Assessing EU electricity flexibility needs: a first look at ACER’s open-source model

ACER published the preliminary version of EU-Flex, an open-source electricity market model developed to assess flexibility needs across the EU.

Electricity flexibility is the power system’s ability to respond to changes in supply and demand. As renewable generation grows and electrification expands across sectors, the EU will need greater flexibility to ensure security of supply, integrate new renewable sources and keep electricity affordable. 

Why estimate flexibility needs?

Under the EU’s (2024) Electricity Market Design reform, ACER is tasked with estimating flexibility needs across the EU, identifying potential gaps between these needs and available flexibility and recommending actions to address cross-border issues. The first assessment is planned for July 2027.

To support this work, ACER developed EU-Flex, an open-source model that simulates the European electricity market. The model provides insights into the flexibility challenges facing the EU power system, and how cross-border cooperation can help address them.

What’s in this preliminary release?

By sharing the model ahead of the 2027 assessment, ACER aims to make its analysis more transparent, allowing stakeholders to explore the proposed approach and contribute to the model’s development.

The release includes:

• a short paper introducing the model and demonstrating its use through a test case;

• a preliminary version of the model, with its source code and test case input data; and

• a document describing the underlying methodology.

Have your say!

Interested stakeholders have until 17 December 2026 to share their views on the:

• paper and methodology, through ACER’s public consultation; and

• preliminary model, via ACER’s GitHub repository.

Want to learn more?

On 17 November 2026, ACER will hold a webinar to present the model, explain its key features and demonstrate how to run it. Register for free.