Humid climate

A humid climate exposes PV equipment to long periods of high humidity, dew and high surface conductivity, which can trigger hydrolytic degradation of module materials. Moisture that gets into the module, together with acetic acid released when EVA encapsulant hydrolyses, corrodes the cell metallization and causes severe metallization corrosion that shows up as dark areas in EL images. In humid subtropical regions, fungal biofilms grow on module surfaces and cause widespread fungal soiling losses that may not recover after rain. Deep backsheet cracking is often followed by moisture ingress and corrosion, and this happens more often and more severely in hot and humid conditions. Where dissimilar metals touch, such as an aluminium frame on a steel structure, galvanic corrosion forms around fastening screws in humid areas, so the metals should be insulated from each other. Field data from Florida showed modules in a hot, humid subtropical climate degrading almost twice as fast as the same modules at dry or cool sites. To limit losses, include bio-soiling in cleaning schedules and check that cleaning actually restores output, and do not assume rainfall resets the loss. Install modules only within the humidity limits set by the manufacturer; one installation manual specifies below 85 RH%.

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• sentence 1: support check: partial - Table lists humidity, dew and high surface conductivity as stressors that can induce hydrolytic degradation, but does not link them to humid climates specifically or say 'long periods'.
• sentence 2: support check: partial - Moisture, EVA hydrolysis producing acetic acid, metallization corrosion and EL dark areas are stated, but 'severe' corrosion is not stated and moisture is described as root cause of dark EL areas after long exposure.
• sentence 3: support check: partial - Passages support persistent losses in humid subtropical regions possibly not recovering after rain and mention sub-aerial biofilms, but do not explicitly say fungal biofilms grow on module surfaces (only that biofilms are confirmed by inspection).
• sentence 8: support check: partial - Passage gives humidity < 85RH% as an installation condition, but doesn't state the general 'only within manufacturer limits' principle beyond this one manual, and it doesn't identify the source as one manual's specification explicitly. -->