Dynamic Tariffs & Off-Peak Heating: When to Heat Cheaper (2026)
Updated: 2026-10-01 · ~2 min read
The two routes to cheaper heating
Scroll the table sideways →
| Tariff type | How it works | What you need | Typical savings (indicative) |
|---|---|---|---|
| Off-peak / two-rate (e.g. PL G12, UK Economy 7/9, DE two-rate) | nights and early mornings cheaper (typically 0.5×–0.9× peak price) | pump with DHW/heating buffer (200–500 L tank) + scheduling | 10–20% of the heating bill |
| Dynamic (spot-based, e.g. day-ahead market prices via supplier — available in DE, PL and growing elsewhere) | price changes every ~30–60 min; cheapest windows are usually at night, expensive at morning/afternoon peaks | buffer tank (200–500 L) + controller with price feed (built-in or external); manually "catching" dips isn't worth it | 15–30% with good automation |
Why it doesn't work without a buffer
A heat pump heats the water in your installation/DHW. Without a storage tank, "heating in a cheap hour" is just thermostat-driven room heating (which still burns power whenever it's cold). The buffer stores heat from cheap hours and delivers it during expensive ones — that IS the savings mechanism. In underfloor heating, the floor mass acts as a natural buffer, so the tank matters less, but the tariff still works through zone scheduling.
What automation actually delivers
- Price-profile controller: built into the pump or an external controller (supplier API / PV+BMS systems) plans buffer charging in the cheapest windows.
- Forecast, not reaction: a well-configured system looks at tomorrow's prices, not today's — it doesn't "catch" single dips one by one.
- DHW in cheap hours: the boiler/cylinder charges at night; daytime runs on the buffer.
When dynamic tariffs DON'T make sense (honestly)
- No buffer and no price-aware control — a dynamic tariff can INCREASE your bill (heating during peaks).
- Expensive buffer installation (~€1,500–4,000 all-in in the EU): do the payback math first — at ~€300–600/year savings you're looking at ~3–7 years.
Decision checklist
- Do you have (or plan) a 200–500 L buffer? → yes: off-peak/dynamic pays off.
- Can your pump's controller plan heating by price? → if not, consider an external controller.
- How big is your usage? Dynamic tariffs usually shine above ~3,000 kWh/season.
Affiliate slot: buffer tanks, controllers — to be wired via a marketplace after publisher registration.
Sources
- EU dynamic tariff offerings (spot-based tariffs; DE/PL examples) and two-rate tariff structures; as of October 1, 2026 — check your local supplier.
- Heat pump buffer sizing and off-peak operation practice; industry references; as of October 1, 2026.