Flexibility activation (Flexibilitätsabruf) · Glossary

A flexibility activation is the specific process in which an available or contractually committed flexibility option is activated. Examples: a battery charges or discharges. A heat pump temporarily reduces its electrical power. An electric vehicle shifts its charging session. A refrigeration system uses its thermal inertia, or an industrial process changes its load. An activation is therefore not the mere existence of flexibility. It refers to its actual use in a specific situation, at a specific point in time and with a specific technical objective.

A flexibility activation is usually described by several parameters. The activatable power is stated in kilowatts or megawatts. It indicates how much a facility can change its feed-in or withdrawal relative to a reference behaviour. The duration indicates how long this change can be sustained. Power multiplied by duration gives the amount of energy in kilowatt-hours or megawatt-hours. An example: 2 MW over 30 minutes corresponds to 1 MWh. Further parameters are response time, lead time, ramp rate, availability, measurability and recovery time. A battery storage system often responds quickly but is limited by its state of charge. A heat pump can shift load if the building and the hot water tank have sufficient thermal reserve. An industrial process can move large amounts of power, but often only within narrow production windows.

The term separates several levels that are often mixed up in debates about flexible consumers and storage. Flexibility potential initially only means that a facility can be changed technically or operationally. Flexibility provision means that this potential is made usable, for example through control technology, a metering concept, a contract, prequalification or an offer on a market. The flexibility activation is the moment at which this possibility becomes an actually effective change in power. Without this step, flexibility remains a property of devices or processes. It is then not yet a reliable resource for grid operation, the market or security of supply.

Technical function and measurable effect

An activation always changes a load or feed-in profile relative to an expected course. This expected course is often called a schedule, forecast or reference load (baseline). In industrial load control and in demand response, this reference is particularly important. The effect can only be measured if it is clear what would have happened without the activation. If the reference is set too high, an effect is paid for that never took place. For a storage system, the effect is usually easier to capture because charging and discharging power are measured directly. Even there, the state of charge remains important: a storage system cannot deliver the same power as often and for as long as desired.

An activation can increase or reduce power. From the perspective of the power system, it is therefore not enough to speak only of “reducing consumption”. A load can be increased when a lot of renewable electricity is available or when strong photovoltaic feed-in raises the local voltage. It can be reduced when a grid congestion threatens or when the residual load rises sharply. When charging, a storage system acts like additional consumption, and when discharging like feed-in. The direction of the activation therefore depends on the objective and on the location in the grid.

Location is not a minor technical matter. An activation at transmission grid level may be suitable for frequency maintenance or system-wide balancing. However, it does not automatically resolve a congestion in a specific low-voltage grid. Conversely, grid-supportive control in the distribution grid can have a local effect without becoming relevant for the wholesale market. Flexibility therefore has to be assessed not only by quantity, but also by grid level, connection point and temporal availability.

Distinction from balancing energy, redispatch and self-optimisation

Flexibility activation is an umbrella term. It can encompass various mechanisms but is not identical to any single one of them. In the case of balancing energy, prequalified facilities are activated. They compensate short-term deviations between generation and consumption and thereby stabilise the grid frequency. There, precise requirements apply regarding response time, availability, measurement and settlement.

Redispatch, by contrast, serves congestion management. In this process, generation or consumption schedules are changed so that lines and other equipment are not overloaded. It is therefore not primarily about frequency, but about the spatial distribution of feed-in and load in the grid. In Germany, redispatch is no longer limited to the transmission grid. Since 1 October 2021, the “Redispatch 2.0” procedure has applied on the basis of NABEG 2.0. In principle, it includes all facilities of 100 kW and above, including renewable energy and CHP facilities. Since then, in addition to the transmission system operators, the distribution system operators have also been more strongly involved. Redispatch can also include flexibility activations, for example when storage systems or controllable decentralised facilities are used.

Self-consumption optimisation must also be distinguished. When a home battery stores solar power at midday and discharges in the evening, flexibility is used technically. However, a systemic flexibility activation exists only when the use responds to an external signal: a contract, a grid need or a market price. In addition, the effect must be reliably plannable for third parties. Private optimisation may happen to be beneficial to the system. This does not yet make it a resource that can be called upon by grid operators or markets.

Market, contract and responsibility

A flexibility activation needs rules. They determine who may trigger it, who must respond, how the effect is measured and how conflicts are handled. In market-based activations, this happens via prices, bids and schedules. Facility operators or an aggregator pool flexible units and offer them on a market. Activation takes place when the offer is economically selected or a price signal triggers an automatic response.

In grid-operational activations, the trigger lies with the grid operator. It must comply with voltage, current loading and equipment limits. Particularly in the distribution grid, a new coordination task arises because heat pumps, charging points, photovoltaic systems and battery storage systems are being connected in large numbers at lower grid levels. A single device is small. Many simultaneous charging sessions or feed-in peaks can, however, become relevant locally. A flexibility activation can then complement or temporally stretch grid expansion. It cannot automatically replace it, because permanent load increases and structural congestion still require physical grid capacity.

At EU level, Article 32 of the Electricity Market Directive (EU) 2019/944 obliges the Member States to create a regulatory framework. It is intended to enable distribution system operators to procure flexibility services, including congestion management, and to give them incentives to do so. The aim is greater efficiency in the operation and development of the distribution grid. In Germany, § 14c EnWG implements this. If an operator of an electricity distribution grid procures flexibility services for this purpose, this must be done in a transparent, non-discriminatory and market-based manner. The specifications and standardised market products must be approved by the Bundesnetzagentur (Federal Network Agency). The authority may also determine exemptions if market-based procurement would not be economically efficient, would cause serious market distortions or would aggravate congestion. The provisions on redispatch and grid security measures as well as § 14a EnWG remain unaffected.

An example of a non-market-based, grid-operational activation in Germany is § 14a EnWG with the determinations of the Bundesnetzagentur of November 2023. It applies to controllable consumption devices such as private charging points, heat pumps, air conditioning systems and storage systems drawing power from the grid. The prerequisites are a grid connection capacity of more than 4.2 kW, a connection at low voltage and, as a rule, commissioning from 1 January 2024. The grid operator may temporarily throttle their power consumption only if an acute overload or damage to the grid threatens. A complete shutdown is not permitted. In principle, a minimum power of 4.2 kW per device must be retained. Special calculations apply to large heat pumps and to several devices at one connection. In return, grid charges are reduced. Transitional rules apply to existing installations with older agreements.

Contractual activations lie between these forms. A company can commit to a supplier or service provider to reduce its load in certain hours. A household customer can agree to a tariff under which charging power or heat pump operation is adjusted within defined limits. Such models work only if comfort, production reliability and technical limits are respected. An activation that is theoretically possible but damages acceptance, process stability or device lifetime is not a robust resource.

Typical misunderstandings

A common misunderstanding is to treat flexibility as a free reserve. Many facilities can shift their load, but not make it disappear. If an electric car charges later, the required energy usually has to be made up. If a heat pump is briefly throttled, the later additional demand depends on the building envelope, outdoor temperature, storage size and comfort limits. An activation can therefore reduce a peak and at the same time trigger a counter-reaction later, the so-called catch-up effect or rebound. For the power system, therefore, the entire load profile counts, not just the moment of activation.

It is equally problematic to equate installed device power with activatable power. One million charging points of eleven kilowatts each add up arithmetically to eleven gigawatts. However, it does not follow that this power is available, controllable, contractually committed and simultaneously activatable at any time. Vehicles must be connected. Users must specify charging targets or at least accept limits. Measurement and control technology, for example via a smart meter, must work. And the activation must not burden local grids elsewhere. In addition, there are legal limits: when throttling under § 14a EnWG, a minimum power is retained, so that only a part of the connection capacity can be reduced at all.

Remuneration is also often viewed too simply. What can be paid for is the mere standby provision of power, the energy actually activated, the avoided grid load or a combination of these. This is more than a bookkeeping question. Whoever remunerates availability sets different incentives than someone who pays only for activations. If only the activation is paid, it may not be worthwhile for operators to keep rarely used capacity available. If standby provision is remunerated too generously, costs arise for resources of limited benefit. The rules therefore determine which facilities participate and how reliably they respond.

Significance in the power system

With a growing share of weather-dependent generation and increasing electrification, flexibility activation is becoming more important. Photovoltaics and wind energy do not generate according to demand, but according to weather conditions. Heat pumps, electromobility and electric industrial processes increase electricity demand, but at the same time bring new shiftable loads into the system. The value lies not only in the amount of energy, but in the time of use. A kilowatt-hour in an overloaded evening hour has a different effect from the same kilowatt-hour in an hour with a lot of local solar generation.

Flexibility activations can help to make better use of power plants, grids and storage systems. They can dampen price peaks, reduce the curtailment of renewable facilities, ease congestion and reduce the need for short-term balancing measures. However, their effect depends on coordination. A price signal that causes many facilities to charge at the same time can create new grid problems locally. A grid-supportive activation can collide with market prices. An aggregator may optimise for a balancing group, while the distribution system operator has to comply with a different local limit. Conflicts arise where technical possibility, market rule and responsibility diverge.

For flexibility activations to become dependable, data, controllability and responsibilities must fit together. Smart meters, secure communication channels, standardised interfaces and clear settlement rules are not side issues but prerequisites for practical application. At the same time, limits are needed. Grid operators must not intervene arbitrarily in consumption decisions. In Germany, throttling under § 14a EnWG, for example, is tied to an imminent grid overload and to a minimum power. Markets must not ignore physical grid limits. And customers must know which restrictions they accept and what consideration they receive.

The term flexibility activation makes clear the difference between possible adjustment and reliable system impact. Flexible devices alone are not yet a solution. They become effective only when power, duration, location, trigger, measurement, remuneration and responsibility are regulated. Then an activation actually takes place at the right moment, and its consequences in the grid and on the market remain manageable.

Sources

§14a EnWG Steuerbare Verbrauchseinrichtungen – Integration von steuerbaren Verbrauchseinrichtungen — Bundesnetzagentur; unbekannt. Verbraucherportal, Abschnitte zu Anwendungsbereich, Dimmen und Mindestleistung
§ 14c EnWG – Marktgestützte Beschaffung von Flexibilitätsdienstleistungen im Elektrizitätsverteilernetz; Festlegungskompetenz — lxgesetze.de (Gesetzestext EnWG); unbekannt (Fassung in Kraft seit 29.07.2022). § 14c Abs. 1 und 2; Abs. 4 laut rewis.io-Wiedergabe
Netzengpassmanagement – Redispatch 2.0 — Bundesnetzagentur; unbekannt. Abschnitt Redispatch 2.0
Richtlinie (EU) 2019/944 mit gemeinsamen Vorschriften für den Elektrizitätsbinnenmarkt — Europäische Union (EUR-Lex); 2019-06-05. Artikel 32 Abs. 1 (Anreize für die Nutzung von Flexibilität in Verteilernetzen)

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Edited by eCMS on 11.11.2026 19:47