Photovoltaic glare option: shaping the energy transition with IMMI

One of the ways renewable energy is being expanded is through the installation of photovoltaic systems. These plants convert part of the irradiated solar energy into electrical energy, although some of the light is reflected and can cause glare on neighboring buildings and roads - what may be merely annoying for the former can become a real accident hazard for the latter.

The main legal basis for expansion is the Renewable Energy Sources Act (EEG). An official set of rules for assessing photovoltaic glare, on the other hand, does not currently exist. However, general case law is based on the guidance provided by the Bund/Länder-Arbeitsgemeinschaft für Immissionsschutz LAI.

IMMI calculates glare - using astronomical formulas and taking refraction into account

IMMI provides the tools for calculating and assessing glare from photovoltaic installations in our photovoltaic library. Here, for every minute of the year during which the sun is above the horizon, it is checked for every solar module and for every immission point whether glare is present. The sun position is calculated to the minute, depending on the geographical position of the plant, using astronomical formulas. In this process - this is a unique feature of IMMI - the atmospheric refraction is taken into account, which leads to an apparent elevation of the sun by up to half a degree near the horizon.

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For each position of the sun (1-minute cycle), the reflection at each module is calculated. This calculated directional vector of reflection is applied to the observed receptor point and checked to see if it is inversely incident on the current module. If this is the case, glare is present. During this calculation, it is also checked whether the reflected beam hits an obstacle. This can be, for example, another solar module, a bush or a wall or a terrain edge. This also allows measures to be planned to reduce glare.

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Precise use of resources for glare reduction thanks to precise calculation

Detailed result lists for glare duration, glare days, minute glare times throughout the year, etc. are listed for each immission point. In addition, the number of glare minutes is recorded for each solar module examined. This allows critical modules that contribute significantly to glare to be identified. Based on the IMMI analysis, these can then be specifically provided with reflection-preventing coatings.

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