Design and Fabrication of an Infrared Imaging Setup for Solar Cell Defect Detection

Solar panels consist of solar cells that use the energy of the sunlight to produce an electric current and output electrical power. Solar cells may contain defects that are created during the manufacturing process or can develop new defects after production while operating in the field or during transportation. Detection of these defects and monitoring the health of solar panels are extremely important since defects reduce cell efficiency and can jeopardize the operation of a solar panel. A common type of defect is microcrack which are often not visible to the naked eye or a regular camera. Infrared (IR) electroluminescence imaging technique has the capability to detect these micro-cracks, and in some cases other types of defects. Commercial electroluminescence (EL) experiment setups are very expensive. Our research project is focused on the design and fabrication of a low-cost infrared electroluminescence imaging system to test silicon solar cells. For this research, we have used a digital CMOS sensor-based camera since they are cheaply available and have the capability to capture some portion of the infrared spectrum. The digital camera was modified by removing its infrared-blocking filter and retrofitting an NIR pass filter. The experimental setup consists of the modified camera with a lens, optical filter, a regulated power supply, and aluminum extrusion mounting hardware. A regulated power supply unit injects a current into the solar cell, and a python program controls the camera and the experimental setup. The python program acquires the infrared image directly to a computer and then presents it to the user for visual inspection. Our in-house built EL imaging setup can be used to detect microcrack defects and help to sort good quality solar cells