Outdoor PL imaging of crystalline silicon modules at constant operating point

Photoluminescence (PL) imaging is a powerful inspection technique that has found widespread applications in photovoltaic research and in high volume production. Recently, the use of this technology has been expanded to include the inspection of field-deployed solar modules under full sunlight conditions. However, the methods demonstrated so far require electrical switching of the tested modules between two electrical operating points, the PL signal given as the difference between two near-infrared images. In the current work we propose a simplified approach in which PL images are taken without the need for toggling between two operating points. The principles of the technique, which has significant practical advantages, are discussed and experimental proof of concept data are provided.