Lisbon, Aug. 10, 2026 (Lusa) - Portugal's electricity grid magaging company, REN – Redes Energéticas Nacionais – estimates that Wednesday's solar eclipse will reduce solar power generation by 45%.
In a statement, REN said that the phenomenon «will cause an estimated loss of solar generation of 450 MW [megawatts], which will represent around 7% of consumption and 45% of the National Electricity System's projected solar generation for this time slot (average figures)».
REN also stated that it has been working, in collaboration with other European electricity transmission system operators, to prepare the National Electricity System (SEN) for the effects of the solar eclipse due to take place in the late afternoon of 12 August (Wednesday).
According to REN, the estimated figures relate to centralised solar generation measured by the organisation itself and do not take into account other solar generation associated with certain self-consumption generation units.
REN is also assessing this effect, which will be duly incorporated into the consumption forecasts for that day to «reduce and mitigate, in real time, any unexpected effects».
To mitigate the impacts of the loss of generation, REN explained that it will be necessary to mobilise additional reserves generated by hydro and/or thermal power.
Despite these impacts, the effects of this eclipse are mitigated by the fact that it occurs in the late afternoon, when solar generation is already declining.
In July, solar generation accounted for 19% of consumption in Portugal, whilst hydro accounted for 16%, wind 13% and biomass 5%.
This Wednesday, for the first time since 1912, Portugal will be able to witness a solar eclipse, but only in a small area of the Montesinho Natural Park, in Bragança, will the eclipse be total.
In the rest of the country, the eclipse will be partial, with the percentage of the Sun obscured varying between 92% and 99% on the mainland and between 74% and 77% in the Azores and Madeira.
What happens is that the Moon will come between the Earth and the Sun, obscuring it as seen from the Earth.
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