Powerwall on Octopus Agile: the half-hourly game
In plain English: Octopus’s dynamic tariff — the price changes every 30 minutes with the wholesale market, and tomorrow’s prices publish around 4 PM today.
Agile is the most alive electricity price in Britain. It rewards exactly one thing: moving energy from the half-hours nobody wants power to the half-hours everybody does. That is a battery’s entire job description.
The plan at a glance
| Period | Typical hours | Typical price |
|---|---|---|
| Overnight | ~midnight–6 AM | 5–15p/kWh |
| Daytime | varies | 15–25p/kWh |
| Evening peak | ~4–7 PM | 25–40p+/kWh |
| Plunge events | windy/sunny low-demand spells | below zero — you are paid to consume |
Shapes are typical, not fixed — Agile reprices every half hour and every day is different. Prices include VAT; the daily standing charge applies regardless.
What this plan means for a Powerwall
Fixed-window strategies die on Agile because the windows move. The winning behavior is price-following: charge the battery in the cheapest half-hours (usually overnight, sometimes a random windy Tuesday afternoon), carry the house through the evening spike, and treat plunge events as free fuel. With grid charging enabled, a 13.5 kWh Powerwall filling at 8p and displacing 35p evening imports clears roughly £3 of value on a good day — before a single plunge event.
Plunge pricing is the sport. When wholesale prices go negative, Agile follows: your import price drops below zero and every kWh you pull is money in your pocket. Charge the Powerwall, charge the car, run the dryer — being greedy is the correct strategy for those half-hours.
The automations worth having
A price-below trigger that grid-charges the Powerwall whenever the live price drops under your fill threshold; a negative-price trigger that opens everything up (battery and EV) the moment you’re being paid; a price-above trigger that drops the reserve and lets the battery carry the peak; and alerts that verify the charge or discharge actually happened rather than assuming it did.
How SolDial runs Agile natively
Pick Octopus Agile on the Hourly tab and SolDial resolves your grid region from your postcode automatically. Your dashboard shows the live half-hour price and the full day’s curve; tomorrow’s posted prices appear as the day-ahead plan when Octopus publishes them around 4 PM. Automations trigger on the exact half-hour price — negative thresholds included — and savings are measured against real Agile history, not an average.
Does this apply to my exact situation?
Plans vary by region, retailer, and season, and rates get revised. SolDial recomputes the strategy — and the honest savings math — from your plan as you set it in the app, not a blog’s snapshot. If your plan differs from this page, the app follows your plan.