Offshore photovoltaics refer to photovoltaic power generation systems built in marine environments. These photovoltaic power stations are typically installed on floating platforms, which can be either fixed or capable of floating with the changing water levels. Offshore photovoltaic power stations can be divided into two main types: nearshore (coastal) photovoltaics and farshore photovoltaics.

I. Advantages of Developing Offshore Photovoltaics in China

China has several advantages in developing offshore photovoltaics, mainly in the following aspects:

1. Rich Solar Energy Resources: Coastal areas in China receive long durations of sunlight, providing abundant solar resources for offshore photovoltaic power stations.

2. Vast Construction Space: With over 18,000 kilometers of coastline and vast nearshore waters, there is ample space for offshore photovoltaic power stations. Marine space is not restricted by land resources, allowing for large-scale deployment of photovoltaic stations and efficient use of spatial resources.

3. High Power Generation Efficiency: The sea surface is free from obstructions, with long durations of sunlight, resulting in high efficiency. Typically, offshore photovoltaic projects generate 5%-10% more power than land-based ones. The natural cooling effect of the sea surface helps reduce the working temperature of photovoltaic modules, thus enhancing power generation efficiency.

4. Local Power Consumption Advantage: Coastal areas tend to be densely populated with high levels of economic development, resulting in a large demand for electricity. Therefore, the electricity generated by offshore photovoltaic stations can be directly supplied to local areas, reducing transmission losses.

5. Shorter Construction Period: Compared to traditional energy projects, offshore photovoltaic power stations have shorter construction periods and can be put into operation more quickly.

6. Water Conservation: Unlike traditional thermal power plants, offshore photovoltaic stations do not consume large amounts of water, which helps alleviate water resource pressure.

7. Reduced Land Use: Offshore photovoltaic stations avoid occupying valuable land resources, which is particularly important in regions with scarce land.

8. Diverse Application Scenarios: Offshore photovoltaic power stations can be constructed independently or integrated with other industries such as marine fisheries, seawater desalination, and marine tourism, achieving multiple functions.

9. Policy Support: Government policies supporting clean energy provide guarantees and financial subsidies for offshore photovoltaic projects.

10. Technological Innovation and Cost Reduction: With advancements in technology and the scaling effect, the cost of offshore photovoltaics is gradually decreasing, making it more attractive for investors.

11. Addressing Climate Change: The development of offshore photovoltaics helps reduce greenhouse gas emissions, which is crucial for achieving the "dual carbon" goals (carbon peak and carbon neutrality).

In conclusion, China has clear geographical and resource advantages for developing offshore photovoltaics. Combined with government support and technological advancements, the offshore photovoltaic industry is poised to become an important force in promoting clean energy development.

II. Major Corrosion Challenges Facing Offshore Photovoltaics

Offshore photovoltaics face various corrosion threats, mainly due to the special nature of the marine environment. The following are the main types of corrosion encountered by offshore photovoltaics:

Seawater Corrosion: Seawater is a complex electrolyte solution containing high concentrations of salts, dissolved gases (such as oxygen and carbon dioxide), and microorganisms. These factors can lead to electrochemical reactions on metal surfaces, causing corrosion.

Marine Microbial Corrosion: Marine microorganisms (such as sulfate-reducing bacteria) produce acidic substances during their metabolism, which can chemically react with metal surfaces, leading to severe corrosion.

Fatigue Corrosion: Wind turbines undergo periodic mechanical load changes during operation. These dynamic loads cause microcracks in metal materials, which, over time, expand and eventually lead to metal fatigue failure.

Stress Corrosion Cracking: This type of corrosion occurs when metals are subjected to tensile stress in a specific corrosive environment, causing cracking. Offshore photovoltaic equipment is subjected to various stresses during operation, and the combination of these stresses with corrosive agents leads to stress corrosion cracking.

Biofouling Corrosion: Marine organisms (such as mollusks and algae) attach to parts of the wind turbines, and their life activities and the remains left behind after their death accelerate material corrosion.

Atmospheric Corrosion: For non-submerged parts of offshore photovoltaic equipment, high humidity, strong salt mist, and intense sunlight can cause atmospheric corrosion of metal components.

III. Mengneng Coatings Experts’ Strategy to Tackle Corrosion

To address these corrosion issues, offshore photovoltaic systems have adopted a series of measures:

Use of Corrosion-Resistant Materials: Materials such as stainless steel, aluminum alloys, or special steel (e.g., magnesium-aluminum-zinc-coated steel plates) are used for photovoltaic frames and other metal components.

Surface Treatment Technology: Surface treatment technologies such as hot-dip galvanizing and aluminum-magnesium-zinc coating are used to enhance the corrosion resistance of metal parts.

Special Coatings: Graphene-based heavy-duty anti-corrosion coatings, such as graphene epoxy zinc primer and polyurethane coatings, are applied to metal components.

Cathodic Protection: Sacrificial anodes or impressed current methods are used to provide cathodic protection, preventing metal components from corroding.

Regular Maintenance: Regular inspections and maintenance of photovoltaic modules and their supports are carried out, including cleaning biological attachments and repairing damaged anti-corrosion layers.

Through these measures, we can effectively reduce corrosion issues in offshore photovoltaic systems, enhancing system reliability and extending service life.

I. Reference Standards

Current national standards, relevant regulations, and mandatory standard provisions;

"Code for Construction and Acceptance of Building Anti-corrosion Engineering" (GB50212-2002)

"Standard for Corrosion and Rust Removal Levels of Steel Surface Before Coating" (GB8923-1988)

"Safety Regulations for Coating Operations and Safety Management Rules" (GB6514-1995)

"Quality Requirements for Anti-corrosion Coatings" (GB6514-1991)

"Safety Regulations for Coating Operations, Paint Process Safety, and Ventilation Purification" (DJ/T6931-1999)

"Code for Construction and Acceptance of Industrial Equipment and Pipeline Anti-corrosion Engineering" (HGJ229-91)

"Safety Regulations for Coating Operations and Safety of Surface Preparation Process" (GB7692-87)

"Noise Limits at Construction Sites" (GB12523-90)

ISO9001 Quality Management System Documents

ISO14001 Environmental Management System Documents

GB/T28001 Occupational Health and Safety Management System Documents

I. Design Basis

Environmental Conditions: The corrosion level of atmospheric environments on steel structures can be determined according to Table 1.

I. Harsh Marine Corrosion Environment

Offshore photovoltaic projects can help alleviate the electricity shortage in the eastern regions; typical photovoltaic projects located in deserts, remote areas, and regions with significant temperature differences between day and night, as well as strong sandstorms, face high transmission costs and maintenance difficulties. Offshore photovoltaic projects, on the other hand, effectively reduce temperature and enhance conversion efficiency, while also reducing transmission costs and losses. Moreover, large-scale offshore photovoltaic projects can help address the large-scale appearance of green algae tides.

However, photovoltaic equipment exposed to the atmospheric and marine environment for extended periods, especially in splash zones and submerged areas, faces severe corrosion, significantly affecting the lifespan of offshore photovoltaic equipment.

II. DreamCoat's Comprehensive Solution

DreamCoat specializes in the research, development, production, and sales of industrial heavy-duty anti-corrosion coatings, including marine anti-corrosion coatings. We provide an integrated solution for offshore photovoltaics, including steel piles, PHC piles, support systems, composite frames, and booster stations.

A. DreamCoat Third-Generation Cold Spray Zinc System

DreamCoat cold spray zinc coating is a high-performance, single-component, zinc-rich coating that contains over 96% zinc in the dry film, making it an excellent alternative to hot-dip galvanized coatings. This coating is easy to apply and does not require complex mixing steps, allowing it to be sprayed or brushed directly. Cold spray zinc not only offers powerful cathodic protection but also provides a barrier-type anti-corrosion function, effectively protecting metal structures in harsh corrosion environments for extended periods. Its color changes gradually as the zinc powder oxidizes, giving it a similar appearance to a hot-dip galvanized layer. Due to these characteristics, cold spray zinc coatings are widely used in electric power facilities, high-voltage transmission towers, substations, pipeline anti-corrosion, and iron frame coatings, especially in applications like offshore wind power facilities and offshore photovoltaic stations, where they are subjected to extreme environmental conditions.

B. DreamCoat Fourth-Generation Graphene System

The natural environment of offshore photovoltaic systems is extremely harsh, with very strong winds and wave impacts, exposure to intense direct sunlight, alternating cold and hot currents, wind, rain, and snow. Offshore photovoltaic systems, especially those near the coast, are also exposed to salt mist corrosion, while splash zones and submerged areas face microbiological and electrochemical corrosion. Therefore, a strong and effective anti-corrosion coating system is essential to protect the lifespan of offshore photovoltaic equipment. DreamCoat provides an integrated anti-corrosion solution for offshore photovoltaic systems through coating technologies, including supports, fixed columns, fixed plates, and floating boards.

1. Excellent Weather Resistance: The chemical bonds are stable, the coating does not crack under ultraviolet exposure, does not powder, and can withstand temperatures between -45°C and 120°C, providing strong weather resistance.

2. Environmental Properties: With high volume solids, this coating is an environmentally friendly heavy-duty anti-corrosion solution that meets environmental protection standards.

3. Corrosion Resistance: Graphene provides excellent anti-corrosion properties, resisting corrosion from marine atmosphere, acids, alkalis, saltwater, and various solvents. It has passed the salt spray test for over 3000 hours, ensuring long-term stable anti-corrosion performance.

4. Conductivity: Graphene is a better conductive material than zinc, offering higher conductivity, greater chemical stability, and better adsorption, ensuring long-term stable resistance to electrochemical corrosion.

C. Mengneng Self-Cleaning Anti-Fouling Coating

Mengneng Self-Cleaning Anti-Fouling Coating is a new type of anti-fouling coating with nanostructured organic silicon, enhanced toughness, wear resistance, and self-cleaning properties. Through nano-modification of organic silicon resin and overall formulation design, it significantly enhances the coating's toughness and wear resistance on a low surface energy interface and adopts unique antibacterial technology to provide excellent marine fouling resistance. The coating is VOC-free and environmentally friendly.

1. Excellent low surface energy anti-fouling, effectively preventing barnacles and other marine organisms from attaching to the steel pipe piles of photovoltaics, low toxicity, and eco-friendly.

2. Excellent flexible tensile properties, enhanced toughness of the coating film, resistant to bending and deformation. The coating does not crack or peel off after rolling.

3. Mengneng anti-fouling coating has high hardness, resistant to compression. Under high pressure, the coating does not crack or peel off.

4. Smooth surface, low working resistance, no impact on hoisting and winding.

5. Cures at room temperature, easy to repair, excellent construction performance.

6. The coating film is smooth and flexible, and photovoltaic steel pipe piles can withstand cleaning by underwater robots.

I. PHOTOVOLTAIC STEEL STRUCTURE PLATFORM CORROSION PROTECTION DESIGN

The corrosion protection of steel pipe piles in offshore photovoltaics is crucial, as these steel piles are exposed to extreme marine environments and face various corrosion threats. To ensure the safety and reliability of the steel pipe piles and their related structures, corrosion protection measures must comply with strict standards and requirements. Below are some key corrosion protection requirements:

The outer surface of the foundations in splash zones and tidal zones is usually protected with corrosion-resistant coatings and protective outer jackets.

For fully submerged and marine sediment zones, combined protection with corrosion-resistant coatings and cathodic protection is applied.

The corrosion-resistant coatings should be selected from high-performance coatings such as graphene glass flake coatings, including epoxy resins and polyurethane, to ensure long-term effectiveness.

The interior of the steel pipe piles also requires appropriate corrosion protection, especially for the interior walls of single pile foundations.

Table A: Corrosion Protection Design for Photovoltaic Trusses, Braces, and Purlins Coatings

Table B: Paint Anti-corrosion Design for Steel Pipe Piles (Splash Zone, Immersion Zone)

Table C: Paint Anti-corrosion Design for Steel Pipe Piles (Atmospheric Zone)

I. Hot-dip Galvanized Photovoltaic Brackets

Hot-dip galvanized photovoltaic brackets are structures used to support solar photovoltaic panels. Their main feature is the coating of zinc on the steel surface through the hot-dip galvanizing process, which enhances the corrosion resistance of the brackets. These brackets are typically used in outdoor environments and need to withstand various weather conditions, so high requirements are placed on the material's weatherability and stability.

When used in offshore photovoltaic systems, although hot-dip galvanizing itself has a certain degree of corrosion resistance, the pure galvanized layer may not provide sufficient protection in a high-salt, high-humidity, and highly corrosive marine environment. Therefore, additional corrosion protection is needed through coatings. DreamCoat engineers recommend the following coating scheme for protection.

II. Table 1.1, Second-Generation Coating Anti-corrosion Technology for Hot-dip Galvanized Photovoltaic Brackets

The three-layer coating system provides excellent corrosion resistance. The epoxy zinc-rich primer contains a large amount of zinc powder, providing cathodic protection for the photovoltaic bracket. The epoxy micaceous iron oxide intermediate coating forms a dense barrier layer that effectively isolates oxygen and moisture. The polyurethane topcoat offers superior weather resistance and chemical resistance, protecting the structure from UV radiation, rainwater erosion, and other environmental factors.

Table 1.2: Hot-dip Galvanized Photovoltaic Support Frames Using Fourth-Generation Coating Technology

The graphene low-surface treatment coating is especially suitable for surfaces that are difficult or impossible to sandblast or shot-blast, and can only be rusted manually or with power tools. It tolerates ST2 surface treatment, and is often used in the maintenance of steel coatings, and can be applied to a variety of substrates, including aging coatings, galvanized layers, and steel treated by spraying. It provides good corrosion protection for offshore photovoltaic support frames. It can be used alone or in combination with other primers and topcoats.

Table 1.3: Hot-dip Galvanized Photovoltaic Support Frames Using Powder Coating Technology

This product system is a composite system that combines hot-dip galvanized substrate with powder coating for long-term corrosion protection, preventing the galvanized layer from oxidizing and ensuring long-lasting cathodic protection. It provides a colorful appearance for the support frame surface, and the coating system withstands strong ultraviolet exposure without chalking, fading, or cracking. Its excellent corrosion resistance eliminates the need for additional cathodic protection or external anode blocks, offering over 25 years of protection and is the best solution for marine atmospheric zones.

II. Zinc-Aluminum-Magnesium Photovoltaic Support Frames

Zinc-aluminum-magnesium photovoltaic support frames are made from a zinc-aluminum-magnesium alloy material. The density of this alloy is lower than that of traditional steel, while it offers higher strength. This allows the zinc-aluminum-magnesium photovoltaic support frames to maintain sufficient load-bearing capacity while reducing their own weight, lowering transportation and installation costs, and adapting to complex terrain installation requirements. Zinc-aluminum-magnesium alloys have far superior corrosion resistance compared to ordinary steel in harsh environments, such as humid and highly saline conditions, which is critical for photovoltaic support frames that need to operate stably over the long term. These frames also have a long service life, significantly reducing maintenance and replacement costs due to corrosion.

Even though zinc-aluminum-magnesium support frames offer better corrosion resistance, they still require a coating due to the extremely corrosive nature of the marine environment. The salts and chloride ions in seawater accelerate the electrochemical corrosion process of metal materials. Salt mist, humid air, and UV radiation can damage the surface of the frames, leading to the failure of protective layers. In addition, the attachment of marine organisms increases the corrosion pressure. Therefore, to ensure the long-term stability and durability of photovoltaic support frames in the marine environment, an additional anti-corrosion coating is typically applied to the zinc-aluminum-magnesium frames' surface, such as a long-life heavy-duty anti-corrosion coating with a double-layer modified graphene low-surface-treatment primer. This forms a more effective protective layer, extending the service life and better resisting the multiple corrosion factors of the marine environment.

Table 2.1: Zinc-Aluminum-Magnesium Photovoltaic Support Frames Using Fourth-Generation Anti-Corrosion Technology

Table 2.2: Zinc-Aluminum-Magnesium Photovoltaic Support Frames Using Powder Technology

Long-Lasting Anti-Corrosion: The high-temperature baked powder coating forms an isolating protective layer for the zinc layer, allowing the zinc-aluminum-magnesium galvanized layer to continue providing cathodic protection for an extended period. Environmental Performance: Zero VOC, no solid waste, and no organic compound emissions. Scalable Production: Suitable for automatic production lines, offering high efficiency and easy quality control. Edge Wrapping: The edges of the support frames form a complete wrap, preventing corrosion at these vulnerable spots.

III. CARBON STEEL PHOTOVOLTAIC BRACKETS

The carbon steel photovoltaic bracket refers to a support system made of carbon steel, typically using Q235 steel as the main material. This includes different types of steel, such as I-beams, channel steel, angle steel, round steel, square steel, C-shaped steel, and H-shaped steel. Carbon steel photovoltaic brackets are widely used in residential, industrial solar power systems, and solar power plants due to their stable performance, mature manufacturing process, high load-bearing capacity, and easy installation.

In marine environments, carbon steel photovoltaic brackets need to be coated with paint primarily because the corrosiveness of the marine environment is very strong. Salt and chloride ions in seawater accelerate the electrochemical corrosion process of metals, and salt spray, humid air, and ultraviolet radiation can damage the surface of the brackets, leading to failure of protective coatings. In addition, the attachment of marine organisms increases corrosion pressure. Coating creates a protective layer on the surface of the carbon steel brackets, further preventing corrosive media from contacting the metal surface, extending the bracket's service life, and ensuring the long-term stable operation of the photovoltaic system.

Table 3.1 Carbon Steel Bracket Using Second-Generation Coating Technology

The three-layer coating system provides excellent corrosion protection, with the zinc-rich epoxy primer containing a high amount of zinc powder to provide cathodic protection to the photovoltaic brackets. The micaceous iron oxide intermediate coat forms a dense barrier that effectively isolates oxygen and moisture. The polyurethane topcoat offers excellent weather resistance and chemical resistance, protecting against UV radiation, rain erosion, and other environmental factors.

Table 3.2 Carbon Steel Photovoltaic Bracket Using Fourth-Generation Paint Technology

The graphene conjugated structure allows high electron mobility, providing good conductivity between zinc particles. This facilitates electrochemical contact between zinc particles in the coating and the steel substrate treated by sandblasting or shot peening, forming a conductive network. Graphene's impermeability to corrosive media, along with the synergistic interaction between the two, enhances the cathodic and shielding performance.

I. FUNCTION OF PHOTOVOLTAIC BOOSTER STATION

The photovoltaic booster station is a key component in the solar power generation system, primarily used to convert the DC power generated by solar panels into high-voltage AC power for long-distance transmission. The main functions of the photovoltaic booster station include:

Boosting: Converts the low-voltage DC power generated by solar panels into high-voltage AC power for long-distance transmission.

Grid connection: Ensures a stable connection between the photovoltaic power generation system and the public grid, adjusting voltage and frequency to match the grid.

Improve power generation efficiency: By boosting the voltage, the current in the transmission process is reduced, thus lowering line losses and improving overall power generation efficiency.

II. COMPOSITION OF PHOTOVOLTAIC BOOSTER STATION

Inverter: Converts the DC power generated by solar panels into AC power.

Oil-immersed transformer: The main factors causing corrosion on the internal walls of the transformer include chemical corrosion, electrochemical corrosion, microbial corrosion, fatigue corrosion caused by thermal cycling, and environmental factors. Chemical corrosion is typically caused by acidic substances produced by the oxidation of transformer oil; electrochemical corrosion occurs when different metal components come into contact with moisture; microbial corrosion is caused by metabolic activities of microorganisms in the oil; thermal cycling corrosion is related to the thermal expansion and contraction of transformer oil; and environmental factors, especially high humidity and salinity in coastal climates, accelerate this process. Additionally, temperature differences and damage to protective coatings increase the risk of corrosion.

Distribution equipment: Includes circuit breakers, isolators, grounding switches, current transformers, voltage transformers, surge arresters, busbars, etc., used for controlling and protecting the power system.

Control system: Monitors and adjusts the operational status of the power system.

Table 1: Transformer Internal Wall Coating Technology

When applying anti-corrosion coating to the internal walls of the oil-immersed transformer, it is essential to choose epoxy-based coatings that are resistant to oil and temperature. Ensure that the internal walls are clean and free from rust, with surface treatment to the specified roughness. Control the coating environment to ensure suitable temperature and humidity. Ensure the film thickness is uniform and no coating is missed. For two-component coatings, mix in the proper ratio and use promptly. Fully cure the coating after application to avoid collisions. Periodically inspect and maintain the coating, repairing it as needed.

Table 2: Oil-Immersed Transformer External Wall Coating Technology

When applying anti-corrosion coating to the external walls of oil-immersed transformers, select the primer and finish with good adhesion and durability in harsh environments. Apply a three-coat system with the specified surface treatment. Ensure that the primer and topcoat films are evenly applied, with appropriate curing and drying time. Regularly check the surface for rust, and if necessary, apply touch-up coating to avoid corrosion affecting the transformer’s service life.

During the daily operation of marine photovoltaic mounting frames, the damage to the galvanized coating is inevitable. This is mainly caused by mechanical damage during installation, transportation, and maintenance, or natural corrosion due to prolonged exposure to outdoor environments. Once the galvanized layer is damaged, it loses its original corrosion protection function, which in turn affects the structural safety and service life of the photovoltaic mounting frame. Therefore, timely and effective repair of the damaged galvanized layer is crucial.

1. Overview of Daily Operation Issues

Photovoltaic mounting frames typically use hot-dip galvanizing to provide corrosion protection. However, in practice, for various reasons, the galvanized coating may experience localized damage or corrosion. For example, operations such as cutting or welding may damage the integrity of the galvanized layer, while prolonged exposure to sunlight and rain can lead to the gradual aging of the galvanized coating. If these issues are not addressed, they will directly affect the stability and reliability of the photovoltaic mounting frame.

2. Features of Cold-Sprayed Zinc Coating

To address the above issues, DreamNeng Cold-Sprayed Zinc Coating, as an efficient and fast repair material, has become an ideal choice. This coating contains a high concentration of zinc powder, which provides cathodic protection. Even when the coating is damaged, it continues to protect the metal substrate. In addition, it has the following advantages:

- Easy to apply: No heating equipment is required, and it can be sprayed or brushed directly on-site.

- Strong compatibility: It can be directly applied to a clean hot-dip galvanized surface without additional pretreatment.

- Fast curing: It cures quickly, reducing repair time and minimizing downtime losses.

- Good weather resistance: It has excellent weather resistance and chemical resistance, allowing it to maintain long-term stability in harsh environments.

3. Application Steps for Cold-Sprayed Zinc Coating

1. Surface preparation: Remove corrosion products and impurities from the damaged area, ensuring the surface is clean and dry.

2. Apply Cold-Sprayed Zinc Coating: Select the appropriate tool (e.g., spray gun or brush) based on the area to be repaired, and apply the DreamNeng Cold-Sprayed Zinc Coating evenly.

3. Inspection and curing: After application, inspect the coating for uniformity and integrity, and ensure it is fully cured.

4. Post-treatment: To further enhance the corrosion resistance, a protective topcoat can be applied over the cold-sprayed zinc layer.

Table 1: Cold-Sprayed Zinc Coating System

5. Conclusion

Using DreamNeng Cold-Sprayed Zinc Coating to repair the galvanized layer on photovoltaic mounting frames can not only quickly and effectively address localized damage, but also significantly enhance the corrosion resistance and overall service life of the frames. This method is simple and efficient, reducing maintenance costs, and is one of the key measures in the daily operation and maintenance of photovoltaic mounting frames. With technological advancements and the application of new materials, DreamNeng Cold-Sprayed Zinc Coating will play a greater role in the corrosion protection field of photovoltaic mounting frames.