The ultimate objective of Task 25/63 is to provide information to facilitate the highest economically feasible wind energy share within electricity power systems worldwide. The task supports this goal by analyzing and further developing the methodology to assess the impact of wind power on power systems.

This information facilitates economically feasible wind energy penetration in electricity systems worldwide. Task 25/63 brings best practices from energy system study methods as well as experience and study results to member countries and a wider audience through IEA, IRENA, Global Power System Transformation (G-PST) and Energy System Integration Group (ESIG). On top of these international network stakeholders, the system operators are the main target group of Task 25; they are joining Task 25 work directly (from Denmark, Italy, France) and as observers (Germany, Finland, Spain, Japan, Sweden, the UK).

Task 25 ran from 2006 to 2024. As the work evolved from wind integration studies to cover both wind and solar energy, and both electricity and energy systems, the name of Task 25 was changed from Design and Operation of Power Systems with Large Amounts of Wind Power to Design and Operation of Energy Systems with Large Amounts of Variable Generation 2018. A new task – Task 25/63 Twenty Fifty Integration of Variable Energy (TWENTY-FIVE) – started in 2025, building on the collaboration and knowledge developed during 2006–2024.

The international forum has been formed for the exchange of experience gained and studies conducted. The case studies address different aspects of power system operation and design:

1. Planning
2. Operations
3. Stability
4. Markets