Reading your smart meter data

Your smart meter can tell you more than a monthly bill does. It can show when you use electricity, whether a time-of-use tariff actually fits your habits and whether a strange bill is probably down to real usage, estimated readings or a timing mismatch.

The main trap is expecting every screen to match at once. Your meter, in-home display, Octopus app, online account, bill and third-party tools can all be looking at slightly different data or different dates. Start with what you are trying to answer, then pick the right source.

The quick checks

If you only need to know whether Octopus is receiving readings, do this first:

1. Open the Octopus app or online account. Look for recent electricity and gas readings or daily usage.
2. Check the latest bill. If readings are marked estimated, or with an E, Citizens Advice says your supplier probably is not receiving automatic readings.
3. Compare with the physical meter. The meter itself is the best check when the account, bill or display looks odd.
4. Allow for setup time after a switch or installation. Citizens Advice says readings can take a few weeks to appear on bills after a recent supplier switch or account setup.
5. Report persistent gaps. If the account keeps showing estimated bills or missing smart data, ask Octopus to check whether the meter is communicating properly.

For a separate screen problem, use the in-home display guide. A dead or stale display does not automatically mean the meter has stopped sending readings.

The Octopus app and online account

The app is the simplest place to start. It can show daily usage, half-hourly electricity detail and cost views based on your tariff. Gas data can be less immediate, and all app data depends on readings arriving from the smart-meter network and being processed by Octopus.

That means a blank day in the graph is not always a billing emergency. It might be a delay, a temporary communication issue, a smart-meter setup problem, or a difference between the dates used by the graph and the dates used by your bill.

The app is most useful for:

• seeing whether usage is landing in the cheap window on Go, Intelligent Go, Agile or Cosy
• spotting high-use days before the bill arrives
• comparing weekdays with weekends
• checking whether an appliance, EV charger or heating pattern is changing the shape of your day
• noticing whether smart readings have stopped and bills have become estimated

If an app usage graph and a bill do not line up, read why app usage and bills do not always match before assuming one of them is wrong.

Octopus Home Mini

The Octopus Home Mini is a small device that connects to your smart meter and sends more frequent usage data into the Octopus app over Wi-Fi. It is useful if you want a more live view than the standard delayed smart-meter data.

Treat it as an extra monitoring device, not a requirement for switching to Octopus. It needs a compatible smart meter setup, a working home area network and reliable Wi-Fi. Demand has often been higher than supply, so availability can vary.

When it works well, the Home Mini is handy for checking immediate electricity changes around EV charging, cooking, heating controls or standby load. For billing checks, still use the account, bill and meter readings.

The Octopus API

Octopus also exposes customer data through its API. The useful authenticated consumption endpoints can return half-hourly electricity consumption and gas consumption when Octopus has the meter details and readings available. The public price endpoints can return current and historical tariff rates.

To use the customer endpoints, you normally need:

• your Octopus API key from the web dashboard
• your account number
• the electricity MPAN and meter serial number, or the gas MPRN and meter serial number
• care around dates, time zones, pagination and daylight-saving changes

The REST API can aggregate consumption by day, week, month or quarter as well as returning half-hour periods. Octopus also documents that export MPAN data can be returned through the consumption-style endpoint, even though the field is still called consumption.

The API is powerful, but it is not the first thing most households need. Use it if you want a spreadsheet, Home Assistant dashboard, cost reconciliation or a deeper comparison of usage against tariff windows. For ordinary billing queries, the bill, app and meter readings are usually easier.

Third-party tools

Several third-party tools can help you explore usage data. Some use the Octopus API. Others connect through the smart-meter network or their own hardware.

Common options include:

• Octopus Watch, which is useful for Agile, Go and Intelligent Go customers who want price alerts, smart-tariff views and usage analysis
• Bright or Glow from Hildebrand, which can access smart-meter data through the DCC route where your meter setup supports it
• Loop, which focuses on consumption analysis and energy-saving patterns
• Home Assistant, which can pull Octopus tariff, account and consumption data into a local smart-home dashboard
• Emoncms or other monitoring tools, which can combine API data with local sensors if you want a more technical setup

Before giving any third-party app access, check what data it will see, whether it stores your API key, how to revoke access and whether you are comfortable sharing account-level details.

What to look for in electricity data

Half-hourly electricity data becomes most useful when you stop looking only at the total and start looking at the shape.

Baseload: Look at your lowest overnight half-hours. A persistent background load can come from fridges, freezers, pumps, networking kit, aquariums, towel rails, dehumidifiers or devices that never properly sleep. Do not assume one high night proves a fault; look for a repeated pattern.

Cheap-window share: If you are on Go, Intelligent Go, Agile or Cosy, check how much of your use happens during cheaper periods. EV charging, water heating, batteries, dishwashers and laundry are the usual flexible loads, though safety and noise still matter.

Short spikes: Kettles, ovens, showers, tumble dryers and EV chargers can create obvious peaks. Spikes are not automatically bad, but they explain why one day costs more than another.

Seasonal shape: Winter electricity use can rise if you have electric heating, a heat pump, more tumble-dryer use or more time at home. Summer use can rise with cooling, dehumidifiers, garden equipment or extra EV mileage.

Missing periods: Gaps in half-hourly data can distort app totals, API exports and tariff comparisons. If a calculation looks odd, check whether the source data is complete before trusting the conclusion.

What to look for in gas data

Gas data is mainly useful for heating and hot water patterns. Daily totals are often more helpful than individual half-hours, because gas meter reporting and conversion can make the detail less intuitive than electricity.

Look for:

• summer baseline use for hot water and cooking
• winter peaks around heating demand
• whether heating controls are creating long continuous burns or short regular cycles
• whether a smart thermostat or schedule change actually reduced total gas use
• whether a future heat pump estimate is based on real annual gas demand rather than a guess

The Octopus API documentation notes an important technical detail: for gas, SMETS1 consumption can be returned pre-converted to kWh, while SMETS2 data can be returned in cubic metres. If you are using API data directly, check the unit before comparing figures.

Half-hourly settlement

Market-wide Half-Hourly Settlement, usually shortened to MHHS, is the industry move towards settling electricity based on actual half-hourly consumption rather than profile estimates. Elexon says suppliers began migrating meters from 22 October 2025, with full implementation expected in May 2027.

You do not need to do anything just because MHHS is happening. The practical point for households is simpler: half-hourly data is becoming more central to how the energy system works, and tariffs that reward flexible use should become easier for suppliers to support.

Octopus already makes that visible through Agile, Go, Intelligent Go, Cosy and other smart-tariff ideas. Your own half-hourly data helps you check whether those tariffs suit your home rather than relying on a headline rate.

When missing data matters

A short app gap is often just a delay. It matters more if:

• bills are being estimated repeatedly
• a smart tariff is not billing the right periods
• an export meter is missing readings
• you cannot see whether EV charging, a heat pump or a battery is using the expected window
• a recent switch left the meter out of smart mode
• the physical meter reading and account reading are drifting apart

Citizens Advice says suppliers must take specific steps within five working days when you report that a smart meter is not working properly, including checking whether it is working as it should and trying to find out why. If those steps are not completed in time, compensation rules may apply.

If you recently switched supplier, DCC says SMETS2 meters should normally keep smart functionality through the switch. Older SMETS1 meters are more likely to need extra attention if they have not been fully migrated to the DCC system. The smart-meter switching guide explains that in more detail.

The bottom line

Use the Octopus app for everyday awareness, your bill and meter readings for billing checks, the API for deeper analysis and third-party tools only when they solve a specific problem.

If you are deciding whether Octopus is a good fit, the data is most useful when it answers a practical question: can you move enough usage into a cheap window, are your readings arriving reliably and does your actual pattern support the tariff you are considering?

If you decide Octopus still fits after those checks, you can use Matt’s referral link when you switch.