A review of imaging methods for detection of photoluminescence in field-installed photovoltaic modules

It is predicted that the photovoltaic energy conversion will be the largest installed power capacity by 2027. The least costly option for new electricity generation in many of the world’s countries will be the utility-scale solar photovoltaic electricity generation. Accurate monitoring of solar plants for localizing and detecting faults is expected to be one of the critical tasks facing the energy industry. Imaging of photovoltaic modules for the purpose of fault detection can be more efficient and accurate compared to measurements of electrical parameters. Different spectral regions provide different types of information about a faulty module. Detection of photoluminescence, that is, radiation emitted upon band-to-band recombination after charge carrier excitation with an illumination source, has shown a great potential in the laboratory setting. In the recent years, the first approaches in the outdoor setting have been conducted on silicon modules with the Sun and a LED module as excitation source. The present study sums up the different methods for outdoor photoluminescence imaging and emphasizes their differences regarding filtering of the reflected light from the photoluminescence signal. The different types of photoluminescence images obtained from each method and the image processing algorithms are described. Finally, the interpretation of the different types of photoluminescence images is addressed.