IEA Wind TCP Task 25

Design and Operation of Energy Systems with Large Amounts of Variable Generation

About Task 25

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

Task 25 analyzes and develops methodologies that assess the impact of variable generation on power and energy systems. This information facilitates economically feasible wind energy penetration in electricity systems worldwide. Task 25 summarizes results from participating countries and formulates best practice recommendations for system impact and integration studies.

Task 25 started in 2006 and is now in its sixth term (2021-2024). As the work has 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.

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. Impacts of variability and uncertainty on cycling losses of generators, balancing, and reserve requirements.
  2. Capacity value of wind power.
  3. Efficient use of existing transmission capacity and requirements for new network investments.
  4. System stability issues.


Who can participate in Task 25?

For the 2021-24 phase, 15 member countries and 2 sponsors are involved in Task 25. Most countries have participated in their TSOs (Transmission System Operators) either following their national project or participating directly in the Task 25 meetings.

To participate in the research activities of Task 25, researchers must reside in a country that participates in the IEA Wind Agreement AND has agreed by official letter to participate in Task 25.

To join a task, a member country of the IEA Wind TCP designates a lead institution that agrees to the obligations of task participation (pay the annual fee and agree to perform specified parts of the work plan).

Researchers active (performing part of the work plan) benefit from meetings and professional exchange during the term of the task. Countries participating in the task benefit from the information developed by the task.

Participants can gain access to the Members Only portion of the website by receiving the username and password from the Operating Agent, Niina Helistö.

For more information, contact the Operating Agents (contact information below) or the IEA Wind TCP Secretariat.


Operating Agents

Please contact the Operating Agents below with any questions

Hannele Holttinen

Hannele Holttinen

Task 25 Operating Agent

    Niina Helistö

    Task 25 Operating Agent

      Task 25 Publications

      Find more information about our publications and results here


      Task 25 Roadmap


      Phase l

      State-of-the art Comparison of studies


      Phase ll

      Best practice of Methodology and Experience


      Phase lll

      Recommended Practices RP16
      Fact sheets
      Hourly time series, smoothing impact
      Higher share studies


      Phase lV

      RP Ed.2
      Energy System Coupling


      Phase V

      Instant 100% wind&solar challenges in Energy Systems


      Phase Vl

      100% wind&solar events with Smart Energy Integration

      Any Question at

      Tel: +358 40 5187955

      Recognis Oy w. VTT

      VTT Technical Research Centre Ltd
      Tekniikantie 21, Espoo

      Monday to Friday

      9 am – 17 pm Central European Time

      Send your mail at