Poland and Lithuania have taken another step towards building a second electricity interconnector between the two countries, signing an agreement that establishes how their transmission operators will construct, test and connect the 700 MW Harmony Link at the border. The project is intended to strengthen regional energy security, expand cross-border electricity trading and provide additional resilience for the Baltic states’ connection to continental Europe.
Polish transmission-system operator PSE and its Lithuanian counterpart Litgrid signed the connection-point agreement in Vilnius on 8 October in the presence of Lithuanian Prime Minister Mindaugas Sinkevičius and the two countries’ energy ministers, Miłosz Motyka and Lukas Savickas. The agreement announced by PSE covers the formal and technical arrangements for joining the two national sections of the 220 kV interconnector at the Polish-Lithuanian border.
The document is an important project milestone, but it is not a construction contract and does not mean Harmony Link has been completed. It sets out which operator is responsible for work around the cross-border connection point, how contractors will cooperate, how equipment supplied on either side of the border will be made compatible and how inspections and post-construction testing will be carried out.
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A second electricity bridge between Poland and Lithuania
Harmony Link will be a 700 MW, double-circuit 220 kV alternating-current connection linking Poland’s Ełk Bis substation with a new Gižai substation in Lithuania. It will run through new Polish substations at Norki and Wigry, while the existing 220 kV Ostrołęka–Ełk Bis line will also be upgraded.
The latest design is predominantly land-based and combines underground cable sections with overhead transmission lines. PSE says around 100 kilometres of the Polish section will use underground cable, while Litgrid lists the wider interconnector route at approximately 238 kilometres.
This is a substantially different project from the original Harmony Link concept. Poland and Lithuania had initially planned a roughly 330-kilometre submarine high-voltage direct-current cable, but PSE and Litgrid cancelled procurement in 2023 after the expected cost of the cable and converter stations rose sharply. The operators subsequently selected a land-based AC design which they said could provide comparable system-stability benefits at a more manageable cost.
The two operators made their final investment decisions on the redesigned project in 2024, confirming that it would proceed.
More capacity between Poland and the Baltic states
Harmony Link will complement the existing LitPol Link connection between Poland and Lithuania rather than replace it.
Once the new link enters service, Litgrid expects the maximum electricity-transfer capacity between the two countries to rise to as much as 1,200 MW, compared with the more limited capacity available through the existing infrastructure. Harmony Link itself is designed to provide 700 MW.
That capacity has become strategically more important since Lithuania, Latvia and Estonia disconnected from the Russian and Belarusian electricity systems and synchronised with the continental European network through Poland in February 2025. The European Commission described that switch as ending the Baltic states’ longstanding dependence on the Russian- and Belarus-controlled power system.
Harmony Link was not required for the initial February 2025 synchronisation itself, but remains one of the major infrastructure projects intended to make the new arrangement more resilient and expand commercial electricity exchange between the Baltic region and the rest of continental Europe.
Poland’s Energy Minister Miłosz Motyka said the connection would provide greater operational flexibility, allow the countries to support one another more effectively and improve their ability to respond to threats. Lithuania’s Energy Minister Lukas Savickas said it would also make it easier to use Lithuania’s growing renewable-energy production and increase electricity trading with Poland.
Poland and Lithuania expand energy-security cooperation
The interconnector agreement was accompanied by a broader political commitment on critical infrastructure.
Motyka and Savickas signed a joint statement covering physical and cyber protection of energy infrastructure, cross-border assistance during emergencies, joint exercises and stockpiling of critical equipment. They also called for EU funding to support not only international connections but measures designed to make domestic electricity networks more resistant to disruption.
The agreement comes amid heightened concern across northeastern Europe about the vulnerability of energy, communications and other critical infrastructure.
The ministers reaffirmed a target of bringing Harmony Link into operation by 31 December 2030. On the Lithuanian side, construction is currently scheduled to begin in the second quarter of 2027.
A major EU-backed investment
The project is receiving substantial support through the European Union’s Connecting Europe Facility.
PSE’s 2024 investment decision put the budget for the Polish part of Harmony Link at around PLN 3 billion, with approximately €368 million — around PLN 1.6 billion at the figure used by PSE — coming from EU funds.
On the Lithuanian side, Litgrid’s investment decision set a maximum estimated budget of €220.03 million, with approximately €147.23 million expected from Connecting Europe Facility funding.
Those figures relate to the redesigned land-based project and are more relevant to its current form than older cost estimates published when Harmony Link was still planned as a submarine HVDC cable.
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Lithuania is also seeking separate EU support for additional physical-security measures around the future Gižai substation. Litgrid said this month that the proposed security investment is worth another €48 million, with the measures intended to be ready before Harmony Link begins operation.
For Poland and Lithuania, the project therefore serves several purposes simultaneously: it increases their ability to exchange electricity, provides another physical connection between the Baltic and continental European systems and adds redundancy to infrastructure that has acquired greater strategic importance since the Baltic states separated their grids from Russia and Belarus.
The agreement signed in Vilnius does not put electricity through Harmony Link yet. But by defining precisely how the two national networks will meet at the border, it clears another technical and legal stage on the route towards the planned 2030 connection.
