Cracked front glass

The module glass is cracked in one spot or across the whole module. Tempered glass shatters into small pieces, while annealed glass breaks into large pieces. On non-tempered glass the impact point is easy to find because the glass does not fragment. This helps you tell a surface impact apart from a break that started at the edge. Common causes are hail, stones or other impacts, bad clamps or over-tightened screws, transport damage, and heat from hot spots or arcing. A defective mounting structure can also put extra stress on the glass. Thin glass/glass bifacial modules often crack on the rear glass first, so check the back of the modules as well as the front. Module power often does not drop right away. An inverter isolation or ground fault alarm may be the first sign, especially in wet weather. Visual inspection is the simplest way to find broken glass. IR imaging shows hot spots or hot broken cells, and EL or UV fluorescence shows the cell cracks behind them. Over time, moisture getting in corrodes the cells and circuits. A fully broken module can reduce current in the whole string, so replace modules that pose a safety or insulation risk.

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• sentence 5: support check: partial - u8 says module power is typically not affected immediately and isolation failure may be a first fault signal at the inverter, and u10 ties insulation loss to wet conditions. Neither passage says the isolation alarm is the first sign especially in wet weather, and the sources say 'isolation failure', not 'ground fault alarm'.
• sentence 6: support check: partial - u20 supports visual inspection as simplest, IR for temperature anomalies, and EL or UV fluorescence for cell cracks. The 'hot broken cells' wording is in u3. The claim that EL or UV fluorescence shows the cracks 'behind' the hot spots is the statement's own framing and is not in the passages. -->