ACER Opens Three Routes into Europe’s Balancing Platforms: What Changes for PICASSO and MARI Providers
On 18 September 2026, the EU Agency for the Cooperation of Energy Regulators (ACER) adopted Decisions 12/2026 and 13/2026, amending the implementation frameworks of PICASSO and MARI, the two European platforms for exchanging balancing energy from frequency restoration reserves. ACER announced the decisions on 22 September 2026. With Decisions 12/2026 and 13/2026, ACER harmonised how balancing service providers (BSPs) prequalify across Member States, added two faster routes to market alongside activation testing and simplified the process for smaller participants. The announcement is available on the ACER website.
What changed: prequalification before and after the decision
|
Parameter |
Before Decisions 12/2026 and 13/2026 |
After |
|
Prequalification route |
Activation testing before market entry, defined nationally |
Three options: activation testing, ex-post verification, fast-track; TSO choice subject to national regulatory approval |
|
Switching, re-prequalification, termination, data exchange |
National terms and conditions |
Harmonised requirements in the implementation frameworks; some elements remain national for now |
|
Smaller participants |
Procedures designed around large conventional generators |
Simplified process to support a level playing field |
|
Further harmonisation |
Ad hoc amendments |
Biennial cycle: stakeholder survey, common TSO proposal, public consultation |
|
Amending the frameworks |
Separate procedures per platform |
Common process for PICASSO and MARI |
|
National implementation |
n/a |
Within six months of the decisions, TSOs must submit national proposals; following the relevant national approval, TSOs have up to 24 months to implement the harmonised process |
What are PICASSO and MARI?
Both platforms operate under the EU Electricity Balancing Regulation. PICASSO coordinates the cross-border exchange of automatically activated frequency restoration reserves (aFRR), the reserve that responds within seconds to sudden imbalances. MARI does the same for manually activated reserves (mFRR), which TSOs call on for longer deviations. Together they let TSOs draw on balancing resources across borders through a common merit order instead of relying only on providers in their own control area.
The implementation frameworks are the rulebooks for each platform. They set the terms on which BSPs, whether generators, batteries, aggregated demand or industrial loads, offer balancing energy into the shared pool. The TSOs submitted their amendment proposals on 18 December 2025, and ACER consulted on them from 26 January to 23 February 2026. ACER adopted the amended frameworks on 18 September 2026 and announced the decisions on 22 September 2026.
The three prequalification routes
|
Route |
How it works |
Potential relevance |
|
Activation testing |
The unit demonstrates compliance through testing before full participation. |
Providers prequalified through an upfront test under the applicable national arrangements. Depending on those arrangements, this may include large conventional units. |
|
Ex-post verification |
The unit may receive temporary prequalification while the TSO assesses its performance during operation against the applicable requirements. |
Providers able to demonstrate compliance using operational-performance data, subject to the conditions implemented nationally. Depending on those conditions, this may include batteries and other assets with reliable telemetry. |
|
Fast-track |
A simplified prequalification process applies where the relevant eligibility conditions are met. |
Eligible providers that meet the applicable conditions for the simplified process. Depending on the nationally implemented eligibility criteria, this may include smaller units, aggregated demand response or the repeat prequalification of a previously assessed technology. |
The examples above are illustrative only. They do not mean that a particular technology automatically qualifies for a specified route. The routes available, their eligibility conditions and their application will depend on the relevant TSO’s national proposal and regulatory approval.
ACER states that, compared with activation testing, the other two routes offer faster and easier market access because balancing services are monitored during operation instead of tested upfront. Each TSO decides which routes to offer, and its national regulator approves the choice. The routes available and their application dates may therefore differ between Member States.
Why prequalification has been a barrier
Prequalification is the gate to the balancing market. Before a TSO accepts bids from a unit, it confirms that the unit can deliver the required ramp rate, duration and measurement quality. In several countries the process was built for a small number of large plants: it can take months, involve on-site tests and require documentation that small or distributed assets struggle to produce. ACER’s 2021 study on prequalification processes identified this as a barrier for demand response and small-scale providers, and the new decisions follow from that work.
For a portfolio spread across several countries, harmonised rules also reduce the cost of qualifying the same technology repeatedly under different national standards. ACER added common requirements for switching between BSPs, re-prequalification, termination of prequalification and data exchange, and it notes that further alignment is expected as TSOs gain experience.
Timeline to 2029
- 18 December 2025: TSOs submit amendment proposals to ACER.
- 26 January to 23 February 2026: ACER public consultation.
- 18 September 2026: ACER adopts Decisions 12/2026 and 13/2026.
- 22 September 2026: ACER announces the decisions.
- Within six months of the decisions: TSOs submit proposals to their national regulatory authorities to align national terms and conditions with the harmonised requirements.
- Within 24 months following the relevant national approval: TSOs implement the harmonised prequalification process. Actual application dates may therefore differ between Member States.
What to monitor next
- Which of the three routes each TSO proposes to its national regulator, and when.
- National regulatory approvals and the resulting implementation deadlines per country.
- The first biennial stakeholder survey on remaining differences in BSP terms and conditions.
- Accessions to the platforms in Central and Eastern Europe. Slovenia joined in July 2026 and Hungary was scheduled to join on 1 October 2026, as covered in Slovenia Joins PICASSO and MARI; Hungary to Follow in October.
FAQ
What did ACER decide in September 2026?
ACER approved TSO proposals to harmonise the prequalification of balancing service providers on PICASSO and MARI (Decisions 12/2026 and 13/2026), added a biennial harmonisation cycle, introduced three prequalification options and simplified the process for smaller participants.
What are the three prequalification options?
The options are activation testing, ex-post verification and a fast-track process. Ex-post verification allows temporary prequalification while performance is assessed during operation. Fast-track provides a simplified process where the applicable eligibility conditions are met. Each TSO chooses which options to offer, subject to national regulatory approval.
When will the new rules apply?
TSOs must submit the required national proposals within six months of the decisions. Following approval by the relevant national regulatory authority, TSOs have up to 24 months to implement the harmonised prequalification process. The availability and timing of individual routes may therefore differ between Member States.
Who is affected?
Balancing service providers of all sizes, including batteries, aggregators, demand response and smaller generation units, as well as TSOs and national regulators that must adopt and approve the national rules.
Does the decision change how PICASSO and MARI activate balancing energy?
No. The decisions concern how providers qualify to participate and how the frameworks are amended. Activation and pricing on the platforms are unchanged.
How D.TRADING works with balancing markets
D.TRADING trades power and provides route-to-market services for battery storage across Central, Eastern and South-Eastern Europe, including the balancing markets that PICASSO and MARI connect.
About D.TRADING
D.TRADING is a B2B energy and commodity trading company operating across Central, Eastern, and South-Eastern Europe, including Ukraine, with hubs in Baar (Switzerland), Zagreb (Croatia), Amsterdam (Netherlands), and Kyiv (Ukraine). The company operates in 26 countries.
The company trades power, gas, LNG, and fuels for enterprise and wholesale counterparties, with services that include structured trading, renewable offtake, battery storage route-to-market, and guarantees of origin. In 2025, it traded 12.1 TWh of power and 7.0 TWh of natural gas for more than 130 clients.
Disclaimer
This article is prepared by D.TRADING for general informational purposes only and does not constitute legal, financial, investment, accounting, tax, or regulatory advice. The information contained herein is based on publicly available sources and reflects opinion on the regulatory environment as of the publication date. D.TRADING makes no representations or warranties, express or implied, as to the accuracy, completeness, or timeliness of the information provided. This document is not an offer or solicitation to buy or sell any energy products, commodities, or financial instruments.
