Technical Information

Types of Smart Meter

There are two main types of smart meters – the older models known as SMETS 1 (Smart Meter Equipment Technical Specifications) and the newer versions that were rolled out in 2018, known as SMETS 2.

Most of these communicate with your supplier through the 2G/2.5G mobile network. Unfortunately a number of different unlinked systems are used to manage these meters and so if you change suppliers it is likely that your new supplier will not be able to operate your Smart Meter and it will become a ‘dumb’ meter for operational purposes.
However most of these are currently being upgraded to work with the central DCC system which will allow smooth switching between suppliers.
This specification is more advanced and meters were first rolled out in 2018. A more modern communication network is used with these meters and all suppliers will use it this – keeping your smart meter smart when switching suppliers.

Roll-out Progress

The rollout of Smart Meters has been slower than required and the government has introduced two schemes.

In the schemes SMETS1 meters counted towards the targets until 15th March 2019 and customers are allowed to refuse a Smart Meter when offered.

The first and current government scheme to require suppliers to install smart meters is known as "All Reasonable Steps" or ARS. This means suppliers are required to forecast the number of installs for the year ahead and then they must meet that target by using All Reasonable Steps to install at customers’ premises. The suppliers forecast should be such that they can reach 97% of premises by the end of the scheme. The end date has changed a number of times as the bullet points below show. A few suppliers have been fined for not achieving their own targets.
  • 30 November 2012 - Legal obligation established on energy suppliers to take all reasonable steps to install smart meters
  • 16 March 2019 - Only SMETS2 meters now count towards suppliers' target
  • 31 December 2019 - First deadline to complete
  • 31 December 2020 - Deadline extended due to slow progress
  • 30 June 2021 - Deadline extended due to Covid-19 delays.
Post 2020 Rollout
Under the new scheme the government sets an annual milestone for each supplier based on a straight line so that they eventually reach a coverage of between 85% and 100%. The allowed tolerance to meet the set target will grow over the 4 years with a maximum tolerance of 15% in the final year.
  • 1 July 2021 - Legal obligation on energy suppliers to install smart meters to government targets
  • 31 December 2024 - First deadline to complete
  • 30 June 2025 - Deadline extended due to Covid-19 delays.
New and Replacement Obligation
This related obligation requires energy suppliers to use smart meters for all new metering points and all meters requiring replacement. Although it is subject to all reasonable steps, Ofgem have said it is reasonable for a supplier to charge for the installation of a conventional meter if a smart meter is refused.
  • 30 June 2019 - New and Replacement Obligation (NRO) established.

Number of Meters on DCC

The Data Communications Company (DCC), which was set up by the government to manage Smart Meter communications on behalf of suppliers, reported the number of Smart Meters live on 10th November 2021 as:

Number of Meters on DCC
SMETS Version Number %
SMETS 1 6,305,296 39%
SMETS 2 9,694,858 61%
Total 16,000,154 100%

The figure above only includes SMETS1 meters transferred to DCC. Many SMETS1 meters still remain on older management systems.

Operating as Smart or Dumb

Many customers have noticed that their SMETS1 smart meters lose functionality when changing suppliers. This is because different unlinked systems have been used in the past to manage SMETS1 meters. Therefore when a new supplier took over a SMETS1 meter they usually could not operate it and therefore it went "dumb" or operated as a traditional meter.

This should now be addressed with most SMETS1 meters moving to the DCC systems, however, the improvement in the percentage of Smart Mode meters is very slow at less than 1% per quarter.

SMETS 1 & 2 Meters Operating Mode
Mode Number %
Smart (smart mode) and advanced meters 21,596,000 82%
Smart (traditional or dumb mode) 4,777,000 18%
Total 26,373,000 100%

These figures are from BEIS (Department of Business, Energy & Industrial Strategy) for the Domestic and Non-domestic markets as at the 30th September 2021.

Check your own Smart Meter

Citizens Advice have developed a tool to tell you what type of smart meter you have in your home and if it's working in smart mode. The tool can also tell you if your meter should work in smart mode after switching supplier.

Access the tool here: Citizens Advice Smart Meter Checker.

Number of Installs

Elexon, who manage electricity industry data, report SMETS1 and SMETS2 meter installation data every month. Although this is for electricity only it gives a good indication of overall progress.

August 2021 Electricity Install Progress Report Monthly Report on number of Electricity Meters installed by type

In August 2021 the SMETS2 installs decreased to 163k. The SMETS1 installs have increased to 8k, so overall the odds of you getting a SMETS2 meter are 95%. This has stayed at around 95% for a while now; we would recommend people say Yes to a SMETS2 Smart Meter now.

Here is a link to Elexon's report:

Wide Area Network

The Smart Metering Wide Area Network (SMWAN or WAN for short) is the name given to the communications network between the communications hub sitting on top of your electricity meter and the company responsible for collecting the data and passing it on to other businesses such as suppliers. This company will usually be the Data Communications Company (DCC) which the government has set up especially for the role of supporting SMETS1 and SMETS2 meters. Depending on the Communications Service Provider (CSP), which varies by areas of the UK, the technology can change depending on what works best in a local area. Sometimes your comms hub will communicate directly with DCC and sometimes it will talk through other comms hubs around you to reach a particular comms hub which has direct communications with DCC. This form of communications looks like a mesh when you draw out the possible links between meters and is therefore known as a Mesh network.

UK WAN coverage map

Scotland and the North of England

Long-Range Radio communications (LRR) is used by Arqiva Limited in Scotland and the North of England. The LRR system uses infrastructure and technology similar to that already used for other important national communications networks, such as those for emergency services and keeping lifeboat stations connected. Communication towers communicate directly with smart meter Communications Hubs in homes.
By 2021 Arqiva Limited will have achieved their contacted coverage of at least 99.5%.

Rest of England and Wales

The 2G/3G cellular radio communications network is used by Telefónica (O2) in the rest of England and Wales. This system is commonly used by mobile phones. In a cellular system, geographical areas are divided into regular shaped "cells".
Additionally Telefónica also use local mesh networks to fill in the mobile coverage gaps.
By 2021 Telefónica will have achieved their contacted coverage of at least 99.25% in the Central and South Regions.

Home Area Network

The Home Area Network or HAN is similar to your home broadband wireless network and will be used to communicate between the meters, the In Home Display (IHD) and other items as and when they become available.

Typical In Home Display

The IHD is a small standalone display which you might typically keep in your kitchen which shows your current energy consumption for both electricity and gas. It shows that as kWh (kilowatt hours, the unit used to measure energy usage) and in pounds and pence. It also shows your energy usage over various time periods, the current day, week, month and year. IHDs have a minimum set of features which are specified in the Smart Metering Equipment Technical Specifications.

Normally the Communications Hub that manages the HAN sits on top of your electricity meter and communicates with the electricity meter, gas meter and IHD.

The communication protocol used for the Smart Meter HAN is Zigbee as it is simple, inexpensive, low power and secure. The range of this technology is about 15m, but this is reduced by obstructions such as walls and doors.

UK WAN coverage map

Where the meter is a long way from the location of the IHD, or thick walls are in the way, the current technology (Zigbee at 2.4GHz) won't work. This could be the case for up to 30% of properties.

A different communications method (Zigbee 868MHz or Dual Band HAN) available from mid 2020 will improve this for about 3.5% of properties but that still leaves a large number for whom Smart Meters won't work.

For these final properties, for example where meters are in a basement a long way from the customer's IHD, a separate company has been set up to investigate solutions, prepare contracts and procure the equipment. The company is the Alt HAN Co Ltd and solutions are expected in 2021.

HAN Solutions

  1. Standard HAN 2.4GHz
    • 70% of premises
    • Normal small and medium houses
    • Nominal range of 15m
  2. Dual Band HAN 868MHz
    • 25% of premises
    • Large houses and buildings, thick walls
    • Signal can travel further but is lower bandwidth and therefore slower
    • Available August 2020 for testing, January 2021 for mass roll-out
    • More expensive than Standard, additional £24.20 per meter set
  3. Alternative HAN solutions
    • Between 2% and 3.5% of premises
    • Long distance between meters and IHD, for flats with meters in a basement
    • Most expensive solution
    • New company Alt HAN Co Ltd formed to manage this
    • Solutions being tested:
    • Installed from 2021 onwards
    • Total additional cost £290M
  4. No solution (too costly)
    • Between 1.5% and 3% of premises.
    • Extreme distances
    • Faraday cage buildings

Meter Alerts

Smart Meters can send information about the meter's environment and status as well as meter readings. This information can be used to diagnose meter faults, detect theft and security issues. There are some 250 events which can be sent in this way, suppliers and distributors will monitor these alerts, and take action at the appropriate point. For example a memory alert may mean the meter is faulty, whereas a reverse flow alert could mean that someone has reversed the meter in order steal energy.

Alerts add a high volume of messages to the communications flows, for example in October 2021 some 646 million messages were sent and received in total.


Security has been considered very carefully for Smart Meters. The communications network is not part of the internet, it is a closed network only accessible to parties with the right security keys and physical connections. Additionally there is no central database containing customers' information, the information is only stored on the Smart Meters and sent through DCC onto Suppliers and other parties who have a right to that data and where the customer has given them permission. The customer information inside messages is encrypted and only the receiving party can look at the data, the DCC cannot view the data. The parties receiving the data undergo a rigorous security assessment at the beginning and then have regular security audits.

The UK Product Security and Telecommunications Infrastructure (PSTI) Bill (2021) did not cover Smart Meters as they are already covered by robust regulation.

The National Cyber Security Centre has an excellent document explaining how the security works in relatively simple English.

End to End Security Model


The ability to purchase electricity and gas on a PAYG (Pay As You Go) basis is a big advantage of Smart Meters. Once you've paid, top up can be sent to your meter automatically without having to use chargeable key fobs. If communication to the meter is down you can still top up by entering the long reference number provided with your purchase into the meter, although this may not be an easy thing to do. For customers on PAYG who have difficulty with reliable communications and entering the long number, a separate number entry pad can be provided by your supplier. However it should be noted that many suppliers didn't start to offer the PAYG service until late 2018.

Distribution Network

As well as Suppliers getting information from smart meters the Distribution Network Operators (DNOs), who look after the cables in the ground, will also get information. They can use this information to detect when cables might get too hot, the voltage drops in an area (known as a brownout) and when the power cuts out. The detailed information of performance over time can be used to help plan reinforcement of the network as demand increases.


Both SMETS1 and SMETS2 meters are being installed currently. If you are wondering if you have a SMETS2 meter, look up your meter model number in the table below which lists all currently approved SMETS2 meters.

List of SMETS 2 Meter Models
Manufacturer Model ESME / GSME Type
Aclara SGM1415B ESME 5 terminal
Aclara SGM1416B ESME 5 terminal
Aclara SGM1422B ESME Twin Element
Aclara SGM1411B ESME
Aclara SGM1412 ESME
Aclara SGM1431B ESME Polyphase
Aclara SGM1432B ESME Polyphase
Aclara SGM1433B ESME Polyphase
EDMI ES-12B ESME 5 terminal
EDMI ES-30B ESME Polyphase
EDMI GS-60A GSME Ultrasonic
EDMI GS-60B GSME Ultrasonic
Flonidan G4SZV-1 GSME Diaphragm
Flonidan G4SZV-2 GSME
GWI G4-MG-SE-GM-V2 FVI GSME Diaphragm: Front Viewing Index
GWI G4-MG-SE-GM-V2 TVI GSME Diaphragm: Top Viewing Index (for semi-concealed applications)
Honeywell AS302P ESME
Itron EM425-UK2 ESME
Itron FGBB03 GSME Ultrasonic
Kaifa MA120 ESME
Kaifa MA120B ESME 5 Terminal
Landis & Gyr E470-5394 ESME
Landis & Gyr E470-5424 ESME
Landis & Gyr G470-672 GSME Ultrasonic
Landis & Gyr G470-682 GSME 868MHz
Secure Liberty 101 ESME
Secure Liberty Gas 200 GSME

ESME = Electricity Smart Metering Equipment
GSME = Gas Smart Metering Equipment.

Five terminal electricity meters have an additional live connector for an off-peak load switched by a timer. The other four terminals are live and neutral in, and 24 hour live and neutral out.

Diaphragm type gas meters have been used for many years. Within the meter there are two or more chambers formed by movable diaphragms. With the gas flow directed by internal valves, the chambers alternately fill and expel gas, producing a nearly continuous flow through the meter. As the diaphragms expand and contract, levers connected to cranks can link to a counter or provide an electrical pulse to measure the gas volume.

Ultrasonic gas meters measure very small difference in time that it takes an ultrasonic pulse to travel with and against the flowing gas stream. A microprocessor can then calculate the gas used. The main advantages of ultrasonic gas meters are that they have no moving parts and are therefore more reliable, and they are more accurate than conventional gas meters.

Semi-concealed gas meters are installed against the outer wall of a building and partially buried into the ground.

Moving SMETS1 meters to DCC

As SMETS1 meters where originally installed on different management systems, they often failed when transferring between suppliers and stopped communicating. Having got DCC and SMETS2 meters working, it was decided to upgrade the SMETS1 meters to allow them to be managed through DCC. This would then allow them to operate correctly for most functions including sending meter readings and switching supplier.

The upgrade process involves updating the meter's firmware remotely and making changes in the old management system and in DCC. The migration process to the new DCC SMETS2 system is called Enrolment and Adoption (E&A).

This does not change the radio communication technology, so if your SMETS1 meter does not communicate currently it cannot be upgraded. In this case your supplier may eventually install a SMETS2 meter if there is a SMETS2 radio signal.

If you are wondering if your SMETS1 meter is going to be upgraded, look up your meter model number in the table below.

SMETS1 Meter Models for adoption by DCC
Manufacturer Model ESME / GSME Type
Aclara SGM1312 ESME
Elster AS300P ESME
Elster BK-G4E GSME Diaphragm
Elster BK-G4E GSME Diaphragm (EI5)
Floridan G4SZV GSME Diaphragm
Itron EM425-UK ESME
Itron RF1 sV ZB GSME Diaphragm
Landis+Gyr E470-5299A ESME
Landis+Gyr E6VG370 GSME Ultrasonic
Secure Meters (UK) Limited EG4v10 GSME Diaphragm
Secure Meters (UK) Limited EG4v11 GSME Diaphragm
Secure Meters (UK) Limited EG4v15 GSME Diaphragm
Secure Meters (UK) Limited Liberty 100 E1S0B1 ESME

When will SMETS1 meters be connected to DCC?

The original milestones have been delayed a number of times and the proposed dates are shown in the table below.

By 5th August 2021 5,004,926 SMETS1 meters had been migrated to the DCC's systems.

DCC expect the migration programme to complete by September 2022.

Plan to connect SMETS1 meters to DCC
Meter Manufacturer Start Complete
Secure January 2021 Expected March 2022
Elster Started Planned October 2021
Aclara Started Planned October 2021
Itron Started Planned October 2021
Landis+Gyr May 2021 Expected September 2022

Communications Hub - SMETS2

The communications hub fits on top of the electricity meter and is owned by the DCC, unlike the meter which is owned either by your supplier or a MAP (Meter Asset Provider) to whom your supplier pays a rental charge. The interface connection to the meter is called the Intimate Communications Hub Interface (ICHI).The comms hub provides both the WAN and the HAN. The Wide Area Network talks to the DCC and the Home Area Network talks to the gas meter and the IHD.

Different comms hubs are used in different regions, see the table below.

SMETS2 Comms Hub Variants
CSP Region WAN Variant Manufacturer Comms WAN Technology External Aerial Port
(Arqiva Limited)
Standard 420 EDMI Long Range Radio No
Variant 450
Central & South
SKU1 Cellular WNC (Wistron NeWeb Corp.) & Toshiba Cellular
SKU2 Cellular + Mesh Toshiba Cellular & Mesh 1 Cellular
SKU3 SIMCH Cellular & Mesh 1 Cellular
1 Mesh

SKU = Stock Keeping Unit
SIMCH = Special Installation Mesh Communications Hub.

You can see on the table above that the Toshiba comms hub can take one or two aerials. Surveys have determined in advance where these will be used. The table below shows the purpose of the different aerial types.

SMETS2 Aerial Types
Aerial Type % Installs Radio Use Manufacturer Dimensions (mm) On which Hubs
Low Gain
6% Cellular Panorama 165 x 32 x 20 Toshiba SKU2
(and SKU3 if poor signal)
Low Gain
WNC 128 x 25 x 17
High Gain
4% Panorama 372 x 33 x 20
High Gain
WNC 320 x 41 x 17
High Gain
0.5% Panorama 695 x 25 x 25 Toshiba SKU2/3
High Gain
Oriel 580 x 100 x 40
0.25% Mesh TBA Toshiba SKU3
0.25% TBA
No aerial 89%

The table below shows the different frequency bands used.

SMETS2 Frequency Bands
Frequency Band (MHz) CHAS WAN / HAN CSP Area
WAN (includes 'buddy mode') North excluding Fylingdales
WAN (includes 'buddy mode') North at Fylingdales
HAN North, Central and South
WAN MESH Central and South
WAN Central and South
2100 WNC DBCH,
WAN Central and South
2400 All CHAS Units HAN North, Central and South

CHAS = Communication Hub Antenna Structure,
CSP = Communications Service Provider,
DBCH = Dual Band Comms Hub,
Fylingdales (Fyl) = RAF radar base where frequency interferes with normal Smart Meter communications,
SBCH = Single Band Comms Hub.

The Variant 450 comms hub for the North at Fylingdales is expected to be first available in February 2022.

What do the indicators mean on a SMETS2 Comms Hub?

On the front of a comms hub there are a series of LED indicators showing the functional status of the metering system. Each LED has a legend as shown below:

CSP Region - Central & South

SW - Software
This shows the status of the hub’s software.
WAN - Wide Area Network
Shows your communication hub’s ability to communicate with the DCC and your supplier.
MESH - Mesh Communications Network
This light will be on if your meter is communicating through the Mesh network. It will be off if your meter is only using the normal WAN to communicate. The Mesh network has been built to allow more meters to communicate in areas with poor or no WAN signal.
HAN - Home Area Network
This light shows the connection status of your electricity meter, gas meter and IHD with your communications hub on the HAN.
GAS - Gas Meter
This light tells you if a gas meter is connected to the HAN. If you don’t have a gas meter installed this light will be off.

CSP Region - North

WAN - Wide Area Network
Shows your communication hub’s ability to communicate with the DCC and your supplier.
HAN - Home Area Network
This light shows the connection status of your electricity meter, gas meter and IHD with your communications hub on the HAN.

What does the flashing rate mean?

The frequency of flashing relates to the status of the function as follows:

  - Power Up
LEDs are shown without flashing for 10 seconds after power up to allow the operator to see that all LEDs are working.
  - Normal
A slow flash rate of 1 flash per 5 seconds means that the process is in its normal state.
  - Transient
A flash rate of 1 flash per 2 seconds means that the process is in a transient state such as making a communications connection.
  - Error
Fast flash rate of 2 flashes per second means that there is an error. Call your supplier if this does not change after 48 hours.
  - Off
The communications hub is powered down.
(Page updated: 2021-12-01)

Questions & Answers

What is the SMETS1 end date?
The government are keen for all SMETS (Smart Meter Equipment Technical Specifications) smart meters to interoperate on one system so customers can switch suppliers easily. To encourage this they are discouraging suppliers installing the older SMETS1 meters and incentivising them to move to the new SMETS2 meters. If suppliers wanted the installations to count towards their government targets they could not install SMETS1 meters (or upgrade firmware to SMETS1) after 5th December 2018. Note that some suppliers had a special dispensation and were able to carry on until 15th March 2019.
Additionally due to the extra complexity of prepayments meters, the end date for them was 15th March 2019.
However, suppliers can still install SMETS1 meters if they wish, but it will not count towards their government targets. They may do this to use up old meters stocks or where the customer does not yet have a signal from the new DCC system. (Updated: 2020-02-09)

Are smart meters safe?
Yes. Smart meters are subject to the same safety regulations and testing of any in-home technological devices, including baby monitors and mobile phones. Additionally the meters are secure having a security system developed by industry and government experts including GCHQ's National Cyber Security Centre. A side benefit is that many safety problems are being spotted in peoples homes during installation of the smart meter which would not have been spotted without a visit. (Updated: 2019-10-21)

Can a Smart Meter interfere with my WiFi?
Yes interference can occur for up to an hour while your WiFi and the Smart Meter each find the best channel to avoid each other.
Both your WiFi and the Zigbee network used by Smart Meters operate in the same 2.4GHz radio band and the band is divided into channels. Most modern WiFi routers can scan channels in order to pick the ones with the least interferences from other devices and the Smart Meter Zigbee system can do the same. As some door bells and remote controls can also use the 2.4Ghz band it may take an hour or two for the best channels to be chosen.
If interference problems continue, you can log onto your WiFi router and select the channel manually to see if that helps. It is not possible to override the automatic channel selection on the Smart Meter. (Updated: 2020-01-20)

What is a SMETS2 meter?
Over six million meters have now been installed to the Smart Metering Equipment Technical Specification (SMETS) 2 standard. These are the most advanced meters available and communicate through the Data Communications Company (DCC). Suppliers were obliged by government rules to stop installing SMETS1 meters by 15 March 2019 and only install SMETS2 meters. Suppliers started to install SMETS2 meters in Q2 2017 and in large volumes from autumn 2018. (Updated: 2021-02-17)

When will my SMETS1 meter operate again?
The upgrade and transfer of SMETS1 (Smart Meter Equipment Technical Specifications) meters into DCC's systems is planned to occur between June 2019 and the end of 2022.
For more information see Enrolment and Adoption on DCC's website.
Provided your meters are on the list of meters which can fit into this process on table SMETS 1 Meters for adoption by DCC they should start working again during that transfer period. (Updated: 2021-12-06)

What is a CAD?
A CAD is a Consumer Access Device which provides access to your meter data through WiFi. These are relatively new and usually integrated into the IHD (In Home Display) provided by suppliers. One example of such a device is the Chameleon IHD3.
The IHD still needs a link to the meters to retrieve the data first so CADs do not provide an alternative solution where the meters and IHD are separated by a large distance. (Updated: 2020-03-05)

How are they tested for accuracy through their life?
Smart meters fall into the MID scheme (Measuring Instruments Directive) which means they are certified at their introduction to market as being accurate but are not given a certification period as traditional meters used to be. Their life depends on their performance during MID In-service testing (IST). The Office for Product Safety & Standards gathers samples of meters from suppliers, if they prove to be in-accurate that type/age of meter will be replaced in customer premises. (Updated: 2019-08-23)

Does my SMETS1 meters have to be replaced?
In early 2018 the government and industry agreed to build interfaces which allow the earlier SMETS1 (Smart Meter Equipment Technical Specifications) Smart Meters to be moved to the new DCC system supporting SMETS2 meters. This means that, although you may have lost Smart functionally when you changed supplier, when it is enrolled into the new DCC system that functionally will come back, and you’ll be able to change suppliers without technical problems. The process of moving the meters across system is called enrolment and adoption.
See our Technical page for a list of SMETS1 meter types that can be upgraded. (Updated: 2021-12-06)

What is Zigbee?
Zigbee is a communication protocol for radio networks. It is designed to be simpler, use less power and be cheaper than other systems and therefore is ideal for mass deployment in Smart Meters.
In Smart Meters the Zigbee protocol is used to communicate between the communications hub, electricity meter, gas meter and IHD (In Home Display). (Updated: 2020-02-09)

Who pays for the meter electricity?
The customer does not pay for the electricity used to power the meter directly as the meter takes its own power from a point before measurement takes place. The power used by the meter will fall into distribution losses which also includes the energy lost through the distribution cables as well. This was also the case with traditional meters.
Ultimately all customers pay for this as a percentage increase which is applied by area. For a technical explanation see Electricity Distribution System Losses. (Updated: 2020-08-19)

What is Market-wide Half Hourly Settlement?
Market-wide Half Hourly Settlement (MHHS) will allow the electricity industry to move way from average consumption profiles for customers to using half hourly data.
Currently domestic and small business electricity use is modelled on a small number of average usage profiles. Obviously when you add up what was supplied and what was used they are not the same because of the use of average profiles. So the use of half hourly data will improve this and means that suppliers will have a more accurate wholesale energy bill.
This could improve customers' bills as the commercial risk for suppliers is slightly reduced.
This does not change tariffs for customers or what data domestic customers allow their smart meters to send unless they agree. (Updated: 2021-06-17)

Can my supply be turned off remotely?
Smart meters have the facility to remotely disconnect and reconnect both the electricity and gas supply. However, most suppliers seem to have decided it is too dangerous to remotely disconnect or reconnect, as in the case of disconnection they cannot always be sure that the customer isn't relying on a supply for serious health reasons and in the case of reconnection the customer may have left a cooker on for example. (Updated: 2015-01-23)

How do I top-up my smart meter PAYG if the mobile network is down?
Normally your PAYG (Pay As You Go) top-up will be sent automatically to the smart meter, however, if the communications link through the mobile network is not available then this cannot happen.
Firstly you can use the emergency credit that most suppliers offer. If that runs out you can enter the long authorisation number that you received when you paid for the credit into the meter or IHD (In Home Display) to apply your credit. This very difficult to do on the meter so use the IHD if you can. (Updated: 2019-10-21)

What is a Dual Band Comms Hub?
The current Communication Hubs have a single band 2.4 GHz HAN (Home Area Network) frequency and are known as Single Band Comms Hubs (SBCH) and should provide HAN coverage between meters and the IHD (In Home Display) in approximately 70% of premises.
For some buildings like blocks of flats or where walls are very thick, the smart meter can't communicate with the Comms Hub. So by mid 2020, a more sophisticated hub with a choice of frequencies will be available. These are called Dual Band Comms Hubs. They use a HAN frequency of 868MHz along with the existing 2.4GHz frequency. Dual Band Comms Hubs (DBCH) are expected to increase coverage to 95% of premises. (Updated: 2020-02-09)

What is the HAN range?
The range of the Smart Meter HAN (Home Area Network) is about 15m, but this is reduced by obstructions such as walls and doors. Where the meter is a long way from the location of the IHD (In Home Display), or thick walls are in the way, the current technology (Zigbee at 2.4GHz) won't work. This could be the case for up to 30% of properties.
A different communications method (Zigbee 868MHz) available from mid 2020 will improve this for about 3.5% of properties but that still leaves a large number for whom Smart Meters won't work.
For these final properties, for example where meters are in a basement a long way from the customer's IHD, a separate company has been set up to investigate solutions, prepare contracts and procure the equipment. The company is the Alt HAN Co Ltd and solutions are expected in 2021. (Updated: 2021-10-03)

Can a Smart Meter replace my Radio Teleswitch?
Yes a Smart Meter can provide similar functionality to the Radio Teleswitch System (RTS). RTS is used to stagger the switch on and off times of tariffs such as Economy 7 so that a surge in power doesn't occur from all the storage radiators in the country switching on at the same time.
If you are on a tariff switched by RTS we recommend you speak to your supplier to get a Smart Meter and ask what tariff you can move to. The RTS service uses the BBC Radio 4 long wave signal and is planned to end in March 2023. (Updated: 2021-04-25)

Can I look at my energy usage on the internet?
You will be able to view your energy usage on the internet at some stage. Suppliers are all working on new systems to make this possible. (Updated: 2015-01-23)

How much data is stored on a Smart Meter?
The SMETS2 specification requires the following data to be recorded and stored.
Half-hourly electricity data:
  • 13 months of consumption (Active Energy Import)
  • 3 months of active energy exported
  • 3 months of reactive energy imported
  • 3 months of reactive energy exported.
Gas data:
  • 3 months of half-hourly consumption
  • 13 months of monthly consumption.
(Updated: 2020-11-07)

Do Smart Meters use 5G?
No Smart Meters currently use 5G. Even in the future a move to 5G is unlikely as the amounts of data transferred are very small and long distance communication is the main requirement. 5G is a higher frequency technology and generally low frequencies are most reliable and capable of penetrating obstructions like buildings, which is why 4G will often work in more places than 5G. Higher frequencies are also more easily scattered by objects. (Updated: 2021-04-07)

Do Smart Meters measure voltage?
Yes, Smart Meters provide a record of voltage. This is of great interest to the Distribution Network Operators (DNOs) as they are responsible for setting the voltage on the network by adjusting the taps on transformers. The voltage on the network is more difficult than ever to control due to varying local generation.
UK Power Networks carried out a project on the Use of smart meter information for network planning and operation which included voltage.
Also see this document from Western Power Distribution giving their Smart Meter Strategy. (Updated: 2021-05-03)

Can I lay a cable to help join the devices together?
The meters and IHD (In Home Display) can only be joined through a radio link. This applies to all three standards of meters pre-SMETS, SMETS1 and SMETS2. However, one or two suppliers may be able to offer a zigbee booster, this is similar to the wireless booster you can buy for your home broadband and just plug into a power socket.
Our recommendation would be to let your supplier sort it out, as a communications hub (868MHz) with better reach will be available to suppliers to install with SMETS2 meters where needed from mid 2020. (Updated: 2020-02-09)

What is the gas mirror?
Communications from the comms hub on the electricity meter to the gas mater can be slow and may drop out sometimes. To make the system more efficient the engineers came up with the idea of a "Gas Mirror" which is to keep a copy of the gas meter software in the comms hub.
Any changes such as new firmware destined for the gas meter are transferred to the "Gas Mirror" first and then sent to the gas meter over time. (Updated: 2020-10-24)

Can smart meters be upgraded?
Smart meters can have a firmware upgrade just like your computer or mobile phone. The upgrade will be used to fix faults and add new functionality and should be carried out in the background with little impact on the customer. Indeed this feature is being used to allow SMETS1 meters to be upgraded for the SMETS2 systems; this will allow them all to interoperate. (Updated: 2019-10-21)

Do SMETS2 meters support solar panels?
Yes all SMETS2 meters support solar panels as this was included in the SMETS2 specification. However, this does not mean your suppliers will support it. A lot of work is required in a supplier's back office systems to set up the meter correctly, and process and store the messages required to operate export properly.
We suggest you check with your own supplier whether they can support export yet. (Updated: 2021-02-12)

How does the smart meter record energy generation if a solar panel is installed?
All smart meters will record the export and import separately, and you will be able to see the readings by stepping through them on the meter display. All the meters should show all 4 power quadrants. You can ignore the reactive ones and just look at active import and export.

Power quadrants:
  • Active energy import (Wh) - this is what we are billed for normally
  • Reactive energy import (varh)
  • Active energy export (Wh) - this is your useful export power
  • Reactive energy export (varh).
The bad news is that many companies have not set up their systems to automatically collect or use the export information, as it would have taken time and money they don't have for such a low volume user base. (Updated: 2018-10-02)

What is dithering?
When a Smart Meter loses power and powers up it sends an alert message to suppliers and network operators to let them know. If a large area had lost power and thus a large number of meters were to send these messages at once it would put a heavy load on the communications network. To prevent this the meters "dither", that is to say they all wait a short random period before sending those first messages thus avoiding the simultaneous peak. For the first two years (to September 2018) the dithering period was up to 2 minutes. After that a decision will be made on whether to set it to the default 5 minutes. (Updated: 2016-02-16)

How often will my IHD be updated with data from my meters?
Your IHD (In Home Display) will be updated by your electricity meter about every 10 seconds and by your gas meter about every 30 minutes. The gas meter updates less often in order to preserve its battery life which in normal use is expected to be at least 10-15 years. (Updated: 2020-10-23)

My supplier says my signal is too weak?
Smart meters communicate through mobile communications and so the signal strength is an important factor to consider for installation.
For SMETS1 meters the installer will usually test on site and make a decision there and then whether to install. If there is not a sufficient signal they will usually walk away.
For SMETS2 there are more options. The communications are provided by the Data Communications Company (DCC) and suppliers can check that a premises has communications before visiting a site. Once on site they can check with a signal checking device if the signal is strong enough in the meter location. If it isn’t they can fit a number of different aerials to try to boost the signal. If that doesn’t work an external aerial or an alternative mesh communications method is available in some areas. Even then they can leave the meter de-commissioned and ask the DCC to get the communications working. (Updated: 2017-02-01)

Are Three-phase SMETS2 meters available yet?
The SMETS2 standard covers Three-phase meters but few suppliers have put in orders for them yet. They are likely to appear over the next couple of years.
See Wikipedia for an explanation of Three-phase power. (Updated: 2021-02-12)

What is a HAN-connected auxiliary load control switch (HCALCS)?
Similar to an ALCS (Auxiliary load control switch), a HCALCS allows large domestic loads, such as electric vehicles chargers, to be controlled independently of the main power supply. However, rather than being integrated with the meter directly, the switch is remotely connected via the Home Area Network. This provides more flexibility, avoiding the need for new wiring back to the meter when a new load is connected. (Updated: 2021-04-09)

Can I fit an aerial?
You cannot fit an aerial yourself. All Comms Hubs and Aerials for Smart Meters have to be supplied via approved channels and can only be installed by authorised engineers. In fact attempting to install one yourself will trigger the tamper alarm on the meter which could mean a chargeable visit from your supplier. (Updated: 2021-11-16)

What is an Auxiliary load control switch (ALCS)?
Large domestic loads like storage heaters or heat pumps can be connected and controlled independently of the customer's main supply. An ALCS inside a smart meter can switch the electricity supply to the devices connected to it on or off based on an agreed switching pattern. It works in the same way as traditional Economy 7 meters, providing a scheduled period of power to connected devices. Subject to an agreement made between supplier and customer this could also support ad hoc commands allowing switches to respond to wider network conditions such as periods of excess renewable generation. (Updated: 2021-04-09)

Are the meters battery powered?
The electricity meter is mains powered but the gas meter is battery powered. The gas meter battery can be replaced by a Smart Meter Installer and is excepted to last the life of the meter (10 to 15 years), however, its life can be greatly reduced heavy communications such as repeated firmware updates. (Updated: 2016-01-27)

What is a SMETS1 meter?
Over 7 million electricity meters and a similar number of gas meters built to the first Smart Metering Equipment Technical Specification (SMETS) 1 have now been installed. These meters are better than ADM meters (Advanced Domestic Meters) but not as good as SMETS2 meters. Each supplier uses them through a different support and communications network; this means they have different functionality and effectively limits the customer from moving from one supplier to another with the same smart meter. For this reason customers often lose smart functionality when changing suppliers. Meters to the SMETS2 standard do not have this restriction as they share a common communication process. (Updated: 2018-05-05)

Do smart meters work with home generated renewable energy?
Traditional meters are only capable of recording consumption and consequently don't take into account any energy generated by a household. If you have or are planning to install solar panels or any other renewable energy generating system in your home, a smart meter will enable you to measure how much energy you produce. The smart meter will also calculate whether or not there is a surplus which you could sell back to the grid.
However, as this is not a common requirement suppliers have been slow in implementing systems to support it - you will have to shop around for the supplier which can support your requirements. (Updated: 2019-10-21)

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