Most electricity tariffs work on a flat rate — you pay the same per kilowatt hour whether it’s two in the afternoon or half seven in the evening when half the country switches the kettle on. Octopus Agile doesn’t work like that. It prices electricity differently every thirty minutes, following the wholesale market, which means the gap between the cheapest and most expensive periods in a day can be enormous.

On a breezy spring morning with lots of wind generation, Agile prices sometimes go negative. You’re being paid to use electricity. On a cold, still evening when demand peaks and generation is tight, the same unit might cost 40p or more. If you can shift when you use electricity, or store cheap units and use them later, Agile can cut your bills significantly. Home batteries are the main way people do that.

How Octopus Agile Actually Works

Octopus publishes the next day’s half-hourly prices at around four in the afternoon via their API and their app. Prices reflect the day-ahead wholesale electricity market plus Octopus’s standing charges and margins.

The range varies with season and conditions. In summer, overnight prices are often 5-15p/kWh. Winter evenings during high demand can hit the price cap ceiling of around 100p/kWh (the actual cap changes — check current Ofgem rates). Plunge pricing events, where prices go negative, happen a few times a week during high renewable generation periods, particularly on windy nights.

There’s also an export rate for households with solar. The Agile export tariff follows a similar half-hourly structure, meaning you earn more exporting at peak times. This is separate from the standard Smart Export Guarantee, and often pays considerably better if you can time your export.

The Battery Pairing

A home battery on its own doesn’t save you much on a flat-rate tariff. You’d charge from the grid and discharge at home, paying the same rate either way. The economics only work when you can buy cheap and use or export dear — which is exactly what Agile enables.

The standard playbook:

Charge during cheap periods. Most battery systems support scheduled charging with a target time and minimum price threshold. Set the battery to charge only when Agile prices are below, say, 10p/kWh. In practice that means overnight or during mid-morning lulls.

Discharge during peak times. The evening peak, typically between four and seven, is when Agile prices climb. Drawing from battery rather than grid during that window avoids the most expensive units.

Use plunge pricing when it happens. Some battery management apps will automatically charge to capacity during negative-price periods. Even without smart automation, checking the Octopus app the evening before and setting a manual charging window works fine.

Most of the major battery brands play well with Agile. GivEnergy batteries have native Octopus integration via the GivEnergy app. Tesla Powerwall 3 works through the Tesla app with time-based control. Solis, Sunsynk, and Fox ESS inverters all support scheduled charging that you can configure around Agile prices. Ohme, Myenergi, and similar smart chargers handle EVs the same way.

The Numbers

Whether Agile saves you money depends on your usage patterns and battery size. A rough calculation for a household with a 10kWh battery:

  • Charge 10kWh overnight at an average of 8p/kWh: 80p
  • Avoid 10kWh of peak consumption at an average of 30p/kWh: saves £3.00
  • Net saving per full cycle: roughly £2.20

Do two charge-discharge cycles daily and you’re looking at around £1,600 per year in savings before standing charges and before factoring in any export earnings. That’s a simplification — real savings depend on actual Agile prices, your battery’s round-trip efficiency (typically 90-95%), and whether you’re also exporting solar.

The standing charge on Agile is higher than standard tariffs, which matters for lower-consumption households. Run the numbers based on your own usage before switching.

Getting Set Up

You need a smart meter with half-hourly export to join Octopus Agile — Octopus will install one if you don’t have one already, and it’s free. The meter needs to communicate readings every thirty minutes so your bill accurately reflects the time-of-use pricing.

From there, switch is straightforward via the Octopus website. You get access to their API (documented well and widely used by home automation enthusiasts) and the Kraken app.

Home automation platforms like Home Assistant have dedicated Octopus Energy integrations that pull in the half-hourly price data and let you automate battery charging, immersion heater scheduling, and EV charging based on real-time and forecast prices. If you’re willing to spend a few hours setting it up, that level of automation extracts considerably more value than manual scheduling.

What to Watch

Agile isn’t for everyone. If you have no flexibility in when you run appliances and no battery, the half-hourly pricing can go against you — you’ll pay peak prices if your usage happens to fall in expensive slots.

The tariff also requires a degree of engagement. Prices vary daily, so a set-and-forget approach leaves money on the table. Automation through Home Assistant or similar helps, but there’s a setup cost to that.

For households with solar, battery storage, and the appetite to manage their energy actively, Agile is one of the better tariff structures available in Great Britain right now. The combination of negative pricing, transparent data, and a reasonable API makes it genuinely useful rather than just a marketing angle.