Strong solar growth helped Europe's power system absorb an even weaker hydropower summer in 2026 than it faced during the drought of 2022, according to an analysis for PV Magazine.
That surge in solar not only made up for the hydro losses, but also changed how reservoirs and pumped storage facilities were used through the day.
Here's what to know
In reviewing the 10 European systems with complete hydro and solar records, the study found hydro generation totaled 31.65 terawatt-hours from June 1 to Aug. 15 in 2026.
That made it the lowest summer reading in the seven-year dataset. Over the same period in 2022, those systems produced 33.69 TWh, putting 2026 about 6% lower.
Solar followed the opposite path over that span, increasing from 45.27 TWh in 2022 to 84.44 TWh in 2026.
Taken together, hydro and solar generation climbed from 78.96 TWh to 116.09 TWh, a gain of 47%.
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The location of the stress changed, too. In 2022, Iberia was the main weak spot, but by week 31 of 2026 the pressure had shifted toward France, the Alps, and the Danube region.
By then, reservoir storage in France had fallen below the historical lower bound for that time of year.
More background
As solar output peaked around midday, reservoir hydro backed off during those hours and shifted more of its generation toward the evening demand period.
Pumped storage moved even more sharply. In Austria, Germany, Spain, and Portugal, the main charging window was before dawn in 2020, but by 2026 it had shifted to the early afternoon, around 1:00 p.m. or 2:00 p.m.
Over six summers, the correlation between hourly solar output and hourly pumping rose from near zero to 0.86.
Negative midday prices also became far more common. In 2026, Germany and Spain recorded them in about 29% and 28% of those hours, respectively, after almost none in 2020.
Even so, solar does not fix the whole problem. It can help manage the grid's daily pattern, but it cannot restore reservoir levels that were already depleted by late summer.
What's being done?
One obvious response is to keep expanding solar while using storage in a more targeted way.
In four systems, pumped-storage charging increased from 3.99 TWh in 2020 to 7.71 TWh in 2026. Midday charging was up 5.6-fold, while overnight charging fell 88%.
That creates a way to absorb surplus solar at midday that might otherwise flood the grid and shift it into the evening, when demand is still elevated and solar output is fading.
It also allows hydropower operators to hold onto scarce water for the hours when that generation has the greatest value.
A second priority is improving interconnections between countries.
Some of the biggest solar gains were concentrated in places like Spain and Germany, while the most intense hydro strain emerged in other regions.
Stronger cross-border transmission would help route low-cost clean electricity to the areas under the most pressure.
Europe is getting better at handling bright midday periods with solar and storage, but weak reservoir conditions going into autumn still mean the hours after sunset will need careful management.
According to PV Magazine, Safa Sen, market engagement lead for CWE at WSP, said, "solar covered the summer energy gap nearly three times over and rebuilt the middle of the day around itself, but it refilled nothing."
Where can I learn more?
Extreme weather can suddenly swell solar supply, while land costs and panel performance still shape how much of that electricity actually reaches the grid.
• Across northwest Europe, the heat dome flooded the grid with solar and pushed prices below zero.
• In Rajasthan, India, land sale costs are rising as clean energy developers compete with farmland.
• On solar farms, rain and pollen reshape output as soiling patterns defy simple assumptions.
Read side by side, they show why solar's big growth numbers still hinge on weather, siting, and day-to-day operating conditions. Those details matter when grids are counting on solar to help offset weak hydropower.
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