A home battery is most valuable when paired with a time-of-use electricity tariff — one that charges different rates at different times of day. Charge your battery when electricity is cheap, discharge when it's expensive. Here's how the main UK options compare in 2025.
How time-of-use tariffs work with a battery
Standard UK electricity tariffs charge a flat rate regardless of when you use power. Time-of-use (TOU) tariffs charge different rates depending on the time — typically cheaper overnight and more expensive during evening peak hours. A battery lets you arbitrage this difference: charge at the low rate, discharge at the high rate.
The spread between cheap and expensive rates is the key metric. A spread of 15–20p/kWh, cycled daily on a 10kWh battery, could save £500–£700 per year. The wider the spread and the more consistently you cycle the battery, the better the economics.
Octopus Agile
Octopus Agile is the most dynamic TOU tariff available in the UK. Prices change every 30 minutes based on wholesale electricity costs, and are published the day ahead. Rates range from negative (you're paid to use electricity) to a cap during very high demand periods.
For battery owners, Agile offers the largest potential savings — but requires either manual management or a battery that integrates directly with the Agile API (the GivEnergy, Tesla Powerwall 3, and several other batteries support this). Average overnight rates on Agile are typically 5–10p/kWh, against daytime peaks of 20–35p/kWh — a spread of 15–25p.
Intelligent Octopus
Intelligent Octopus offers a simpler proposition than Agile — a cheap overnight rate (currently around 7–9p/kWh) for 6 hours per night, with a standard daytime rate of around 24p/kWh. It requires a compatible smart device (Tesla Powerwall, certain EV chargers, or smart heat pumps) that Octopus can control directly to ensure charging happens at the cheapest time.
For most battery owners, Intelligent Octopus is the most straightforward and reliable option. The rate is guaranteed rather than dynamic, the integration is seamless if you have a compatible battery, and the savings are predictable. Tesla Powerwall 3 owners get particularly deep integration.
Economy 7
Economy 7 is the UK's original time-of-use tariff — cheap electricity for 7 hours overnight (typically midnight to 7am or 1am to 8am), at a higher rate during the day. It predates smart meters and is designed for storage heaters, but works well with any battery that can be scheduled to charge during the cheap period.
Economy 7 overnight rates in 2025 are typically 12–17p/kWh, with daytime rates of 28–35p/kWh. The savings potential is similar to Intelligent Octopus but without smart integration — you'll need to manually configure your battery's charge schedule. Check that your battery's BMS supports scheduled charging before switching.
How to switch and what to check first
To access any smart TOU tariff you need a smart meter (SMETS2 or later). If you don't have one, contact your current supplier — installation is free under the smart meter rollout programme. Most suppliers can install within 2–4 weeks.
Before switching tariffs, calculate whether your battery's daily cycling will offset the higher daytime rate on a TOU tariff versus your current flat rate. If you have solar, factor in that your panels will cover much of your daytime usage anyway — making the cheaper overnight rate for battery charging the main benefit.
What savings to realistically expect
A 10kWh battery on Intelligent Octopus, cycling once per day at a 16p/kWh spread (charging at 8p, avoiding 24p imports), saves around £160 per 100 cycles — or roughly £480–£580 per year based on typical cycling patterns. Combined with solar self-consumption, total annual savings from a 5kW solar + 10kWh battery system on a TOU tariff can reach £1,000–£1,300 for a medium-to-high electricity user.
These are realistic mid-range figures for a well-configured system. Higher electricity users, particularly those charging an EV, can see significantly larger savings as they have more load to shift to the cheap overnight window.