Portugal makes grid-forming mandatory for batteries above 45 MW
Victoria Shinder2 min readLarge batteries connecting to Portugal's grid will have to behave like a stabilising power source, not just a store of energy. Decree No. 464-A/2026/1, published last week, requires every battery energy storage project above 45 MW to be able to run in grid-forming mode and provide synthetic inertia, Energy-Storage.news reports. Plants between 10 MW and 45 MW are covered by separate terms.
The government says the decree is meant to strengthen the operational and supply security of the national electricity system as the number of battery projects grows. Portugal is targeting 6.9 GW of storage by 2030, reached 80% renewables in January 2026, and was part of the near-total Iberian blackout in spring 2025, which started a debate about grid stability. According to the report, grid-forming inverters do not materially raise the cost of a system, but they add simulation, modelling and testing work during commissioning. Similar requirements are under discussion at ENTSO-E; Germany has an inertia market but no mandate.
Separately, the government will award around 1 GW (1,050 MVA) of grid capacity for battery projects. The connections come with limits: transmission operator REN can curtail up to 500 hours of charging and discharging a year for standalone projects and up to 750 hours of charging for co-located ones. Projects need a minimum duration of four hours, there is a 0.75% auction operator fee, and bidding rules vary by location. Systems being built in Portugal today range from two to four hours.
What it means
Making grid-forming a connection condition rather than a paid service shifts the cost into project design, and the four-hour minimum excludes the two-hour systems that dominate current construction. Together with curtailment rights for REN, the tender is designed for system security first and merchant revenue second. Developers will judge it on how often those 500 or 750 hours are actually used.