Testo — 872 thermal imager

Our arithmetic: the manual’s table gives 1.3 mrad next to the SuperResolution entry, while a 42° field of view across 320 pixels works out to about 2.3 mrad per native pixel (we read 1.3 mrad as the SuperResolution figure; the manual’s layout is ambiguous). At 2.3 mrad one pixel covers about 23 mm at 10 m. Current module cells are roughly 160–210 mm wide, so a cell spans only about seven to nine native pixels at 10 m — enough to spot a hot cell, but a poor tool for small defects at long range or from the ground at utility scale.

The manual says the camera needs about 10 minutes after switch-on to adjust for maximum measuring accuracy, so switch it on before you reach the array rather than at the first string.

Do not point the camera at the sun or any object above 650 °C — the manual warns the microbolometer detector can be damaged and the manufacturer gives no warranty for such damage. Reflections of the sky and sun off glass are a real issue when inspecting modules, so plan the viewing angle.

Emissivity (0.01–1) and reflected temperature must be set correctly. A module’s front is a coated glass surface that reflects the sky and surroundings, so treat absolute temperatures with care and rely on differences between cells. For PV thermography procedures, the relevant guidance is IEC TS 62446-3 — check its imaging-condition requirements before you use any camera for commissioning reports.