Solution: Glare Assessment for Photovoltaic Systems

Large reflective surfaces (photovoltaic systems, glass and metal façades, etc.) can cast sunlight over large areas where people are dazzled at work or in traffic. In case of doubt, it is advisable to have the glare effect of the building project analyzed by a lighting expert.

Our eyes can adapt relatively well to a luminance range of up to around¹⁰⁴ –¹⁰⁵ cd/m², but above this, absolute glare must be assumed. The core problem with many PV systems, however, is that the sun can still have a luminance of over¹⁰⁸ cd/m² even at low levels, which means that the threshold of absolute glare is exceeded even with a reflectance of only 1% on the PV elements.

In order to deal with the increasing number of problematic cases due to the growing attractiveness of photovoltaic systems, the report “Medical Assessment Principles of Passive Glare” published by the Institute of Environmental Hygiene, ZPH of the Medical University of Vienna in 2013 and the OVE Guideline R 11-3 “Glare from Photovoltaic Systems” in 2016 set out fundamental specifications for Austria regarding the determination and assessment of system-related reflections. Similar regulations now also exist in Germany and Switzerland.

The fact that the OVE Guideline R 11-3:2016 was withdrawn on 01.12.2024 is the responsibility of the Austrian Electrotechnical Association (OVE). Irrespective of this, the methodology for assessing solar reflections described in the guideline has been tested and recognized until new rules of technology replace the previous method in the future.

In this regard, there are already several court rulings on the local custom and reasonableness of PV-related reflections.