Portugal | New Grid Rules Require Grid-Forming Capability for Large Battery Storage Plants

October 26, 2026

Portugal has introduced new grid connection requirements for battery energy storage systems (BESS), making grid-forming capability and synthetic inertia mandatory for large-scale storage plants connected to the transmission network. The new rules took effect on October 23, 2026, and apply to grid connection applications submitted from that date.

Under the new regulatory ordinance, battery storage plants connected to Portugal’s transmission grid, as well as facilities with a rated capacity of 45 MW or more, must provide grid-forming functionality and synthetic inertia. Storage facilities with a capacity of 500 kW or above must also automatically switch from charging to discharging when grid frequency falls, helping the power system respond to potential frequency disturbances.

The requirements extend existing European generator connection principles to battery storage systems, covering both charging and discharging operations. Plants with a capacity of 1 MW or more must also be technically capable of providing frequency containment and restoration reserves, voltage regulation and reactive power control. Facilities above 1 MW are subject to real-time monitoring and remote-control requirements.

The regulation comes as Portugal prepares for a substantial expansion of its energy storage sector. The country’s draft national storage strategy targets 6.9 GW of storage capacity by 2030, while government-backed funding programmes and planned procurement initiatives are expected to support more than 1 GW of storage projects.

Portugal’s battery storage market remains at an early stage. According to the Portuguese renewable energy association APREN, the country had approximately 20 MW of operational battery storage capacity at the end of 2025. In January 2025, the government awarded €100 million in funding to 43 storage projects with a combined capacity of around 500 MW.

Grid-forming technology enables inverters to help establish and maintain grid voltage and frequency, rather than simply following existing grid conditions. As renewable penetration increases and conventional synchronous generation declines, these capabilities can become increasingly important for maintaining system stability.

By introducing specific technical requirements ahead of the European Union’s ongoing revision of its generator connection rules, Portugal is seeking to prepare its power system for a growing fleet of battery storage assets. The policy could also influence equipment selection, project design and grid compliance requirements for developers and battery system suppliers entering the Portuguese market.

The new rules highlight a broader shift in Europe’s storage market: alongside cost and capacity, grid-support functionality is becoming an increasingly important consideration in the deployment of utility-scale battery energy storage systems.