Executive Summary

ENTSO-E Summer Outlook 2025: No adequacy risk is identified in Continental Europe, Nordics and Great Britain. Islands that are isolated or scarcely interconnected (Ireland, Malta, and Cyprus) will require close monitoring.

All risks identified for the summer season are driven by weather conditions in combinations with other adverse factors. Dedicated non-market resources help alleviate these risks in Ireland and entirely eliminate risks in Malta.

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Your Questions, Our Answers

• What is the Seasonal Outlook?

  ENTSO-E’s Seasonal Outlooks investigate at pan-European level the security of electricity supply ahead of each winter and summer period. They are released twice a year with a Summer Outlook in June and a Winter Outlook in December. The role of the Outlooks is to identify when and where system adequacy – the balance between supply and demand for electricity – is at risk. Outlooks are not forecasts of the future. Rather, they identify potential vulnerabilities for the upcoming season which can be addressed proactively with preparation or mitigation measures.
  
  The Outlooks are the product of cooperation between 40 European electricity TSOs. Because of their pan-European scope, the Outlooks complement the analysis carried out in national and regional assessments, which provide a more detailed picture of adequacy at local level. They promote cooperation across Europe and between regional and national stakeholders.
  
  Performing the Seasonal Outlooks (Seasonal Adequacy Assessments) is one of ENTSO-E’s legal mandates as specified in the Clean Energy Package and as defined in Article 9 of the Risk Preparedness Regulation (Regulation (EU) 2019/941). ENTSO-E performs this assessment to inform national authorities, TSOs and relevant stakeholders of the potential risks related to the security of electricity supply in the coming season. The Seasonal Outlooks reflect the implementation of the methodology as developed by ENTSO-E as per Article 8 of the Risk Preparedness Regulation and as approved by ACER on 6 March 2020. Earlier Seasonal Outlooks (published before 2020) follow another deterministic approach.

• How are electricity TSOs preparing to maintain security of supply?

  Cross-border cooperation and close coordination at all levels are key to ensure that balance is maintained between supply and demand in the European power system. TSOs’ national analysis regarding short-term adequacy risks and potential stress situations use as a reference the pan-European methodology but may incorporate higher granularity and local sensitivities to provide a more detailed view of the local situation.
  
  At regional level, TSOs coordinate via established short-term adequacy forecasts and processes which aim to help optimize the operational cooperation between TSOs and Regional Coordination Centres (RCCs) in case of scarcity situations.
  
  On the basis of latest TSO data, RCCs perform regional adequacy assessments from week-ahead to day-ahead to detect situations where a lack of electricity adequacy could occur, taking into account cross-border exchanges and operational security limits. Concerned TSOs can then take measures and coordinate as necessary to reduce adequacy risks in the respective timeframe. A good level of exchange capacity is also a crucial resource. TSOs will coordinate to maximize exchange capacities regionally through close coordination and cooperation within relevant RCCs.
  
  TSOs are also closely coordinating at pan-European level within ENTSO-E. ENTSO-E diligently monitors the evolution of the adequacy situation and, in case of major assumption change, release updates throughout the season. Regular exchanges are also taking place with the European Commission, EU Member States and other relevant stakeholders. Coordination between National Risk Preparedness Plans is ensured through regular exchanges in the Electricity Coordination Group and the Gas Coordination Group.

• Does the Seasonal Outlook consider the probability and impact of a heat wave?

  The Seasonal Outlook considers multiple possibilities regarding weather and temperature, which can impact generation (e.g. more or less wind) and consumption of electricity (e.g. cooling). Our simulations are performed for multiple so-called ‘climate years’. These cover 36 future summer projections to capture sufficient spread of possible winter scenarios. In these future projections of climate data, temperatures are calculated through different climate models, all in line with SSP 2-4.5. In addition, multiple hydro samples are used, from a wet to a very dry season. This allows us to take into consideration a variety of weather conditions, including heat waves or droughts. The results presented in the Seasonal Outlook are an average of many different possible weather conditions.

• What are non-market resources?

  Non-market resources can include generation, demand-side-response and storage resources, among others depending on the country. They are normally dedicated to ensuring grid security and stability, as well as transmission reliability margins used for coping with variability of power flow. As such, they are kept outside the market but can be called upon in the event of a supply shortage to ensure security of supply.
  
  The reference scenario considers all resources available to supply demand in a market-based approach. This means that non-market resources are not yet deployed. However, when our simulations identify an adequacy risk in a country, ENTSO-E carries out another simulation taking into account the additional contribution of non-market resources when they exist at national level. These resources can also help mitigate risks in other countries.

• What are operational mitigation measures?

  After all market and non-market resources are exhausted, TSOs trigger available operational mitigation measures to avoid a controlled shedding of demand. The main mitigation measure is voltage reduction. It consists in a light drop in voltage for a few hours and results in reduced consumption while keeping all consumers supplied. As a last resort, TSOs might curtail load locally in a preventive way to secure the system. Such operational mitigation measures are not assessed in an adequacy study.

• What are Loss of Load Expectation and Expected Energy Not Served?

  Each of the scenario and sensitivity undergoes a probabilistic assessment to identify adequacy risks, expressed in Loss of Load Expectation/Probability and Expected Energy Not Served.
  
  The Loss of load expectation (LOLE) is an estimate of how many hours supply would not meet demand and can be checked against national reliability standards to confirm whether the adequacy situation is acceptable. It is important to understand that any LOLE value is essentially a risk assessment and an economic trade-off to be evaluated by policy makers and regulators at national level. A non-zero LOLE value is by no means an actual prediction of outage, because exceptional measures can always be taken.
  
  Loss of load probability (weekly LOLP) represents a probability that lack of supply in a respective scenario could be expected for at least 1 hour and for any amount (even 1 MW). Weekly LOLP under normal market conditions represents the probability that system operators would need to look for non-market resources.
  
  Expected energy not served (EENS) means the expected amount of energy not being served to consumers during the period considered, due to system capacity shortages or unexpected outages of assets.

• How are ENTSO-E neighbouring countries considered in the Seasonal Outlook?

  The interconnected system is a key resource for wider system adequacy. ENTSO-E’s Seasonal Outlook gives results for all ENTSO-E member systems. Data inputs and assumptions from neighbouring interconnected countries are also integrated into the modelling. As in every Outlook, data is collected for Turkey and included in the assessment as a market zone. The system of Great Britain is strongly interconnected in the North Sea region and a dedicated collaboration is set up with National Grid ESO to exchange data. Other neighbouring systems are modelled in a simplified manner by fixed flows or assuming zero flows for the purpose of identifying adequacy risks.