Red Eléctrica de España, Spain’s transmission system operator (TSO), has published for the first time detailed maps of demand access capacity in the transmission grid, formally incorporating the demand-side perspective into the access and connection framework.
The snapshot reveals a highly constrained network: only 25% of transmission nodes currently have available capacity for new demand, either under general priority rules or via competitive tenders.
According to the TSO, the transmission grid has already granted access and connection permits for 129 GW of wind power and solar PV projects, alongside 16 GW of energy storage and 19 GW of demand facilities. This level of commitment explains the high node-level saturation reflected in the newly released maps.
Since the approval of the current grid development plan in 2022, 11.8 GW of capacity has been granted for new electrical loads. None of these facilities has yet entered into operation.
These projects have a five-year deadline from the date of permit award to reach commissioning.
In aggregate terms, demand holding permits and awaiting connection exclusively to the transmission grid would represent an increase of nearly 25% of Spain’s current electricity demand. This introduces additional pressure on grid planning and on the system’s actual absorption capacity, particularly in a context of high renewable energy penetration.
Based on updated data, the system shows:
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38,646 MW available for demand with power electronics interface (PEI) compliant with fault ride-through requirements. This figure corresponds to the minimum unallocated margin under WSCR criteria, static generation and dynamic-1 criteria.
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92,887 MW available for PEI-based energy storage, calculated as the minimum unallocated margin under static storage and dynamic criteria.
The official dataset published by the Directorate-General for System Operation breaks down occupied access capacity for demand and storage by connection point. It differentiates between capacity already in service and capacity pending commissioning.
It also identifies voltage level, autonomous community and grid type (transmission or distribution), enabling stakeholders to pinpoint effective congestion. At numerous 400 kV nodes, more than 300 MW is already committed, with some positions exceeding 500 MW between operational and pending capacity, highlighting a strong geographical concentration of grid saturation.
Until now, developers only had visibility on generation capacity. With this publication, the TSO provides transparency on available headroom for new loads and storage projects under three applicable technical criteria: static, dynamic and, where relevant, short-circuit power.
On a territorial basis, the regions with the highest aggregated margins for demand PEI are:
| Region | Available Demand Capacity (MW) |
|---|---|
| Galicia | 9,309 |
| Castile and León | 7,855 |
| Andalusia | 7,434 |
For energy storage, the leading regions are:
| Region | Available Storage Capacity (MW) |
|---|---|
| Castile and León | >18,000 |
| Aragon | ~11,000 |
| Andalusia | >10,000 |
| Galicia | >10,000 |
These aggregated figures — excluding double-node configurations — provide a key reference for industrial projects, process electrification, data centres, green hydrogen production and large-scale storage developments.
APPA Renovables described the publication as “a key benchmark for the development of demand and storage projects”. However, the association cautioned that “capacity may be affected by reserves for tenders, shared capacity zones or pending reference values”, requiring detailed node-by-node analysis.
The published margins reflect the situation under current technical-regulatory criteria but do not guarantee automatic availability.
Storage as flexible demand: economic impact
The update also includes the total volume of firm demand and storage permits granted, remaining grantable capacity, the limiting criterion at each node, the distinction between PEI1 and PEI2 loads, and distribution grid access capacity where a reference value has been agreed.
This last element is particularly relevant in territories where transmission-distribution coordination determines the real feasibility of projects, especially in distributed generation and industrial electrification schemes.
During a sector webinar following the publication, the TSO stressed that the tool aims to provide the market with forward-looking visibility for investment planning, particularly in a system with high renewable energy penetration and increasing grid integration challenges.
The context is marked by renewable curtailment, negative wholesale electricity prices and widespread node saturation. In this environment, flexible demand is increasingly viewed as a structural balancing tool.
UNEF, Spain’s solar PV association, highlighted the direct economic impact of enabling storage to access the grid as flexible demand. According to sector data cited by the association, “an asset that cannot draw power from the grid earns €20,653/MW less than if it were connected”, equivalent to roughly 9% lower annual revenues under a 2025 scenario.
UNEF also reported that during the second and third quarters, average revenue losses approach 5%, while from October onwards, the gap can reach up to 14% in certain months.
For the association, this differential underscores the urgency of accelerating storage connections as flexible demand in a context of growing appetite for energy storage, grid flexibility and investment in renewables.
With this update, Red Eléctrica enhances the level of detail available for access and connection analysis, formally integrating demand into nodal planning.
Generation, storage and flexible consumption are now assessed under a unified technical framework, reshaping how utilities, independent power producers (IPPs), investment funds and large industrial consumers evaluate project location, capacity and timelines.
The next phase will depend on the evolution of access procedures, capacity reservations for tenders and regulatory coordination — factors that will ultimately determine the real materialisation of the 38.6 GW of demand and 92.9 GW of storage currently identified as available grid headroom.
