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Glossary · Energy industry & energy transition

Real-time price

Real-Time Price electricity tariff electricity market flexibility Dynamic Tariff Exchange electricity price

Real-time price refers to an electricity price that is coupled closely in time to the current market situation or to a scarcity in the power system expected at short notice. It usually does not mean a price that is newly formed every second. It means a tariff in which the energy price follows wholesale prices for short delivery periods, i.e. for one hour or one quarter-hour. What a kilowatt-hour costs then depends on the time window in which it is consumed. In Germany, the technical term for such contracts is dynamic electricity tariff. Real-time price is rather a colloquial term without its own statutory definition.

What is billed is the quantity of energy, i.e. the kilowatt-hour. A real-time price does not say how much electrical power a device is currently drawing. It says what a certain quantity of energy costs in a certain time window. An example: an electric car charging at 11 kilowatts for one hour takes up 11 kilowatt-hours. If a kilowatt-hour costs 20 cents in a midday hour with plenty of solar power and 40 cents in the evening, the same charge costs 2.20 euros once and 4.40 euros the other time. The figures are chosen for illustration only. The time of consumption thus becomes an economic variable.

Distinction from dynamic tariff and exchange electricity price

Real-time price, dynamic electricity tariff, exchange electricity price and spot market price are often treated as equivalent. The terms are close to one another but do not mean the same thing. A dynamic electricity tariff is a contract between supplier and customer. The German Energy Industry Act defines it in § 3 No. 95 EnWG: the contract must reflect the price fluctuations on the spot markets, expressly including the day-ahead and intraday markets. The intervals must correspond at least to the settlement intervals of the respective market. In addition to the exchange component, the end-customer price includes procurement and sales mark-ups, metering costs, grid charges, taxes and levies. The exchange electricity price, by contrast, is the wholesale price for a specific delivery period. It reflects only the energy price, not the complete end-customer price.

The word real-time is also imprecise. Many tariffs described this way are based on prices of the day-ahead market. There, in a joint European auction at 12:00 on the previous day, a price is determined for each delivery interval of the following day. The customer therefore knows the price in advance. Since delivery day 1 October 2025, this coupled day-ahead auction has been settled in quarter-hours instead of hours in all participating bidding zones. Ireland is excepted, with 30-minute intervals. The earlier statement that day-ahead prices are set for each hour is therefore outdated. On the intraday market, trading continues until shortly before delivery. Tariffs based on this react at shorter notice but are rarer for households, because billing, communication and control are more complex. A price formed continuously according to grid frequency, local grid load or balancing energy demand would be a different instrument, both technically and legally.

A real-time price is also not a signal of the state of the grid. A low exchange price can arise because a lot of wind and solar power is available across the whole price zone or across Europe. At the same time, a local distribution grid may be running at full capacity. Additional consumption would then be desirable from a market perspective but problematic from a grid perspective. Time-variable energy prices alone can therefore not avoid every grid overload.

Why time-based prices are becoming more important in the power system

Generation and consumption must be in balance at all times. Wind and solar power fluctuate with the weather. As a result, the value of electricity changes more strongly over the course of the day and year than in a system dominated by schedulable power plants and fuel costs. With a lot of wind or sun, electricity can become very cheap on the wholesale market, and at times there are even negative electricity prices. With high demand, little renewable generation and tight power plant capacity, prices rise. A real-time price makes these differences visible. The incentive thereby shifts from simply saving electricity to the question of when electricity is used.

This concerns above all controllable loads. A heat pump can temporarily store heat in the building mass or in buffer tanks. Electric cars often stand for many hours but only need to charge for part of that time. A battery storage system can take in electricity in cheap hours and release it later. In industry, too, there is room for manoeuvre, for example in refrigeration, compressed air, electrolysis or certain batch processes. Such room for manoeuvre is called flexibility. Real-time prices can reward flexibility economically but do not create technical controllability. A refrigerator can hardly be sensibly shifted according to prices. A washing machine can be shifted to a limited extent, but the financial effect is usually small. Devices with high power and storage capability achieve a great deal.

Price components, incentives and risks

The end-customer price does not consist only of procurement costs. Grid charges, metering charges, concession fee, electricity tax, value-added tax and other components make up a large part. If only the procurement share is dynamic, this weakens the price signal. An exchange price of zero therefore does not mean that electricity is free for the household. If price differences are passed on strongly, the possible savings rise, but so do the risks. Those without flexibility and without automatic control can pay significantly more in expensive hours. With fixed-price tariffs, the supplier bears part of the price risk and factors it into the tariff. With dynamic tariffs, this risk is partly passed on to the customer. That makes sense if the customer can react, and is problematic if the customer bears the risk without being able to adapt.

Legal framework in Germany

  • Obligation to offer: Under § 41a para. 2 EnWG, all electricity suppliers have had to offer a contract with a dynamic tariff since 1 January 2025. This applies to final consumers who have an intelligent metering system. Previously the obligation applied only to suppliers with more than 100,000 final consumers. According to the Bundesnetzagentur, this does not give rise to an obligation to conclude a contract with every interested party, since freedom of contract applies.

  • Information: Suppliers must inform comprehensively about costs, advantages, disadvantages and risks and offer information on the installation of an intelligent metering system. Before concluding the contract, the customer is entitled to a short summary, including a breakdown of the price components.

  • Other tariff types: Suppliers with more than 200,000 final consumers must additionally offer a fixed-price contract with a term of at least twelve months. In addition, there must be at least one tariff for household customers under which only the total consumption quantity of a period is transmitted.

  • Grid side: Since 2025, distribution system operators have also had to offer time-variable grid charges to operators of controllable consumption devices under § 14a EnWG. This instrument is independent of the supplier's dynamic energy price.

Metering, billing and automation

Prices close to real time presuppose that consumption is measured with precise timing. A conventional Ferraris meter records only the total quantity over a longer period. It cannot be determined with it whether a kilowatt-hour was consumed in a cheap or an expensive quarter-hour. For a dynamic tariff under § 41a EnWG, an intelligent metering system is required in Germany. The Bundesnetzagentur names it expressly as a prerequisite. Any metering device with time resolution is therefore not sufficient under this legal position.

The second prerequisite is automation. Hardly any household follows prices permanently and switches devices by hand. A real-time price only takes effect when an energy management system, a wallbox, a heat pump controller or a storage system reacts automatically to price thresholds. The control must also take into account comfort, minimum charge level, hot water demand, connection capacity and technical limits. This raises further questions: Who may control devices? What data do the supplier, metering point operator and grid operator receive? The real-time price therefore also concerns data protection, consumer protection, technical standards and the division of tasks between market participants and grid operators.

Typical misunderstandings

  • "Real-time prices are automatically fairer": This is true only to a limited extent. Households differ greatly in whether they have flexible devices, home ownership, a charging option or automation. Flexible customers can save, inflexible customers bear higher risks.

  • "Negative prices mean worthless electricity": Negative exchange prices show that more feed-in is offered than can easily be absorbed under the applicable market rules, technical minimum outputs and demand. Causes can also be support rules or limited grid capacity. Real-time prices can shift demand into such periods but do not alone explain why negative prices arise.

  • "Prices secure supply": High prices can indicate scarcity and reduce flexible demand. However, security of supply is ensured by grid operation, available power plants, balancing energy, balancing group management and protection mechanisms. Prices coordinate; they do not replace operational responsibility.

  • "The exchange price shows local bottlenecks": A uniform price for a price zone cannot reflect whether a particular local substation is at full capacity. Other instruments are needed for that, such as grid-oriented control, time-variable grid charges or local flexibility mechanisms.

Assessment

The real-time price makes visible that the timing of electricity consumption matters. This fits a power system in which generation, consumption and storage must be coordinated more closely. Whether it works depends on several conditions: time-accurate metering, understandable tariffs, automation, controllable consumers, transparent price components and a clear separation between market price and grid operation. A real-time price can reward flexibility but cannot create it. It can pass on wholesale prices but cannot explain all cost components. It takes local grid bottlenecks into account only if additional rules or price signals are provided for this. What matters is less the promise of low prices than the question of which consumers can respond technically, economically and reliably to scarcity and surpluses.

Sources

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Edited by eCMS on 11.11.2026 19:42

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