“Ciel & Terre validates new floating PV technologies through a dedicated R&D laboratory and rigorous multi-stage testing protocols designed to replicate real-world extreme conditions before any commercial deployment. Our Bangalore R&D lab conducts endurance tests on all system components, including various types of floats, ear and CP connections, and panel mounting interfaces for fixation systems.”
Ciel & Terre pioneered the patented Hydrelio® floating PV technology over a decade ago. What specific technical challenges were encountered in early platform development (e.g., buoyancy stability, material durability), and how have your designs evolved since then?
CIEL ET TERRE established itself as a global leader in floating PV, known for delivering reliable, bankable, and flexible “all-in-one” solution adapt effectively to diverse site conditions. After starting the floating business in 2006, the company introduced its first patented floating system,
The Hydrelio® product line consists of products tailored and designed to meet the specific needs of regions and markets. Our initial design is the Classic Hydrelio model.
• Classic design: with Standard tilt 12°, and easy operations and maintenance are its major features.
• Equatorial design: features a fixed 5° tilt, optimised for equatorial adaptation. It provides straightforward anchoring control and a costeffective transportation solution, specifically optimised for a 4-in-a-row configuration.
• Air design: 11° float with a racking system, extra ventilation, and a cost-effective transport solution as well.
• Air Optim: supports high-capacity modules up to 670 Wp, reflecting the company’s continuous innovation and commitment to advancing floating solar technology.
• FUSIO: a patented triangular float structure with Quincunx PV arrangements, enhances cooling and enables approximately 2–3% higher power generation beyond existing floating structures; redefines O&M with a catamaran boat—an innovative, first-of-its-kind solution—that can access every panel, simplifies transportation, and offers superior strength and stability, supporting modules up to 800 Wp (M10, G12).
This entire model was tested under extreme wind conditions at ONERA, French Aerospace, for wind tunnel testing and computational fluid dynamics, with bending fatigue tested at IFP EB.
UV corrosion test has been conducted for over 20 years of lifetime, covering IFP EN, PEP, and VALUTEC, and ensuring drinking water compliance with BS standards. Additional testing includes HDPE and colourant control, DQP, thickness control, cooling jig specifications, dimension control, leak testing, and more, which have been integrated into our design and innovation space.
CTI collaborates with many leading experts for wind resistance, Wave and current resistance, mechanical resistance, floatability, UV resistance, drinking water compliance, and temperature resistance. We collaborated with Principia, a leading offshore player, to implement & integrate wind and wave design with cost-effective solutions.
Ciel & Terre’s early Hydrelio® development faced significant engineering challenges, especially in achieving reliable buoyancy and stability on water bodies with large water level variations. The HDPE floats can withstand long-term UV exposure, continuous water contact, and mechanical stresses, while providing safe, non-slip access for maintenance. Over time, the system evolved into a modular structure with main and secondary floats that improve buoyancy, spacing, and walkway stability, along with stronger anchoring systems capable of resisting winds up to 210 km/h. Later improvements, particularly Hydrelio aiR Optim, further enhanced structural strength, ease of maintenance, and long-term durability.
Floating solar projects are generally built for a 25-year lifespan, but they operate in highly dynamic environments where water level changes, undercurrents, and wave forces can greatly impact platform stability and anchoring performance.
This makes a thorough site assessment essential, including topographic surveys, bathymetric studies, and hydrological analysis, to ensure each installation is engineered for its specific conditions rather than replicated from another site.
Factors such as reservoir draining cycles, extreme weather events, wind and wave loads, tides in offshore locations, and saline or brackish water exposure all influence structural design, material selection, and system cost.
Floating solar introduces unique engineering demands for anchoring, mooring, and structural integrity across different water bodies. Can you discuss the major design considerations for these systems, and how innovations like rock bolt anchoring improve reliability in challenging environments?
Floating solar systems must be engineered to withstand wind, waves, currents, and water level fluctuations, making anchoring and mooring crucial for long-term stability. Effective designs require accurate environmental data and systems that evenly distribute forces across floats and anchors to prevent overstressing components. Specialised anchoring methods enhance reliability, including site-adapted technologies such as screw, plate, and dead weight anchors. We introduced ‘Rock bolt anchoring’ to combat the hard rock surface.
The CTI R&D team developed and customised this technology through a rigorous testing process over several years, with successful collaboration among Germany, France, and India. The hard surface prevents traditional helical anchoring from working. Displacement occurs if dead weight is dropped because the contour is uneven. Therefore, a special drilling system called the rock bolt system, developed by India, France, and Germany, is used to drill the weathered surface. The first-ever such technology was implemented in our RUMSL 120MWp project.
As floating solar systems scale globally, what are the current technical innovations Ciel & Terre is prioritizing—such as higherefficiency modules, advanced anchoring solutions, or smart monitoring—and how do these innovations improve performance and reduce operational costs?
Ciel & Terre’s current innovations focus on nextgeneration floating structures, advanced anchoring, and improved O&M systems, all aimed at boosting performance and lowering lifecycle costs. Our new floating solar technology, Fusio®, uses a stable honeycomb structure and improved airflow to increase energy yield by up to 2% while supporting larger modules. We also deployed rock-bolt anchoring for hard-rock reservoirs, providing higher stability than traditional anchors and reducing failure risks in harsh sites. Additionally, innovations like FRP inverter barges and catamaran-based maintenance systems enhance durability, cut transmission losses, and streamline O&M, lowering overall operational costs.
The FRP inverter barge is made from reinforced fibreglass polymer, a unique design that can endure harsh site conditions and is approved for deployment on rivers and lakes. Our floating barge can carry over 60 tons, making it suitable for heavy transformers and inverters. The FRP barge provides a 50% higher strength-to-weight ratio than steel. It is 30% lighter, reducing costs.
FPV maintenance is transformed through its unique catamaran-based approach, where a specialized boat glides directly over the floating solar structure, offering easy, quick, and safe access to every PV panel, inverter, and cabling. The system removes the need for operators to walk on the array or manually carry heavy electrical devices across the FPV plant. Additional intelligent features, such as integrated PV cleaning systems, ensure smooth, efficient, and user-friendly maintenance operations.
Large-scale floating solar deployments must adapt to varying climatic and hydrological conditions. What are the most important environmental or site-specific factors you consider during system design, and what adaptation strategies have proven most effective?
Floating solar system design must consider key site factors, including water depth, water-level fluctuations, soil composition, wind exposure, currents, and bathymetry, all of which directly affect anchoring layout and mooring loads.
Environmental forces such as wind, waves, and potential flooding must be modelled early to ensure platform stability and prevent drift or structural failure in large arrays.
Effective adaptation strategies include selecting site-specific anchoring types, such as screw anchors for cohesive soils, plate anchors for soft ground, dead-weight anchors for penetration-impossible conditions, and pillar anchoring for significant water-level variations.
These tailored anchoring and mooring solutions work together to maintain structural integrity, distribute environmental forces evenly, and ensure long-term reliability across diverse climates and hydrological conditions.
We design our anchoring and mooring systems according to Bureau Veritas NR 493, a strong engineering standard comparable to DNVGL guidelines, ensuring reliability and long-term structural integrity. Our quasi-static design approach uses a BV safety factor of 1.67 for intact conditions, meaning all mooring lines are assumed to be fully functional without damage or removal, thus maintaining conservative margins. Advanced numerical modelling using Orcaflex is performed to analyse mooring line behaviour, especially complex interactions like crisscross configurations and load redistribution under environmental forces. Additionally, we have developed a proprietary inhouse anchoring and mooring engineering tool that enables precise, site-specific analysis during the quasi-static and positioning stages, including asbuilt validation. This integrated approach guarantees optimised layouts, accurate load predictions, and customised designs aligned with actual field conditions rather than generic assumptions.
From an R&D and testing perspective, how does Ciel & Terre validate new floating PV technologies (e.g., stress testing for UV exposure, thermal expansion, mechanical loads) before they are implemented at commercial scale?
Ciel & Terre validates new floating PV technologies through a dedicated R&D laboratory and rigorous multi-stage testing protocols designed to replicate real-world extreme conditions before any commercial deployment. Our Bangalore R&D lab conducts endurance tests on all system components, including various types of floats, ear and CP connections, and panel mounting interfaces for fixation systems. Additionally, we simulate UV exposure, thermal expansion, hydrodynamic loads, and millions of mechanical fatigue cycles using a real-time wave breaker bench.
We use custom test benches to simulate water movement fatigue, abrasion on float interfaces, and mechanical loads on PV fixation systems, adjusting designs when tests show stress concentration or wear patterns. This validation infrastructure allows Ciel & Terre to ensure reliability, refine new solutions before rollout, and continually improve technologies based on both lab results and feedback from existing global installations.
Sustainability and ecosystem compatibility are core to your projects. How are ecological impact assessments integrated into engineering and deployment, and what technical measures ensure that floating solar farms are environmentally responsible?
Ciel & Terre integrates ecological considerations directly into site assessment and engineering design, beginning with analysis of water depth, fluctuation levels, soil type, and environmental forces to minimise disturbance to ecosystems.
Our floats are environmentally friendly and compatible with drinking water reservoirs, as evidenced by our plant at Queen Elizabeth Dam, UK, which is a drinking water dam. They also comply with ROHS (British standard 6920). Third-party environmental studies have been conducted in the US to determine whether our plan affects the survival of endangered species and migratory birds.
Our system is designed with sufficient gaps to allow sunlight to penetrate and facilitate air exchange, ensuring it does not harm flora and fauna and helps minimise algae growth when using Hydrelio systems.
Our research shows that shading and cooling in our floating system have increased fish breeding by up to 30%. Environment-specific anchoring helps avoid sediment disruption. Additionally, our 100% recycled product is made from a chemical-resistant material and contains 100% virgin material. We pay close attention to detail, such as using polyester mooring lines instead of plastic. Our designs are environmentally friendly and are not installed in protected natural tourism or fishing areas.
