The December 2025 monthly report from APPA Renovables confirms a trend that is rapidly consolidating in Spain’s power system: energy storage is no longer a future promise, but an active and expanding reality.
During the month, 37,371.93 MW of grid access applications were filed for storage facilities, the largest volume across all categories of new connection requests. This places storage ahead of other demand types, including grid-connected self-consumption (almost 25.6 GW) and conventional demand (23.34 GW).
In total, December saw 90.42 GW of demand-side access requests submitted through 122 applications, highlighting the accelerating deployment of storage solutions, both standalone and hybridised with renewable generation.
The surge in storage demand reflects the growing need to integrate higher volumes of renewable energy into an increasingly electrified system. In December alone, renewables produced 11,359 GWh, accounting for 48.9% of Spain’s electricity mix.
However, challenges persist—particularly for solar PV. The technology recorded a capture rate of 0.83, with an average capture price of €64.53/MWh, while wind power achieved a higher capture rate of 0.90 at €68.89/MWh.
High renewable output has also intensified technical constraints within the system. Adjustment services data show 5,188 GWh of renewable energy curtailed (“downward regulation”) during December, compared with just 42.2 GWh requiring upward regulation. In real-time operation, the imbalance was even clearer: 1,822 GWh curtailed versus 59.8 GWh increased—underscoring the urgent need for flexibility tools such as energy storage.
Spain’s wholesale electricity market recorded an average daily price of €58.29/MWh in December. Prices bottomed out at 14:00, while peaking at €105.25/MWh at 20:00.
Such volatility strengthens the business case for storage, enabling energy arbitrage, peak shaving, and enhanced grid stability—key services in systems with high shares of variable renewable energy.
Despite the momentum, grid access remains under strain. As of December 2025, 16.54 GW of access capacity is reserved for competitive tenders and nodes classified as being of special interest, spread across 386 grid nodes nationwide.
Regions such as Andalusia, Castile and León, and Catalonia concentrate the largest volumes of reserved capacity for both generation and storage projects.
At the same time, national electricity demand reached 22,582 GWh in December, a 4.2% increase compared with the same month in 2024, reinforcing the need for backup and flexibility infrastructure capable of managing supply variability.
Spain’s transmission system operator, Red Eléctrica de España, is also advancing specific demand-side access tenders aimed at channelling new projects into strategic areas of the grid.
According to a recent analysis by Energía Estratégica, 80 demand nodes have been identified across 14 autonomous communities, with a strong concentration in Andalusia, Castile and León, and Aragón. These tenders are expected to streamline the rollout of storage and flexible demand projects, optimise existing infrastructure and promote a more balanced territorial distribution of grid access.
As Spain’s power system becomes increasingly reliant on intermittent sources, the role of storage is becoming unavoidable. The APPA Renovables report makes clear that storage now sits at the heart of national energy planning.
If the current volume of applications materialises, Spain could add tens of gigawatts of storage capacity over the coming years—transforming the flexibility, stability and overall efficiency of its electricity mix.
These issues will take centre stage at the Future Energy Summit Iberia, to be held on 12 February in Madrid. The event will bring together representatives from the IDAE, leaders of energy communities and senior executives from across the sector to discuss the expansion of storage, grid access management and the evolving regulatory framework needed to accelerate Spain’s energy transition.
