Mechanical stress reduction

Mechanical stress reduction means cutting down the physical loads on modules that make cell interconnection failure get worse over time. It goes together with replacing modules whose interconnect failures are already electrically active. Reducing stress slows further damage but does not repair broken connections. Interconnections are stressed mechanically during transport, and in operation by repeated wind load, hail and thermomechanical cycling. Static or cyclic mechanical loading can cause broken interconnects, solder bond failures, cell breakage and glass breakage. The joint between the busbars and the string interconnect ribbon fatigues more easily than the other interconnections, so it needs the most protection. When wind or hail bends a framed module, the rear side is put under tension. Microcracks left from transport or installation can then grow. A loose or detached junction box also puts mechanical stress on its internal contacts and can break them, so fix junction box attachment as part of this action. Hotspots from partial shading add thermomechanical stress on the interconnections, so dealing with mechanical loads alone may not stop the fatigue.

<!-- review notes

• sentence 2: support check: partial - Replacing modules with electrically active failures is stated, but the claim that stress reduction slows damage without repairing connections is only implied.
• sentence 5: support check: partial - The busbar–ribbon connection being more subject to fatigue is stated, but the conclusion that it needs the most protection is not.
• sentence 7: support check: partial - A loose junction box putting mechanical stress on its contacts and risking breaking them is stated, but the instruction to fix attachment as part of this action is not.
• sentence 8: support check: partial - Hotspots from partial shading accentuating thermomechanical stress and interconnect fatigue is stated, but the claim that handling mechanical loads alone may not stop the fatigue is an inference. -->