Agile and Dynamic Half-Hourly Electricity Tariffs

Agile and dynamic half-hourly electricity tariffs are the most granular pricing a UK household can be on. Instead of one unit rate, or a day and night rate, the price of a unit of electricity changes every 30 minutes, tracking what electricity actually costs on the wholesale market. At quiet times, overnight or on windy afternoons, rates can be far below a standard tariff; at peak times they can be well above it. The tariff that made this model widely known in the UK is Octopus Energy's Agile tariff, on which customers find out the electricity unit rates they will pay for the next 24 hours between 4pm and 8pm daily¹.

None of this is possible without a smart meter. Half-hourly tariffs depend on the meter recording your use in 30-minute blocks and sending those readings to your supplier automatically. Official guidance is clear that smart meters enable accurate billing by automatically recording energy use in half-hour periods, and that this half-hourly recording is what enables a supplier to charge different rates for use at different times of the day or week². If you are weighing this against other options, our wider guide to UK energy tariffs covers the full range, and time-of-use tariffs explain the simpler block-priced versions.

Why a half-hourly tariff needs a smart meter

A traditional meter records one number: the total units consumed since it was last read. A supplier billing on that basis cannot tell when you used electricity, only how much. That is fine for a flat-rate tariff, but it makes any time-sensitive pricing impossible, which is why older meters lock households out of the whole flexible end of the market.

A smart meter works differently. It automatically sends your electricity and gas meter readings to your supplier, and it records energy use in half-hour periods². For electricity, the meter can provide readings as often as every half hour⁷. That record of when you used power, not just how much, is the foundation of every agile and dynamic tariff: the supplier needs to know exactly which 30-minute block each unit fell into before it can charge the price that applied in that block².

The half-hourly recording also does the reverse job. As Smart Energy GB puts it, the half-hourly recording of energy use "enables your supplier to charge different rates for use at different times of the day or week"³. The same mechanism supports heat pumps, EV chargers and other flexible schemes, and Smart Energy GB is blunt that you "will need a smart meter to access the full benefits of flexible schemes and smart tariffs"³. If you are considering an EV or heat pump tariff specifically, we cover whether you need a smart meter for one separately.

How the prices are published a day ahead

A dynamic tariff is not a mystery box. The rates are published in advance, so a household can plan its day around them. On Octopus Energy's Agile tariff, customers find out the electricity unit rates they will pay for the next 24 hours between 4pm and 8pm daily¹. That means each evening you can see, half hour by half hour, what tomorrow will cost, and decide when to run the washing machine, charge the car or heat water.

This day-ahead structure is what separates a genuinely dynamic tariff from a tracker tariff, which also follows wholesale prices but applies one rate to the whole day rather than 48 separate ones. With a tracker, shifting your usage within the day saves nothing, because every hour costs the same. With a half-hourly tariff, shifting usage is the whole point: the same kilowatt-hour can cost a fraction of the peak price, or occasionally nothing at all, depending on when you use it.

The published rates reflect the wholesale market, which is why they swing. When electricity is scarce, evening peak blocks are expensive; when wind and solar generation are abundant, blocks in the middle of the day or overnight can be very cheap. The practical skill for a household is reading the published rates each evening and moving flexible loads into the cheap blocks, which is the subject of our guide to shifting electricity use to cheap-rate periods.

Picking your data sharing frequency: every 30 minutes, day or month

A smart meter does not have to send readings every 30 minutes. How often your smart meter sends data to your supplier is your choice: monthly is the minimum, and daily or half-hourly are optional⁵. The DCC, which runs the network the meters communicate over, describes automatic readings being provided monthly, weekly, daily, or even half-hourly⁸. For electricity, readings can be taken every day, or every half hour⁷.

For a dynamic tariff the choice is made for you by the tariff's own rules: your smart meter will need to be set up to provide automatic meter readings every 30 minutes, so that your provider can bill each block at its own rate¹. On a flat tariff, monthly is enough, and some households prefer it on privacy grounds.

The trade-off is worth understanding. Half-hourly data is what unlocks dynamic pricing, and it is also what makes your bill exact: smart meters enable billing based on actual rather than estimated usage, with energy use automatically recorded in half-hour periods². Monthly data still gives you accurate bills, but it gives the supplier only a monthly total, which no half-hourly tariff can be built on. If you later want to move to a dynamic tariff, the data-sharing setting has to change to half-hourly first.

The way time-of-use rates apply after installation

Once the meter is recording in half-hour blocks, the supplier can price those blocks however the tariff defines. Time-of-use tariffs use your smart meter to log electricity use and charge you different rates during different time windows⁹. The Welsh Government's consumer guidance describes the same mechanism: these tariffs "use your smart meter to log electricity use, and charge you different rates during different time windows"⁹.

The block structure varies by tariff. A simple time-of-use tariff has two or three windows, a peak and an off-peak, as with Economy 7. A dynamic tariff goes further and prices all 48 blocks individually against the wholesale market. In between sit hybrid designs, including EV tariffs with a cheap overnight window and a standard rate for the rest of the day. The Energy Ombudsman confirms that all smart meters can support tariffs which charge different prices at different times throughout the day and night, including Economy 7, and that Economy 10 meters are also available¹⁰.

The official guidance on the benefits is consistent. Access to time-of-use tariffs means cheaper rates during off-peak hours and incentives for energy usage on high-supply days¹¹. The same logic runs through government schemes: under ECO4, a supported measure can be combined with a time-of-use tariff and will be used with a functioning electricity smart meter¹². Smart meters also enable access to smart tariffs and demand-flexibility events, which could reward you for using energy during off-peak times or when lots of clean electricity is available³, the subject of our page on flexibility payments for households.

The drawbacks of dynamic tariffs

The limitations are structural, and worth stating as firmly as the benefits.

• A smart meter will not automatically save you money. Citizens Advice says it plainly: "A smart meter won't automatically save you money"⁷. The saving comes from changing when you use energy, not from the meter itself.
• You do not control the rates. Except by switching, you do not control the tariff your energy supplier sets, but you can change how much energy you use¹³. On a dynamic tariff the rates follow the wholesale market, and you cannot opt out of an expensive evening peak.
• Peak blocks can be punishing. The whole point of the pricing is that scarcity costs money. A household that cannot shift its usage out of peak periods pays the market's worst prices for them.
• It needs engagement. Because Agile rates are published between 4pm and 8pm daily for the next 24 hours¹, a household that never looks at them gets the pricing without the planning.
• The meter must stay in smart mode. If the meter stops communicating, the supplier cannot bill half-hourly, and the household may be moved to a different arrangement until it is fixed.
• Switching can break the smart function. Your meter may not work in smart mode when you move to a new supplier, and you may need to take meter readings manually and submit them instead¹⁴.

For a household's energy independence, the honest summary is this: a dynamic tariff gives you a direct link to the real cost of electricity, which rewards a home that can generate, store or time-shift its own use. But it also deepens your dependence on the supplier's pricing system and on the meter's communications working, and it does nothing at all for a home that cannot move its consumption.

Who sees your half-hourly readings

Half-hourly data is the most detailed picture of a household's life that an energy supplier can hold, so the privacy question is a fair one. The answer from the DCC, which operates the network, is that only your energy supplier can see how much energy you are using and when⁶. The readings travel over the DCC's secure network to your supplier, and not over your own connection: a smart meter does not need, or connect to, the public internet or your home Wi-Fi¹⁵.

The data has defined uses. Official guidance lists them: the data you share through your smart meter is used to bill you for the energy you use, to offer you new products and services such as new tariffs if you have given permission for this to happen, and to help make the energy system more efficient by recording demand more accurately¹⁶. That is the scope, and it is worth noting the permission point: being offered new tariffs on the back of your data requires your consent.

Two protections follow from this. First, the frequency choice is yours: monthly is the minimum and half-hourly is optional⁵, so a household on a flat tariff can decline the granular sharing. Second, the DCC network is separate from your home broadband¹⁵, so the meter is not a device sitting on your Wi-Fi, and a broadband outage does not expose or interrupt its readings.

What happens when meters fail or go offline

Meters fail, and a dynamic tariff fails with them. Official guidance lists the fault modes: your smart meter may stop recording the energy you use, or may no longer send readings to your supplier⁴. When that happens, the half-hourly record the tariff depends on is broken, and the supplier will fall back on other ways of billing, which can mean estimates.

The remedy is to contact your supplier. Ofgem's guidance says to contact your energy supplier if you have a problem relating to late, incorrect or missing bills, back billing, being overcharged, a faulty meter, poor customer service, or a refusal to refund credit from your account¹⁷. If the supplier does not resolve it, the complaint can be escalated, and Ofgem monitors suppliers and network operators closely to make sure they meet the rules set out in licences, regulations and law, provide good customer service, and reply quickly to customers who contact them.

A bill that does arrive should be checkable. As set out by Ofgem, your domestic energy bill should contain your policy or account number, supply number or meter point number, usage, previous usage, tariff, complaints information, balance, charges and fees, payment date, and any changes to tariff¹⁸. If you have been overcharged or are owed money, including credit from your account, there is a route to check what you are owed¹⁹. The one comfort for households is that a smart meter in working order removes the main cause of estimated bills in the first place: you get bills based on accurate meter readings and not estimates⁴.

Changing provider on a half-hourly meter plan

Switching is always available: if you pay a supplier directly for the electricity or gas you use at home, you can choose to switch to a different supplier or tariff at any time²⁰. On a dynamic tariff, two things happen at a switch.

The first is financial. When you switch to a new supplier, your old supplier will refund any credit in your final bill, and you could get compensation if they do not²¹. The second is technical, and it matters more here. Your meter may not work in smart mode when you move to the new supplier, and you may need to take meter readings manually and submit them to your new supplier instead¹⁴. A meter that has dropped out of smart mode cannot send half-hourly readings, so a dynamic tariff cannot be billed on it until the smart function is restored. The guidance adds a hopeful note: your meter may work in smart mode again if you change tariffs or suppliers¹⁴.

Supplier failure follows the same pattern. You do not need to do anything if your current supplier goes out of business: Ofgem will automatically move you to a new supplier and make sure your energy supply is not interrupted¹⁴. The new supplier may set its own tariff terms, and the meter's smart mode may be affected in the same way as any switch. If you are comparing a dynamic tariff with a wholesale-linked single-rate product, our comparison of Octopus Agile vs Octopus Tracker works through the differences.

Special situations: prepay meters, tenants and more

Half-hourly pricing is not limited to credit customers, but the cases differ.

• Prepayment. A smart meter in prepayment mode lets you add credit automatically or without having to visit a shop⁴. If you have a prepayment meter and you owe your supplier up to £500, you can still switch supplier²⁰, so debt does not by itself lock a prepayment household out of the market.
• Remote switching to prepayment. Where an existing supply meter is switched to prepayment mode without the consumer's consent, the supplier must ensure the consumer receives prepayment meter credit, unless it is technically infeasible or otherwise outside the supplier's control²². Under draft heat network consumer protection guidance, if no contact is made with the consumer during a site welfare visit and all engagement attempts have been exhausted, the supplier may proceed with a remote mode switch to prepayment mode²².
• Renting. Renters can access smart meters and the tariffs that depend on them, and grant support exists for relevant installations: the Electric Vehicle Chargepoint Grant for Renters and Flat Owners is available, though you cannot apply if you have already claimed that grant or its predecessors, the Electric Vehicle Homecharge Scheme or the Domestic Recharge Scheme²³.
• Solar and generation. Households with panels are not excluded: you can get a smart meter installed by your energy supplier at no extra cost²⁴, and if you receive generation payments, your generation payments will not be affected²⁵. Export payments are a separate arrangement, covered in our guide to the Smart Export Guarantee.

For prepayment households in particular, the dynamic-tariff landscape is narrower, and our page on prepayment and pay as you go tariffs covers what is generally available.

Getting a meter that can record half-hourly

The meter itself is free. Contact your supplier to get a smart meter for free⁴; there is no upfront charge⁵, and you can get one installed by your energy supplier at no extra cost²⁴. Energy suppliers aim to provide every home and business in England, Scotland, and Wales with free smart meters⁸, so availability is national across Great Britain. Northern Ireland's market is separate, and we cover tariffs in Northern Ireland elsewhere.

Two things are worth knowing before you ask. First, you have the right to refuse a smart meter if you do not want one⁵, and energy companies have been asked by the government to take all reasonable steps to install smart meters in homes⁵, but the choice remains yours. Second, refusing has a cost in the other direction: there are certain tariffs that are only available to smart meter customers, including some of the cheapest tariffs on the market²⁶, and refusing excludes you from cheaper tariffs which are only available if you have a smart meter²⁴. A smart meter also gives access to more flexible tariffs, including dual-rate tariffs¹⁶.

If you already have a first-generation smart meter that has dropped out of smart mode, there is a programme of upgrading Britain's first-generation smart meters so they keep working⁶. And if you want the meter but not the granular data, a supplier may be able to set up a meter to work in dumb mode, with all communications switched off⁵, though that removes the half-hourly readings a dynamic tariff needs. To check what your current meter allows before you switch anything, see which tariffs your meter and home allow.