Solar Battery Tariffs: Import, Export and Time-of-Use Choices

Choosing the right tariff for your hardware

Solar panels and batteries change when a home buys electricity and whether it sells any back. That makes timing, storage losses and product eligibility as important as a headline unit rate.

The useful question is not which product wins in general, but which energy tariff choices fit your equipment and actual load shape. This guide separates four common setups and shows what each one needs to compare.

Understanding the core concepts

Most solar-and-battery tariff decisions come down to four actions. Self-consumption means using solar electricity as it is generated. Export means sending surplus electricity to the grid for payment. Grid charging fills a battery with bought electricity, normally in a cheaper time band. Peak avoidance uses solar or stored energy instead of buying during a dearer band.

Battery storage is not lossless. Some electricity is lost while charging and discharging, so compare tariffs using the usable energy returned by the system rather than assuming every stored kWh comes back. The battery manufacturer’s current efficiency and usable-capacity figures are the right inputs for your model.

Those losses reduce the value of grid arbitrage and change the choice between storing solar electricity and exporting it. A small price gap can disappear once the lost energy and standing charge are included.

Current costs and government support

Treat hardware economics as a separate decision from the tariff. Our home-battery market evidence tracks certified registrations and published installation costs, with updates as new official releases arrive.

Compare like with like: system size, included equipment, geography and the date of the evidence can all change the headline figure.

The solar installation cost evidence covers system prices and output on its own stated basis. Use it as a starting point, then get property-specific quotes and check capacity, usable energy, inverter limits, warranty terms and any installation work.

Home 1: Solar without a battery

Solar without a battery gives you little control over when surplus electricity is available. Using appliances during daylight can raise self-consumption, while the remainder is available to export if the installation and meter meet the tariff rules.

Compare the import tariff for electricity bought from the grid separately from the export tariff for electricity sold. The Smart Export Guarantee creates a route for eligible small-scale generators in Great Britain to be paid, but suppliers set their own rates and conditions.^[1]

A flat export rate can be easier to assess when generation follows daylight rather than a schedule. A time-varying export tariff may still work, but only if enough generation reaches its better-paid periods; do not infer that from the headline rate alone.

Use the solar panel calculator to estimate generation, bill savings and export under stated assumptions, then replace its defaults with a site-specific installer estimate where you have one.

Home 2: Battery without solar

A battery without solar is mainly an import-tariff decision. The household buys electricity in a cheaper time band, stores it and uses the returned energy when import prices are higher.

Compare the length and price of the cheaper window with the full day rate and standing charge. The battery must have enough usable capacity and charging power to cover the load you plan to move, after its losses.

Export is a separate question because product rules differ on grid-charged electricity. Start with bill avoidance, model your own pattern with the smart meter tariff replay, and check the export supplier’s current eligibility before assuming arbitrage income.

Home 3: Solar plus battery

Solar plus a battery offers more control. Surplus daytime generation can be stored for later use, while a time-of-use tariff may also support grid charging when winter generation is lower.

The important comparison is the value of using stored electricity in the home against the export payment you give up. Include charging losses, battery limits and the fact that import and export volumes occur at different times.

A paired import-and-export product such as the one described on the Octopus Flux tariff page is one option, not an automatic winner. Compare its complete import schedule, standing charge, export schedule and eligibility with separate import and export choices.

Seasonal behaviour matters. A schedule built around summer surplus may have little solar energy to move in winter, while frequent grid charging can change both the savings calculation and how the battery is cycled.

Home 4: EV plus battery

An electric car adds a large, flexible load, so compare the whole home and car together. Annual mileage, real-world vehicle efficiency, charging losses and the hours the car is plugged in matter more than battery labels.

Use the EV tariff comparison to test dedicated products on one shared overnight profile, then check whether the car or charger is compatible with any supplier-controlled option. General time-of-use tariffs remain alternatives rather than being silently relabelled as EV tariffs.

Coordinate the two schedules. A home battery can otherwise discharge while the car is charging, moving stored electricity into the larger load when the intention was to use cheap grid electricity.

Check the inverter and charger instructions before changing controls. One supplier, vehicle app, charger or battery should not unknowingly work against another schedule.

Summary: What to compare for your setup

Use this selector as a shortlist, then test the shortlisted tariff against your own import, export and half-hourly data.

Import vs export: Keeping the maths separate

Keep import costs and export earnings as two calculations. Import cost uses the electricity bought in each rate period plus the standing charge. Export earnings use the electricity actually sent to the grid and the export rate applying then.

Subtract the annual export earnings from the annual import cost only after both sides have been calculated from their own volumes and timings. Subtracting one headline pence-per-kWh rate from another assumes equal volumes, which a real home does not have.

Import and export suppliers can often differ, but a supplier may reserve a product or rate for customers who also take its import supply, bought qualifying hardware or meet another condition. Check the current terms before modelling them as independent choices.

The Octopus export tariff page shows the supported products and their current eligibility within this site’s data coverage. It is an Octopus comparison, not a substitute for checking the wider export market.

Automated tariffs and supplier control

An automated tariff lets the supplier schedule a compatible battery rather than relying on a fixed user-set timer. That can simplify optimisation, but it changes eligibility and who controls charging and discharging.

Compatibility is product-specific and can change. Check the battery, inverter, smart-meter data and account requirements directly with the supplier before treating an automated tariff as available to your home.

Our Intelligent Octopus Flux page records the supported tariff’s live status and terms. It must not be read as evidence that an unlisted battery will work or that the supplier will accept every applicant.^[1]

Does a battery always save money?

No tariff can prove that a battery always saves money. The result depends on the installed cost, usable capacity, charging power, household load shape, solar generation, import schedule, export opportunity and how long the hardware performs.

Cycling and warranty terms matter as well. A schedule that charges and discharges more often may create more tariff value while using more of the battery’s warranted throughput, so check the manufacturer’s conditions instead of assuming every extra cycle is free.

Stored solar also has an opportunity cost: using it later avoids an import, while exporting it earns a payment now. Compare those two values after losses rather than assuming self-consumption or export always wins.

Use cautious assumptions and test more than one season. The battery may lower bills and still fail to recover its purchase cost within the period you expect.

Pre-switch checklist

Before you sign up for a new solar or battery tariff, run through this practical checklist to ensure your setup is ready and the numbers make sense.