier using a secure network¹⁹. That network is the DCC's standalone system, and it is deliberately separate from the internet. Your smart meter doesn't need, or connect to, the public internet or your home Wi-Fi²⁰. Sending a meter reading doesn't require an internet connection, as smart meters work using the DCC's secure, standalone network⁴.

This answers one of the most common household worries in one stroke: no, the meter does not sit on your home network, it cannot be reached through your router, and it does not slow your broadband or compete with it for bandwidth. SMETS2 meters use the DCC's bespoke secure network to communicate, meaning you don't need to have good mobile signal in your home for the meter to work⁸. SMETS1 meters, before migration, use a third-party communications network to send metering information to the energy supplier⁹, which is the older arrangement described above.

The security of the system is treated as a design requirement rather than an afterthought, and the network is described consistently in official material as secure¹⁹. For a household thinking about independence, the data picture is worth understanding plainly: the meter records your consumption in detail, and that data has real value, both to you, for sizing and managing your own energy use, and to your supplier, for billing and settlement. The household's control over who sees that data is a subject in its own right, covered in smart meter data and smart meter security. The dependence that remains is on the DCC network carrying the readings; the measuring itself, and the in-home display, keep working locally whatever happens to the link.

What a smart meter enables: prepayment and tariffs

For prepayment customers the smart meter is more than a convenience. Smart meters are free to use and available for payment-on-account or prepay customers¹¹, and a smart prepayment meter changes how topping up works: you may be able to top up online or using your supplier's mobile app²¹. Cash is not excluded, since you can still pay at a local Paypoint store or Post Office using the meter's key or card, or a barcode for smart prepayment meters²¹. So the full range of payment habits survives the change to a smart meter.

On credit tariffs, the meter opens doors that a traditional meter cannot. With a smart meter you can access more flexible tariffs, including dual-rate tariffs¹, because the supplier can bill against the time of day the energy was actually used rather than a single flat reading. Time-of-use tariffs, where electricity costs less at certain hours, depend on the meter recording when you use power, which is exactly what a smart meter does. The smart meters and time-of-use tariffs relationship is the practical expression of this, and half-hourly settlement, covered under half-hourly settlement, is the market change behind it.

For a household with solar panels, or planning them, the same data serves a second purpose: it shows what you import from the grid hour by hour, which is the number you need for sizing a battery or judging whether export payments are worthwhile. The smart meter with solar panels question is a common one, and the answer is that the meter and the panels coexist well, provided the meter is working in smart mode.

Situations where a smart meter may not function, and your right to say no

No law compels a household to have a smart meter. It is your right to refuse the installation of a smart meter, though replacement options may be limited if a traditional meter is faulty or unsafe⁹, because suppliers are no longer installing old-style meters as standard. The DCC states the position plainly: you can get a smart meter installed by your energy supplier at no extra cost, but the choice remains yours¹⁸.

The regulatory framework has recently tightened around how suppliers handle refusals and installations. Under the conditions attached to first-time smart meter appointments, the obligation on a supplier does not apply where:

• it reasonably concludes a smart meter cannot be successfully installed;
• remote meter readings would not be received; or
• the customer has, on or after 23rd February 2026, actively refused one or more offers of a first-time smart meter appointment²².

Meters can also fail in use. Your smart meter may stop recording the energy you use, or may no longer send readings to your supplier¹. When that happens the meter is said not to be operating in smart mode, and Ofgem has been consulting on guaranteed standards to govern it. The proposed standard covers a smart meter not operating in smart mode where no action of another party, other than the energy supplier, is required to provide a resolution, the consumer has not agreed to the meter not operating in smart mode, and a solution exists that will resolve the issue²³. The consultation also sets out exemptions, including where the consumer has requested no communication, where no appropriate technical solution is available, and where the consumer's own role in booking appointments or interacting with the meter is the obstacle²². The standard would apply to both gas and electricity, SMETS1 and SMETS2 meters, including unenrolled SMETS1 meters²². Even when a meter is not operating in smart mode, you will also still be able to take manual readings²⁴, so billing accuracy does not depend on the smart link.

There are also situations where installation is genuinely difficult, for example some flats with communal meter boxes or properties where the meter is outside the home; in those cases you can still apply, and the supplier assesses what is possible⁴. The why you cannot get a smart meter page covers the practical obstacles in detail.

The national rollout and future plans

The rollout has a long history and a firm direction of travel. The Government's original target was to effectively complete the rollout by 2019²⁵, a date that passed unmet, and the Public Accounts Committee has been blunt in its assessment of the programme's delays. After a six-month extension to the existing obligation, a new four-year framework was implemented from July 2021²⁶, and that four-year obligation has now concluded²⁷.

What follows is a period of consolidation rather than a fresh installation drive. The programme will review further opportunities to use observed data in place of model assumptions ahead of reporting on the rollout to end 2025²⁹, which signals a shift from installing meters to making the installed base work properly. Two fixed points shape what happens to the meters already on walls:

• Half-hourly settlement: the Market-wide Half-Hourly Settlement programme remains on track to migrate all meters by May 2027³⁰, a market change that depends on the smart meter base.
• The 2G switch-off: the 2G network will be switched off in 2033, with SMETS1 meters needing physical replacement and SMETS2 meters needing a replacement Communications Hub⁷, so the last of the first generation has a hard end date.

For households, the practical reading of all this is reassuring. The migration programme has already enrolled almost all the SMETS1 meters DCC can proactively identify and upgrade¹¹, so the dumb-meter problem is largely historical. Any SMETS1 meter still working today will either be upgraded over the air or replaced before the 2G switch-off, at no charge to the household. The direction of the market, from half-hourly settlement to time-of-use tariffs to flexibility services, all assumes a smart meter in the home, and the SMETS2 network is the piece of infrastructure that makes a household's data portable between suppliers rather than locked to one. That portability, more than any single feature, is what the second generation was built to deliver.