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.
- SMETS 1 – Most of these communicate with your supplier through the 3G mobile network. Unfortunately a number of different systems, not linked together, 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.
- SMETS 2 – This specification is more advanced and meters were first rolled out in 2018. A purpose built communication network is used with these meters and all suppliers will use it this – making switching easier and keeping your smart meter smart.
Roll-out Progress
The good people at Elexon (they 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.
February 2020 Electricity Install Progress Report
In February 2020 the SMETS2 installs decreased from 194k to 193k. The SMETS1 installs have also decreased from 26k to 21k, so the odds of you getting a SMETS2 meter have now improved to 80%. We would like to see that get to 85% before we recommend people say Yes to a Smart Meter to ensure you get the most secure model and with the most features.
Here is a link to Elexon’s report: https://www.elexon.co.uk/data/key-data-reports/smart-meter-technical-detail-report/.
Wide Area Network
The Wide Area Network or WAN is the name given to the communications network between the meters and the company responsible for collecting the data and passing it on to other businesses such as suppliers. This company will usually be the DCC (Data Communications Company) which the government has set up especially for this role supporting the final SMETS2 meters. Depending on the Communications Service Provider, which varies by areas of the UK, the technology can change depending on what works best in a local area. Sometimes your meter will communicate directly with DCC and sometimes it will talk through the meters around you to reach a particular meter 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.
Home Area Network
The Home Area Network or HAN is a bit like your home broadband wireless network and will be used to communicate between the meters, the In Home Display and other items as and when they become available. The communication protocol chosen for Smart Meters 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.
Normally the Communications Hub that manages the HAN sits on top of your electricity meter and communicates with the electricity meter, gas meter and In Home Display. The range of the Smart Meter HAN 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 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.
HAN Solutions
- Standard HAN 2.4GHz
- Normal small and medium houses
- Nominal range of 15m
- 70% of premises
- Dual Band HAN 868MHz
- Large houses and buildings, thick walls
- Signal can travel further but is lower bandwidth and therefore slower
- 25% of premises
- Available mid 2020
- More expensive than Standard, additional £24.20 per meter set
- Alternative HAN solutions
- Long distance between meters and IHD, for flats with meters in a basement
- Between 2% and 3.5% of premises
- Most expensive solution
- New company Alt HAN Co Ltd formed to manage this
- Solutions being tested:
- Power Line Carrier (PLC) device
- Leaky Feeder Aerials
- Larger aerials on comms hub
- Installed from 2021 onwards
- Total additional cost £290M
- No solution (too costly)
- Extreme distances
- Faraday cage buildings
- Between 1.5% and 3% of premises.
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.
Security
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 National Cyber Security Centre has an excellent document explaining how the security works in relatively simple English.
PAYG
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.
Meters
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.
| 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 | SGM1412B | ESME | |
| EDMI | ES-10A | ESME | |
| EDMI | ES-10B | ESME | |
| EDMI | ES-12B | ESME | 5 terminal |
| EDMI | GS-60A | GSME | Ultrasonic |
| EDMI | GS-60B | GSME | Ultrasonic |
| EDMI | BK-G4E | GSME | Diaphragm |
| Flonidan | G4SZV-1 | GSME | Diaphragm |
| 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 | |
| Kaifa | MA120 | ESME | |
| Landis & Gyr | E470-5394 | ESME | |
| Landis & Gyr | E470-5424 | ESME | |
| Landis & Gyr | G470-672 | GSME | Ultrasonic |
| 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 a 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.
Existing SMETS1 meters in the table below will be migrated to the new DCC SMETS2 system through the enrolment and adoption process. If you are wondering if you have one of these SMETS1 meters, look up your meter model number in the table below.
| Manufacturer | Model | ESME / GSME | Type |
|---|---|---|---|
| Aclara | SGM1311 | ESME | |
| Aclara | SGM1312 | ESME | |
| EDMI | MK7B | ESME | |
| Elster | AS300P | ESME | |
| Elster | BK-G4E | GSME | Diaphragm |
| Floridan | G4SZV | GSME | Diaphragm |
| Itron | EM425-UK | ESME | |
| Itron | RF1 sV ZB | GSME | Diaphragm |
| L+G (Landis & Gyr) | E470-5299A | ESME | |
| L+G (Landis & Gyr) | E6VG370 | GSME | Ultrasonic |
| Secure Meters (UK) Limited | EG4v10 | 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 and are subject to a DCC consultation which closed on 20 November 2019. The proposed dates are shown below.
SMETS1 meters will be migrated to DCC in five batches over three capability phases. Once the capability is made ready on the dates below, the migration will happen within the following months.
- Initial Operating Capability (IOC) – meters operated by CGI Instant Energy (IE)
- 24 Nov 2019 - Elster Honeywell and Itron meters
- 23 Feb 2020 - Aclara meters
- Middle Operating Capability (MOC)
- 15 Mar 2020 - Elster Honeywell meters currently operated by MDS (Morrison Data Services)
- 28 Jun 2020 - Secure meters operated by the Secure Meters group
- Final Operating Capability (FOC)
- 26 Jul 2020 - Landis + Gyr (L+G) meters currently operated by either BG SMSO (Smart Meter System Operator), DXC or CGI Instant Energy (IE) and, if directed by Government, the EDMI meter group.
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.
| CSP Region | WAN Variant | Manufacturer | Comms WAN Technology | External Aerial Port |
|---|---|---|---|---|
| North (Arqiva Limited) |
Standard 420 | EDMI | Long Range Radio | No |
| Variant 450 | ||||
| Central & South (Telefonica) |
SKU1 Cellular | WNC (Wistron NeWeb Corp.) & Toshiba | Cellular | |
| SKU2 Cellular + Mesh | Toshiba | Cellular & Mesh | 1 Cellular | |
| SKU3 SIMCH | Cellular & Mesh | 1 Cellular 1 Mesh |
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.
| Aerial Type | Radio Use | Manufacturer | Dimensions (mm) | On which Hubs |
|---|---|---|---|---|
| T1 Low Gain |
Cellular | Panorama | 165 x 32 x 20 | Toshiba SKU2 (and SKU3 if poor signal) |
| T1 Low Gain |
WNC | 128 x 25 x 17 | ||
| T2 High Gain |
Panorama | 372 x 33 x 20 | ||
| T2 High Gain |
WNC | 320 x 41 x 17 | ||
| T3 High Gain |
Panorama | 695 x 25 x 25 | Toshiba SKU2/3 | T3 High Gain |
Oriel | 580 x 100 x 40 |
| M1 Short |
Mesh | TBA | Toshiba SKU3 | |
| M2 Long |
TBA | |||
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:
- SW - Software
- This shows the status of the hub’s software.
- WAN - Wide Area Network
- Shows your communication hub’s ability to communicate with your supplier. This light will be off if your meter is using the MESH network to communicate.
- 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 using the normal WAN to communicate. The Mesh network has been built to allow more meters to communicate in areas with poor or no 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 (Home Area Network).
- GAS - Gas Meter
- This light tells you if a gas meter is connected. If you don’t have a gas meter installed this light will be off.
The frequency of flashing relates to the status of the function as follows:
- - Power Up
- To allow the operator to see that all LEDs are working they are shown without flashing for a short period after power up.
- - 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.
- - Transient
- A flash rate of 1 flash per second means that the process is in a transient state such as making a communications connection.
- - Normal
- A slow flash rate of 1 flash per 2 seconds means that the process is in its normal state.
- - Off
- The communications hub is powered down.
Questions & Answers
See our Technical page for a list of SMETS1 meter types that can be upgraded. (Updated: 2019-10-21)
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)
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)
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: 2019-10-17)
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)
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)
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 to apply your credit. This very difficult to do on the meter so use the IHD if you can. (Updated: 2019-10-21)
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)
The range of the Smart Meter HAN 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 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: 2020-02-09)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)
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).
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)
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)
