Market coupling has emerged as a pivotal reform within the European electricity landscape, particularly impacting South-Eastern Europe (SEE). This initiative connects national day-ahead markets through implicit capacity allocation, facilitating the movement of electricity from regions with lower prices to those with higher prices. While this strategy aims to enhance welfare and mitigate price volatility, its implementation in SEE has been marked by both significant advancements and notable shortcomings.
Recent developments indicate substantial progress in market integration. Most SEE countries, including Serbia, Romania, Bulgaria, and Greece, are now linked to the broader European market through day-ahead coupling. This integration has led to a pricing structure that increasingly reflects regional dynamics rather than isolated domestic factors. Furthermore, cross-border trading volumes have surged, contributing to improved price convergence under stable operating conditions.
However, recent stress events have illuminated the vulnerabilities within this framework. During peak demand periods or when renewable energy generation is low, price disparities can quickly re-emerge. These instances raise critical concerns about whether market coupling has fostered genuine structural resilience or simply redistributed existing volatility across the region.
Quantitative analyses reveal a complex picture. In typical circumstances, market coupling has successfully reduced average price differences between neighboring SEE markets by 10–20% compared to pre-coupling scenarios. Conversely, during periods of stress, price spreads can widen significantly—sometimes exceeding €100/MWh for prolonged durations—coinciding with diminished cross-zonal capacity availability due to maintenance or operational constraints.
This evidence suggests that the effectiveness of market coupling is contingent upon several factors. It tends to function optimally when there is sufficient capacity and aligned operational rules. However, institutional and technical limitations can hinder its performance. Therefore, while SEE’s market coupling enhances efficiency during stable conditions, it falls short of ensuring stability amid disruptions.
The limitations of day-ahead coupling highlight the necessity for broader integration strategies. A singular focus on day-ahead markets does not sufficiently address real-time volatility in an energy system increasingly reliant on variable renewable sources. The development of intraday markets and balancing platforms remains uneven across SEE countries. Without robust intraday and balancing integration, the benefits of day-ahead price convergence may dissipate rapidly under changing conditions.
The impact of these limitations became evident during the summer of 2024. Despite formal market coupling mechanisms in place, significant evening price spikes were recorded in various parts of SEE due to surges in post-sunset demand coupled with constrained imports. Analyses indicated that better utilization of cross-zonal capacity could have alleviated many of these issues, underscoring the fragility of coupling in the absence of adequate capacity availability.
The interaction between market coupling and national policy frameworks complicates this landscape further. Variability in capacity mechanisms, network tariffs, and renewable support schemes across SEE countries distorts price signals and hampers cross-border electricity flows. For instance, discrepancies arise when one market subsidizes availability while another operates solely based on energy pricing, leading to divergent dispatch incentives. While coupling effectively transmits prices across borders, it does not necessarily relay critical investment signals needed for future development.
Institutional fragmentation also poses challenges for deeper integration. Some SEE nations are EU members subject to comprehensive market design obligations; others function under transitional arrangements within the Energy Community framework. Although strides have been made towards alignment, disparities persist regarding implementation speed and regulatory practices—issues that become particularly pronounced during times of crisis when coordinated responses are essential.
The potential benefits from enhanced market coupling are considerable from a welfare standpoint. Research indicates that integrating balancing markets alone could yield over €1.6 billion in welfare gains across Europe. For SEE specifically, extending integration beyond day-ahead trading into balancing and reserve sharing could facilitate more effective flexibility management where it is most needed, thereby decreasing both price volatility and reserve costs significantly.
The governance aspect presents a political challenge for deeper integration efforts. Achieving greater cooperation among transmission system operators necessitates trust-building measures, harmonization of grid codes, and a readiness to share control over resources. In regions where energy sovereignty narratives are strong, these tasks can be particularly complex. Nevertheless, failure to address these governance challenges may lead to ongoing exposure to volatility that threatens energy security through reliance on imports during crises.
The path forward for SEE involves not just pursuing deeper market coupling but doing so with coherence and urgency. Incremental progress risks entrenching a framework where theoretical integration does not translate into practical resilience during critical moments. Accelerated efforts towards aligning capacity calculations, outage planning processes, intraday markets, and balancing platforms may pave the way for more robust stability in an increasingly volatile energy landscape.
The evolution of market coupling in SEE has already transformed electricity trading dynamics; however, its future trajectory will determine whether it serves as a stabilizing force or remains an incomplete solution amidst ongoing challenges related to high-renewable energy systems.
