UK export tariffs explained
Every kWh your home sends to the grid can earn money, but how much depends on which export tariff you are on and when you export. With a battery, the "when" is something you control.
The Smart Export Guarantee
The Smart Export Guarantee (SEG) is the scheme behind most UK export payments. Since 2020, larger electricity suppliers must offer at least one export tariff to eligible small-scale generators, such as home solar. The rate must always be above zero. Suppliers set their own rates, so they vary a lot, and you can take your export to a different supplier from your import.
To qualify, you generally need:
- a smart meter that records exports half-hourly
- an eligible installation, usually with its certification (for example MCS) for the solar panels
Rules for exporting energy stored in a battery, especially energy bought from the grid, vary by supplier and tariff. Check the terms.
The main kinds of export tariff
Flat-rate export
One price per kWh, whenever you export. Outgoing Octopus is an example (the supplier can still change the rate). It is simple and predictable. With a battery, it removes any reason to time your exports, so the battery is usually better spent powering your own home, since import usually costs more than export pays.
Half-hourly export
A price for every half-hour that follows the wholesale market, like Octopus Agile Outgoing. Prices are typically highest in the early evening, when the grid needs power most, and lowest in the middle of sunny days, when everyone's panels are exporting at once. A battery lets you hold midday solar back and sell it into the evening instead.
Peak-export tariffs (Flux-style)
Tariffs such as Octopus Flux pair import and export on the same time bands:
- a cheap overnight window for both buying and selling
- a day rate
- a premium peak every day, typically 16:00–19:00, when export pays the most
They are built for solar-plus-battery homes. The classic pattern is to charge cheaply overnight, run the house on solar during the day, and sell the battery into the peak, keeping just enough for the rest of the evening. They usually require taking import from the same supplier.
Comparing them
| Flat rate | Half-hourly | Peak (Flux-style) | |
|---|---|---|---|
| Rate varies by time? | No | Every 30 minutes | Fixed bands |
| Rewards a battery? | Little | Yes, via timing | Strongly, at the peak |
| Effort | None | Daily, best automated | Set up once, tweak by season |
| Best for | Solar without a battery | Automated batteries | Solar plus a large battery |
Export limits
How fast you can export matters as much as the price. In Great Britain, smaller systems are connected under a simple notification process (G98). For a typical single-phase home that allows roughly 3.68 kW of generation. Larger or combined solar-plus-battery systems usually need the network operator's approval in advance (G99), and the operator may set an export limit.
An export limit changes the strategy:
- On a sunny day the panels alone can reach the limit, so the battery can't add to exports at midday. Any solar above the limit has to go into the battery or be wasted.
- So the battery should often start a sunny day emptier, with room to soak up the excess, and then sell into the evening, when the export capacity is free again.
- Over a peak window, the limit caps how much you can sell. At 3.68 kW, a three-hour peak moves at most about 11 kWh.
Working that out each day, from the forecast, the battery level and the prices, is fiddly by hand. It is one of the jobs SunHarvest was built for: rules can react to solar remaining today and the best export price in the next N hours, and the AI planner takes the forecast into account automatically.
Setting up export in SunHarvest
- In Prices › Your tariff › Export, choose your Octopus export product and region, or enter a fixed or time-of-use export rate.
- On the Powerwall, set Export to Solar + battery ("Everything" in the Tesla app) if you want the battery to sell. Solar only never exports battery energy.
- For a peak tariff, a single rule does the core job: when the clock reaches 16:00, force export until 19:00. Add a condition on battery level so you keep enough for the evening.
- Check Earned on Home and Energy to see what export is really making you.
General information, not financial or electrical advice. SEG rules, tariff terms and connection requirements change; check with your supplier, your installer and your network operator. SunHarvest is not affiliated with Octopus Energy.