How Does a Smart Meter Work?

A smart meter is a gas or electricity meter that measures consumption and sends the readings to the energy supplier automatically, without anyone visiting the property or reading a dial¹. It replaces the meter already in the house and does the same job of measuring, with two additions: it can communicate in both directions, sending and receiving information wirelessly², and it comes with an in-home display that shows energy use and its cost in near real time³.

The readings do not travel over home broadband. They go across a separate national network run by the Data Communications Company, which is used solely for smart metering, does not connect to the public internet or home Wi-Fi, and wraps the data in two layers of encryption before it leaves the house⁴. Electricity consumption can be recorded every half hour and transmitted⁷, and readings reach the supplier at least once a month, with half-hourly, daily or in some cases monthly schedules in use⁸.

Three parts make the system work: the meter itself, the communications link to the supplier, and the display in the kitchen. Nothing in it generates energy, stores it or reduces a unit price. A smart meter does not automatically save money⁹: it measures, and what a household does with the measurement determines whether anything changes.

What a smart meter is and what it does

A smart meter measures how much gas and electricity a property uses, and sends that data directly to the energy supplier¹. Suppliers use the data to bill for energy actually used rather than estimated, to offer products and services such as new tariffs where the household has given permission, and to help make the energy system more efficient by recording demand more accurately².

The functional difference from a traditional meter is two-way communication: a smart meter can send and receive information wirelessly¹⁵. That is what makes remote operations possible, including changing the meter between credit and prepayment mode without a new meter being fitted, and adding prepayment credit over the air⁵.

Accurate billing is the change most households notice first. Energy use is recorded automatically in half-hour periods, which allows suppliers to bill on actual consumption³. What it does not do is identify individual appliances. A smart meter measures household energy use as a whole and does not know when a particular appliance is switched on or off¹⁶. Appliance-level detail needs separate equipment, such as smart plugs or a home energy monitor.

The parts: meter, home area network, in-home display

A smart metering installation has two visible parts: the meter or meters, and the display screen¹⁷. Between them sits the home area network, a secure short-range link. The meter sends data to the in-home display using the home area network¹¹. That local link is why the display is paired to the meter in that specific property, and why it is left behind on moving out¹⁸.

Beyond the house, readings are transmitted to a wide area network made up of mobile phone or radio masts, and on to the supplier⁵. The distinction matters in practice: a display showing nothing while the supplier still receives readings is a home area network or display problem, whereas readings that stop arriving while the display still works points at the wide area link. The technical rules behind both are set by the Smart Meter Equipment Technical Specification, known as SMETS¹⁹; the difference between the first and second generation is covered on the page on SMETS1 and SMETS2 meters.

How readings travel: the DCC's secure network, not your Wi-Fi

When a smart meter is installed, readings are sent automatically over the DCC's secure network to the energy supplier⁴. Sending a reading does not require an internet connection, because the meters work on the DCC's secure, standalone network¹¹. Smart Energy GB states the position flatly for households worried about their broadband:

No home Wi-Fi, broadband, router or internet package is needed for a smart meter to send readings¹². The network carries two layers of encryption and operates entirely separately from the public internet⁶, and the DCC states that data is wrapped in those two layers before transmission over a dedicated communications system, backed by the National Cyber Security Centre and in line with governance and data protection standards¹¹. The most heavily used message type on the network is the meter read, which lets suppliers read energy usage remotely⁵. Through the same network, smart meter data can be shared securely between authorised users to support smart energy services⁶.

For the household, the practical consequence is a dependency swap. There is no reliance on a home router, but there is reliance on mobile or radio coverage at the meter position and on the DCC's central systems continuing to run. Where coverage is poor, a meter can be installed and still fail to communicate. More detail sits on the page about how smart meters communicate.

The in-home display: what it shows and how often it updates

Smart meters come with an in-home display so that households can see and manage energy use³. It is a portable touchscreen device showing near real-time energy usage data⁶, covering how much energy is being used and what it is costing, over the day, week or month²⁰.

Near real time is the accurate description: the display is fed by the meter over the home area network, not by the supplier's billing system, so it responds to a kettle or an oven within seconds rather than showing yesterday's account balance. That immediacy is the mechanism by which the display can change behaviour, and it is also the limit: the figure covers the whole property at once, so isolating one appliance means switching things off and watching what moves.

Displays can break, and cover exists. If a display breaks or goes missing in the first twelve months, a free replacement is available from the energy supplier²¹. Replacing a display should not involve replacing the meters: the new display is paired with the existing smart meter²². More on what the screens show is on the page about in-home displays.

Credit mode and prepay mode: two ways the display works

All smart meters can operate in prepayment or credit mode²³, and the display has two modes to match, depending on how energy is paid for⁴. In credit mode the display concentrates on consumption and cost. In prepay mode, credit in pounds and pence appears on the display alongside consumption²⁴.

The change between modes does not usually need new hardware. Because smart meters are set up to work for both prepay and credit customers, a supplier can switch between credit and prepay without a whole new meter²⁵, and can switch a meter to credit mode remotely²⁶.

Ofgem states that a household with a smart prepayment meter may be able to top up online or using the supplier's app²⁹. Shop top-ups remain available²⁷. One point worth stating plainly: a smart meter cannot cut off power by itself³⁰. Remote disconnection is a supplier action governed by rules, not something the meter decides. The subject is developed on the page on smart prepayment meters.

What data is sent, and what is not stored

The meter sends meter readings and the technical information needed for billing, meter operation and smart services. It does not record conversations, browsing history, personal activities or details about individual appliances¹². Personal details such as name, address and bank account details are not stored on, or transmitted by, the meter⁸.

Smart meters only give data about how much energy is used¹⁷. Readings can only be shared with the energy supplier, and the supplier cannot share them further without permission³¹. Electricity consumption can be recorded every half hour and transmitted, which is the basis of half-hourly settlement in the wholesale market⁷.

Households wanting the data for their own purposes, held locally rather than only in a supplier's systems, need a separate route: see consumer access devices and smart meter data.

Accuracy: certified, and the same as a traditional meter

By law, all smart meters must be approved by and certified by the Office for Product Safety and Standards to prove their accuracy¹³. The Office for Product Safety and Standards ensures that electricity meters are accurate, working closely with energy suppliers³². For measuring electricity or gas usage, smart meters are as accurate as traditional meters¹³.

Communication failure and measurement failure are different things, and conflating them is the commonest confusion about smart metering. Most smart meters operate exactly as they should, and of those that do not, they still accurately measure energy use³³. A meter that has lost its link records consumption correctly; what stops is the automatic reading. The remedy in that case is a manual reading, not a new meter.

The Smart Metering Installation Code of Practice also requires that companies properly explain how the smart meters work, and outline how households can use the data available to them to improve their energy efficiency³⁴. Accuracy disputes have a formal route through the supplier and, ultimately, meter examination³². See smart meter standards and accuracy.

What a smart meter costs, and why it will not save money by itself

There is no direct cost for a smart meter, and expenses are recouped through energy bills over time¹. Installation and maintenance are covered by standing charges, as with traditional meters¹⁴, and installation is provided at no extra charge by the supplier²².

The saving question needs care. Citizens Advice puts it plainly: a smart meter will not automatically save money⁹. It does not automatically save energy, although it can help a household manage usage more easily³⁵. Smart meters do not directly reduce electricity or gas unit prices. What they change is information: near real-time feedback on the display, accurate rather than estimated bills, and eligibility for tariffs that price by time. A household that looks at the display, identifies waste and acts can save; a household that does not will see the same consumption billed more accurately. Figures on typical savings are discussed on how much a smart meter can save and smart meter cost.

Tariffs and flexibility: dual-rate and time-of-use options

A smart meter gives access to more flexible tariffs, including dual-rate tariffs². Smart meters are compatible with Economy 7 tariffs and fixed rate tariffs, and can enable newer time-of-use tariffs, allowing a change of tariff without changing the meter³⁶. Time-of-use tariffs use the smart meter to log electricity use and charge different rates during different time windows³⁷.

That capability is the main technical reason a household interested in energy independence would want one. Shifting a battery charge, an immersion heater or an electric vehicle into a cheap window only pays if the meter can tell the supplier when the energy was used. Customers need a smart meter to get all the benefits from new flexible energy tariffs³⁸, and access to time-of-use tariffs brings cheaper rates during off-peak hours and incentives for using energy on high-supply days¹. The trade-off is that the same mechanism allows higher prices at peak times. See smart meters and time-of-use tariffs and household flexibility and reward schemes.

Smart mode, dumb mode and switching supplier

A meter in "dumb" mode still measures but no longer reports. Ofgem lists the situations in which a meter is not operating in smart mode: it loses connection with the supplier, it loses connection after a change of supplier, or it was installed without being connected to the national communication system³⁹. Citizens Advice adds two common triggers: having an older type of smart meter and switching supplier, or a supplier going out of business⁴⁰.

Where a supplier fails, the meter may not work in smart mode with the new supplier, and readings may have to be taken manually and submitted; the meter may work in smart mode again after a change of tariff or supplier⁴¹. First-generation SMETS1 meters are the usual cause: they can lose their smart functions on switching, although the majority have now been reconnected to the smart meter network. Second-generation meters keep all their smart functions across suppliers with no interruption⁸.

A meter can also be deliberately set to work in dumb mode, with all communications switched off⁴³. More at why a smart meter is in dumb mode.

Faults and fixes: who is responsible

The supplier is responsible for installing the meter and for making sure it works properly⁹. If a smart meter stops working, the supplier handles maintenance and will fix or replace the meter as needed¹, and should send someone to look at the problem⁴³. The two common symptoms are that a meter stops recording energy used, or no longer sends readings to the supplier².

Compensation rules apply to some failures. Under the smart meter Guaranteed Standards, if an installation fails due to a fault within the energy supplier's control, the consumer receives compensation⁴⁴. Ofgem intends to review the outcomes of those standards in the first quarter of 2027. Citizens Advice has recommended closing the accountability gap between energy suppliers and the DCC so that suppliers are held accountable when smart metering equipment does not work, including changes to DCC contracts if needed⁴⁵. The practical point for a household is that there is one point of contact, the supplier, regardless of which part of the chain has failed. See smart meter faults and troubleshooting.

The rollout: who can get one, and by when

Energy suppliers have been rolling out smart meters since 2012⁴⁶. A four-year Rollout Framework ran from 1 January 2022 to 31 December 2025, setting installation obligations on suppliers⁴⁷, and the DCC refers to completing the rollout by the end of 2030⁴⁸. Once government considers the rollout complete, responsibility for smart metering passes to Ofgem and the Smart Energy Code governance⁴⁶.

Coverage is not universal. The National Audit Office recorded the government's proposal for 80% of homes to have smart meters by the end of 2025, and noted that a technical solution allowing smart meters to function in more than 99% of homes was expected from July 2023⁴⁹. Smart meter uptake rose from 62% in August and September 2023 to 68% in January 2025⁵⁰.

Installation is not compulsory. A household offered one can refuse⁵¹, and there is currently no requirement for suppliers to install a smart meter on request, although a household that wants one can contact its supplier¹⁵. Any household that pays for energy, whether owning or renting, should be able to book an installation where the meter is expected to work at the property³. Which? notes that in practice most energy companies no longer stock traditional meters, so a meter due for replacement is usually replaced with a smart one⁵². Arrangements differ across the UK: Northern Ireland has its own position, covered on smart meters in Northern Ireland, alongside pages for Scotland and Wales.

Renting, solar panels and moving house

Renters who pay the gas or electricity bills can choose to have a smart meter installed⁵³. The Energy Ombudsman states that a private renter can choose one if the bills are in their name or they prepay for energy, after checking the tenancy agreement and letting the landlord know¹⁵. There may be rules in a tenancy contract about how energy is supplied, including the type of meter that can be fitted⁵³. Where a tenant has no smart meter, readings are estimated; with one, readings go to the supplier automatically so the landlord does not need to estimate⁵⁴. See monitoring in flats and rented homes.

Solar is not a barrier: smart meters are designed to be able to work with solar panels, and the supplier should be able to offer one as part of the rollout⁵³. Export arrangements are covered on export metering and limitation.

On moving, the in-home display stays. It is designed to work with the smart meter at that property and will not normally work elsewhere, so it is left for whoever moves in⁵⁵; the same applies to tenants moving out of a rented home⁵⁶. On arrival at a new address, seeing current energy use on the display indicates the meter is in smart mode⁵⁵.

What it means for a household's independence

A smart meter adds no generation, no storage and no control. It removes the dependence on estimated billing and on someone reading a dial, and it opens the door to tariffs that reward shifting consumption, which is the precondition for a battery or heat pump being run economically. Set against that, it introduces dependence on the DCC network and its mobile or radio coverage, on the supplier for maintenance and for the display, and on the supplier's systems for the data itself, since readings can only be shared with the supplier and cannot be passed on without permission³¹. For a household that wants its own consumption data held locally, the meter is a starting point rather than a solution; the wider picture is set out in the guide to smart meters and home energy management and on smart meters, monitoring and energy independence.