Partly heated cell in IR

In the IR image only part of a cell runs warmer, a pointed or localized heating, rather than the whole cell warming evenly. Localized hot spots are mainly linked to multicrystalline cells and local junction breakdown, while monocrystalline hot cells tend to heat across the whole cell area. Common causes are partial shading, for example a bird dropping or a lightning protection rod, a cracked part of a cell, or an imaging artifact. When a crack is the cause, the power reduction depends on the shape and size of the cracked part, and a close visual inspection of the cell may reveal the crack. Persistent hotspots are also associated with solder bond defects, soiling shadows, bypass diode behaviour or mismatch that drives part of the module into reverse bias. Image modules under load in steady state on a clear day with low wind, at a minimum of 700 W/m2 per one source or above 600 W/m2 per another, and compare short circuit, open circuit and maximum power point conditions where possible. Heated cells with temperature gradients of 10 to 20 °C are considered unproblematic for now but should be watched in regular thermographic inspections.

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• sentence 1: support check: partial - The u6 row gives 'Pointed heating' as the pattern, but the passages don't explicitly state that only part of a cell is warmer rather than the whole cell, and u14 describes hot cells as homogeneous. -->