| Floating solar
cope with fluctuating water levels and strong winds. In the 120 MWp segment developed by Ciel & Terre, over 407,000 Hydrelio aiR OPTIM 1400-3 floats were deployed in a three-row configuration. Anchoring in this area required a non-conventional approach: rock bolt anchoring drilled into the hard, uneven reservoir bed, ensuring secure fixation against hydrodynamic and wind forces. The electrical configuration also reflects adaptation to floating deployment. Several sites use floating inverter barges, fibre-reinforced plastic (FRP) platforms capable of supporting over 40 tons of inverter and transformer equipment, thereby reducing cable runs and associated transmission losses. In the 90 MW installation, Sineng Electric EP-3300-HB-UD central inverters were deployed, offering high efficiency (~99%), three-level topology, and a DC/AC ratio up to 1.8. Manufacturing processes for the floats included spin-welding of plastic joints, which improves durability by preventing leakage and accommodating thermal expansion under extreme weather conditions.
Alqueva project, Portugal
The Alqueva Floating Photovoltaic (FPV) project, inaugurated in July 2022 by EDP, is Europe’s largest floating solar installation on a reservoir. Located in southern Portugal, the facility occupies approximately 4ha of the Alqueva Dam reservoir and comprises around 12,000 photovoltaic panels with an installed capacity of 5MW. This setup generates about 7.5GWh of electricity annually, meeting about 30% of the area’s energy needs The FPV system is integrated into the existing Alqueva pumped storage hydropower facility, creating a hybrid renewable energy system. Additionally, the system includes a 1MW / 2MWh lithium-ion battery storage solution to manage energy dispatch and ensure grid stability
Structurally, the floating platform is supported by approximately 25,000 floatation elements made from a cork-composite material developed in collaboration with Corticeira Amorim and Isigenere. This innovative material offers enhanced UV and chemical resistance
and a reduced carbon footprint compared to traditional materials. The anchoring system employs elastic mooring components designed to accommodate the dynamic water levels and wave action within the reservoir. This approach minimizes mechanical stress on the structure and ensures long-term stability. The system’s design considers local hydrodynamic conditions to mitigate potential impacts on aquatic ecosystems.
Sirindhorn Dam Floating Solar Farm, Thailand
The Sirindhorn Dam Floating Solar Farm, located in Ubon Ratchathani Province, Thailand, is a hybrid renewable energy project that integrates floating FPV technology with an existing hydropower facility. Inaugurated in November 2021, the project features a 45MW floating solar array installed on the Sirindhorn Reservoir, which spans approximately 288 km. This hybrid system is managed through an advanced Energy Management System (EMS), developed in collaboration with Siemens, which coordinates the dispatch of both energy sources to the grid, enhancing overall system stability and efficiency. The floating solar installation comprises
approximately 144,000 solar panels, covering less than 1% of the reservoir’s surface area. This strategic deployment minimizes land use while maximizing energy production. The system is designed to reduce water evaporation by approximately 460,000 cubic meters annually, contributing to water conservation and improved reservoir management. The project has been recognized for its innovative approach to renewable energy generation and its potential for scalability. It serves as a model for integrating floating solar technology with existing hydropower infrastructure, demonstrating a viable pathway for enhancing renewable energy capacity without the need for additional land acquisition. The success of the projecy has led to plans for similar projects at other EGAT-operated reservoirs, aiming to significantly increase Thailand’s renewable energy capacity.
AlpinSolar project at Muttsee Dam, Switzerland
The Muttsee Dam, located at 2,500m above sea level in the Glarus Alps of Switzerland, is home to the AlpinSolar project – the country’s largest alpine solar installation. This pioneering photovoltaic (PV) system has been fully operational since August 2022. AlpinSolar comprises approximately 5,000 PV modules installed on the dam wall, covering about 10,000m2
. The system has a capacity of 2.2MW
and generates around 3.3GWh of electricity annually, sufficient to power approximately 700 homes. Notably, the project’s location above the fog line and its optimal south-facing orientation allow it to produce up to three times more electricity during winter months compared to similar installations in Switzerland’s Central Plateau. This increased efficiency is attributed to the albedo effect, where sunlight reflected from the snow enhances solar panel output, and the cooler temperatures at high altitudes, which improve PV module performance . The AlpinSolar project is a collaborative effort between Axpo, IWB, and Denner. Denner, a major Swiss discount retailer, has committed to purchasing the electricity generated for a 20- year term, supporting its sustainability goals by sourcing 100% renewable energy. In addition to its energy production capabilities, AlpinSolar plays a crucial role in supporting the stability of Switzerland’s electrical grid. From August 2025, the installation began providing balancing energy to the national grid operator, Swissgrid, as part of the PV4Balancing pilot project. This initiative aims to address fluctuations in electricity supply and demand, particularly during periods of high renewable generation or low consumption. The AlpinSolar project also serves as a valuable research platform. Collaborations with institutions such as the Swiss Federal Institute of Technology Lausanne (EPFL) and the Snow and Avalanche Research Institute (SLF) are underway to study the performance of PV systems in alpine environments. Research focuses on factors like panel tilt angles, snow and wind loads, and the impact of high-altitude conditions on solar energy production.
AlpinSolar project at Muttsee Dam, Switzerland
Sirindhorn Dam Floating Solar Farm, Thailand
www.waterpowermagazine.com | October 2025 | 39
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