SunHarvest

Prices and tariffs

SunHarvest deliberately keeps two tariffs apart: what you really pay and earn, and the price curve the Powerwall is told to optimise against.

  • Your real tariff is the truth about what a kWh costs and earns you. It is used for every money figure, for price signals in rules and by the AI. It is never sent to Tesla.
  • The Powerwall's tariff is the curve Time-Based Control optimises against. It does not have to match reality. A preset with a huge sell window makes the Powerwall export hard, and a fake cheap buy window makes it charge. The real economics are always measured against your real tariff.

For the background, read how Powerwall time-based control works.

Your real tariff (Tariffs › Your tariff)

Set each direction separately: Import (what you pay) and Export (what you earn).

Octopus feed (half-hourly)

Pick your product from the live list: Agile, Flux, Go, Intelligent Octopus Go, Cosy, Outgoing and others, fixed and variable alike. Then pick your region from the 14 UK distribution regions, listed by name.

If your product is not listed, perhaps because it is an older generation that has gone off sale, choose Other product code. Type the code from your Octopus account page or bill. Prices sync within seconds and are recorded from then on. Tomorrow's prices arrive around 16:00.

On a fixed deal?

Your rates were set when you signed up, but the feed follows whatever Octopus publishes now. Copy to fixed rates turns the product's rates into the fixed / time-of-use fields, ready to correct to the rates on your contract and save.

Fixed and time-of-use rates

Enter a base price per kWh, a standing charge per day, and optional time windows with from and to times and which days they apply. Windows override the base price. A window that ends at or before it starts wraps past midnight, e.g. 23:30–05:30 for an overnight rate.

Not with Octopus? Enter your rates manually; the AI and the money figures work the same.

The Powerwall's tariff (Tariffs › Powerwall tariff)

This shows what is on the Powerwall now and when it was seen. From here you can:

  • Push today's real prices. This renders your real tariff into the Powerwall so Time-Based Control follows real prices. A built-in rule can do this for you every day just after midnight. It is on the Rules tab, switched off until you enable it.
  • Capture the current Powerwall tariff as a named preset.
  • Keep a list of presets that you can apply, duplicate, edit or delete. A preset has a name, a daily charge, and periods with their times, buy price and sell price. Presets are what the "apply tariff preset" rule action picks from.

How the money figures are worked out

Every half-hour of recorded energy is priced against your real tariff for that half-hour:

  • Spent is imported energy times the import price, plus the standing charge.
  • Earned is exported energy times the export price.
  • Net is the difference between the two.
  • On Pro, Saved compares the day with what the same household use would have cost with no solar and no battery.

That is why it pays to get the tariff exactly right. A wrong region or product code makes every figure slightly off.

Choosing a tariff in the first place? See Octopus Agile with a home battery and UK export tariffs explained.