Lenders and investors require evidence of the connection between the commercial case and the physical project before financial close. Is the reservoir sufficiently characterised? Can the mooring system sustain the full spectrum of water levels and environmental loads? Will grid export be available on the specified date? Are floating-specific losses accounted for in the energy-yield model? Do construction interfaces have supervisors who can manage them?
Technical due diligence for floating solar projects involves examining these questions separately. It does not eliminate uncertainty, and it does not pass design responsibility to the reviewer. It is intended to see whether the material risks have been explored, considered in the design, costed into the budget, planned for in the programme, documented in contracts, and accounted for in the financing assumptions.
Technical Feasibility Is Not the Same as Bankability
A feasibility study asks whether a project appears technically and commercially viable. A lender's technical due diligence goes further. It checks whether the evidence is ready to support debt assumptions and to define qualifications, closing requirements, or monitoring actions.
IREDA's scope for an Independent Engineer covers independent energy-yield assessment, site assessment, cost review, design and contractor assessment, construction scheduling, approvals, evacuation arrangements, contract review, and O&M budget assessment. It also covers construction monitoring, drawdown certification, performance testing, and completion review. This shows that a lender review is not only about equipment specifications.
A lender's technical adviser may provide a report that classifies findings by materiality, recommends mitigation measures, identifies conditions precedent, and sets out recommendations for continued monitoring. The adviser is not there to certify that failure is impossible. An independent review does not replace the responsibilities of the designer, EPC contractor, suppliers, or project company. This structured approach helps lenders evaluate whether key technical risks have been adequately addressed before financial close.
| Due-diligence area | Evidence reviewed | Main bankability question |
|---|---|---|
| Site and reservoir | Bathymetry, hydrology, operating levels, wind, waves, bed conditions, and access | Does the design basis represent the actual site? |
| Floating structure | Calculations, materials, tests, manufacturing controls, and operating history | Can the platform carry project loads throughout its intended life? |
| Anchoring and mooring | Load analysis, anchor capacity, line selection, fatigue, and installation plan | Will the array remain within permitted movement under normal and extreme conditions? |
| Electrical system | Single-line diagrams, equipment selection, cables, protection, and shore transition | Can electricity be collected safely in a moving water environment? |
| Grid evacuation | Studies, approvals, route, substation capacity, and completion programme | Can the plant export its contracted power on schedule? |
| Energy yield | Resource data, loss model, availability, and uncertainty analysis | Does projected generation support the financial model? |
| Construction | Method statements, logistics, programme, contractors, and contingency | Can the project be delivered at the proposed cost and date? |
| Contracts and warranties | Scope boundaries, guarantees, liabilities, damages, and exclusions | Are material risks assigned clearly and enforceably? |
| O&M | Inspection plan, staffing, access, spares, and replacements | Are lifecycle costs and downtime assumptions credible? |
| Environment and permits | Reservoir rights, approvals, safety conditions, and stakeholder obligations | Can the project be constructed and operated under its permits and agreements? |
The Reservoir Must Be Understood Before the System Is Financed
The due-diligence process starts with site data, not a supplier catalogue.
Site Data Assessment
Bathymetry defines water depth, underwater topography, and possible anchor locations. Hydrological records establish normal operating levels, seasonal drawdown, floods, and rates of water-level change. Structural and mooring loads are affected by wind, fetch, waves, currents, and reservoir operations. Bed investigations affect anchor selection, anchor capacity, tolerances, and vessel needs.
Design Inputs
According to the World Bank guidance for India, bathymetry, water depth, water-level variation, environmental conditions, ground conditions, and marine growth all influence mooring-system design. It also points out that anchor selection should be done on a case-by-case basis, and that a detailed site investigation may be required for proposed anchor locations.
Due-Diligence Checklist
The scope of due diligence should confirm:
- Does the survey cover the entire project area?
- Are operating assumptions confirmed by the reservoir owner?
- Have extreme conditions been chosen on a defensible basis?
If the drawdown range is underestimated in the design, mooring-line lengths may need to increase, the cable route may need to be adjusted, a different anchor type may be needed, or the mooring arrangement may have to be moved. Capital expenditure, programme, and construction equipment are all affected by each of these changes.
Shore Access
Shore access is also a consideration. Do not assume assembly areas, launching zones, crane locations, or routes for future component replacement based on satellite images.
Float-System Bankability Depends on the Complete Design
Understanding the difference between technology bankability and project bankability is essential.
A project could lack connector details, have insufficient freeboard, provide a narrow maintenance access way, or rely on unqualified assumptions about wind and wave loading — despite having test results and operating experience with a float material. A module brand does not guarantee the platform on which it sits.
Technical Review Scope
The technical review should include:
- Design basis
- Load combinations
- Structural calculations
- Buoyancy
- Connection forces
- Maintenance loading
- Impact
- Ultraviolet exposure
- Creep
- Fatigue
- Corrosion
- Thermal movement
- Manufacturing controls
- Material traceability
- Physical testing
- Tolerances
- Inspection requirements
- The procedure for replacing damaged components
Certification to an individual standard is evidence for a defined property or test. It is not an assurance that the entire system is appropriate for all reservoir conditions. The World Bank's 2023 assessment highlights the gap between current component specifications and the mechanical and environmental loads seen in floating applications, which further emphasises the need for project-specific engineering.
Anchoring and Mooring Can Change the Project Economics
Drawing lines around an array is not a validated mooring design.
Technical Assessment Requirements
The lender must understand the environmental loads, analytical method, array movements, line loads, anchor reactions, pretension, fatigue, abrasion, corrosion, creep, and accidental cases. They must also have evidence that the reservoir-bed assumptions are consistent with the chosen anchor and installation technique.
Mooring System Complexity
A floating array may consist of hundreds of mooring lines. Different anchor locations, line composition, bathymetry, and pretension can result in load-sharing differences. The World Bank guidance therefore suggests that these uncertainties should be taken into account in the analysis, and not reduced to idealised geometry.
Installation Risk
Installation risk also applies. Certain anchors have specific bed-composition, special-equipment, or extra pulling-power needs. Some leave a large footprint or can be hard to locate. Insufficient quantities of anchors, or the wrong installation spread, can drive up costs and prolong the project.
A review of inspection access and replacement should be included in due diligence. Even a system designed for long-term operation requires validation of wear, corrosion, tension, or movement criteria. The O&M plan and budget should address how conditions will be monitored if underwater inspection is not possible.
Electrical Design Must Account for Movement and Water Exposure
The same fundamental electrical principles apply, but with the added factor of cables and equipment moving with the floating structure.
Scope of the Review
The review should include:
- The design of the strings
- The location of the transformers
- Flexible sections of cable
- Combiner boxes
- Earthing
- Lightning protection
- Isolation
- Communications
- Supervisory control and data acquisition (SCADA)
- Metering
- Emergency shutdown
Cable Movement and Electrical Risks
Cables in floating arrays can undergo cyclic bending, abrasion, and tension from waves and changing reservoir levels. The World Bank report on India points out that stresses beyond those experienced on land can cause fatigue in cable restraints and terminations in floating systems. It also establishes an uncertainty around earthing, corrosion, and electrical protection that is characteristic of floating solar.
Due diligence should identify the single points of failure and how much generation is exposed to them. It should also consider whether major equipment can be readily reached, isolated, lifted, and replaced under realistic site conditions. A transformer on a floating platform and one on shore present different risks, access needs, and cable-loss profiles, and are not necessarily preferred in every project.
Grid Evacuation Must Be Evidenced, Not Inferred
The presence of a connection application, a nearby substation, or an existing hydropower switchyard does not guarantee the proposed export capacity of the plant.
Scope of the Review
The review should define:
- The permitted export capacity
- Point of connection
- Voltage
- Necessary network upgrades
- Evacuation-line route
- Land rights
- Protection system
- Metering boundary
- Communication requirements
- The responsibility for each construction package
Project Coordination
The project programme needs to coordinate the floating plant with utility-owned works, transformer deliveries, line completion, testing, and energisation. If the array cannot export power because of a delay, financing costs continue while revenue commencement slips.
Lender Due Diligence
The lender-engineer scope of work for IREDA includes a review of the power-sale arrangements and the adequacy of the evacuation. India's transmission planning criteria also mandate system studies and inter-state, intra-state, and dedicated transmission planning.
Regulatory Compliance
The applicable grid framework in India depends on the connection arrangement. The CEA maintains the connectivity regulations from 2007 onward as part of its official archive, and further project-specific rules may be issued by the CERC, the CTUIL, state transmission utilities, and load-dispatch entities. Requirements should be validated at the time of the transaction rather than reproduced from an older one.
The Energy-Yield Forecast Must Withstand Independent Review
The revenue model depends on generation, so one of the most important technical inputs is the energy-yield assessment.
Scope of the Review
The review should include:
- Solar-resource datasets
- Long-term correction
- Interannual variability
- Module characteristics
- Temperature modelling
- Orientation
- Shading
- Mismatch
- Inverter clipping
- Cable and transformer losses
- Auxiliary consumption
- Soiling
- Degradation
- Availability
- Grid outages
- Curtailment
Understanding P50 and P90
P50 is a forecast with a 50 per cent probability of being exceeded; P90 is a more conservative forecast with a 90 per cent probability of being exceeded. These are probability estimates based on an uncertainty model, not output guarantees. P50 and P90 are standard lender-oriented energy-yield outputs in IFC's utility-scale solar guide, which emphasises the importance of data and modelling uncertainty.
Floating PV-Specific Uncertainties
Floating PV introduces additional uncertainty. In 2025, IEA PVPS reviewed the energy-yield tools currently in use and concluded that they are not yet robust enough to capture all floating-specific effects. Areas requiring further evidence include module temperature, wave-induced irradiance effects, soiling, and long-term performance loss.
Construction Cost and Schedule Require Interface Testing
The cost of the project is not always reflected by the EPC quotation.
The lender review should include the owner-supplied package and exclusions — for example reservoir studies, anchors, shore works, access roads, temporary facilities, assembly areas, vessels, cranes, transmission infrastructure, permits, testing, spares, insurance, and environmental measures.
The schedule should cover detailed design, manufacturing, factory inspection, transport, shoreline preparation, float assembly, anchor installation, cable works, and substation completion and commissioning. Weather and monsoon constraints should be identified as explicit assumptions rather than treated as blanket allowances.
| Technical finding | Possible financial consequence | Typical mitigation |
|---|---|---|
| Incomplete bathymetry | Anchor redesign, quantity changes, and installation delay | Complete targeted survey and retain design allowance until verification |
| Unconfirmed anchor capacity | Additional anchors, proof testing, or revised mooring layout | Bed investigation, capacity testing, and independent calculation review |
| Optimistic energy-yield assumptions | Overstated revenue and debt-service capacity | Independent yield model, uncertainty analysis, and sensitivity cases |
| Delayed grid works | Later commercial operation and added financing cost | Firm interface programme, responsibility matrix, and schedule contingency |
| Unclear EPC boundary | Change orders, disputes, and uncovered work | Detailed scope matrix and coordinated technical schedules |
| Restricted shore access | Higher installation and replacement cost | Logistics study, permanent access plan, and lifting strategy |
| Land-based O&M assumptions | Under-budgeted labour, boats, inspections, and downtime | Reservoir-specific task plan, staffing model, and spares strategy |
| Limited technology record | Greater uncertainty over failure and replacement | Testing, warranties, monitoring, contingency, and staged acceptance |
Contracts Must Match the Engineering Interfaces
A fixed-price EPC contract can still include exclusions, liability limits, and gaps at interfaces.
Assignment of Responsibilities
Responsibility must be clearly assigned across:
- Project company
- Floating supplier
- Mooring designer
- Anchor installer
- Electrical contractor
- Transmission contractor
- Reservoir owner
- Reservoir O&M company
Care is needed where one party provides the float, another calculates mooring loads, and a third installs anchors. Clearly defining these responsibilities is an important part of the review.
Lender-Engineer Review Scope
IREDA's lender-engineer scope covers delay and non-performance damages, owner and contractor responsibilities, liability caps, change orders, force majeure, and O&M terms, among other performance obligations.
Contractual Guarantees vs. Performance Expectations
Contractual guarantees should be distinguished from what is expected of performance. A warranty outlines the guarantees and limitations offered by the supplier. A plant performance guarantee covers guaranteed plant performance under agreed test conditions. Neither automatically includes all the losses captured within the financial model.
Completion Testing
Completion tests should be matched to the design and commercial assumptions:
- Installed capacity
- Electrical compliance
- Performance
- Reliability
- Grid acceptance
The reviewer should also determine what would happen if testing were deferred because of grid or reservoir conditions.
O&M Assumptions Must Reflect Working Over Water
The operating budget may still omit significant expenses if it primarily covers module cleaning and inverter servicing.
Floating PV also involves inspection of floats, connectors, walkways, cable supports, mooring lines, anchor movement, corrosion, biofouling, and storm damage. These activities may require long access routes, boats, water-safety equipment, and specialised technicians.
Access is a major O&M limitation identified in the IEA PVPS review: reaching components can be more complex and time-consuming than in a ground-mounted plant, requiring more person-hours and longer outages. Its budgeting guidance covers site conditions, mooring technology, logistics, monitoring, training, spares, and emergency reserves.
Lifting requirements, component lead times, and planned inverter or transformer replacement should be included in the financial model. It should also capture warranty-maintenance requirements, because the value of a warranty is limited if the work needed to maintain it is not included in the O&M scope.
Reservoir Rights and Environmental Duties Can Constrain Operation
Technical review is intertwined with environmental and social due diligence because it involves permissions that affect engineering and operating assumptions.
The project must hold clear rights to occupy the water space, access the shoreline, anchor, and maintain evacuation facilities. Reservoir operations, dam-safety zones, fisheries, navigation, water supply, waste handling, emergency response, and eventual removal may all impose design or working constraints.
A technical layout that works is not enough if it does not meet the drawdown requirements of the reservoir, operator access, or community use. These conditions should be broken down into drawings, procedures, responsibilities, costs, and schedule allowances — not left as general language in the permit.
What Needs to Be Resolved Before Financial Close?
Specific closing conditions depend on the lender, state, project stage, and financing arrangement. The principal site rights, design basis, surveys, energy-yield case, grid pathway, project cost, construction programme, major contracts, permits, and O&M strategy would normally be advanced enough to allow an assessment of material risk.
Some final documents will be conditions precedent to financial close or first drawdown. Detailed-design reviews, manufacturing inspections, construction monitoring, variation control, commissioning, and performance testing typically follow financing.
The lender's adviser can review these issues, but the adviser remains a reviewer. Design and delivery responsibilities stay with the parties designated by contract. IREDA's published terms demonstrate this arc, from initial attention through construction monitoring, drawdown review, and completion reporting.
Bankability Is Built Through Evidence
Commercial assumptions that are supported by site data, calculations, surveys, contracts, and executable plans make a floating solar project a better financing proposition.
The reservoir itself should be able to meet the design basis. The float and mooring system must account for real loads. Electrical and evacuation infrastructure needs to deliver the permitted export. The energy forecast should be a range of possibilities, not a single best case. Work on the water, contractor interfaces, and water access need to be factored into costs and schedules. And the plant's O&M — including inspection and repair — should be planned across the whole project lifecycle.
Floatex Solar's published scope features bathymetry, wind-and-wave studies, water-level analysis, floating system engineering, mooring and anchoring, electrical design, installation, and grid tie-in. Early coordination of these disciplines can give a project the solid technical basis that independent reviewers and financing stakeholders need to evaluate it.
Technical due diligence cannot resolve every uncertainty. It can indicate whether the residual uncertainty has been explored, communicated, valued, allocated, and dealt with consistently with the financial situation. That evidence-based approach is what builds the technical confidence lenders and investors require before financial close.
Sources and References
- Indian Renewable Energy Development Agency, 2022 — RFP for Lender's Independent Engineer services.
- World Bank, 2023 — Unlocking Floating Solar Photovoltaics Potential in India, Volume 2: Guidance Document.
- IEA PVPS Task 13, 2025 — Floating Photovoltaic Power Plants: A Review of Energy Yield, Reliability, and Maintenance.
- International Finance Corporation, 2015 — Utility-Scale Solar Photovoltaic Power Plants: A Project Developer's Guide.
- Central Electricity Authority, 2025 — Manual on Transmission Planning Criteria (with Amendment I).
- Central Electricity Authority — Connectivity to the Grid archive.
- DNV — Technical and commercial due diligence for renewable projects.
- DNV, 2021 — Cirata floating PV technical advisory.
