The photovoltaic bracket industry uniformly adopts ISO 12944 atmospheric cohesiveness classification (C1 – CX) as the grading basis, and then deducts the coating thickness and process according to the material (carbon steel/aluminum alloy/fastener). The selection logic is: first determine the level based on the on-site environment, and then match the anti-corrosion plan according to the material.
1,Why corrosion prevention is the 'invisible lifeline' of photovoltaic brackets
The photovoltaic bracket needs to support the photovoltaic modules outdoors for 25 years of operation. Its failure often does not result in a sudden collapse, but rather occurs quietly in places that no one looks at every day, such as fastener threads, cut end faces, and column bottom plates - until the bracket begins to shift and the components show hidden cracks, the operation and maintenance team will turn back to find the cause.
2, Choosing the wrong corrosion level comes at a double cost: if you choose it too low, it will rust through in five or ten years, and the replacement cost will be several times the original cost; Choosing too high, coastal standards are piling up on inland projects, eating up profits for nothing. Therefore, understanding the corrosion rating system is not a matter of process details, but rather a core technical capability directly related to project bidding pricing, customer trust, and long-term quality reputation.
3, Core System: ISO 12944 Classification of Atmospheric Corrosivity
The internationally recognized classification of atmospheric corrosiveness comes from ISO 12944-2, which divides the atmosphere into six levels based on the corrosion rate of metals in the environment. Photovoltaic bracket projects rarely encounter C1 (indoor), and actually deal with five levels from C2 to CX.
4,Anti corrosion grade of photovoltaic bracket (IS012944C-1-CX)
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C1-C2 Low |
C3 Medium |
C4 High |
C5 Very high |
C6 Extreme high |
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Indoor dryness /low pollution in rural areas /arid plateau |
Urban suburbs /light industrial areas/moderate humidity |
Coastal towns (1-5km away from the sea)/chemical industrial areas/high humidity |
Surfing Coast/Heavy Industry Zone/ Perennial salt spray and high humidity |
Offshore platform/dock splash zone/strong chloride |
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Carbon steel components are hot-dip galvanized (HDG,ISO1461) |
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4-045 um |
55-70 um |
≥85 um The key component suggestion is 100-115 um. |
≥85 um Or dual coating system |
Specialized Design |
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Anodizing of Aluminum Alloy Components (IS07599/QUALANOD) |
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AA5-AA10 |
AA15 |
AA20 |
AA25 |
AA25+ |
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The most easily underestimated weak point of fasteners |
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HDG bolt or SS304 (A2) |
HDG/TDC or SS304 (A2) |
TDC or SS316(A4) |
TDC or SS316(A4) |
Specialized solution |