Site network (Arealnetz) · Glossary

A site network is an electrical network within a spatially delimited area. It connects several consumption points, generation plants, storage units or charging points with one another and is usually connected to the public electricity grid via one or a few grid connection points. Typical examples are industrial parks, chemical sites, airports, hospitals, university campuses, large commercial sites, ports and new residential and mixed-use neighbourhoods. Site networks also exist for gas. This article deals with the electricity network.

The term first describes a technical arrangement. It includes lines, switchgear, transformers, metering points and protection technology, as well as separate operational management on a contiguous site. There is no uniform legal concept with always identical consequences. In German energy law, a site network can be classified in different ways: as a customer installation (Kundenanlage), as a direct line, as a closed distribution system under § 110 EnWG, or as a regulated energy supply network. This classification determines who levies grid charges, how metering and billing are organised, whether grid connection and grid access obligations apply, and what obligations the operator has. The following legal statements refer to Germany as of November 2026.

Technology and key parameters

Larger industrial sites often have their own medium-voltage ring with several transformers and downstream low-voltage networks. Smaller neighbourhoods usually work with low voltage only. Important parameters are the connection capacity in kilowatts or megawatts, the quantity of electricity drawn in kilowatt hours, the load profile, the short-circuit power, the voltage quality and the permissible loading of individual lines and items of equipment. For operation, therefore, annual consumption is not the only thing that matters; above all, what matters is when which power is drawn or fed in. An analogy: a car park does not have to be designed for the number of cars per year, but for its fullest moment. The same applies to the grid connection of a site. With an energy management system, load peaks can be smoothed, self-consumption increased and the existing connection better utilised.

Legal classification after the rulings of the CJEU and the BGH

Previously, many site networks in Germany were treated as a customer installation under § 3 no. 24a EnWG. Among other things, the decisive factor was whether the installation is insignificant for effective competition. On 28 November 2024, the Court of Justice of the European Union (Case C-293/23) declared this approach incompatible with the Electricity Market Directive (EU) 2019/944. According to the ruling, whether a distribution system exists depends on only two criteria: electricity is transmitted at high, medium or low voltage, and it is intended for sale to wholesalers or final customers. Size, quantity of electricity, number of connections or a lack of significance for competition play no role in this. Exceptions exist only where the Directive expressly provides for them, for example for closed distribution systems.

The Federal Court of Justice implemented this in its decision of 13 May 2025 (EnVR 83/20). Since then, only what is not a distribution system within the meaning of the Directive can qualify as a customer installation. In the case decided, a supplier wanted to supply tenants of several apartment blocks with electricity from combined heat and power units via its own lines. The BGH classified these lines as a regulated distribution system. According to the BGH, what remains possible is above all line systems through which no electricity is sold, for example for self-supply or in the case of jointly used installations of owners of apartments or properties. For a site network this means: if its operator supplies electricity to third parties on the site for payment, this generally points to a distribution system. The earlier assumption that a site network is typically an unregulated customer installation can no longer be maintained in that form.

For existing installations, the legislator has created a transitional rule. The Bundestag adopted it on 13 November 2025 with the EnWG amendment. Under the new § 118 para. 7 EnWG, for customer installations that were connected to an energy supply network before the amendment entered into force, the regulatory requirements for networks apply only from 1 January 2029. This transitional period expressly does not apply to installations connected later. They must already now be examined case by case according to the standards of the CJEU and the BGH. There is no formal procedure by which the classification can be determined in advance. The Bundestag has called on the Federal Government to present, in good time before the period expires, a permanent solution compatible with Union law. With the amendment, the definitions were renumbered, according to the BDEW: customer installations are now found in § 3 nos. 65 and 66 EnWG.

Closed distribution system and direct line

For industrial and commercial sites, the closed distribution system under § 110 EnWG is the most important alternative. The regulatory authority classifies a network as such upon application by the operator. The network must be located in a geographically limited industrial or commercial area or an area with shared services. In addition, one of two conditions must be met: the activities or production processes of the network users are linked for specific technical or safety reasons, or the network distributes energy primarily to the owner, the operator or affiliated undertakings. Household customers may be supplied only in small numbers and must then be connected to the operator, for example as employees. From the submission of a complete application, the network is provisionally treated as a closed distribution system. The operator is then exempt from a number of obligations, for example from incentive regulation. Any network user can have the grid charges reviewed by the authority. They are deemed lawful if they do not exceed those of the adjacent general supply network at the same voltage level.

Residential neighbourhoods with many tenants generally do not meet these requirements because of the household customers. According to the BDEW's assessment, entire housing estates are therefore usually to be classified as a network. For industrial sites and hospitals, the specific design is what matters. The direct line could offer more scope: in its judgment of 17 September 2026 (C-722/24 and C-756/24), the CJEU interpreted this concept more broadly. According to the judgment, a further customer may be connected to an existing line via which the generator already supplies other customers. In addition, a customer may retain its connection to the public grid as a reserve. The direct line is a legal concept in its own right and does not replace the customer installation. Whether German authorities and courts will in future recognise typical site and neighbourhood concepts as a direct line remains open.

Distinction from the public grid and from the microgrid

The public distribution grid serves general supply and is in principle open to every final consumer. A site network, by contrast, supplies a delimited location or a clearly defined group of users. However, this spatial limitation does not mean that no regulation applies. Under European law, even a small, privately operated line system can be a regulated distribution system. A microgrid is a locally coordinated system of generation, consumption and storage that, under certain conditions, can also operate in island mode, separated from the public grid. Many site networks are operated similarly, for example with photovoltaics, combined heat and power units, battery storage, charging infrastructure and load management. That does not yet make them capable of island operation. This requires dedicated control technology, suitable protection concepts, control of frequency and voltage, and sufficient firm generation or storage capacity.

Why site networks matter in practice

Electrification often occurs in spatially concentrated form. An industrial park replaces fossil process heat with electrical installations. A logistics site builds charging points for commercial vehicles. A hospital combines emergency power, photovoltaics, battery storage and cooling supply. A neighbourhood gets heat pumps and charging points. In a site network, these new loads can be organised: locally generated electricity is consumed where it is produced, charging processes are scheduled over time and loads are shifted. A battery storage unit can, for example, prevent several fast-charging points from exceeding the connection capacity at the same time. A heat pump can preferably run when a lot of solar power is available on the site.

For the upstream grid operator, the point of handover matters most. It shows the maximum power the site draws or feeds in. A well-controlled site network can reduce or spread out additional connection needs over time. But it can also create new requirements, for example through high feed-in from photovoltaics or combined heat and power, through many vehicles charging at the same time, or through faults in the site network that have repercussions on the upstream grid.

Economic consequences of the classification

Whether a site network is economically worthwhile often depends on rules that do not follow from the technology. In the case of a customer installation, no grid charges and grid-related levies are incurred for electricity generated and consumed within the installation. If, by contrast, the site network is classified as an energy supply network, its operator becomes a grid operator. According to the BDEW, this includes, among other things, an authorisation under § 4 EnWG, obligations regarding grid connection and grid access, transparency and charge setting, tasks in metering and balancing, and participation in the burden-sharing mechanism under the Energy Financing Act (Energiefinanzierungsgesetz). Depending on size, unbundling obligations are added. As ways out, the BDEW mentions that the operator takes on these tasks itself, commissions another grid operator as a service provider, or transfers the site network to the upstream grid operator.

Free choice of supplier and clean metering are particularly important. Final consumers on the site must not be de facto tied to a particular electricity supplier. A summation meter at the grid connection point is often sufficient for internal optimisation. However, it is not always sufficient for the correct allocation of supplied quantities, self-consumption, feed-in and grid use. A site network is also not a way of avoiding the costs of the public grid. As long as the site depends on backup from the upstream grid, that backup remains a service that must be paid for.

Typical misunderstandings

Site network means self-sufficiency: Most site networks remain permanently connected to the public grid. They need it as a safeguard during periods of low wind and sun (Dunkelflaute), plant faults or load peaks. High self-consumption reduces the quantity of electricity drawn, but does not replace firm capacity.
Site network means customer installation: According to the CJEU and the BGH, a line system through which electricity is sold to third parties is generally a distribution system. Existing installations are exempt from this only on a transitional basis until the end of 2028.
Site networks are inherently climate-friendly: The climate impact depends on the generators used and on operation. A site with fossil self-generation can be economically worthwhile without benefiting the overall system.
Local optimisation is automatically grid-serving: A site network initially pursues the goals of its operator. If many sites react to the same price signals at the same time, new load peaks can arise. A storage unit that only maximises self-consumption does not necessarily relieve critical grid situations.

Classification within the electricity system

In site networks, technical operational management, market rules and local investment decisions come together. Many new installations are being built behind grid connection points, such as photovoltaics on warehouse roofs, battery storage, electrolysers, charging parks, heat pumps and controllable industrial processes. For security of supply, a site network can offer additional robustness. This requires selective protection concepts, backup power installations, where applicable black-start-capable components, clear responsibilities in the event of a fault and regular tests. For the planning of public grids, the load profile at the handover point is decisive. What is grid-serving is not the site network as such, but its actual behaviour towards the upstream grid. The term is used precisely when technical limits, legal classification, operator role and behaviour at the grid connection point are considered together.

Sources

Gesetz über die Elektrizitäts- und Gasversorgung (EnWG) § 110 Geschlossene Verteilernetze — Bundesministerium der Justiz / Bundesamt für Justiz (gesetze-im-internet.de); unbekannt (konsolidierte Fassung, abgerufen November 2026). § 110 Abs. 1 bis 4 EnWG
Anwendungshilfe Kundenanlagen: Rechtliche Bewertung der Konsequenzen aus der aktuellen Rechtsprechung des EuGH und des BGH (Version 1) — BDEW Bundesverband der Energie- und Wasserwirtschaft e.V.; 2025-11-26. Abschnitte 3.1, 3.4, 3.6, 3.9, 3.12, 3.15, 3.18, 3.25
EnWG-Novelle: Nur eine Übergangslösung für Kundenanlagenbetreiber — Gleiss Lutz; 2025-11-28. Abschnitte Aktueller Anknüpfungspunkt, Hintergrund, Auswirkungen
EuGH zur Direktleitung: Neue Spielräume nach dem Kundenanlagen-Urteil? — Recht energisch (Fachblog); 2026-09-18. gesamter Beitrag

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Edited by eCMS on 11.11.2026 14:30