What Is a Smart Meter and How Does It Work?

Smart meters are becoming a normal part of the UK’s energy system. Millions of homes now have them, and energy suppliers are continuing to replace traditional meters with smart meters.

But what actually makes a meter “smart”?

A smart meter does the basic job of any energy meter: it measures how much electricity or gas you use. The difference is that it can also communicate information electronically. This allows meter readings to be sent to your energy supplier automatically, rather than relying on you to read the meter and submit the figures yourself.

Smart meters can also give you much more information about your energy consumption. An accompanying in-home display can show how much energy you are using and, depending on your tariff and equipment, what that energy is costing you.

This can help you understand where your energy is going, avoid estimated bills and make better use of tariffs that charge different prices at different times.

However, a smart meter is not an automatic money-saving device. It does not make electricity or gas cheaper simply because it has been installed. The financial benefit comes from having better information, more accurate billing and access to services that can help you manage when and how you use energy.

This guide explains what smart meters are, how they work, how they are used in the UK, what happens to your data, what happens when you switch supplier, and what to do if your smart meter stops communicating.

What Is a Smart Meter?

A smart meter is a digital energy meter that measures your electricity or gas consumption and can communicate meter readings to your energy supplier.

Traditional meters measure energy consumption, but normally require someone to physically read the meter. If you do not provide a reading, your supplier may have to estimate how much energy you have used.

A smart meter is designed to remove much of that manual process.

When it is operating correctly in smart mode, the meter can send readings automatically to your supplier. Ofgem requires suppliers to take all reasonable steps to ensure smart meters automatically send readings.

This means you normally do not need to walk to your meter and read the numbers yourself every month.

What Does a Smart Meter Actually Measure?

A smart meter measures your energy consumption in kilowatt-hours (kWh).

For electricity, the meter measures the amount of electrical energy your property uses.

For gas, the smart gas meter measures the volume of gas passing through the meter. The information is then used by the energy supplier to calculate your consumption in the units needed for billing.

Your supplier combines your consumption information with the unit rates and standing charges that apply to your tariff to calculate your bill.

What Makes a Smart Meter Different from a Traditional Meter?

The biggest difference is communication.

The smart meter is therefore more than a digital version of an old meter. It is part of a communications system that allows information to move between your property, your energy supplier and the wider energy market.

How Does a Smart Meter Work?

The easiest way to understand a smart meter is to follow the information from your home to your supplier.

1. Your meter measures your energy consumption.
2. The meter stores the consumption information.
3. The smart meter communications equipment sends the relevant data through the smart metering communications network.
4. The information reaches your energy supplier.
5. Your supplier uses the readings for billing and other services you have agreed to receive.
6. Your in-home display can provide you with information about your consumption and, where supported, its cost.

The communications network is an important part of the system. In Great Britain, the Data Communications Company (DCC) operates the centralised communications network used for smart metering. Ofgem regulates the DCC.

What Is the Smart Meter Network?

In Great Britain, smart meters communicate through the dedicated smart metering communications infrastructure. This includes a Wide Area Network (WAN) that allows the meter to communicate beyond your property.

The WAN uses communications technologies including mobile phone and radio signals, depending on where you live and the equipment installed. The WAN is the network used to send smart meter readings to the supplier and that the DCC is responsible for the WAN.

Does a Smart Meter Need Wi-Fi?

No, your smart meter does not need your home’s Wi-Fi connection to send its meter readings.

The smart meter has its own communications arrangements. Your in-home display is also designed to communicate with the smart meter rather than relying on your home’s Wi-Fi.

This means that changing your broadband provider or having your home Wi-Fi temporarily disconnected does not normally stop your smart meter from recording energy consumption.

It is useful to separate the three systems:

• Smart meter: measures your energy use.
• Smart metering communications network: transfers relevant meter information between the meter and authorised industry participants.
• In-home display: gives you information about your energy use inside your home.

What Is an In-Home Display?

When you have a smart meter installed, your supplier may provide an in-home display (IHD).

The IHD is a small portable screen that you can place somewhere convenient in your home. It is not the smart meter itself.

The display can show information such as:

• how much electricity you are using
• how much gas you are using
• your consumption in kWh
• an estimate of the cost of your energy use
• information over different time periods, depending on the model.

This can allow you to examine consumption over periods such as the current day, week, month or year.

Why Is the In-Home Display Useful?

A traditional energy bill tells you what you have used over a past period. An in-home display can help you see what is happening while you are using energy.

For example, you might notice that your electricity use rises sharply when you:

• turn on an electric shower
• use a tumble dryer
• run a dishwasher
• switch on an electric heater
• charge an electric vehicle.

You can use this information to identify which activities have the greatest effect on your electricity consumption.

Some displays also allow you to set a daily, weekly or monthly budget and alert you when you exceed it.

Will a Smart Meter Save Me Money?

Not automatically.

A smart meter does not reduce the price of electricity or gas simply by being installed.

What it can do is give you better information and more control over your energy use.

If you use the information from your smart meter to reduce unnecessary consumption, shift some electricity use to cheaper periods, or choose a tariff that better matches your circumstances, you may be able to reduce your costs.

How Smart Meters Help You Avoid Estimated Bills

With a traditional meter, your supplier needs meter readings to establish how much energy you have used.

If you do not provide readings, your supplier may estimate your consumption. An estimate can be higher or lower than your actual use. If estimates accumulate over time, you may eventually receive a bill that needs to be corrected when an actual reading becomes available.

A smart meter can reduce the need for this process because it can send readings automatically while operating in smart mode.

This can make billing more closely reflect your actual consumption.

Does a Smart Meter Mean Your Bills Are Always Accurate?

A working smart meter can greatly reduce the need for estimated readings, but it does not mean billing problems are impossible.

Problems can occur if the meter loses communications, if there is an issue with the supplier’s systems, or if information is not correctly transferred when you change supplier.

Smart meters that are not operating in smart mode can still record energy accurately, but they may no longer automatically send readings to the supplier. In that situation, you may need to provide manual readings until the communications problem is resolved.

What Does ‘Smart Mode’ Mean?

Smart mode means that your smart meter is communicating as intended and can automatically send readings to your supplier.

This distinction matters because a meter can still be physically measuring your energy correctly even if it is not communicating properly.

In other words:

• Meter working: it continues measuring your energy consumption.
• Smart mode: it is also communicating with the relevant systems so that readings can be sent automatically.

Ofgem’s latest published performance information shows that the vast majority of smart meters in Great Britain are operating in smart mode, although a proportion are not.

What Happens If My Smart Meter Stops Working in Smart Mode?

If your smart meter stops communicating, the meter does not necessarily stop measuring your energy use.

There are several possible reasons for a communications problem, including:

• a communications connection problem
• a problem following a supplier switch
• technical problems with the meter or communications equipment
• an issue with the wider smart metering network.

Your first point of contact should normally be your energy supplier. Suppliers have obligations relating to smart meter operation and that customers should contact their supplier if a meter is not operating in smart mode.

While the problem is being resolved, you may need to submit meter readings yourself.

What Are SMETS1 and SMETS2 Smart Meters?

You may have heard the terms SMETS1 and SMETS2.

SMETS stands for Smart Metering Equipment Technical Specifications. The terms describe different generations of smart meter technical standards used in Great Britain.

SMETS1

SMETS1 meters were installed during the earlier phase of the smart meter rollout.

Some early SMETS1 meters could lose aspects of their smart functionality when customers switched supplier. This was one of the problems the wider smart metering infrastructure was designed to address.

The majority of SMETS1 meters have subsequently been enrolled into the national communications network. This has allowed many of them to regain or retain smart functionality when customers change supplier.

SMETS2

SMETS2 is the later technical specification.

SMETS2 meters are designed to communicate through the national smart metering infrastructure and are interoperable between suppliers from installation.

This makes switching supplier more straightforward from a smart-meter communications perspective, although technical problems can still occur.

Can I Switch Supplier If I Have a Smart Meter?

Yes.

Having a smart meter does not prevent you from changing energy supplier.

One of the purposes of the national smart metering communications infrastructure is to make smart meters interoperable between suppliers.

However, if you have an older smart meter, it is sensible to check that it will continue to operate in smart mode after you switch. Some older SMETS1 meters experienced communications problems when customers changed supplier, although many have subsequently been enrolled into the national system.

Smart Meters and Electric Vehicles

Charging an electric vehicle can add a substantial new electricity demand to a household.

A smart meter can provide the measurement and communications capability needed by some tariffs that offer different electricity prices according to time.

This can allow an electric vehicle owner to consider charging during lower-cost periods where a suitable tariff is available.

Smart metering therefore forms part of the infrastructure that can make more flexible electricity use possible.

Smart Meters and Solar Panels

A household with solar generation can use some of its electricity on site and export surplus electricity to the grid.

Depending on the equipment and arrangements involved, smart metering can provide more detailed information about electricity imported from and exported to the network.

This can be particularly useful when considering export arrangements and tariffs designed for households that generate their own electricity.

Smart Meters and Heat Pumps

A heat pump uses electricity to provide heating, so a household moving away from a gas boiler may see a significant change in its electricity consumption pattern.

A smart meter can help the household understand how much electricity the heat pump is using and when that consumption occurs.

How Often Does a Smart Meter Send Readings?

The frequency depends on the meter, supplier, settings and service being used.

Commonly, smart meters are automatically set to send electricity readings every half hour and gas readings monthly. Customers may be able to change the frequency in accordance with the available options.

Customers can generally choose less frequent readings if they prefer, although the available settings and implications can vary by supplier and tariff.

More frequent readings can be particularly useful where you have a tariff based on when electricity is used.

Does a Smart Meter Send Information About Everything I Do?

No.

A smart meter measures your overall energy consumption. It does not normally identify individual appliances or tell your supplier that you have switched on a particular television, kettle or washing machine.

The meter may record that your electricity consumption increased substantially over a particular period. It does not ordinarily identify the precise appliance responsible.

This distinction is important when considering smart-meter data and privacy.

What Happens to Smart Meter Data?

Your smart meter generates information about your energy consumption, and that information can be used for legitimate purposes such as billing and providing energy services.

The smart metering system is designed with security and data protections. Suppliers and other organisations do not simply have unrestricted access to every piece of information your meter produces for any purpose.

In Great Britain, the smart metering system is regulated and includes the DCC, which operates the communications infrastructure connecting smart meters with authorised industry participants. Ofgem regulates the DCC and energy suppliers.

When considering a particular supplier or smart energy service, it is still sensible to read the supplier’s privacy information so that you understand how your data is used.

Can Smart Meters Be Used for Prepayment?

Yes.

A smart meter can operate in prepayment mode as well as supporting credit arrangements, depending on the customer’s circumstances and supplier’s arrangements.

Smart prepayment can make managing an account more convenient because some functions can be handled remotely.

For example, customers may be able to:

• top up online
• top up through an app
• check their balance
• access emergency credit where available
• receive information through an in-home display.

Smart prepayment meters can provide online top-up facilities and information such as remaining credit and emergency credit arrangements.

Can a Smart Meter Be Used as a Prepayment Meter Without Physically Replacing It?

In some circumstances, yes.

One of the advantages of smart metering is that certain functions can be managed remotely. A smart meter can support different modes of operation without necessarily requiring a physical meter replacement.

However, changing payment arrangements is subject to supplier processes and consumer-protection requirements. You should speak to your supplier if you want to understand your options.

Are Smart Meters Free to Have Installed?

For domestic customers, you do not normally pay a separate upfront charge for a smart meter installation arranged by your energy supplier.

The costs of the smart metering programme are part of the wider energy system and supplier costs rather than being presented as a separate installation bill to each household.

What Happens During a Smart Meter Installation?

Your energy supplier is responsible for arranging the installation and ensuring the meter works properly.

The installation normally involves:

1. An appointment is arranged.
2. A qualified installer arrives and explains the work.
3. The existing meter is replaced or upgraded.
4. The new smart meter is connected to the relevant communications system.
5. The installer checks that the equipment is operating correctly.
6. You are shown how to use the meter and in-home display.

The precise installation process depends on the property, existing meter, fuel type and equipment.

Does Getting a Smart Meter Change My Tariff?

Installing a smart meter does not automatically mean you have to change to a different energy tariff.

You can normally remain on your existing tariff, subject to its terms.

However, installing a smart meter may give you access to additional tariffs that require smart-meter data, particularly time-of-use tariffs.

This can create new options, but it does not mean you should automatically switch. Always compare the rates and conditions against your existing tariff.

Do I Have to Have a Smart Meter?

Smart meter installation is being driven by the national rollout programme and supplier obligations, but the precise arrangements around offering and installing a smart meter depend on your circumstances, supplier and property.

Your supplier should explain the installation and your options. If you have concerns about accessibility, the location of the meter or how the equipment will work in your property, raise these with your supplier before the appointment.

How Are Smart Meters Being Rolled Out in Great Britain?

The smart meter rollout in Great Britain is a national programme led by the UK Government’s Department for Energy Security and Net Zero, regulated by Ofgem and delivered through energy suppliers.

The programme has been developing for more than a decade. The technical standards and communications infrastructure have also evolved as the rollout has progressed.

By the first quarter of 2026, the programme had moved well beyond the early rollout stage. The government’s quarterly statistics report confirms that the majority of SMETS1 meters have been enrolled into the national communications network and that SMETS2 meters are connected to the DCC network from installation.

What About Smart Meters in Northern Ireland?

It is important not to assume that the Great Britain smart-meter system applies identically across the entire UK.

Northern Ireland has its own electricity and gas market arrangements and a separate regulatory framework. The Utility Regulator is responsible for regulating the electricity, gas and water industries in Northern Ireland.

Northern Ireland is now developing its own smart electricity meter rollout. In April 2026, the Department for the Economy published a policy decision on the design of the smart electricity meter rollout. The decision established an oversight structure involving the Department for the Economy and the Utility Regulator, with NIE Networks responsible for procuring and installing smart meters and supporting IT systems.

This means information about the Great Britain DCC, SMETS1 and SMETS2 arrangements should not automatically be applied to a household in Northern Ireland.

For a UK-wide audience, this distinction is important: smart metering is well established across Great Britain, while Northern Ireland is developing its own rollout framework.

Smart Meters and Energy Efficiency

A smart meter does not improve the energy efficiency of your home by itself.

It can, however, make energy consumption more visible.

This can help you identify patterns that would otherwise be difficult to see.

For example, you might discover that your electricity consumption remains unexpectedly high overnight. You could then investigate whether appliances, heating equipment or other devices are responsible.

You can also use the in-home display to compare your consumption before and after making changes.

This turns energy efficiency from something based largely on assumptions into something you can observe and measure.

Smart Meter Misconception: “It Will Make My Energy Cheaper”

A smart meter does not automatically reduce your tariff.

Your energy supplier still charges you according to your tariff’s unit rates and standing charges.

The potential financial benefit comes from what you do with the information and services the smart meter makes possible.

Smart Meter Misconception: “It Means I Never Need to Check Anything”

Smart meters are designed to reduce the need for manual readings, but it is still sensible to keep an eye on your bills.

Check that:

• your meter readings are being received
• your billed consumption looks reasonable
• your tariff rates are correct
• your standing charge is correct
• your account balance makes sense.

If something does not look right, contact your supplier rather than assuming the smart meter must be correct.

What Should I Do If My In-Home Display Stops Working?

A problem with your in-home display does not necessarily mean that your smart meter has stopped working.

The in-home display is a separate device that receives information from the smart meter.

If the display stops showing information:

1. Check that it has power or charged batteries.
2. Move it closer to the smart meter if appropriate.
3. Restart the display according to the manufacturer’s instructions.
4. Check whether your supplier’s app or online account is still receiving meter information.
5. Contact your supplier if the problem continues.

Your supplier may be able to repair or replace an in-home display depending on the circumstances.

What Should I Do If My Smart Meter Is Not Sending Readings?

Start by contacting your energy supplier.

Explain that your smart meter appears not to be communicating and ask them to check whether it is operating in smart mode.

If necessary, provide manual meter readings while the issue is investigated. This helps your supplier keep your account up to date and reduces the risk of your bills relying on estimates.

Do not assume that you need to replace the entire meter. A communications problem may have another cause.

Smart Meters for Small Businesses

Smart metering is also relevant to small and medium-sized businesses.

For a business, understanding when and where energy is being consumed can help identify avoidable costs.

For example, a business might discover that refrigeration, heating, ventilation, lighting or equipment is consuming significant amounts of electricity outside normal operating hours.

Better consumption information can support decisions about operating hours, equipment settings, energy efficiency and tariff selection.

Businesses should remember, however, that commercial energy contracts are different from domestic tariffs.

Further Reading

About The Centre For Energy Literacy

Energy is becoming more important to the decisions households and businesses make every day. Understanding how meters, tariffs, energy technologies and the wider energy system work gives you a stronger basis for making those decisions.

The Centre For Energy Literacy provides clear, practical information to help UK households and small and medium-sized businesses understand energy and make informed choices about their energy use.