As solar panels age, their performance can suffer due to cracks, bypass diode failures, chemical degradation, and other issues. Thermal infrared and electroluminescence imaging techniques have been used to identify these issues in outdoor photovoltaic solar cells. However, the former provides limited information, and the latter traditionally requires imaging at nighttime as well as sending electrical currents through the panels.

Vuković et al. presented a non-invasive method for taking photoluminescence images that doesn’t impact the solar panels’ power output. Since drops in electrical current occur occasionally in solar cell modules connected to state-of-the-art string inverters, the novel method simply waits until such a drop occurs.

With this method, a short-wave infrared camera takes a series of images and moves on to the next set of solar modules once a drop occurs. The system only needs the imaging apparatus and no additional equipment and has the potential to be much quicker than other similar measurements.

“We are most excited about the fact that this approach makes the photoluminescence imaging possible without interfering with the photovoltaic system,” said author Marija Vuković. “Additionally, these images give us more information than thermal images, and, if acquired from drones, they could be collected quickly and efficiently.”

So far, the method has only been applied from the ground at one test site. In the future, the authors hope to test it on other solar modules, with cameras both on the ground and from drones, in order to scale up the method for commercial usage.

Source: “Non-invasive photoluminescence imaging of silicon PV modules in daylight,” by M. Vuković, M. Jakovljević, A.S. Flø, E. Olsen, and I. Burud, Applied Physics Letters (2022). The article can be accessed at