Dissimilar metal contact

Dissimilar metal contact means two different metals touching directly, such as an aluminium module frame fixed to a steel mounting structure, and it causes galvanic corrosion. This corrosion often shows up around the fastening screws where the two metals meet. The risk is highest in humid or coastal areas. It contributes to a defective mounting structure, and visual inspection can show it as corrosion of the frame or the mounting holes. A weakened or damaged mounting structure compromises the modules on it, and in the worst case modules or the whole structure can come loose from the roof or ground. In DC connectors, metal contacts made of incompatible materials, through chemical incompatibility or different thermal expansion, can also cause problems, mostly at string ends or at inverter and combiner box connections. To reduce exposure, place insulation between the two metals, which is required in humid and coastal areas.

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• sentence 3: support check: partial - Passage says galvanic corrosion is important especially in humid or coastal areas, but doesn't say the risk is 'highest' there; close paraphrase though.
• sentence 4: support check: partial - Corrosion of frame or mounting holes is a visual defect of the mounting structure (VI detection), and galvanic corrosion is discussed under that defect, but the passage doesn't explicitly link galvanic corrosion as the cause of those visual signs. -->