DK1 vs DK2: Practical differences for industrial BESS installations

Denmark looks like one country, but electrically it is split in two. Western Denmark is called DK1, eastern Denmark is called DK2, and the divide runs at the Great Belt (Storebælt). For most businesses that split is invisible day to day, but for an industrial battery it can matter in practice, because prices, system services and local conditions are not necessarily the same in the two areas.

This article explains why Denmark is divided into two zones, what practical differences this creates, and what a company with sites in both areas should be aware of. It is not that one area is generally better than the other, but that the underlying conditions can vary from place to place.

Why Denmark is split in two

The division is not administrative; it is physical. DK1 belongs to the Continental European synchronous area together with, among others, Germany, while DK2 belongs to the Nordic synchronous area together with Sweden, Norway and Finland. The two systems do not run in synchrony, and they therefore cannot be connected with ordinary alternating current. The physical link between them is the Great Belt connection, a 600 MW direct-current link, which couples the two Danish price areas. The connection is not a true interconnect to another country, but it is operated and participates in the market on the same terms as the international interconnectors.

The split itself into DK1 (west of the Great Belt) and DK2 (east of the Great Belt) is also Energinet's official demarcation. Energinet is Denmark's national transmission system operator, and the demarcation is used directly in the tender conditions for system services, where slightly different requirements are placed on providers depending on whether the service is to be delivered in western or eastern Denmark.

That the link between the zones is a direct-current connection with a given capacity means that the two areas cannot freely exchange unlimited power. When there is very cheap electricity in one zone, it cannot always reach the other if the connection is full. That is part of the explanation for why prices can diverge between DK1 and DK2, even though they belong to the same country.

Price differences between the zones

Because DK1 and DK2 are two separate price areas, the electricity price can differ in the two areas at the same time. Prices are set on the common Nordic power exchange and are influenced by how much is produced and consumed locally, and by the capacity on the connections to neighbouring countries. We deliberately state no price levels, because they swing from hour to hour.

One structural difference is still worth knowing. DK2 is generally more exposed to high prices in periods with low production from solar and wind, because DK1 has more and larger interconnectors to draw on, as described in Energinet's Electricity Market Report 2025. That does not mean that DK1 is always cheaper or DK2 always more expensive, but that the two zones have different exposure to the surrounding market. For a battery whose value depends in part on price swings, that difference can matter.

The difference in connections is specific. According to the Danish Utility Regulator's account of Energinet's congestion income, DK1 has connections to Germany, the United Kingdom, the Netherlands, Norway and Sweden, while DK2 has connections to Germany and Sweden. A larger and more diverse set of connections gives DK1 more routes to bring in cheap electricity when local production is low. The same connections are also where price differences between areas give rise to congestion income, when demand for transfer exceeds capacity.

Different system services in the two zones

The zone split also shows up in the markets for system services (the reserves Energinet buys to keep the grid in balance). In DK1, Energinet procures the fast reserve as FCR through the common Continental European market. In DK2, FCR-N, FCR-D and FFR are procured instead, with FCR-N and FCR-D handled in a joint Danish-Swedish market. There is also a difference for the secondary reserve, aFRR: in DK1 the market is local, while DK2 takes part in a common Nordic market. Those differences are described in more detail in our articles on system services. The point here is simply that which product is relevant depends on where the installation sits.

Who operates the grid

Regardless of zone, Energinet is the system operator for all of Denmark and owns and operates the transmission grid. The local distribution grid, which carries electricity the last stretch out to the company, is owned and operated by local grid companies, and they can differ from place to place, including within the same zone. The Danish Utility Regulator (Forsyningstilsynet) supervises the electricity market as an independent authority. This role division is the same in DK1 and DK2, as described by the Ministry of Climate, Energy and Utilities, but the specific grid company and the local conditions vary.

What a company with several sites needs to know

For a company with an installation in only one place, the zone question is simple: the installation belongs to the zone it sits in. For a company with production in several places across the country, the picture is more complex. If you have locations in both DK1 and DK2, you cannot assume that prices, system-service products and local grid conditions are the same. A battery that makes good sense at one location can have a different business case at another, not because of the company, but because of the zone and the local grid.

In practice, that means an installation should be assessed location by location. A blanket assumption that what applies in one place also applies in another does not necessarily hold when the locations sit in different zones. Specifically, it can affect which markets the installation is most valuable in, how price swings look across the day, and which local grid conditions apply. That does not change the fact that an installation can make sense in both zones, but it means the business case should be worked through for each location rather than transferred from one to another.

ZynexGroup's approach to site assessment

We do not have a zone-dependent approach in the sense that we assess an installation differently solely because it sits in DK1 or DK2. We assess each site on its own assumptions: grid connection, consumption profile, local grid conditions and the relevant market products for that specific zone. On that basis we hold a data-driven discussion about what an industrial BESS installation can realistically contribute at the individual location. The zone is one of the factors that enters the assessment, not one that decides it in advance.

Overall perspective

Denmark is divided into two electricity zones, DK1 to the west and DK2 to the east, because they belong to different European synchronous areas and are only connected by a direct-current link across the Great Belt. The division creates differences in prices, in which system services can be delivered, and in local grid conditions. Neither zone is generally better than the other, but the underlying conditions are not the same.

For industrial companies, the useful point is that a battery's value depends on the specific location, including the zone, and that installations should therefore be assessed separately. Especially for companies with production in both zones, it is worth being aware that a solution cannot simply be copied from one end of the country to the other.

Have the potential for your site assessed

If you want to know what an industrial BESS installation can mean at your specific location, we start from your own data: grid connection, consumption profile and history, together with the conditions that apply in that particular zone. On that basis we produce an initial assessment of whether there is a match, and what the next step could then be. You are welcome to contact us.