Methodology for Capturing Number of Pixels Calculation for Detailed Infrared Inspection of Photovoltaic Panels

The needed green transition leads to decentralized production of electricity from PV systems, which means more installations in urban areas that increase the fire-risks. For better PV system performance and fire risk prevention the damaged PV panels must be detected and replaced. The diagnostics is often done by IR or EL thermography analysis that require the capturing number of pixels to be known for more precise results. In this regard, a methodology for precise calculation of the capturing number of pixels and proper camera selection, based on sensor resolution and viewing angles is presented. It is necessary in the daily practice and for training and education purposes of PV system installation specialists. The methodology consists of two main steps. The first one is rough calculations of the capturing number of pixels. The second step consists of corrections of the initial calculations for the actual horizontal and vertical viewing angles of the camera in relation to the monitored PV panel plane. The presented methodology is precise enough for most cases. The calculations for the best- and worst-case scenarios are usually enough, because all other cases are within that range. The corrections of the pixel sizes based on the viewing angles of the camera are necessary because the rough calculations, based on viewing distance only, return results with exponentially growing error for viewing angles further away from 90°. The error doesn’t depend on the viewing plane, but it depends on the viewing angle. For that reason, the vertical viewing plane is usually more critical because the vertical viewing angle for stationary installations often significantly differs from 90° and in this case, the time-consuming corrections are needed for more precise monitoring system design.