Dynamic electricity tariffs price power differently every hour, following the wholesale market. In a good hour it can cost a fraction of a flat rate. In a bad hour it can cost several times as much. Occasionally, on windy sunny days with low demand, the price goes negative and you are paid to consume.
They are increasingly available across Europe and they are not right for everybody. Whether they are right for you depends almost entirely on one question, which is not the one most people ask.
The question that decides it
Not “how much could I save?” but “how much of my consumption can I actually move?”
A dynamic tariff rewards flexibility. If your consumption is a flat profile you cannot shift — lights, cooking, a television, a fridge — then you are simply exposed to price variation with no ability to respond, and you may well pay more than on a fixed rate.
If you have large flexible loads, the picture changes completely. In rough order of how much they help:
- An electric vehicle. The single biggest enabler. A car needing 40 kWh overnight, charged in the cheapest four hours, is a large load moved entirely into low-price territory with zero inconvenience.
- A home battery. Charge cheap, discharge expensive, every day, automatically. This is arbitrage and it works even with no solar panels.
- Electric hot water. A cylinder is a heat battery. Heat it when power is cheap and it holds the energy for hours.
- A heat pump. Partly shiftable, since a well-insulated house can be pre-heated in cheap hours and coast.
- Wet appliances. Dishwasher, washing machine, dryer. Real but modest.
If you have none of the first three, be sceptical. If you have any of them, dynamic pricing is probably the highest-return energy decision available to you, and it requires no hardware beyond what you already own.
How the pricing actually works
Understanding the mechanics helps you avoid the two common mistakes.
Day-ahead prices publish the afternoon before. In most European markets, hourly prices for the following day are known by early afternoon. That means automation can plan a whole day in advance rather than reacting.
The price you pay is not the wholesale price. Network charges, taxes and levies are added, and these are frequently fixed per kilowatt-hour or time-banded separately. So a wholesale price of near zero does not mean free electricity, and the proportional saving is smaller than the wholesale spread suggests. Read the supplier's breakdown to understand what varies and what does not.
Some tariffs have capacity or peak-demand components, charging on your highest recorded draw in a period. Where that applies, avoiding simultaneous large loads matters as much as timing them.
Using one without thinking about it
The failure mode of a dynamic tariff is a household trying to manage it manually. Watching prices and deciding when to run the dishwasher is exhausting, and people stop after three weeks.
Automation is what makes it work, and the pattern is straightforward.
Fetch tomorrow's prices
Most suppliers with dynamic tariffs offer an API or an integration. Your hub pulls the price curve each afternoon.
Rank the hours and schedule
For each flexible load, find the cheapest contiguous block long enough to complete it, and start then. Car charging needs the cheapest four hours before you leave; hot water needs the cheapest two before you need it.
Set guard rails
This is the part people omit and regret. A rule that only ever charges the car in the cheapest hours will occasionally not charge it at all, because the cheapest hours were after you left. Always include a deadline: charge by 07:00 regardless of price, at whatever it costs. Convenience must win over optimisation when they conflict.
Handle negative prices
When the price goes below zero, the optimal behaviour inverts: consume as much as you sensibly can. Charge the car, heat the water, run the battery to full. Equally, if you have solar and are exposed to negative prices on export, you want to stop exporting — which is a specific automation worth having.
What about time-of-use tariffs instead?
Worth knowing that dynamic hourly pricing is not the only option, and for many households a simpler alternative fits better.
Time-of-use tariffs have a small number of fixed bands — a cheap overnight rate and a standard daytime rate, sometimes with an expensive evening peak. The rates are known in advance and do not change hour to hour.
The trade is straightforward. You capture less of the available saving than a well-automated dynamic tariff, and you take on far less risk and require far less automation. A simple overnight schedule captures most of the benefit, and there is no exposure to a price spike.
Our view: if you have an EV and no appetite for managing anything, a time-of-use tariff with the car on a timer is the sensible default. If you have a battery, or you enjoy the optimisation, dynamic pricing rewards the effort. Both are considerably better than a flat rate for a household with a large shiftable load.
The risk that deserves naming
Dynamic tariffs transfer price risk from the supplier to you. In most periods that is favourable, which is why they are usually cheaper on average. In a supply crisis it is not, and households on dynamic tariffs during the 2022 European energy shock experienced that directly.
Several markets have since introduced caps or protections; several have not. Before switching, find out what happens in an extreme month, whether there is a ceiling, and whether you can exit quickly. If a very high bill in one month would cause you real difficulty, a fixed tariff buys certainty and that has genuine value.
What you need in place
- A smart meter capable of half-hourly or better settlement. Dynamic tariffs require it.
- At least one large flexible load — a car, a battery, or electric hot water. Without one, the case is weak.
- A hub that can fetch prices and act on them, ideally processing locally so a broadband outage does not leave your car uncharged.
- Deadlines on every optimisation, so convenience always wins over price.
- Consumption monitoring, so you can check afterwards whether the automation actually did what you intended. It frequently does not, the first few times.
A realistic first month
Before switching, do this: get your consumption in half-hourly data from your current supplier, and apply last year's dynamic prices to it. Most suppliers offering these tariffs will do this comparison, and several independent tools exist. That tells you what you would have paid with no behaviour change — the pessimistic case.
Then estimate the improvement from shifting your one or two large loads. If the pessimistic case is already favourable, the decision is easy. If it depends entirely on perfect shifting, be cautious.
After switching, automate one load first — the car, if you have one — and verify it worked before adding more. Automating four loads simultaneously and then debugging a month of odd bills is a poor use of anyone's evening.