How to choose anti-corrosion measures for photovoltaic brackets in highly corrosive coastal environments?

Photovoltaic support structures are the "skeleton" of a photovoltaic power station, supporting the modules and withstanding wind and temperature changes. Once the support structure is corroded and damaged, the module angles are prone to shift, power generation efficiency decreases, and it may even lead to safety accidents. Photovoltaic power stations are located in various environments, including coastal areas with high salt spray, highly polluted industrial areas, and humid regions, where metal support structures constantly face the challenge of oxidation and corrosion.

Coastal environments are the most severe. The sodium chloride content in inland atmospheres is about 0.8 mg/m², while in marine environments it can reach 12.4~60 mg/m². High concentrations of salt spray can accelerate metal corrosion by 4 to 5 times compared to inland areas. Furthermore, the salt and chloride ions in seawater accelerate electrochemical corrosion; salt spray, humid air, and ultraviolet radiation damage the protective layer on the support structure surface; and the attachment of marine organisms such as algae and shellfish increases both their weight and the risk of corrosion. Therefore, effective anti-corrosion measures must be taken when constructing photovoltaic power stations in coastal areas.

Currently, the mainstream anti-corrosion technologies mainly include the following three:

1. Zinc-Aluminum-Magnesium (ZAM)

This is a new type of alloy coating, with core components including aluminum, zinc, and magnesium. Its innovation lies in its "self-healing" properties: when the coating is scratched, the corrosion products of magnesium actively migrate to the exposed substrate surface, forming a dense protective film that prevents further corrosion. Unlike traditional galvanizing, which relies solely on physical barriers, ZAM achieves a leap from "passive barrier" to "active repair." Typically, a double-sided coating quality of 275g/㎡ (approximately 20 micrometers thick) can achieve or even surpass the protective effect of thicker pure zinc coatings due to the synergistic effect of the alloy components.

2. Hot-Dip Galvanizing

This is the most widely used traditional process. Steel components that have undergone rigorous pretreatment such as degreasing and pickling are immersed in molten zinc at temperatures above 450℃. Through a high-temperature reaction, a zinc-iron alloy layer and a pure zinc layer are formed on the steel surface. Its corrosion protection relies on a dual mechanism: first, a physical barrier—a dense zinc layer isolates it from air, moisture, and salt spray; second, cathodic protection—zinc's electrode potential is lower than iron's, so when the coating is partially damaged, zinc preferentially sacrifices itself to protect the steel substrate from corrosion.

3. Uncoated Weathering Steel

This is a green, high-end corrosion protection solution, its core being "rust-stopping rust." By adding alloying elements such as copper, phosphorus, chromium, and nickel to the steel, a dense, stable, and strongly adhering rust layer naturally forms on the steel surface in the atmosphere. This rust layer acts as a natural barrier, effectively blocking oxygen and moisture, significantly slowing down the corrosion rate. According to industry standards, weathering steel supports must have a corrosion allowance in different environments: no less than 0.25 mm per side in general environments, and no less than 0.5 mm per side in highly corrosive environments, thus ensuring a service life of over 25 years for photovoltaic power stations.

In highly corrosive coastal environments, the three corrosion-resistant support solutions each have their own strengths:

Zinc-aluminum-magnesium coated supports: Possessing self-healing properties, suitable for scratch-prone conditions, offering superior protection compared to traditional galvanizing.

Hot-dip galvanized supports: Mature application, cost-controllable, suitable for projects with well-established conventional steel structure processing systems.

Uncoated weathering steel supports: Requires no painting maintenance, relying on its own rust layer for long-term corrosion protection, reducing later operation and maintenance costs.

All three technologies can meet the 25-year durability requirement. Selection should comprehensively consider corrosion level, budget, construction conditions, and operation and maintenance strategies to match actual needs.