Dynamic Electricity Tariffs in Austria & Germany: The Sober Calculation
Exchange-based electricity can save you a lot, or nothing at all. What it really depends on, worked through soberly.
How dynamic tariffs work
With a dynamic tariff (in Austria and Germany, providers like aWATTar and others), you pay per hour the exchange price (EPEX Spot day-ahead) plus a markup, grid fees, levies, and taxes. Tomorrow's exchange prices are fixed today by around 2 p.m., so you can plan ahead.
Typical pattern: expensive in the morning (7–9 a.m.) and evening (6–9 p.m.), cheap at night and increasingly around midday too, when a lot of solar power is on the grid. On sunny weekends, exchange prices around midday increasingly fall toward zero or below.
The key insight: only the energy price fluctuates
Grid fees, levies, and taxes stay fixed; depending on the region, they make up a substantial share of the final price. If the exchange price fluctuates by 10 ct, your final price fluctuates by exactly those 10 ct, not more. So the savings come only from the kilowatt-hours you actually shift, multiplied by the price difference between the hours.
A back-of-the-envelope calculation: if you shift 2,000 kWh a year (EV plus hot water) on average from 30 ct/kWh hours into 18 ct/kWh hours, you save around €240/year. Shift nothing, and you save nothing, and in a winter high-price situation, a fixed consumption pattern can even end up more expensive than a flat tariff.
Who it pays off for, and who it doesn't
Good candidates: EV drivers (the biggest shiftable load in the house), heat pumps with a buffer tank, hot water tanks, home batteries capable of grid charging. In short: anyone with flexible kWh.
Bad candidates: households without shiftable loads. Cooking, lighting, and the TV follow life, not the exchange. If you only have 2,500 kWh of baseline consumption and nothing to shift, a dynamic tariff mostly just gives you price risk.
The uncomfortable truth about doing it manually: reacting to prices by hand ("it's cheap tonight, I'll plug the car in") works for two weeks, then everyday life wins. The tariff only realizes its value with automation, whether self-built or off the shelf.
What to look for in a provider
- Hourly prices with day-ahead publication (standard with aWATTar & co.)
- A smart meter is a prerequisite: largely rolled out in Austria, not yet universal in Germany depending on the metering point operator
- Flexible entry and exit? Monthly cancellation is the fair norm.
- For PV owners: how is feed-in compensated: fixed, or also exchange-based? That changes the calculation for surplus charging.
Franzl handles exactly this shifting, automatically, freshly every night.
Dynamic tariffs with Franzl