Electroluminescence camera

An electroluminescence camera takes pictures of the light a PV module gives off when DC current is fed into it in the dark. It is used to find micro cracks, shunts, voltage differences and minority carrier lifetime problems. EL cameras use CCD or CMOS sensors. Silicon CCD sensors give higher resolution at lower cost, while InGaAs CMOS sensors are more sensitive to the crystalline silicon emission peak near 1150 nm. A silicon CCD camera is the recommended type for CdTe modules, whose emission peak is much shorter, at 830 nm. In the field, images are taken at twilight, at night or in low light. Another option is to cover the camera and module with curtains held up by a frame. Consumer DSLR or mirrorless cameras can be converted for EL work by removing the UV-IR filter next to the sensor. These converted cameras typically need exposures of 15 to 30 seconds per image. An EL camera can also be mounted on an octocopter for aerial imaging. Focusing and finding the right exposure for each module type take time, and this still limits EL imaging of large plants in the field.

<!-- review notes

• sentence 4: support check: partial - The curtains option is stated, and the u10 passage says images taken at sunset or night. The u4 row gives twilight/night or lowlight/night as test conditions for camera classes, but the statement's wording mixes these and is not exactly stated. -->