Portugal made energy history when its first auction of floating solar rights on dam reservoirs produced a world record: a negative price for future electricity output. One winning bidder agreed not just to sell power cheaply, but to actually pay into the Portuguese electric system for the right to generate it — a signal of just how competitive renewable energy has become.
At a glance
- Floating solar capacity: The auction assigned rights to install panels capable of generating 183 megawatts of electricity across multiple dam reservoirs throughout Portugal.
- Negative energy price: Portuguese utility EDP Renováveis bid -4.13 euros per megawatt hour, meaning it will pay the grid rather than charge it, over a 15-year contract period.
- Consumer savings: Portugal’s environment ministry estimated the auction results will deliver 114 million euros in gains for electricity consumers over the life of the contracts.
Why a negative price matters
Energy auctions typically work like this: developers compete to sell electricity at the lowest possible price, and the grid picks the winner. A negative price flips that logic entirely. EDP Renováveis (EDPR), a unit of Portugal’s main utility EDP, will pay the Portuguese electric system 4.13 euros for every megawatt hour it generates over 15 years.
That sounds counterintuitive — until you understand the hybrid structure behind it. EDPR’s project combines floating solar with wind energy and battery storage at a single grid connection point. The company expects the wind and storage components to be profitable enough to subsidize the solar contract, while cost synergies from sharing infrastructure make the whole package financially viable.
In other words, renewables have become so efficient and so well-integrated that a major energy company is willing to pay for the privilege of producing electricity. That was unthinkable a decade ago.
Floating solar on Western Europe’s largest artificial lake
EDPR will install 70 MW of floating panels on the Alqueva reservoir in southern Portugal — the largest artificial lake in Western Europe. Floating solar has a distinct advantage over land-based installations: panels placed on water stay cooler, which increases their efficiency, and they reduce water evaporation from reservoirs, a meaningful benefit in drought-prone regions like southern Portugal.
Spanish utility Endesa won rights to build a 42 MW floating solar project on the Alto do Rabagão dam in northern Portugal, planning to invest 115 million euros in the project. Renewable firm Finerge secured three separate lots across different dams, adding 38 MW of solar capacity. Together, the projects represent a coordinated push to turn Portugal’s existing hydroelectric infrastructure into multipurpose clean energy hubs.
A pattern of record-breaking solar auctions
This wasn’t Portugal’s first record. The country held on-land solar auctions in 2019 C.E. and 2020 C.E. that both set world records for the lowest future output prices. The 2022 C.E. floating solar auction extended that streak into new territory — both in technology type and in the unprecedented negative price threshold.
For context, wholesale electricity prices on the Iberian market averaged 112 euros per megawatt hour throughout 2021 C.E. By the time of the auction in April 2022 C.E., prices had surged to around 250 euros, partly driven by Russia’s invasion of Ukraine and the resulting spike in natural gas costs. Against that backdrop, locking in floating solar at below-zero prices looks not just impressive but strategically decisive.
Portugal had already been quietly building one of Europe’s most renewable-heavy grids for years. The International Energy Agency has noted Portugal’s consistent progress toward a power system dominated by wind, solar, and hydro. This auction accelerated that trajectory.
The bigger picture for clean energy
Floating solar remains a relatively small slice of global solar capacity, but its potential is significant. The International Renewable Energy Agency has identified floating photovoltaic systems as a growing technology with particular promise in water-scarce regions and countries with limited land for conventional panels. Portugal’s auction results could serve as a model — and a competitive benchmark — for floating solar procurement elsewhere.
The negative pricing achieved here is also a broader signal about the economics of renewable energy. Energy think tank Ember has documented a consistent global trend of solar and wind costs falling faster than most projections anticipated. What Portugal demonstrated is that when renewables are bundled with storage and wind in hybrid systems, the economics can become genuinely radical.
Still, the picture is not without complexity. Floating solar projects require careful environmental assessment to ensure they don’t disrupt aquatic ecosystems or affect water quality. Research published in Nature Water has flagged the need for more long-term ecological monitoring of floating solar installations, particularly in freshwater reservoirs that support biodiversity and local communities.
Portugal’s record-breaking auction shows how far renewable energy economics have traveled. The question now is how quickly the rest of the world can follow.
Read more
For more on this story, see: Reuters
For more from Good News for Humankind, see:
- Renewables now make up at least 49% of global power capacity
- Indigenous land rights and 160 million hectares recognized ahead of COP30
- The Good News for Humankind archive on Portugal
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