Key data
| Regulation | Resolution of September 29, 2026, DGPEM — Prior administrative authorization and construction authorization for the Castor project (battery storage) |
|---|---|
| BOE Publication | October 22, 2026 |
| Entry into force | Not specified in the resolution |
| Project holder | Planta FV 115, SL |
| Authorized battery capacity | 19.993 MW |
| Hybridized solar plant capacity | 49.99 MW (Castor Solar, already operational) |
| Location | Huecas (Toledo) |
| Evacuation substation | Torrijos 220 kV (REE) |
| Applicable regulatory framework | RD 997/2025 |
| Category | Energy / Renewable storage |
| BOE Reference | BOE-A-2026-22068 |
A storage hybridization project has just received dual administrative authorization in record time. The General Directorate of Energy Policy and Mines has granted Planta FV 115, SL prior administrative authorization and construction authorization for the Castor battery system, with 19.993 MW of installed capacity, in Huecas (Toledo). The project will be hybridized with the Castor Solar photovoltaic plant, with 49.99 MW, which is already in operation.
The key to processing agility lies in RD 997/2025, which introduced a special regime for storage projects hybridized with existing renewable installations: exemption from simplified environmental assessment and reduction of timelines. The file was closed without any objections during the public information process and with the approval of all consulted bodies.
What does this regulation establish?
The resolution simultaneously grants two authorizations to the same promoter for the same project:
- Prior administrative authorization: recognizes project viability and enables the promoter to continue with technical and construction procedures.
- Administrative construction authorization: allows physical commencement of battery installation works and evacuation infrastructure.
The key technical and regulatory elements of the resolution are as follows:
| Element | Detail |
|---|---|
| Authorized system | Battery storage — Castor project |
| Installed battery capacity | 19.993 MW |
| Hybridized solar plant | Castor Solar, 49.99 MW (already operational) |
| Evacuation infrastructure | Torrijos 220 kV REE substation (reused, already authorized) |
| Enabling regulatory framework | RD 997/2025 (storage hybridizations) |
| Environmental assessment | Exempt from simplified environmental assessment (RD 997/2025) |
| Public information objections | None |
| Consulted bodies | Approval from all consulted bodies |
| Distribution of responsibilities | Proportional to access capacity among holders sharing infrastructure |
RD 997/2025 is the major facilitator for this type of project: by hybridizing storage with an existing renewable plant, the promoter avoids the simplified environmental assessment process and benefits from reduced administrative timelines. This makes hybridization the fastest route to add storage capacity to Spain's renewable fleet.
Economic and operational impact
For the promoter and the renewable sector in general, this resolution has direct implications in three areas:
- Reduction of processing costs and timelines: exemption from simplified environmental assessment and reuse of evacuation infrastructure (Torrijos 220 kV substation) eliminate two of the major administrative and economic bottlenecks in storage projects.
- Optimization of existing assets: by hybridizing the battery with the Castor Solar photovoltaic plant (49.99 MW already operational), the promoter maximizes the performance of already-amortized network infrastructure, without needing new connections or new access permits.
- Distribution of shared responsibilities: when multiple holders share evacuation infrastructure, the resolution establishes that responsibilities will be distributed proportionally to the access capacity of each installation. This is relevant for promoters with adjacent projects or shared infrastructure.
From a market perspective, the sum of 19.993 MW of storage with a 49.99 MW solar plant enables the promoter to manage the generation curve, shift energy to peak-price hours, and participate in system adjustment services, improving the profitability of the overall project.
Who does it affect?
- Planta FV 115, SL: direct promoter of the project, holder of both authorizations.
- Promoters of operational photovoltaic plants evaluating the addition of storage: this resolution is a direct precedent for the procedure to follow under RD 997/2025.
- Developers of energy storage projects seeking to use the hybridization route to reduce administrative timelines and costs.
- Holders of installations with shared evacuation infrastructure: the proportional responsibility distribution clause directly affects them in managing agreements with other promoters.
- Legal and technical advisors in the energy sector processing storage authorizations before the DGPEM.
- Investors and funds with exposure to renewable assets in Spain evaluating the impact of RD 997/2025 on the speed of new project development.
Practical example
A promoter with an already-operational 50 MW photovoltaic plant in Castilla-La Mancha wanting to add a 20 MW battery system has two options:
- Conventional route: process the storage project as a new installation, with simplified environmental assessment, new access and connection permits, and timelines that can exceed 18-24 months.
- Hybridization route (RD 997/2025): adopt the hybridization regime, as Planta FV 115, SL did with the Castor project. Result: exemption from simplified environmental assessment, reuse of existing evacuation infrastructure (in this case, the Torrijos 220 kV REE substation), and processing without objections. The file is resolved with dual simultaneous authorization (prior + construction) in a single procedure.
The difference in time and administrative cost between both routes can be decisive for the project's financial viability, especially in an environment of high interest rates where each month of delay has real cost.
What should companies do now?
- Review if you have operational photovoltaic plants eligible for hybridization: any operational solar installation can be a candidate for adding storage under RD 997/2025. Identify those with available access capacity at their connection point.
- Verify existing evacuation infrastructure: if the substation or evacuation line is already authorized and has capacity, hybridization avoids new access and connection procedures. Consult with REE or the corresponding grid manager.
- Initiate the procedure under RD 997/2025: submit the application for prior administrative authorization and construction authorization to the General Directorate of Energy Policy and Mines, adopting the project under the hybridization regime to benefit from the exemption from simplified environmental assessment.
- Review shared infrastructure agreements: if you share an evacuation point with other holders, ensure that agreements reflect the proportional distribution of responsibilities according to each installation's access capacity, as established by this resolution.
- Evaluate the impact on market strategy: with hybridized storage, the plant can participate in adjustment services and manage the generation curve. Update the project's financial model to incorporate these additional revenues.
Frequently asked questions
What is storage hybridization with a solar plant and what advantages does it have under RD 997/2025?
Hybridization consists of adding a battery system to an already-operational photovoltaic plant, sharing evacuation infrastructure. RD 997/2025 allows this type of project to be exempt from simplified environmental assessment and processed with reduced administrative timelines. The Castor project (19.993 MW batteries + 49.99 MW solar) in Huecas is a direct example of this route.
What authorizations has Planta FV 115, SL obtained for the Castor project?
It has simultaneously obtained prior administrative authorization and administrative construction authorization, both granted by the General Directorate of Energy Policy and Mines through resolution of September 29, 2026, published in the BOE on October 22, 2026 (BOE-A-2026-22068).
How are responsibilities distributed when multiple holders share evacuation infrastructure?
According to this resolution, responsibilities among holders sharing infrastructure are distributed proportionally to the access capacity of each installation. This applies directly to projects that, like Castor, use a shared substation (in this case, Torrijos 220 kV REE).
What evacuation infrastructure does the Castor project use and why is it relevant?
Evacuation is carried out through the Torrijos 220 kV REE substation, which was already authorized for the Castor Solar plant. By reusing this infrastructure, the promoter avoids new access and connection procedures, reducing storage project costs and timelines.
Can any photovoltaic plant promoter adopt the RD 997/2025 regime to add batteries?
RD 997/2025 enables the hybridization route for storage projects associated with already-operational renewable installations. Exemption from simplified environmental assessment and timeline reduction are the main advantages. To adopt it, the project must be processed before the General Directorate of Energy Policy and Mines complying with the royal decree requirements. The Castor file, which was closed without objections and with approval from all consulted bodies, is the most recent precedent.
Official source
Consult complete regulation at official source (BOE-A-2026-22068)
Disclaimer: This article is for informational purposes only and does not constitute legal advice. For specific decisions, consult a qualified professional. Source: https://www.boe.es/diario_boe/txt.php?id=BOE-A-2026-22068
