Floating Solar Maintenance: What Must Be Inspected and How Often?
Floating solar maintenance is not limited to cleaning modules or responding to inverter alarms. A floating photovoltaic power plant is a complete system operating on water: modules, cables, floaters, connectors, anchoring and mooring equipment, electrical components and monitoring sensors all interact under changing environmental loads.
HelioRec recently carried out operations and maintenance activities on its 10 kWp floating solar demonstrator at the Port of Brest, developed within the STEWART project. This real marine-site intervention provides a practical framework for answering two essential questions: what must be inspected, and how often?
The core principle is preventive maintenance: inspect mechanical systems, electrical systems and monitoring sensors before small changes become safety, reliability or production problems.
A real floating solar maintenance case at the Port of Brest
The Brest demonstrator operates in a demanding nearshore environment where tides, waves, wind, humidity, salt exposure and repeated platform motion must be considered together. Its purpose is not only to generate electricity, but also to build operational knowledge about floating solar performance, environmental interaction and long-term reliability.
During the recent intervention, the HelioRec team examined three essential groups of equipment:
Mechanical systems: floating structures, connections, anchoring equipment and mooring systems.
Electrical systems: photovoltaic modules, cables and associated electrical equipment.
Monitoring sensors: environmental and structural sensors used to maintain confidence in the collected data.
This system-level approach matters because the failure modes are connected. Platform movement can affect cable routing. A worn connection can change structural behaviour. A faulty sensor can hide an emerging load or performance issue. Maintenance therefore needs both physical inspection and reliable data.
What must be inspected?
1. Mechanical systems
Mechanical inspection covers the floating platform and the equipment that keeps it safely in position. On a marine or nearshore site, these components experience cyclic motion and must retain their geometry, buoyancy and load-transfer capacity.
Floaters: cracks, deformation, punctures, water ingress, loss of buoyancy and abnormal freeboard.
Structural supports and module frames: looseness, deformation, fatigue indicators and corrosion.
Connections between floating units: wear, elongation, missing retainers, cracking and unusual movement.
Walkways and access areas: surface condition, safe footing, obstructions and damaged handholds.
Mooring lines and terminations: chafing, corrosion, broken strands, excessive slack, overload signs and contact with sharp surfaces.
Anchoring and attachment points: movement, degradation, damaged pad eyes, shackles, brackets and accessible anchor components.
Overall array position: unexpected displacement, rotation, asymmetry or changes in the designed operating envelope.
Visible mooring components should be reviewed during routine visits. The underwater scope should be defined by the site risk assessment and may require trained divers or a remotely operated vehicle. High-load perimeter lines, previous repair locations and areas exposed to repeated chafing deserve increased attention.
2. Electrical systems
The electrical system combines standard PV equipment with the additional challenges of movement, humidity and limited access. Cable routing and strain relief are especially important because the platform changes position continuously.
PV modules: broken glass, delamination, frame damage, discoloration, hot spots, damaged backsheets and junction-box defects.
Module mounting: clamps, rails, fasteners, clearances and signs of movement.
DC cables and connectors: abrasion, excessive tension, unsupported loops, damaged insulation, loose connections and water exposure.
Junction and combiner boxes: sealing, cable glands, moisture ingress, corrosion and overheating.
Inverters and AC equipment: alarms, ventilation, terminations, enclosure condition and production consistency.
Earthing and bonding: continuity, corrosion and integrity of protective connections.
Thermal imaging can support the inspection by locating abnormal heating in modules, connectors and electrical equipment. For larger plants, drone-based infrared surveys can improve coverage, but findings still require engineering interpretation and targeted follow-up.
3. Environmental and structural monitoring sensors
Monitoring is a maintenance tool, not only a reporting tool. At Brest, HelioRec uses environmental and structural measurements to understand site conditions and the response of the floating platform. The monitoring system includes data relevant to wind, waves, irradiance, temperature and structural or mooring loads.
Inspect sensor housings, supports, connectors and cable routing.
Check power supply, communications, timestamps and data completeness.
Compare readings with expected ranges and independent observations.
Identify drift, frozen values, sudden offsets and repeated communication gaps.
Verify that alarm thresholds, ownership and escalation procedures remain appropriate.
Calibrate or replace instruments according to the manufacturer’s instructions and the project monitoring plan.
Poor-quality data can lead to poor maintenance decisions. Sensor health must therefore be reviewed alongside the physical plant.
How often should a floating solar plant be inspected?
No universal interval fits every floating solar power plant. The maintenance programme must follow the design basis, environmental exposure, OEM manuals, monitoring capability, previous findings, contractual obligations and applicable regulations. The schedule below is a practical starting point.
Frequency | Inspection scope | Purpose |
Continuous | SCADA, inverter, string and sensor data | Detect alarms, production anomalies, communication loss and abnormal trends |
Monthly | Remote engineering review | Compare yield and environmental data, review recurring faults and plan intervention |
Quarterly | Routine on-site visual inspection | Check modules, floaters, connectors, access, visible cables, safety equipment and soiling |
Every 6 months | Detailed mechanical, electrical and sensor inspection | Check fasteners, cable supports, visible moorings, corrosion, freeboard, enclosures and sensor integrity |
Annually | Specialist preventive maintenance | Electrical testing, thermography, structural review, mooring and anchor assessment, calibration and spares review |
After an event | Targeted condition assessment | Inspect after severe wind or waves, unusual tides or water levels, collision, movement, overload alarms or major electrical trips |
Inspection frequency should increase for critical parts, harsh environments, previous defects and components showing accelerated degradation. In marine conditions, salt exposure, corrosion, biofouling and repeated wave loading can justify shorter intervals than for a sheltered freshwater reservoir.
When an additional inspection is required
A calendar alone is not sufficient. Event-driven inspections should be triggered by severe weather, lightning, flooding, extreme low water, unusual tides, floating debris, collision, unexpected array movement, mooring-load alarms, repeated insulation faults or sudden production loss.
Start with remote data and alarms. If a structural, station-keeping or electrical problem is suspected, restrict access and isolate the affected equipment until competent personnel complete the necessary checks.
What every maintenance report should record
A useful O&M report must create traceable evidence. Each finding should be linked to an exact component or location and followed through to close-out.
Inspection date, personnel, weather, tide and water conditions.
Asset identification for modules, floaters, connectors, mooring lines, anchors, sensors and electrical equipment.
Photographs from repeatable viewpoints.
Measurements, observations and comparison with previous inspections.
Risk classification covering safety, production and degradation.
Corrective action, responsible person and target completion date.
Evidence that the action was completed and the maintenance record updated.
Floating solar maintenance checklist
Remote monitoring reviewed and alarms assigned.
Array position, geometry and freeboard appear normal.
Modules, clamps and support structures show no critical damage.
Floaters, connections and access areas remain intact and safe.
Visible mooring lines, terminations and attachment points show no abnormal wear or loading.
Cables remain supported, protected and free from damaging tension or abrasion.
Electrical enclosures show no water ingress, corrosion or overheating.
Environmental and structural sensors provide complete and credible data.
Safety and rescue equipment is present and accessible.
All findings are documented, prioritised and formally closed.
Frequently asked questions
How often should a floating solar power plant be inspected?
A practical baseline combines continuous monitoring, monthly data review, quarterly visual site checks, semi-annual detailed inspections, an annual specialist review and additional checks after storms or abnormal events. The final frequency must reflect site exposure, component manuals, operating history, contractual requirements and local regulations.
What are the three main areas of floating solar maintenance?
HelioRec organises FPV maintenance around mechanical systems, electrical systems and monitoring sensors. These areas are interdependent: structural movement can affect cables, electrical faults can appear in performance data, and sensors help identify changes before they become visible failures.
Can monitoring replace physical inspection?
No. Monitoring can reveal performance deviations, alarms, communication loss and abnormal environmental or structural trends, but it cannot reliably identify every loose connector, damaged float, chafed mooring line, corroded termination or local access hazard.
What should be inspected after severe weather?
Review alarms and production first, then inspect array position, floats, connectors, module supports, cables, electrical enclosures, mooring lines, attachment points and monitoring equipment. Restrict access and isolate affected equipment if movement, impact, overload or electrical damage is suspected.
Why are marine floating solar inspections especially important?
Nearshore sites expose equipment to waves, tides, humidity, salt, corrosion and repeated motion. Regular preventive maintenance helps track degradation, protect safe station keeping, maintain reliable data and build evidence for long-term performance.
Conclusion: maintenance builds long-term evidence
The Brest intervention illustrates what effective floating solar maintenance looks like in practice: mechanical systems, electrical systems and monitoring sensors are inspected as one integrated asset.
Regular preventive maintenance helps HelioRec evaluate long-term performance, anticipate risks and continuously improve the reliability and durability of floating solar installations in demanding marine environments. The same principle applies to every FPV project: define the baseline, monitor continuously, inspect systematically and learn from each intervention.
Technical references
This practical framework is consistent with DNV-RP-0584, Design, development and operation of floating solar photovoltaic systems, and the IEA PVPS Task 13 report Floating Photovoltaic Power Plants: A Review of Energy Yield, Reliability, and Maintenance.
