PV brackets are long-term outdoor service equipment with a 25-year design life. Huge day-night temperature difference and seasonal temperature alternation cause continuous thermal expansion and contraction of brackets and fasteners. Inconsistent expansion coefficients lead to reduced thread preload, batch loosening, thread seizure and stress fracture. Bracket shaking, offset and component crack are mostly caused by uncontrolled fastener thermal deformation.
| Bracket Material | Thermal Deformation Feature | High-frequency Failure | Core Cause |
| Aluminum Alloy Bracket | Large expansion & contraction range | Screw loosening, gasket crushing, hole expansion | Asynchronous deformation between aluminum profile and steel screws |
| Galvanized Steel Bracket | Stable deformation, easy coating aging | Coating peeling, rust seizure, slight loosening | Temperature difference accelerates coating aging and thread rust |
| Stainless Steel Bracket | Uniform deformation, easy stress concentration | Thread seizure, non-detachable locking, brittle fracture | Stainless steel thread self-occlusion under high temperature without lubrication |
1. Aluminum alloy brackets: Adopt stainless steel fasteners + elastic lock washers to compensate thermal gap changes; single hard gasket installation is forbidden to avoid profile hole crushing. 2. Galvanized steel brackets: Use Dacromet or thickened galvanized fasteners to match anti-corrosion grade and reduce aging rust; recheck preload in spring and autumn every year. 3. Stainless steel brackets: Apply anti-seize lubricant during assembly, control final tightening torque and reserve thermal expansion margin.
1. Summer inspection: Focus on joint loosening and thread rust with maximum thermal deformation; 2. Winter inspection: Check bolt fracture and gasket cracking caused by low-temperature embrittlement; 3. Post-rain recheck: Re-tighten rusted threads and supplement anti-rust coating; 4. Unified replacement standard: New replacement parts must match original material and surface treatment to avoid aggravated loosening.