Tracing the glare off photovoltaic panels

Enjoy the sun – with no extra dazzle

© Photo ifong/Shutterstock

New software from Fraunhofer FIT calculates where and when planned PV installations produce dazzling glare. The picture shows – as white lines – the sunlight shining down on the PV modules of the Frankfurt Airport and – as yellow lines – the reflections depending on the time of day and the time of year. Marked in yellow: those sectors of the air corridor (shown in turquois) for incoming or starting planes where dazzling effects may occur.

The glare of large-scale PV installations close to an airport or in the vicinity of a highway is a safety hazard. For this reason, before such an installation may be built, engineers calculate, for a few selected days of the year, if and where there will be dazzling reflections. This task will soon be easier – and the results more comprehensive: A new piece of software will calculate a 3D diagram of all reflections. The software is being developed by Fraunhofer FIT in cooperation with the Mecklenburg-Vorpommern State Office for the Environment, Nature Conservation and Geology, and several consulting engineers.

The software generates a 3D view for any chosen time of day and time of the year and reconstructs the whole scene in a three-dimensional space that shows the map, elevation profile, sun, three-dimensional buildings and the planned PV installation. This allows simulating the trajectory of the sun and the reflections for any chosen period of time and in any desired direction; even the elevation of land areas and obstacles like trees or noise barriers are included in the calculation. On their displays the planners can move the PV installation around and immediately see at what times and in which locations conflicts will arise.

The software was initially produced and evaluated for the region around the Frankfurt Airport. In preparation is a new version that will be able to load topographical maps and can therefore be used for any desired location. This new version will dynamically download map information including elevation data from the German Federal Agency for Cartography and Geodesy and will use this information to generate a three-dimensional view of the area under study, which is the basis for all further calculations.

The software can also be used in the planning of rooftop PV installations, which often create conflicts with neighbors who suffer from the glare. According to the German Law, they may be exposed to dazzle for a maximum time of 30 minutes per day and 30 hours per year. For large-scale PV installations, the State Offices for the Environment commission expert opinions to determine that they are planned in line with the legal requirements. The new software will answer this question faster and more reliably. If used as a service for the local planners and installers of rooftop PV installations, it might also help keep the neighbors on friendly terms.