When tugboats eased 12,000 solar panels into position on Portugal’s Alqueva reservoir in 2022 C.E., they were installing more than a power source. They were anchoring Europe’s largest floating solar park on a hydro dam — and giving the country a working model for how sun and water can share the same surface to generate clean electricity around the clock.
At a glance
- Floating solar park: The Alqueva installation covers the area of four football pitches and carries an installed capacity of 5 megawatts, enough to power 1,500 families.
- Renewable energy cost: EDP project director Miguel Patena said electricity from the floating park would cost a third of what a gas-fired plant produces at current fuel prices.
- Battery storage: Lithium batteries paired with the panels can store 2 gigawatt-hours of electricity, smoothing out supply on cloudy days and at night.
Why a reservoir makes sense
Floating solar panels have been installed on lakes, industrial ponds, and coastal waters from California to China. But pairing them with an existing hydropower reservoir unlocks a particular efficiency: no new land is needed, no new grid connection has to be built, and the two systems can cover each other’s gaps.
On sunny days, surplus solar power can pump water back up into the reservoir, storing energy in the form of elevation. When clouds arrive or demand spikes at night, the dam releases that water through its turbines. The result is a hybrid plant that produces electricity from both sunlight and gravity — a simple and elegant loop.
Alqueva is Western Europe’s largest artificial lake, so the scale of the potential is significant. The panels are expected to produce 7.5 gigawatt-hours of electricity per year, supplying the equivalent of a third of the combined energy needs of the nearby towns of Moura and Portel.
EDP’s longer arc
The project did not arrive without precedent. In 2017 C.E., EDP — Portugal’s main utility company — installed an 840-panel pilot floating solar array on the Alto Rabagão dam, the first test in Europe of how hydro and solar power could complement each other at scale. Alqueva is the mature result of that experiment.
By the time the Alqueva park launched, renewables and hydropower already accounted for 78 per cent of EDP’s 25.6 gigawatts of installed capacity. The company’s stated goal is to reach 100 per cent green generation by 2030 C.E. EDP executive board member Ana Paula Marques said the war in Ukraine — which pushed gas prices sharply higher across Europe — reinforced the urgency of that transition.
Portugal itself uses almost no Russian hydrocarbons directly, but its gas-fired power plants still felt the squeeze of rising global fuel prices. The floating solar park, with its lower operating cost, offered a practical hedge against that volatility as much as a climate statement.
A benchmark, and a next step
“This project is the biggest floating solar park in a hydro dam in Europe, it is a very good benchmark,” Patena said at the time of the installation.
EDP wasted little time building on it. In April 2022 C.E., the company secured rights to develop a second floating solar farm at Alqueva — this one with 70 megawatts of installed capacity, fourteen times larger than the first. If completed, it would extend Portugal’s lead in this particular form of solar power generation by a wide margin.
Portugal’s geographic advantages help explain the ambition. Long hours of sunshine and steady Atlantic winds have made the country a natural host for renewables investment. What Alqueva adds is a proof of concept: that floating solar is not just viable in theory but cost-competitive, grid-ready, and expandable in practice.
The picture is not complete
Even so, floating solar on reservoirs raises open questions about ecological impact — particularly effects on water temperature, oxygen levels, and aquatic life beneath the panels. Research into these trade-offs is ongoing, and scientists note that long-term monitoring will be essential before the model can be scaled confidently across diverse ecosystems. The 5 MW first phase also remains a modest contribution to Portugal’s overall grid, and the path from pilot to the 70 MW expansion depends on permitting, financing, and engineering challenges that are not yet fully resolved.
Still, the Alqueva project has shown something useful: floating solar panels on hydropower reservoirs can be deployed quickly, at competitive cost, using infrastructure that already exists. In a continent accelerating away from fossil fuels, that combination is hard to overlook.
Read more
For more on this story, see: Euronews Green — Portugal’s floating solar park
For more from Good News for Humankind, see:
- Renewables now make up at least 49% of global power capacity
- Alzheimer’s risk cut in half by drug in landmark prevention trial
- The Good News for Humankind archive on renewable energy
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