What a thermal inspection finds on a solar array

Heat tells you where to look

Solar modules that are working normally run at similar temperatures in the same sun. A thermal camera makes the outliers visible: one hot cell, one hot module, a whole row running warmer than its neighbors, or a checkerboard pattern across panels.

The IEA PVPS review of infrared imaging for PV field applications describes how these patterns are used to locate defects in operating systems.

Common patterns

A single hot cell often points to a cracked cell or local shading. A uniformly warm module or string can mean it is not delivering power to the inverter. Hot connectors and junction boxes can indicate resistance problems. Each pattern is a likely cause, not a diagnosis, and should be confirmed by a qualified technician.

Conditions matter

IEC TS 62446-3 sets the conditions for outdoor PV thermography, including minimum sunlight on the panels and limits on wind and cloud. Scans taken outside those conditions are screening only. Clean the array first: soiling and bird droppings create their own thermal patterns.