The energy transition continues to test the resilience and flexibility of the national energy sector. At the time of 25 September 2025, the wholesale electricity market in Portugal — MIBEL (Iberic Market of Electricity) — evidenced a dynamic of deep contrasts, marked by an apparent moderation in monthly averages, but sustained by intraday volatility capable of challenging operators, traders and large industrial consumers.

The Gross Market Contrast (OMI)

While the cumulative of the month was positioned around the mean values of 61,69 €/MWh — reflecting a relief from earlier periods due to the significant contribution of renewable sources, 25 September illustrated the risks inherent in cyclical volatility:

  • Severe hourly dispersion: Price formation in the daily market (OMIE) continued to reproduce strong valleys during the hours of solar and wind void, countering abrupt ascent ramps in the night-end periods.

  • Exposure risk: For industrial traders and consumers with indexed price structures, these oscillations require constant monitoring and monitoring strategies. hedging strict to avoid severe budgetary deviations.

The Technical Challenge of Operation (REN)

From the point of view of technical management of infrastructure, REN faced the usual challenge of ensuring frequency stability and the balance of the transmission system:

  • Massification of non-manageable renewable energy requires continuous strengthening of system flexibility, where Iberian storage and interconnections play a critical role.

  • The management of energy deviations and associated costs remained a financial pressure vector for smaller market agents.

The Regulatory Quadrant and Impact on Industry

Alongside daily volatility, the sector sailed in expectation of the decisions of the ERSE regarding tariff revisions and the behavior of Network Access Rates (TAR):

  • The Portuguese electro-intensive industries remained particularly attentive to the medium-term price signals, seeking to optimize their plans for self-consumption and load flexibility.

  • The diversification of suppliers and the rigorous audit of electricity contracts have been consolidated as unavoidable priorities to mitigate the risk of tariff shock at the entry of the following quarter.

"The instability we observed at the end of September 2025 is not only due to external shocks in fossil fuels, but to the very complexity of managing a highly dynamic and decarbonized electrical ecosystem."

In short, the portrait of September 25, 2025 reinforced the conviction that the Portuguese electric market operates at an unprecedented level of technical and commercial demand, where digitisation and active demand management are the only effective defenses against the unpredictability of wholesale prices.