As the global energy transition accelerates, hydropower’s flexibility and reliability are being leveraged in new ways – including through its integration with solar photovoltaic systems. Around the world, utilities and developers are pioneering hybrid solar-hydro projects that enhance grid stability, optimise water resource management, and increase renewable generation without expanding land use. From high-altitude reservoirs on the Qinghai–Tibet Plateau to the sunlit dams of Portugal and India, these projects demonstrate how coupling solar and hydropower can deliver round-the-clock renewable energy, reduce evaporation losses, and extend the operational efficiency of existing assets.
Kela project, China
The Kela Photovoltaic Power Station is situated in Kela Township, Yajiang County, within the Garze Tibetan Autonomous Prefecture of Sichuan Province, China. The site lies at elevations ranging from 4,000 to 4,600m above sea level. Construction of the first phase began in July 2022 and the station entered commercial operation in June 2023. The project occupies approximately 1,667ha of plateau terrain, where climatic conditions are characterised by low oxygen levels, strong winds, heavy snowfall, and significant temperature fluctuations. These environmental factors necessitated special construction techniques, including cold-resistant materials and equipment designed to operate reliably in high-altitude conditions.
The installed capacity of the photovoltaic station is 1GW, making it one of the largest single-site solar installations in the world. It is the largest hydro-PV station. The plant consists of millions of photovoltaic modules arranged across the plateau, supported by inverters and an extensive collection system. Power from the PV modules is aggregated at 220 kV substations before being stepped up to 500 kV for transmission. The site includes a dedicated 500 kV collector station, which integrates the photovoltaic output with the nearby Lianghekou Hydropower Station. This configuration enables efficient dispatch of generated power into the Sichuan grid, supporting both local demand and long-distance transmission.
Annual power generation from the Kela photovoltaic station is expected to reach approximately 2 billion kilowatt-hours, corresponding to about 1,735 equivalent full-load hours. Output is subject to diurnal and seasonal variability, with peak generation during the summer months when solar irradiation is highest. The high solar resource availability at the site, combined with the complementary regulation provided by the hydropower reservoir, supports stable annual energy production. The integration with Lianghekou Hydropower Station, which has a capacity of around 3 GW and a reservoir storage of 10.8 billion cubic meters, enables real-time compensation for fluctuations in photovoltaic output.
The construction of the station required extensive logistical coordination due to its remote location and high altitude. Engineering solutions included reinforced support structures to withstand wind and snow loads, as well as optimized panel orientation for maximum solar capture under the plateau’s irradiation conditions.
Omkareshwar Floating Solar Park, India
The Omkareshwar Floating Solar Park is located on the reservoir of the Omkareshwar Dam on the Narmada River in Khandwa district, Madhya Pradesh, India. It is planned as a 600MW floating solar complex, one of the largest of its kind globally, and is being developed in phases by a consortium of entities including SJVN Green Energy Limited (SGEL), NHDC, Tata Power Renewable Energy Limited (TPREL), AMP Energy, and Rewa Ultra Mega Solar Limited (RUMSL). The first phase totals 278MW spread across multiple developers.
Within this phase, SGEL commissioned a 90MW floating solar project on 8 August 2024. It is expected to generate 196.5 million units (MUs) in its first year and around 4,629 MUs over a 25-year operating period. Another segment, the 88MW Unit-D project by NHDC, was commissioned on 29 October 2024 with an annual expected generation of 204.6 MUs. Tata Power Renewable Energy Limited added a 126MW floating solar project in late 2024, spanning about 260ha of reservoir area and using 213,460 bifacial glass-to-glass modules. This unit is expected to generate around 204,580MWh annually, offsetting 173,893 tonnes of CO2 while also reducing reservoir water evaporation by an estimated 32.5 million cubic meters per year.
The projects employ several innovative engineering solutions to adapt to the unique challenges of the reservoir environment. For the 126MW installation, bifacial modules have been selected to take advantage of both direct sunlight and reflected light from the water surface, with cooling effects improving operating efficiency. Structural stability is achieved through mooring systems, wave breakers, and ballast anchors, designed to 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 recognised 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.
