ACER amends the implementation frameworks for two European electricity balancing platforms

On 18 December 2025, ACER received two proposals from all electricity transmission system operators (TSOs) to amend the implementation frameworks for PICASSO and MARI, the EU platforms for exchanging balancing energy from frequency restoration reserves.

With its Decisions 12/2026 and 13/2026, ACER approved both proposals.

What are the implementation frameworks for balancing platforms?

Established under the Electricity Balancing (EB) Regulation, the implementation frameworks harmonise how balancing service providers (BSPs) participate in electricity balancing markets across EU Member States.

These markets allow TSOs to manage unexpected differences between electricity supply and demand. PICASSO coordinates cross-border exchanges of automatically activated balancing energy (e.g. in case of sudden need), while MARI coordinates manually activated balancing energy. Together, they enable TSOs to access balancing resources across borders and maintain system stability.

What did the TSOs propose?

The TSOs proposed to further harmonise the BSP prequalification process, which ensures that power generation or demand units meet the technical and operational requirements to participate in the market and provide balancing services. 

The proposals also introduce a common process for amending the implementation frameworks of PICASSO and MARI to further harmonise the terms and conditions for BSPs.

What did ACER decide? 

ACER approved the proposals, while introducing some amendments:

• A structured harmonisation process. Every two years, TSOs will run stakeholder surveys to identify areas where the terms and conditions for BSPs still need to be aligned across countries. TSOs will then develop a common proposal for further harmonisation and publicly consult on it.
• More harmonised prequalification requirements. ACER introduced additional requirements for switching, re-prequalification, termination of prequalification and data exchange. Given the limited experience with harmonised prequalification, some requirements will continue to be set at national level, with further harmonisation expected as TSOs gain more experience.
• More prequalification options. ACER introduced three prequalification options: activation testing, ex-post verification and a fast-track process. Compared with activation testing, the other two offer faster and easier market access, as balancing services are monitored during operation instead of tested upfront. TSOs can choose any or all three options, subject to approval by their national regulatory authority.
• Easier access for smaller market participants. ACER simplified the prequalification process for smaller participants to help ensure a level playing field. As existing processes were designed around large conventional generators, ACER adapted them to make it easier for all participants that can provide secure and reliable balancing services to enter the market and improve liquidity.

What are the next steps? 

TSOs have six months to submit a proposal to their national regulatory authority to align national terms and conditions with the new requirements. Once approved, TSOs will have 24 months to implement the harmonised prequalification process.