On August 11, solar photovoltaics produced almost a third of all the electricity generated in Spain (32.9%). So far this month it is the main source of generation in the country and around 31% of the total comes from it, according to provisional data from Red Eléctrica. However, there is a paradox: this increase in solar production does not necessarily lead to a reduction in the use of thermal power plants - combined gas and nuclear cycle - which continue to produce at a considerable rate and provide stability to the system. What's more, gas is having even more weight in the summer of 2026 than in 2025 marked by the blackout.
In this context, the second life of the Almaraz nuclear power plant is framed, whose reactors were to have closed in 2027 and 2028, but will finally maintain activity until 2030. The Executive, in fact, has justified the extension mainly by the savings it will mean on the bill in a geopolitical context that has skyrocketed the price of gas and electricity. So far in August, the average price per megawatt hour is 126 euros, 84% more than a year ago. Although Spain has had more than 50% generation from renewable sources for two years, it still needs to resort to this fuel and nuclear power when there is no wind, sun or water to feed the energy system.
In 2023, this milestone was achieved for the first time, with around 50.9% of total generation coming from hydraulic, wind, solar photovoltaic, solar thermal and the combined production of other marginal 'green' sources, according to data from Red Eléctrica. In 2024 it was already possible to greatly exceed this percentage (53.52%) by only adding the contribution of hydraulic, wind and photovoltaic. And in 2025, although the figure fell slightly - there was somewhat less prominence for wind turbines and, above all, an energy zero on April 28 - they also reached 52.41%. So far this year they add up to 55.2% and photovoltaics is, today, the first source of the mix (22.3% of the total), although the percentage will decrease in the coming months.
Meanwhile, just the gas combined cycles and the seven nuclear power plants have generated between 38.4% in 2023 and 33.58% in 2024. In 2026 they are currently at 34.47% and in 2022 they reached 45.15%. That is, in the best of cases - from the point of view of ease of disconnecting from these sources - they provide a third of all the electricity produced in the country.
The Executive's green commitment, included in the National Integrated Energy and Climate Plan (PNIEC), involves abandoning nuclear in the medium term - although the activity of Almaraz has been extended, the final closure date remains in 2035 - and does not contemplate introducing more combined cycle plants. If anything, in the long term the option arises of replacing natural gas with hydrogen. But the system needs stability, redundancy, robustness and inertia that, for the moment, these sources and hydraulics provide, whose contribution traditionally plummets in the summer period.
All in all, photovoltaic solar is the source that has grown the fastest both in installed power and - consequently - in generation. Thus, since 2019 each year it has been increasing its contribution compared to the same month of the previous year and has managed to go from 4.5% of total electricity in June seven years ago (then it was the sixth source) to leading the mix with 29.4% two months ago, a percentage very similar to that achieved in July (28.4%) and August (the aforementioned 31% in the middle of the month, which could still vary). But summer is also when the challenges facing the Spanish energy system are most evident: photovoltaics are booming, but wind power is plummeting and hydropower is also falling. And at night, without solar input, there is more electricity demand than in other months due to the additional consumption required for cooling.
In the coming years the idea, also included in the PNIEC, is to complement this with storage. Either with batteries, with short-term storage, or with turbine hydraulics: two or more connected dams in which water can rise to the highest one in times of renewable surplus and be released later to produce.
In any case, the problem is not only that there are hardly any storage solutions that allow generating electricity when there is no sun or wind, but also having safeguards and redundancy in an electrical mix that has been in the spotlight since the historic blackout of 2025. Last year it relied somewhat more on nuclear - it accounted for 17.7% of generation in June, 20% in July and 21.6% in August - than on gas - 19.6%, 16.7% and 17.8% -, while this year it has been the other way around: 18.4%, 18.3% and 12.7% for nuclear power in these three months compared to 15.6%, 20.2% and 22.7%, respectively.
DEMAND
To this we must add a third variable that also complicates calculations for the future and which, again, is another of the objectives of the Government's energy roadmap: electrification. The arrival of more renewables and systems to store their production will not occur, at least in theory, based on flat demand, but should increase at the same time as consumption. There should be more and more processes that replace fossil fuels with electricity. The most obvious example is the electric vehicle, which will also charge its batteries very frequently at night, without active photovoltaics. However, there is more, from building boilers - increasingly and not because of efficiency or price, but because of European regulations - to industrial ovens.
