Floating solar power plants are designed to be used in areas where stability is not a guarantee. The behaviour of a floating system varies with the water level change, exposure to the wind, currents, and geometry of the site. Anchoring does not however constitute a peripheral consideration- it is a structural cornerstone of the whole floating solar design.
The anchoring systems at Floatex are created as a component of the floating solar solution. Selection of anchoring technology and anchoring technique varies based on the site-specific considerations like water depth, soil nature, hydrology and accessibility. Based on experience in various utility-scale reservoirs and industrial water bodies, Floatex is using various anchoring strategies based on the physical reality of the site.
This article describes the anchoring technologies applied in floating solar projects and explains their application in installations done by Floatex.
Anchoring technologies used in floating solar projects
The floating solar anchoring systems can be broadly divided into a few technology groups. They all have their purpose based on the soil condition, installation limitation and environmental load.
In Floatex projects, the key anchoring technologies are:
- Dead-weight (ballast) anchoring.
- Screw anchoring
- Plate anchoring
- Pile or pillar anchoring
The first step in the selection process is to learn about the site. Anchoring technology is selected to suit the ground conditions instead of trying to impose a general solution on all projects.
Dead-weight anchoring
Dead-weight anchoring is based on mass and friction and not on soil penetration. To withstand the mooring forces, concrete blocks or steel ballast elements are laid on the water body bed.
It has been used in a number of Floatex projects with no ground penetration preferred or where the reservoir conditions demanded a non-intrusive solution. As an example, dead-weight anchoring is adopted in large reservoir-based utility projects like NTPC Kawas as part of the station-keeping strategy.
Dead-weight anchoring is best applicable to:
- Reservoirs with liners or sensitive bed conditions
- Sites where soil properties are variable or uncertain
- Mass installations with anchor accessibility and predictability as key factors.
Although this approach may need more weighty elements, it provides strong and consistent performance.
Screw anchoring
Screw anchors are applied in areas that have good soil conditions that enable transfer of loads through helical penetration. Installed with auger-based equipment, they are normally used in both bank and bottom anchoring.
Screw anchors are common in smaller industrial and captive projects in cohesive soils where there is enough access for installation. Screw anchoring allows:
- Precise positioning of anchor points
- Controlled installation with limited disturbance
- Predictable axial resistance in suitable substrates
This technology is well suited to sites where anchoring locations need to be closely controlled and where installation logistics permit mechanical access.
Plate anchoring
Plate anchoring involves anchors with huge bearing surface that activates soil resistance when tension is exerted. After installation, the plate rotates into its working position and compacts the surrounding soil.
Plate anchors are typically selected for:
- Soft or loose ground conditions
- Sites exposed to strong currents
- Water bodies that experience large variations in the water level.
The technology is highly resistant to axial loads and useful in situations where mooring forces are likely to change considerably over time.
Pile and rock-based anchoring
In sites with firm ground or exposed rock, anchoring solutions must adapt to the substrate rather than rely on weight or embedment alone.
Deployed by us, the Dalmia Cement 4 MW floating solar project in Bihar, is a great example of such an anchoring method. This method enabled direct transfer of anchoring forces into competent material giving high reliability in a limited industrial reservoir.
Pile or rock-based anchoring is particularly relevant for:
- Industrial ponds and process water reservoirs
- Sites that are shallow-depth and of solid bed
- Locations where long-term positional stability is critical
Anchoring methods: Bank, Bottom, and Hybrid Configurations
Bank anchoring
Bank anchoring involves fixing mooring lines to anchor points located on or near the shoreline. This method is commonly used when:
- Shore access is available
- The depth of water is considerable
- Mooring line lengths remain manageable
Bank anchoring can be done with screw anchors, plate anchors, piles or chemical anchors depending on the soil conditions.
Bottom anchoring
In bottom anchoring, the anchor points are set on the bottom of the water body and are mounted with floating equipments.
This method is applied when:
- The floating array is positioned far from the shoreline
- Bank anchoring is unrealistic
- Significant changes in water level have to be accommodated
Depending on site conditions, bottom anchoring arrangements may be either dead-weight, screw, or plate.
Hybrid anchoring
A combination of bank and bottom anchoring is beneficial to some sites. Hybrid arrangements are applied in case of:
- Sections of the array are near shore
- There are other portions that venture into deeper water
- The mooring line lengths must be optimised
Hybrid anchoring gives the system design an opportunity to react directly to the geometry of the site and balance mechanical loads and installation effort.
Anchoring design: Site Data to Engineered Systems
The anchoring systems are designed based on site data and numerical modelling. Key inputs typically include:
- Bathymetry and water depth variation
- Soil and substrate characteristics
- Expected wind and wave loading
- Operational water-level ranges
These parameters define anchor capacity requirements, mooring geometry, and movement envelopes. Design verification is used to verify that the anchoring system is able to offer reliable service during the entire life of the plant.
Why is anchoring central to floating solar performance?
The direct effects of anchoring are:
- Stability of the floating array structure
- Durability of mooring components in the long term.
- Fatigue behaviour during cyclic loading.
- Access and maintenance requirements.
As our diverse projects (NTPC Kawas large utility reservoir, and Dalmia Cement and Hygenco-Jindal industrial plants, to name a few) have shown, anchoring should not be generic, but dependent on site-specific needs.
With the help of site analysis and established anchoring technologies, floating solar power plant can be designed to be reliable in varying environmental conditions.
Conclusion
Anchoring has a decisive influence on the performance of a floating solar power plant in the long run. It is more than a structural requirement and it determines system behaviour, construction efficiency, and long-term reliability.
With the choice of anchoring technologies according to site requirements and an early inclusion in mooring and layout design, Floatex has ensured that floating solar systems remain stable, versatile, and functional to varying loads on the environment.
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