IN Brief:
- Balkan transmission system operators have warned that grid stability must keep pace with renewable energy growth.
- Serbia’s EMS expects to connect around 12GW of renewable capacity over the next six years.
- Regional priorities include transmission investment, digitalisation, storage, coordinated capacity calculation, and cross-border resilience.
Elektromreža Srbije and other transmission system operators in Southeast Europe have warned that renewable energy growth must be matched by grid investment, digitalisation, storage, and stronger regional coordination.
The warning was delivered during the Belgrade Energy Forum 2026 panel on establishing a robust transmission grid for the green transition. System operators placed stability and resilience at the centre of decarbonisation, with renewable capacity additions treated as inseparable from the networks required to integrate them.
Serbia’s transmission system operator expects to connect around 12GW of renewable energy capacity to the transmission grid over the next six years. Serbia’s system has eight interconnection borders and 20 interconnection transmission lines, giving it a significant role in regional electricity flows and market integration.
EMS has invested €620m over the past decade, mainly in transmission infrastructure, while also expanding digital and innovative grid management and maintenance technologies. Investment activity has accelerated in recent years, with further spending planned through the end of the decade. Its strategic plans include four pan-European projects, with the largest share expected to be completed by 2030.
Montenegro’s transmission system operator, CGES, also placed system stability high on the regional agenda. The June 2024 blackout, which affected Montenegro and parts of Albania, Croatia, and Bosnia and Herzegovina, remains a warning for smaller transmission systems exposed to large cross-border flows. Coordinated capacity calculation is being developed as one of the tools for managing those flows more securely.
Montenegro’s grid connection pipeline shows the scale of the challenge. The country currently has connection requests for projects totalling around 7GW, compared with existing generation capacity of around 1GW. Requests for around 4.5GW have been processed, with contracts signed for nearly 3GW.
That imbalance between existing system size and proposed renewable capacity is testing planning frameworks, operational tools, and investment capacity. Renewable development pipelines can grow quickly once land, resource, and investor appetite align, but the grid must absorb the resulting variability, congestion, protection requirements, and cross-border flows.
Austria is facing similar system pressure despite having a more developed electricity network. Austrian Power Grid has pointed to rising cross-border electricity flows, internal reinforcement requirements, and the gap between connection demand and grid development. As renewable capacity increases, even mature European networks are being forced to optimise existing infrastructure while planning major upgrades.
Across Europe, generation growth is increasingly limited by network availability. Portugal provides a clear example, with grid constraints slowing renewable deployment despite strong clean energy ambitions. The Balkan region faces its own geography, interconnection, and market design issues, but the technical pressure is the same: renewable targets cannot be delivered without stronger grids.
Transmission investment now extends beyond building more lines. System operators need digital monitoring, dynamic capacity tools, voltage control, better forecasting, protection upgrades, and more detailed operational data exchange. Shunt reactors, interconnection reinforcement, regional corridors, and coordinated capacity calculation are all part of the same stability problem.
Grid equipment and delivery capacity are also becoming strategic constraints. The alliance between Hitachi Energy and Samsung C&T on high-voltage AC grid infrastructure reflects rising demand for substations, automation, EPC delivery, and transmission equipment across global markets. Southeast Europe is entering that competition as renewable projects move from pipeline to connection.
Solar growth adds further operational complexity. Output can rise and fall quickly across wide areas, particularly when weather systems move across multiple countries. Without storage, flexible demand, stronger interconnection, and active grid management, high renewable penetration can increase congestion, curtailment, and balancing requirements.
The next phase of renewable development in Southeast Europe will therefore be shaped by network delivery as much as generation investment. Transmission operators are connecting new assets, redesigning regional power flows, strengthening system stability, and preparing grids for levels of variability that existing infrastructure was not built to manage.