Harvesting the Sun on the High Seas: Taming Salt Spray and Storms for Offshore Solar

Imagine a solar farm that rises and falls with the tides, its panels cooled by the sea below, generating electricity while waves crash against its floats. This is not a futuristic concept-it is already a reality. In July 2025, Sinopec commissioned China's first commercial floating offshore PV project in a full-seawater environment off the coast of Qingdao. The 7.5 MW station, spanning 60,000 square meters, demonstrates a remarkable advantage: thanks to the cooling effect of seawater, its power generation efficiency is actually 5-8% higher than equivalent land-based installations.

Constructing offshore solar farms is not as easy as just putting panels on floating devices, as they operate in one of the harshest environments for solar energy production: the ocean. According to Van Hua (Project Manager, SGS, a leading certification/testing organization), "There are numerous and ongoing challenges to consider when building an offshore solar array such as salt spray corrosion, high humidity/moisture, extreme temperatures, high wind, mechanical stress, and UV exposure". While continuing to develop further offshore, engineers are engaged in a silent battle with corrosion, moisture, and biofouling; this battle will determine if offshore solar can produce its full potential.

 

 

To understand how difficult it is for a solar panel to operate in the ocean, think about what happens to a typical offshore solar installation. For example, solar panels are continually covered with salt-laden water mist. Humidity levels are almost 100%. Waves beat down on both the floating structure and the anchors holding them in place. The underwater surfaces of the float and any submerged structure will be consumed by marine life looking for a place to attach itself. And all of this must take place while providing reliable electricity from the solar panel for at least 25 years!

Corrosion is the primary threat. Saltwater is an excellent electrolyte, accelerating electrochemical reactions that eat away at metal frames, connectors, and mounting structures . But the damage goes deeper. In standard salt spray tests conducted for marine certification, components must withstand Level 8 salt fog exposure-among the most severe classifications . Without proper protection, corrosion can infiltrate junction boxes, degrade electrical contacts, and ultimately cause system failure.

Moisture ingress is equally insidious. Water vapor can penetrate module encapsulants, leading to potential-induced degradation (PID) and corrosion of cell metallization. During the 44west Atlantic rowing expedition, for which SGS tested solar panels destined for open-ocean deployment, engineers simulated worst-case scenarios by completely submerging panels in conductive saltwater while applying high voltage. The goal: ensure that even if waves wash over the system, there is no dangerous electrical leakage.

Biofouling refers to the build-up of marine organisms, such as barnacles and algae, on submerged surfaces. Biofouling not only adds excess weight and stress on floating structures; it also can shade panels or promote localized corrosion. Traditionally, antifouling paints used to combat biofouling used to be made from biocides that cause a range of negative effects on marine ecosystems and create an environmental contradiction for projects marketed as green.

To meet these challenges, manufacturers are fundamentally rethinking how solar modules are built. HY SOLAR's HT Series offshore modules, which have earned TÜV Rheinland's 2PfG 2930/02.23 certification-the world's first standard for near-shore PV system reliability-incorporate multiple layers of protection.

The front glass receives a double-layer anti-reflective coating that not only improves light transmission but also creates a barrier against moisture ingress. The aluminum frame, typically anodized to AA10 standards for land-based installations, is upgraded to AA20, effectively doubling the thickness of the protective oxide layer. For the encapsulant-the polymer that bonds cells to glass-manufacturers are switching from standard EVA to EPE+EPE structures, which offer superior volume resistivity and moisture barrier properties.

Connectors, often the weakest link in marine environments, are receiving special attention. Double-seal rings, protective plugs, and cold-shrink tubing create redundant barriers against water and salt fog. Some designs incorporate hydrophobic gels that physically block moisture from reaching electrical contacts.

In addition to the floating structures themselves, floating structures will also require some innovative technologies. For example, TECNALIA (a research center) in the Natursea-PV project is creating floating structures that are inspired by the design of lily pads, though they are constructed from ultra-high-performance eco-concrete that has a much lower carbon footprint. These floating structures also have bio-based antifouling coatings made from compounds derived from biomass that will protect against biofouling without using toxic biocides. In December 2025, a full-scale prototype of this floating structure was installed at TECNALIA's Mutriku marine research center (the only facility of its type in the world) in order to validate the floating structure's structural performance, durability, and energy efficiency in actual marine conditions.

Material selection is only half the battle. Engineers are also rethinking how systems are configured to minimize exposure and maximize longevity.

There has been an increase in the number of encapsulation technologies available, as many are exploring using silicone as a potting compound, allowing complete insulation of sensitive electronics. Manufacturers are also redesigning junction boxes to be outfitted with waterproof seals, built-in drainage systems, and corrosion resistant housing.

The other potential option for components that are submerged is the cathodic protection (CP) system used in the shipping industry for preventing corrosion. The CP system operates by connecting submerged metal parts to a sacrificial anode made out of zinc or aluminum so that the submerged metal will corrode towards (and thereby be protected from corrosion by) the sacrificial anode, and the sacrificial anode will dissolve over time.

The Anchoring System is designed to hold and support submerged structures located on the ocean floor. The holding capacity of the anchors has been tested under wind conditions rated at level 13 (height of a typhoon) and for tidal ranges of 3.5 meters, as well as to reduce the overall cost of development when compared to fixed pile foundations by approximately 10%.

Before any offshore solar system can be deployed, it must prove itself in the laboratory. The testing protocol for the 44west expedition panels is instructive:

Visual inspection checks for cracks, delamination, or sealing defects that could become entry points for corrosion

Insulation resistance testing verifies that no dangerous current can leak from internal circuits to the frame

Wet leakage current testing submerges panels in saltwater while applying high voltage, simulating worst-case ocean conditions

Salt mist corrosion testing exposes components to concentrated salt fog for extended periods

Mechanical load testing confirms the structure can withstand wind, waves, and vibration

The results from rigorous testing build confidence that offshore solar can deliver on its promise. As Van Hua notes, "Ensuring the quality and durability of solar panels helps extend product lifespan, reduce failure rates and lower the overall cost of clean energy systems".

Recognizing the strategic importance of offshore solar, China's standardization bodies are moving to establish clear technical guidelines. An ongoing national effort to create a "Technical Specification for the Control of Corrosion in Offshore Photovoltaic Systems", primarily developed by Shandong Electric Power Engineering Consulting Institute, is now underway. This initiative involves a wide range of industry experts such as LONGi, Huawei and several research institutions that are contributing to the establishment of this National Standardisation Project and subsequently will be developed into a soon to be published document.

Offshore solar is moving from being an experimental idea to being a legitimate industry, with offshore solar projects now operational and stricter standards enroute. The Sinopec project is generating 16.7 million kWh of renewable power annualy while displacing 14,000 tons of carbon emissions from the atmosphere and has plans to expand its capacity to 23 MW.

Although there are many challenges that coastal areas must face due to saltwater exposure, storms and wind; through innovative materials; intelligent design; and extensive testing, the solar industry has developed ways to be successful in utilizing solar energy where land meets ocean. As a result, solar has opened new renewable resources to support up to 71% of Earth's surface that is covered by oceans.