The integration of floating photovoltaics (FPV) with hydropower plants is being viewed as an increasingly promising opportunity to enhance energy security across Central and South America, a region where power intermittency and water scarcity could become more problematic for future energy grids.
One area of research has focused on the reservoirs of the Andean region, with five of Argentina’s hydroelectric power plants on the Limay River considered as a case study. These are the:
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- Alicurá (1000MW and capacity factor of 25%).
- Piedra del Águila (1400MW and CF of 45%)
- Pichi Picún Leufú (250MW and CF of 48%)
- El Chocón (1200MW and CF of 29%)
- Arroyito (120MW and CF of 68%)
Collectively generating 12,830GWh annually, these projects have an installed capacity of 3970MW, yielding an overall capacity factor of 37% (equivalent to less than 9 hours of operation per day).
As Dr Luis Juanico and Martin Ducos explain, in practice, “their effective generation capacity is significantly constrained by the availability of water resources, which are highly variable and generally scarce – a characteristic of all mountain rivers”.
Although designed to operate continuously, the average annual capacity factors of these plants reportedly range from 25% to 50% and typically operate to meet peak demand for 6 to 12 hours per day.
“This reflects a significant idle capacity – ranging from 50% to 75%, or 12 to 18 hours daily – in both the power transformation system and the National Interconnected System transmission line,” Juanico and Ducos add.
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By GlobalDataFurthermore, generation is influenced by seasonal and climatic variations such as a recent 35% reduction in generation at Piedra del Águila – driven by a sharp 55% decrease in the flow of the Collón Curá River, a tributary of the Limay.
Juanico and Ducos put forward two proposals in their research. The first doubles installed capacity by adding PV power equivalent to hydroelectric capacity, increasing energy production to 23,707GWh with an investment of US$1.925 billion. The second proposal aims for a higher capacity factor by doubling the PV capacity and adding a four-hour battery storage system. This results in a 92% capacity factor, increasing energy production to 31,899GWh, and requiring an investment of US$4.431 billion.
Although this is a significant increase in cost, the authors add that in comparison installing two nuclear reactors (1800MW each) to generate a similar amount of energy would require an investment and construction timeframe eleven times greater.
- Efficient Cooling Source. The reservoirs offer an abundant supply of crystal-clear, low-mineral water with an annual average temperature of 11°C, significantly cooler than the 21°C average of the Paraná River near Buenos Aires.
- Secure and Isolated Locations. The remoteness of the hydroelectric sites, combined with existing security measures, ensures high levels of protection.
- Clean Air Environment. The absence of soot and pollution guarantees ideal operating conditions for sensitive AI equipment.
According to the authors, both proposals have clear benefits of abundant solar resources – the Andean Patagonia region boasts a high solar resource potential, especially during the summer months when water availability for hydroelectric generation is low; plus low-cost land – the land adjacent to the reservoirs is available at minimal expense due to its remote
desert location.
The authors also believe this synergy could help mitigate Argentina’s frequent summer electricity shortages. In addition, the high modularity and simplicity of solar PV farms allow for rapid deployment and potential operation in under a year because complex infrastructure, such as power stations and high-voltage lines, is already in place.
The proposal could also be replicated in other Andean basins in Argentina, such as the reservoirs in the provinces of Mendoza (Los Reyunos, El Tigre, Agua del Toro, Nihuil I, II, III, and Potrerillos), San Juan (Ullum, Caracoles, Punta Negra, and La Olla), Salta (Cabra Corral), among others. Furthermore, Juanico and Ducos say it could also encompass other Latin American countries, many of which have hydroelectric plants at the foothills of the Andes with significant
solar resources.
Ecuadorian experience
A similar study has been looking at the potential for co-locating FPVs with existing hydropower plants in Ecuador.
As a country that is heavily reliant on hydropower, and with approximately 80% of its electricity generated by hydroelectricity in 2023, Ecuador is facing energy challenges, particularly when the availability of hydro plants is reduced during the dry seasons. And although planned blackouts have been implemented in various provinces to conserve water supplies in reservoirs since October 2023, this hasn’t prevented unforeseen blackouts. A nationwide outage on 19 June 2024 lasted over three hours. Caused by a failure in the Milagro–Zhoray transmission line, it was compounded by a storm that affected two of Ecuador’s largest hydropower plants – Coca Codo Sinclair and Agoyán – during which sediment washed into the facilities, forcing the turbines to shut down.
As Rodriguez-Gallegos et al state in the journal Solar: “Ecuador’s heavy reliance on hydropower for electricity generation, combined with recent blackouts caused by prolonged dry seasons, underscores the importance of diversifying energy sources. The integration of FPVs with HPPs offers a promising opportunity to enhance energy security by reducing dependency on a single energy source.”
Their findings reveal that out of 70 HPPs in Ecuador, 11 present favourable conditions for large-scale FPV deployment. Among these were the 40MW Cumbayá project which exhibited the most suitable conditions, supporting a maximum FPV capacity of 17MWp. Marcel Laniado de Wind HPP (213 MW) and Mazar HPP (170 MW) were also identified as optimal candidates, each with potential FPV capacities equal to their installed hydropower capacities.
Furthermore, the authors add their results show that FPV systems can not only contribute additional electricity to the grid but also improve HPP performance by reducing water evaporation from reservoirs and maintaining generation capacity during dry seasons, when solar irradiation is
typically higher.
And although their study primarily aims to provide scientific evidence on the potential of FPV-HPP co-location, the authors hope it can also ‘serve as a springboard for future research’, helping to guide Ecuadorian government authorities and investors in adopting FPV technology to strengthen the country’s energy infrastructure.
Benefits of floating photovoltaics
Rodriguez-Gallegos et al give an insight into the benefits of floating photovoltaics when installed at existing hydropower plants.
Infrastructure efficiency
Since HPPs are already fully connected to the electrical grid, the same infrastructure can be used by FPV systems to feed electricity into transmission lines. This reduces FPV installation costs and optimises the use of existing grid capacity by increasing the total energy output. Additionally, other shared infrastructure, such as access roads, can be utilised for both HPP and FPV systems, simplifying installation and maintenance.
Water conservation
FPV systems partially block sunlight from reaching the water surface, reducing evaporation, helping to retain more water in reservoirs which can then be used to generate electricity during times of need.
Seasonal synergy
HPPs often face challenges during prolonged dry seasons due to reduced water availability in their reservoirs. FPV systems can help offset this by generating more electricity during dry periods, which are typically associated with high solar irradiance. Conversely, during the rainy season, while FPV energy production may decline, HPPs can generate ample electricity due to increased water availability. This seasonal complementarity enhances overall energy reliability.
Increased capacity
Expanding the energy production of HPPs often requires constructing additional dams, which can raise environmental concerns. While FPV systems also have environmental impacts that must be assessed, they may offer a more environmentally friendly alternative for boosting total energy production by leveraging existing water surfaces without the need for new infrastructure.
Environmental benefits
By shading parts of the water, FPV systems can reduce or prevent algae blooms, which can improve water quality and the overall ecological conditions of the reservoir.
