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Glossary · Energy industry & energy transition

DSO, Distribution System Operator

DSO Distribution System Operator distribution system operator distribution grid grid operation electricity grid grid connection energy transition

DSO stands for Distribution System Operator and refers to the operator of an electricity distribution network. In German, this role is called distribution network operator (Verteilnetzbetreiber, VNB). The German Energy Industry Act (Energiewirtschaftsgesetz) uses the term "Betreiber von Elektrizitätsverteilernetzen" (operator of electricity distribution networks). In the EU Electricity Market Directive it is called "distribution system operator" (German: "Verteilernetzbetreiber"). Both definitions are structured similarly: a DSO carries out the task of distributing electricity. It is responsible for operating, maintaining and, where necessary, expanding the distribution network in a given area, and where applicable also for interconnections with other networks. EU law additionally stresses that, in the long term, the network must be able to meet a reasonable demand for distribution.

In practice, a DSO carries electricity via the distribution network to households, commerce and industry. It also takes in feed-in, for example from photovoltaic systems, wind farms, combined heat and power plants and storage systems. This includes low-voltage and medium-voltage networks and, in Germany, also the high-voltage level, usually at 110 kilovolts. According to the 2025 Monitoring Report of the Bundesnetzagentur (Federal Network Agency) and the Bundeskartellamt (Federal Cartel Office), the 82 distribution network operators that are required to submit network expansion plans cover the entire high-voltage level and about 80 percent of medium and low voltage. In Germany, high voltage is therefore essentially part of the distribution network and not of the transmission network.

Tasks in network operation

A DSO does not merely pass on electricity. At all times it must operate its network in such a way that lines, transformers and switchgear are not overloaded and the voltage stays within the permissible bands. It must quickly localise and clear faults. Its core tasks include:

  • Voltage control and switching operations, that is, managing the state of the network in normal operation and during disturbances.

  • Network planning and network expansion, including the reinforcement of individual feeders or of a local distribution transformer.

  • Maintenance and fault clearance. For the reporting year 2024, 830 network operators reported 164,645 supply interruptions in the low and medium voltage levels to the Bundesnetzagentur.

  • Processing connection requests, non-discriminatory network access and informing network users.

  • Coordination with upstream and downstream network operators, especially with the transmission system operator.

Distinction from TSO, supplier and metering point operator

A DSO must be distinguished from the TSO (Transmission System Operator), in German Übertragungsnetzbetreiber. The TSO operates the transmission network at extra-high-voltage level, in Germany mainly at 220 and 380 kilovolts. In its control area, the TSO is responsible for frequency maintenance, balancing reserve and supra-regional system security. The DSO works closer to the customer. It deals with substations, medium-voltage rings, streets, rooftop PV and charging points in residential neighbourhoods. Because the two levels are physically coupled, the EU Electricity Market Regulation obliges network operators to cooperate in planning and operation. This includes the exchange of the necessary data on generation, demand response, ongoing operation and investment planning. More on this under TSO-DSO coordination.

A DSO is not an electricity supplier. The supplier sells energy to end customers and procures it on the market. The DSO provides the network infrastructure and charges regulated network charges for it. Electricity networks are a natural monopoly: parallel low-voltage networks between which customers could choose are not built in a street. EU law therefore stipulates that a distribution system operator must not discriminate against network users, above all not in favour of affiliated undertakings. Unbundling rules also apply. In Germany, vertically integrated undertakings must ensure that their distribution network operator is legally independent of other energy supply activities. Excepted are undertakings to whose electricity distribution network fewer than 100,000 customers are connected. This applies to the great majority of the roughly 800 to 900 German VNBs, including many municipal utilities (Stadtwerke).

The metering point operator is also a separate role. In Germany, the distribution network operator is often at the same time the default metering point operator (grundzuständiger Messstellenbetreiber) in its area, but the tasks remain legally separate. The meter records consumption and feed-in. The network operator is responsible for the physical network capacity and permissible operating states.

The law sets two further limits. Under EU law and § 7 EnWG, operators of electricity distribution networks may in principle not own, develop, manage or operate energy storage facilities. Under EU law, something similar applies to publicly accessible charging points. For both cases there are narrowly limited exceptions, for example where no other interested party is found in a tender procedure or where charging points are for own use. Storage and charging infrastructure are thus in principle to be left to competition.

Why distribution networks are central to the energy transition

Most new energy transition installations are connected not to the transmission network but to the distribution network. This applies to rooftop PV, heat pumps, wallboxes, home storage systems and also many wind and ground-mounted solar plants. In the past, electricity flowed predominantly in one direction, from top to bottom. Today a residential area often generates more solar power at midday than it consumes. Power then flows back through the local distribution transformer into the medium voltage. In the evening, the same network section can be heavily loaded by heat pumps and charging sessions.

For the DSO, therefore, what matters is less the annual energy in kilowatt-hours than the power in kilowatts or megawatts at particular times and at particular network points. An illustrative example: a heat pump reduces a house's total energy demand because it uses ambient heat. But if many heat pumps in a street run at the same time on a cold evening and electric cars are also plugged in there, the feeder can reach its limit. The climate balance of the individual devices is unaffected by this. The 2025 Monitoring Report shows how large the task is: the 82 large distribution network operators alone expect investments of around 110 billion euros by 2033 for expansion that determines network sizing.

Network connection, congestion and flexibility

Anyone who wants to connect a PV system, a storage unit, a charging point or a commercial business submits a connection request to the DSO. The DSO checks whether the network connection at the desired location is possible with the requested capacity or whether the network has to be reinforced. Congestion in the distribution network is usually very local, for example at a transformer, in a cable feeder or in a medium-voltage line. A nationwide electricity surplus says nothing about whether further wallboxes in a particular street can charge at full power at the same time. Conversely, a local network congestion does not mean that energy is lacking in the overall system.

This is why flexibility is gaining importance for DSOs. It means shifting consumption, feed-in or storage in time without restricting use unreasonably. An electric car rarely needs to charge at full power every minute, and a heat pump can use the building's heat storage capacity. Flexibility is only beneficial to the grid, however, if it is reliably available at the right place and at the right time. If many installations react simultaneously to low exchange prices, new local load peaks can arise. In Germany, § 14a EnWG governs the grid-oriented control of controllable consumption devices such as heat pumps and wallboxes. In return, those affected receive reduced network charges. As of 31 December 2024, the distribution network operators reported 264,874 market locations covered by the new rules. Most of these are settled under Module 1, that is, with a flat-rate reduction of charges.

Regulation, data and common misunderstandings

DSOs are financed essentially through network charges. In Germany, the Bundesnetzagentur and the state regulatory authorities set the framework for this, above all through incentive regulation (Anreizregulierung). How these rules are designed influences whether a DSO tends to invest in copper and transformers, in digitalisation or in the use of flexibility. Slow connections are not always due to the network operator alone. Besides inefficient processes and staff shortages, actual construction times, permits, delivery times for equipment and regulatory incentives play a role.

The data role is also growing. A network with many decentralised installations can no longer be planned using standard load profiles alone. Under EU law, the DSO must provide network users with the information they need for efficient network access. At the same time it must safeguard data protection and IT security. A rural DSO with a lot of PV and long lines faces different tasks from an urban DSO with dense charging infrastructure and little space for construction.

In short: DSO denotes the regulated operator of regional and local network infrastructure. It is not an electricity seller and is not responsible for the balance of the overall system, which in Germany lies with the transmission system operators. Nor does it merely manage passive lines. Its importance is growing because electrification and decentralised generation raise the requirements for local network capacity, connection processes, data and flexibility.

Sources

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Edited by eCMS on 11.11.2026 19:42

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