Characterisation of the Glare Properties of Photovoltaic Modules and PV Systems Using a Photographic Camera

Abstract

With the increasing prevalence of photovoltaic (PV) installations on north-facing roofs in urban areas, the issue of glare on PV modules is becoming more significant. This paper presents a method for measuring and characterising the intensity and type of glare using a commercially available photo camera. The method utilises the fact that brightness information is inherently contained in a photograph. Due to the strong non-linearity of brightness information in an image, especially when using High Dynamic Range (HDR) functionality, an image needs to be divided into multiple sub-images with clearly defined settings, and the linear range extracted from each of them. The information obtained in this way is then assembled into a new image. The resulting luminance image describes the intensity and shape of glare, forming the basis for calculating the occurrence of glare (times and days of the year) in a simplified manner.