Smart meters: national-scale data sources

The smart meter rollout happened in two technology generations, and the gap between them produced one of the most painful interoperability failures in British energy.

SMETS1 meters (Smart Metering Equipment Technical Specifications, first generation) were installed from 2011. Each supplier chose its own communications provider and protocol, so when a customer switched supplier the new supplier often could not talk to the meter it had inherited. The meter fell back to “dumb” mode: it kept recording usage but could no longer send readings remotely, and the household went back to manual reads, which defeated the point of a smart meter.

That stranding affected millions of consumers and became a political embarrassment. The answer was the Data Communications Company (DCC) migration programme, which moves SMETS1 meters onto the shared network so that smart functionality survives a supplier switch. About 15 million SMETS1 meters sat in the programme's eligible scope, and just over 11.1 million had migrated to the DCC by May 2026. The work is slow because each meter type needs its own firmware and protocol handling before it can be enrolled.

SMETS2 meters were designed to avoid all of this. They talk only through the DCC using protocols defined in the Smart Energy Code. Inside the home a Home Area Network (HAN) running ZigBee at 2.4 GHz links the electricity meter, the gas meter, the In-Home Display (IHD) and any Consumer Access Devices (CADs). A SMETS2 meter supports remote prepayment switching, remote firmware updates and a change of supplier without losing smart mode.

The estate is now largely smart. At the end of March 2026 DESNZ reported more than 41 million smart and advanced meters in homes and small businesses across Great Britain, with 72 percent of all meters operating in smart or advanced mode. The scale is national, but the settlement job is narrower: Elexon expects Market-wide Half-Hourly Settlement to process up to 500 billion half-hourly readings a year.

Getting readings from tens of millions of meters to the organisations that need them takes a network of real scale. The DCC runs it as a Wide Area Network (WAN), and it is not one technology. Great Britain is split into regions, and the region decides which carrier a meter uses.

In the North region, which covers Scotland and northern England, meters reach the DCC over Arqiva long-range radio. This carries well across rural and hard-to-reach ground where cellular coverage is patchy, with meters relaying through the radio network to reach a base station. In the Central and South regions, which between them cover the rest of England and all of Wales, meters use Telefonica cellular, now run by Virgin Media O2 (VMO2), over the mobile network. A common mistake is to file Wales with the northern radio region: in the DCC design Wales is cellular.

The cellular estate is moving off 2G and 3G. The DCC agreed new 4G communications hubs for the North on 30 May 2025, running on the Vodafone network, as part of a wider move to 4G so that meters keep working as the older mobile generations are retired.

The DCC does not hold its licence forever. The current smart meter communication licence runs to September 2027. Ofgem decided the successor arrangements, known as DCC2, in April 2026, and the transfer of the business to the new licensee is expected in November 2026.

Inside the home the HAN does the local work. The gas meter has no WAN connection of its own: it sends its readings to the electricity meter over ZigBee, and the electricity meter passes them on to the DCC. That extra hop adds a little latency and one more point where gas data can fail.

To understand why smart meter data is both valuable and sensitive, look at what 48 half-hourly readings from a single day actually reveal. The pattern below is not hypothetical: it is what your meter records every day.

06:30 - the morning spike. Consumption jumps from near-zero to 1.5 kW. The kettle goes on, lights come on, the shower heats up. The time of this spike reveals when the occupants wake. A consistent 05:00 spike might indicate shift work. A 09:30 spike might indicate retirement or working from home.

08:00 to 17:00 - the daytime profile. If consumption drops to baseline (fridge, standby loads, around 200-400 W), the home is likely unoccupied. If it stays elevated, someone is working from home. A mid-morning spike might be a washing machine. A sustained 2-3 kW draw might be a home office with monitors and a desktop computer.

18:00 to 19:00 - the evening peak. A 3 kW spike for 30 minutes is an oven or hob. Multiple shorter spikes suggest a microwave-heavy household. The timing and size of cooking peaks correlate with household composition: families cook differently from single occupants.

22:00 to 06:00 - the overnight plateau. A sustained 7 kW draw from midnight to 06:00 is almost certainly an electric vehicle charging. A 3 kW overnight draw might be a storage heater. Complete silence (just standby at 100-200 W) for several days might indicate the occupants are on holiday, information that could be of interest to burglars.

Around midday, the export question. A home with solar panels does not drive the import meter below zero. The import register never goes negative. Electricity sent back to the grid is measured on a separate export register, held against its own export MPAN, so import and export are counted independently. The size and timing of the export still reveal the scale and orientation of the array, and because the Smart Export Guarantee pays on measured export, it needs half-hourly export data to settle. A later module in the applied stage, on export and microgeneration, follows that data to the supplier.

The patterns extend beyond single days. Weekly patterns can reveal religion (low Friday evening consumption followed by Saturday absence might indicate observant Judaism; Sunday morning absence might indicate church attendance). Irregular patterns over weeks might indicate health issues. Sudden changes in routine might indicate relationship changes.

This is precisely why the Information Commissioner's Office classifies half-hourly smart meter data as personal data under UK GDPR. It is not merely a record of energy use: it is a detailed diary of domestic life, recorded 48 times a day, every day, from a known address that can be linked to identifiable individuals.

A smart meter is not only a sensor, it is also a small controller. It can hold tariff data, the prices and time bands a supplier sends down, so a time-of-use tariff can be applied at the meter and shown to the household rather than reconciled weeks later on a bill. That is what lets an off-peak overnight rate or a same-day flexible price work without anyone reading the meter by hand.

Two devices sit on the HAN to make that data useful in the home. The IHD is the screen most households recognise: it shows live consumption and cost so the numbers mean something day to day. A CAD is the more open cousin. It bridges HAN data to a home network or app, which is how a third party, with the household's consent, can build energy management or automation on top of the meter.

Everything a party asks the meter to do travels as a DCC service request, defined in the DCC User Interface Specification (DUIS). The read types are not interchangeable. Service Request 4.1.1, Read Instantaneous Import, returns the import register there and then, which suits a one-off check such as a switch or a query. The scheduled half-hourly reads that billing and settlement depend on come from the 4.8 family, Read Active Import Profile Data, which delivers the profile a day at a time. Matching the read type to the job matters: an instantaneous read is the wrong tool for building a settlement profile.

Two changes hang over all of this. A broadband-based option, VWAN, is being introduced for the locations where no wireless signal reaches, using the customer's own internet connection to bring otherwise unreachable meters onto the network. And the retirement of 2G and 3G puts roughly 7 million meters at risk: any still relying on those older mobile networks when they are switched off will go dark unless they are moved to 4G or another carrier first. The 4G communications hubs agreed for the North are the start of that migration, not the end of it.