Transelectrica grid stability renewable energy Romania — NRG-IA

Rapid integration of wind and solar parks — what happened Transelectrica is facing daily variations of over 3,000 MW in the national grid, as the energy transition transforms the transmission system operator from a simple carrier into a critical security dispatcher. In an analysis published by Economedia, it is highlighted how the accelerated integration of wind and solar power plants is fundamentally altering the architecture of the Romanian energy system. While in the past energy flowed unidirectionally from large coal or hydro plants to consumers, today's flows are bidirectional and highly variable. The national energy system (NES) is undergoing a profound structural shift. Green energy production is no longer a marginal element but has become the central component of the energy mix during peak production hours, according to data analyzed by Economedia. This shift forces the transmission operator, Transelectrica, to manage rapid load changes within intervals of just a few minutes. When the wind suddenly drops or clouds cover photovoltaic parks, the grid must instantly compensate for the deficit from other sources or imports. Maintaining a constant frequency at 50 Hz is becoming a second-by-second mission, highly complex in the absence of sufficient traditional dispatchable reserves. Furthermore, the rise of prosumers, who inject energy directly into low-voltage distribution networks, reverses traditional power flows. The transmission operator no longer just delivers energy from high voltage to consumers, but must balance a system where small local producers massively reduce net consumption from the grid at midday, causing significant voltage fluctuations. Volatility of green production and the rise of household prosumers The primary cause of this unprecedented complexity is the asymmetry between the installation rate of renewable capacities and the modernization rate of physical transmission grids. According to specialists cited by Economedia, wind and solar plants are built rapidly, often in areas rich in natural resources, such as Dobrogea or the south of the country, which are located far from major industrial consumption centers. This geographical concentration creates severe congestion on existing high-voltage lines. Dobrogea, for instance, concentrates over 3,000 MW of wind capacity, but the evacuation capacity to consumers in the center and west of the country is limited by the physical capacity of the transmission lines. Additionally, the lack of battery storage capacities at the system level amplifies imbalances. Without storage, every additional megawatt-hour produced by the sun or wind must either be consumed instantly, exported, or reduced through curtailment—an extreme measure that directly impacts developers' revenues. Increased risk of congestion and pressure on transmission tariffs The direct consequences of this pressure are reflected in both the physical stability of the grid and the bills paid by consumers. To maintain system balance, Transelectrica is forced to contract expensive system services from dispatchable plants (primarily gas or hydro), costs that are subsequently transferred into the transmission tariffs approved by ANRE. Costs for system technological services have risen significantly in recent years, directly reflecting the financial effort required to maintain stability. In the energy market, grid congestion limits cross-border transactions and can lead to negative prices at midday, followed by price spikes in the evening when solar production drops and demand rises. This dynamic makes suppliers—and ultimately industrial and residential consumers—vulnerable to extreme wholesale price volatility. The physical grid is no longer just a distribution channel; it has become the determining factor of the final electricity price. Completion of major infrastructure projects and mandatory storage The deadline for adapting the grid to the new energy mix depends directly on the completion of Transelectrica's major infrastructure projects, such as upgrading the Banat axis to 400 kV and cross-border interconnections scheduled through 2030. At the same time, future regulations could impose an obligation on renewable developers to install minimum battery storage capacities to obtain technical grid connection permits. The major short-term risk remains the limitation of connecting new green parks in saturated areas if investments in new high-voltage lines do not keep pace with private investors' appetite. ANRE's decisions regarding the recognition of these investments in tariffs will be crucial for Transelectrica's ability to finance these strategic national energy infrastructure works.