An electric car is a flexible load that almost always charges overnight. That makes it an ideal candidate for a spot (dynamic) tariff. When does it make sense, how much do you save and what to watch out for?
What a spot (dynamic) tariff is
With a classic tariff you pay a fixed price for energy all year. With a spot (dynamic) tariff the price of energy changes every hour according to the wholesale market (the day-ahead market is run by OTE and linked to the European exchange). At night and around midday, when demand is low or solar output is high, electricity tends to be cheap; in the morning and evening peaks it is more expensive. Anyone who can shift consumption into the cheap hours can save on energy. An electric car is ideal for this, because it almost always charges overnight.
What the electricity price is made of
To keep expectations realistic: only the energy (commodity) part is spot-based. The rest is regulated and does not move with the spot price:
- Energy – with spot it changes hourly. This is where the saving arises.
- Distribution and system services, renewables levy, electricity tax – regulated prices, paid the same regardless of the hour.
- Supplier margin and fees, VAT.
When electricity is cheapest
The daily curve varies from day to day, but the pattern repeats. Roughly:
| Time of day | Typical energy price | Good for charging |
|---|---|---|
| Night (about 00–05) | lowest | ideal – the car charges while you sleep |
| Midday (sunny days) | low | good, especially with solar |
| Morning peak (7–9) | high | better to avoid |
| Evening peak (17–21) | highest | postpone charging to the night |
How much you can really save
The actual saving depends on your consumption, the car and above all on price developments. Here is an illustrative example of a household that drives about 15,000 km a year and charges roughly 3,000 kWh a year at home:
| Charging at peak | Charging in cheap hours | |
|---|---|---|
| When the car charges | any time after arrival | scheduled for night and midday |
| Commodity price (indicative) | higher average | much lower average |
| Annual difference on commodity | — | on the order of thousands of CZK |
The point is not the exact number but the principle: an EV is a flexible load. When charging is automatically shifted into the cheap hours, the commodity part of the bill drops without any manual effort. You can estimate your own case in our charging calculator.
Spot tariff, or a two-rate (night) tariff?
Spot is not the only route to cheaper charging. The classic alternative is a two-rate tariff with a low rate for e-mobility – the grid operator grants a low rate for part of the day if you have a suitable fuse and meet the rate conditions. The difference in principle:
- Spot tariff: the price follows the market hour by hour. It is lowest at night and around midday, but it fluctuates. The maximum saving goes to those who can steer charging by price.
- Two-rate tariff: a fixed low price in predefined hours. More predictable, no spike risk, but no chance to catch the truly cheapest hours.
For peace of mind without watching prices a two-rate tariff is simpler; for maximum saving and a household with solar, spot is usually more interesting. Both share one thing: you need a wallbox that schedules charging into the right hours.
What you need for it
- A supplier with a spot (dynamic) tariff – many now offer one. Compare fixed fees and terms.
- A smart wallbox that can schedule charging – either by time (a night window) or by price. Without it you would have to plug in manually at the right moment.
- Visibility of consumption – so you know how much you charged and when.
Spot tariff and solar
The best combination is with solar. During the day you charge mainly from your own roof surpluses, and when the sun is not enough or you charge at night, you reach for cheap spot hours. A smart wallbox with its own meter knows how much the array is producing and how much the house consumes, and steers charging accordingly. Instead of exporting surpluses for a pittance, you store them in the car. We cover this in the article on charging from solar.
Practical tips for cheap charging
- Schedule a night window. Most cars sit overnight anyway; set charging for the lowest-price hours.
- Do not charge to 100 % needlessly. For everyday driving 80 % is enough; you save the battery and money and leave room for daytime solar surpluses.
- Watch the supplier's fixed fees. At low consumption a monthly fee can erase the spot benefit.
- Use the app. In IONT.info you see how much and when you charged and easily confirm that scheduling works.
Common myths about the spot tariff
- "Spot is only for enthusiasts who watch prices all day." It is not. Once you set scheduling on the wallbox, it runs itself. Next-day prices are known the afternoon before.
- "I will halve my whole bill." No. Spot affects only the energy component; distribution and levies are fixed. The saving is on part of the bill, not all of it.
- "If the price spikes, I will pay a fortune." Overnight charging is outside the peaks. And even a spike is a few hours a month, not the whole bill.
- "I need an expensive home battery for it." You do not. The EV itself is a battery on wheels – you just charge it at the right time.
When spot is not worth it
A spot tariff should not be pushed on everyone. If you charge irregularly and cannot shift it, if your annual consumption is very low, or if the supplier charges a high monthly fee, a classic or two-rate product may be simpler and cheaper. Spot pays off for those with flexible consumption – and an EV has it – who use a smart wallbox for automatic control.
Risks and what to watch
- Volatility. The spot price can spike sharply in a crisis. Those who cannot shift consumption may end up worse off; for overnight charging the risk is small.
- Supplier fixed fees. A monthly fee on the tariff can erode the benefit at lower consumption.
- Reserved capacity and the fuse. If several appliances meet in a cheap hour, watch the main fuse – dynamic power management (below) handles this.
How we solve it at IONT tech
The e:car WALL SMART and PREMIUM wallboxes can schedule charging into chosen hours and have dynamic power management (Load Balance) with their own meter on the main supply. They recognise the house consumption and solar surpluses and do not overload the main fuse, even when several appliances run at night. You see consumption and charging history in the IONT.info app. More on the features in Smart wallbox and in the e:car WALL overview.
Want to charge smart and cheap?
We will help with a wallbox that schedules charging into cheap hours and watches the fuse, and quote installation with a certified partner.
Často kladené otázky
Is a spot tariff worth it for an electric car?
Yes, if you can shift charging into the cheap hours – easy with an EV, because it charges overnight. The saving arises on the energy (commodity) part of the price; distribution and levies are regulated and do not change with spot.
When is spot electricity cheapest?
Most often at night (about 00–05) and at midday on sunny days when solar output is high. The morning and evening peaks are the most expensive. Current hourly prices are published by OTE.
How much can a spot tariff save?
It depends on consumption and price trends. For a household charging several thousand kWh a year at home, the saving on the commodity part is on the order of thousands of CZK a year. Calculate it from your own consumption.
What do I need to charge in the cheap hours?
A supplier with a spot tariff and a smart wallbox that can schedule charging by time or price. The e:car WALL SMART and PREMIUM do this and also watch the home's main fuse.
Is a spot tariff risky?
The energy price can spike briefly. Those who cannot shift consumption may end up worse off, but for overnight EV charging the risk is small. Also weigh the supplier's fixed monthly fees.