Renewable energy sources strengthened their role in Spain’s power system during September 2025, contributing more than half of the country’s total generation, according to the monthly report by APPA Renovables. In total, renewable production reached 11,555 GWh, representing 53.3% of the electricity mix, confirming the upward trend of clean energy despite continued market volatility.

Solar photovoltaic remained the leading renewable technology, with a 23.2% share, followed by wind (18.6%) and hydropower (7.8%). Together, these three technologies accounted for nearly half of Spain’s total electricity generation, reflecting a solid degree of technological diversification. The report also notes a more stable wind performance and a slight recovery in hydropower compared to the same month of 2024.

The average day-ahead market price stood at €61.04/MWh, 15.9% lower than in September of the previous year, with hourly lows of €8.50/MWh at 14:00 and peaks of €124.30/MWh at 21:00. This widening price gap, combined with 66 hours of zero or negative prices and 158 hours between €0 and €30/MWh, illustrates the increasing pressure of daytime solar generation on the grid and the urgent need for storage to absorb renewable surpluses.

Grid access and connection: a system under strain

APPA highlights the structural challenges of Spain’s grid access and connection system, which remains a bottleneck for new capacity additions. As of September 2025, there were 386 nodes reserved for generation tenders and court rulings (TSJ), with a total associated capacity of 165,319 MW, along with 71 nodes reserved for demand and storage, concentrating the main points of grid congestion.

The total capacity with granted access permits reached 135,787 MW, a 0.3% increase compared to August, while pending access requests amounted to 56,677 MW, 1.9% higher than the previous month. These figures confirm the intense pressure of the renewable project pipeline on the grid, widening the gap between projects with permits and those still awaiting available connection points.

By region, Andalusia, Castilla y León, Catalonia and Madrid host the largest number of reserved nodes and unavailable capacity, each exceeding 10,000 MW. Meanwhile, Castilla-La Mancha, Aragon and Galicia continue to register high volumes of requests for both generation and storage, reflecting sustained investor interest in regions with high renewable potential.

In parallel, non-integrated renewable energy (ERNI) reached 316.3 GWh in September, revealing that the grid could not absorb all available renewable output. This represents a significant portion of curtailed generation due to technical limitations and congestion at evacuation nodes, reinforcing the need for investment in grid infrastructure, interconnections, and flexibility mechanisms.

Balancing services also experienced a sharp rise, with an average price of €17.50/MWh, 61.9% higher than in September 2024, driven by hourly volatility and increased reliance on backup mechanisms during periods of low renewable output.

In terms of storage, the report notes that access requests for consumption or storage facilities connected to the transmission network reached 32,906 MW, reflecting growing interest in hybrid projects combining storage and self-consumption. However, most of these projects still lack effective connection availability.

Overall, the data portray a sector in expansion but facing structural limitations in grid infrastructure that risk slowing the integration of new renewable capacity. For APPA Renovables, the September results are a reminder of the urgent need to accelerate network planning, enhance dynamic grid management, and promote hybridisation and storage as key strategies to sustain Spain’s energy transition.