Eclipse reduces solar power production by more than 20%

REN – Redes Energéticas Nacionais, in close collaboration with other European electricity transmission system operators, has been preparing the Portuguese National Electricity System (SEN) for the effects of the partial solar eclipse that will take place tomorrow, 29 March. The phenomenon will occur over mainland Portugal between 9:30 AM and 11:30 AM, causing an estimated generation loss of 560 MW, representing approximately 8.5% of consumption and 23% of the National Electricity System's projected production during this period.

During the eclipse, a loss of 10 MW per minute is expected, followed by a recovery at a rate of 22 MW per minute. This will pose operational challenges in balancing generation and consumption within the SEN and managing imbalance in interconnection with Spain. T

o mitigate the impacts of the generation loss caused by the eclipse, additional reserves will need to be allocated through hydro and/or thermal generation.

These estimated figures only cover centralised solar production and generation recorded/measured by REN, excluding solar production from certain Self-Consumption Production Units, which will also have an impact by increasing consumption. This effect is also being estimated by REN and is duly incorporated into consumption forecasts for the day to minimise and mitigate unexpected impacts in real time.

Preparation for this event has been carried out in close coordination with other European transmission operators, namely through the Short-Term Adequacy (STA) service, which ensures the balance between electricity generation and consumption over a seven-day period.

At the European Synchronous Grid level, a generation loss is expected, followed by a recovery of approximately 21,000 MW.
In recent months, Portugal has maintained a sustainable path in progressively integrating endogenous renewable sources, supported by successive records in renewable energy production.

At the same time, it continues to uphold the primary goals of security of supply and service quality within the SEN, even in challenging and adverse situations such as this.