What electricity tariff should I choose with solar and a battery?

With a battery in the system, the winning tariff is rarely the cheapest flat rate — it is the one with the widest usable spread between cheap and expensive hours, because the battery lets you buy in the trough and skip the peak. Compare tariffs on the spread you can capture, plus the export rate, not on the headline unit price.

Why storage changes the ranking

A flat tariff makes your consumption profile irrelevant: one price, no room for skill. Time-of-use and dynamic tariffs pay you for flexibility — and a solar-plus-battery home is the most flexible customer there is. It can charge the battery in a cheap overnight window, run the house from stored energy through the evening peak, and time exports to the best-paid hours.

The landscape differs by market but the logic holds everywhere: in the UK, TOU and dynamic products (Octopus Go, Flux, Agile and peers) pair explicitly with batteries, and export tariffs vary several-fold — see the separate export tariff answer. Ireland’s day/night meters plus the Clean Export Guarantee follow the same pattern. In Australia, TOU plus 5-minute wholesale plans (e.g. Amber) reward exactly the same choreography.

What to do

1. Reconstruct a real month against each candidate tariff — your import/export half-hourly data run through each price sheet beats every marketing page. Smart-meter portals or Home Assistant give you the raw data.
2. Score three numbers per tariff: cheap-window price (your battery’s cost basis), peak price you avoid, export rate. The spread × your battery’s daily cycle is the prize.
3. Check the constraints — dynamic tariffs usually require a smart meter and expose you to price spikes on grey weeks; the no-battery dynamic answer covers who should stay away.
4. Feed the choice into automation — the tariff only pays if charging follows both prices and tomorrow’s production; a per-system forecast plus simple rules captures most of the value without daily fiddling.