Detecting Defects in Photovoltaic Cells and Panels With the Help of Time-Resolved Thermography Under Outdoor Environmental Conditions

Abstract

This paper investigates defects in photovoltaic (PV) cell and panels, in particular, the size and location of defects. We concentrate on characterising photovoltaics under outdoor environmental conditions with the help of synchronized thermography (ST) and time-resolved thermography (TRT). Infrared (IR) images are obtained under changing solar radiation levels and moderate wind speeds with the help of a portable IR-camera. We demonstrate that IR-images obtained outdoors by ST and TRT provide the same information in the same accuracy as IR-images recorded indoors. We elaborate the differences in parameters such as measurement time and region-of-interest (ROI) which need to be adjusted when moving from indoor to outdoor environments. Our technique allows maintenance staff to carry out measurements on the site of a PV power plant to identify PV panels with defects in an easy way.

Thermography of Photovoltaic Panels and Defect Detection Under Outdoor Environmental Conditions

“…In this paper, we extend our analyses presented in [23] related to possible ambient temperatures during measurements. More precisely, we focus on harsh outdoor environmental conditions in which ambient temperatures are below zero degree Celsius.…”

“…It is worth noting that the usability and accuracy of thermography measurement technologies in the available literature [20], [21], [23] has been tested only under common outdoor environmental conditions, but not during harsh outdoor environmental conditions. Hence, in this work, we aim to verify potential impacts of harsh outdoor environmental conditions on thermography measurement results.…”

“…3 shows the available data from the back of the PV panel DSP-5P manufactured by the [lux.pro] solar Corporation which was used within experiments. This type of PV panel was also used in previous research [11], [16], [17], [23].…”

“…3: Data provided by the PV manufacturer tions. As in [16], [17], [23], [24], an external power supply was used to forward bias the DUT and heat up the PV cells within the panel. If there is any defect present in a PV cell, the defect area of that PV cell does not conduct any current and, thus, will not heat up like the rest of the area of that cell.…”

The Solution for the Thermographic Measurement of the Temperature of a Small Object

“…In order to correctly assess temperature distribution on the housing of electronic components, it is necessary to take into account all factors that can influence the measurement [ 6 , 7 , 8 ]. The most important of them include the value of the emissivity coefficient ε [ 9 ], the reflected temperature ϑ r [ 10 ], the distance between the lens and the observed object d [ 11 ], the ambient temperature ϑ a [ 12 ], the temperature of the external optical system [ 13 ], the transmittance of the external optical system [ 14 , 15 ], the relative humidity ω [ 16 ], the viewing angle β [ 7 ], and the sharpness of the recorded thermogram [ 17 , 18 , 19 ]. An assessment of the influence of the abovementioned factors on the accuracy of the thermographic temperature measurement of small-sized electronic components is possible thanks to the use of a microscopic thermography stand.…”