Development of a Soiling Detection for Photovoltaic modules Based On Static Cameras

Abstract

During the operation of photovoltaic power plants, soiling reduces the generated power by 3 to 4% on the global average. For quantitative soiling analysis, measurement equipment commercially available covers only small measurement areas. Other published optical measurement methods of soiling use drones. One limitation of these methods is the short duration of the drone flight. Continuous measurements can be enabled by static cameras, such as, surveillance camera. This study presents a method to determine the soiling of PV plants over a large area with a high resolution. Depending on the PV park, already existing cameras can be used, avoiding extra costs. A commercially available surveillance camera captures RGB images of the modules to be measured. The method is based on the evaluation of the light scattered by the dirt particles increasing the brightness of the module’s dirty areas. In the first step of the analysis, perspective-rectified orthoimages are calculated. Then the brightness analysis is performed, considering the given geometry. The results showed for optimal conditions, that is, a clear sky, the method has a relative deviation to the electrical reference measurement of 2% to 4% and a relative error of 12% to 14% for a clear sky with some clouds. In case of adverse meteorological conditions, the accuracy decreases. In addition, iit was found that, apart from the predicted limitations of the method, one more aspect needs to be considered, which is the existence of bird drops.