PV Glare & Law: A Practical Guide

Photovoltaic systems are booming – but with more solar power, conflicts are also increasing: glare from reflected light is becoming a stumbling block in approvals. While the EU aims to accelerate expansion with the new Buildings Directive (external link) (EPBD 2026), many countries are simultaneously tightening glare protection rules. Where previously only performance mattered, authorities now scrutinize: How long and how intense may solar modules cause glare? Those who do not plan ahead risk costly retrofits – or, in the worst case, dismantling.

Europe: Regulatory drivers and regional standards

In Europe, the revised EPBD (Energy Performance of Buildings Directive) forms the common framework. Since May 2026, it requires member states to fully exploit the solar potential on almost all new buildings. As there is no uniform “ISO standard for glare,” implementation varies between countries.

Germany: Residential space vs. infrastructure

In Germany, assessment is carried out on two levels: protection of the neighborhood and traffic safety.

The 30-minute rule (LAI)

For protected residential spaces, the guideline of the Federal/State Working Group on Immission Control (LAI) (external link) has established itself as the gold standard. Courts refer to two threshold values:

• 30 minutes per day: Maximum astronomical glare duration.
• 30 hours per year: Cumulative annual total exposure.

Technical avoidability is becoming increasingly important. Courts are increasingly ruling that mitigation measures (such as structured surfaces or retrofitting with anti-glare films) are to be expected from the operator as soon as they are technically feasible – regardless of meeting the time limits.

Critical infrastructure and the FBA key issues paper

For highways, railway lines, or airports, the focus shifts to pure traffic safety. The Federal Highway Authority (FBA) has established binding criteria with its key issues paper (external link) (as of Nov. 2025). In the traffic-relevant field of view (horizontal ±30°, vertical up to 10°), time limits no longer apply. Decisive are strict physical limit values:

• From 30,000 cd/m²: Potential glare; detailed assessment of contrast reduction required.
• From 100,000 cd/m²: Absolute glare; exclusion criterion for approval. A glare expert here does not assess nuisance but whether the eye’s adaptation ability is maintained and signal systems remain recognizable at all times. Since the FBA requires the use of the latest technology, reflection-reducing measures such as microstructured surfaces are often mandatory conditions for grid connection on federal highways.

A detailed classification of these values compared to natural sunlight can be found here.

Austria: The Shift to Technology Neutrality

In December 2024, the complete withdrawal of the OVE Guideline R 11-3 (external link) marked a legal turning point. The experts’ reasoning was groundbreaking: glare is not a PV-specific emission but originates from all reflective surfaces (such as glass facades or metal). Since then, glare is assessed technology-neutrally under the neighborhood protection provisions of the General Civil Code (§ 364 para. 2 ABGB). Impacts can be prohibited if they exceed the "local customary level." The medical gold standard for experts today is the work "Medical Assessment Criteria for Passive Glare (external link)" from MedUni Vienna, which classifies individual disturbance effects based on actual retinal exposure.

Switzerland: Precision through the FOEN Model

Switzerland relies on a differentiated model from the Federal Office for the Environment (FOEN) (external link), which relates intensity to frequency. Graduated limits apply: 30 minutes daily with unlimited frequency, 60 minutes on a maximum of 60 days, or up to 120 minutes on a maximum of 20 days per year. The absolute upper limit is 60 hours of cumulative glare per year. Since January 2026, Art. 32abis RPV (external link) has tightened requirements: facade systems must be executed "sufficiently adapted" according to the state of the art. Swiss expert reports are also globally leading in considering beam divergence. At shallow incidence angles above 40°, light scatters more strongly, which significantly affects luminance (cd/m2) — a physical effect precisely modeled in modern simulations by the Bern University of Applied Sciences (BFH).

European Neighbors: Infrastructure Expertise and Neighborhood Law

In large parts of the EU, such as France or Spain, regulation is primarily governed by general neighborhood law and integration into the environmental impact assessment (EIA) for major projects.

The Netherlands are a particular pioneer. Here, the infrastructure authority Rijkswaterstaat acts as the central pace-setter. As a global leader in “Solar Highways” (PV in noise barriers or on dikes), Rijkswaterstaat works closely with research institutes such as TNO. They define strict safety limits for glare affecting drivers and ship captains on canals. Due to the extremely high population density in the Netherlands, the reflection studies there are often regarded as an informal “Best Practice” standard for the entire Benelux region.

United Kingdom: The “Glint and Glare Assessment” as a Planning Hurdle

In the United Kingdom, detailed proof is often a mandatory prerequisite for granting Planning Permission. British planning authorities (LPAs) require proactive simulations that follow a clear traffic light logic:

• Green (No Impact): Approvable.
• Yellow (Moderate Impact): Requires mandatory mitigation measures (e.g., structured surfaces).
• Red (Major Impact): Leads to rejection without fundamental plan changes.

A special focus is on the safety of railways. A special focus is on the safety of railways. Network Rail (external link) requires, based on the standard NR/L2/SIG/10157 (external link), proof that reflections neither dazzle train drivers nor impair the visibility of signals (Signal Sighting). British assessments are considered a blueprint for investors in 2026 to design projects as "future-proof" already in the planning stage.

USA: Flight Safety vs. Local Neighborhood Law

In the USA, the legal system is strictly divided. While the federal level regulates flight safety, the protection of local residents is the responsibility of local authorities.

FAA Regulation (Federal Level)

Since the regulation update in May 2021, the FAA aviation authority has focused almost exclusively on protecting control towers (ATCT). Glare affecting pilots is often considered acceptable today, as it resembles reflections from water surfaces. Proof is provided via Form 7460-1, with the FAA no longer prescribing specific tools, thus placing methodological responsibility on the assessors.

Zoning and Public Nuisance (Local Level)

Outside airports, local zoning boards make decisions. Significant impairment may lead to classification as a "Public Nuisance," which under US law can result in severe consequences such as demolition orders. Technically, a strict distinction is made between glint (short flashes < 1 second) and glare (sustained glare > 1 second). The industry standard is the simulation of retinal irradiance according to the SGHAT standard (external link) of the Sandia National Laboratories.

Asia: Strict Limits in the Vertical City

In the densely populated metropolises of Asia, such as Singapore or Tokyo, the focus is almost exclusively on Building-Integrated Photovoltaics (BIPV) and facade solutions. The Building and Construction Authority (BCA) in Singapore has set strict reflection limits for facades due to the extreme building density. During the approval phase, computer clustering is used to simulate how reflections affect opposite high-rise buildings. The goal is to prevent visual disturbances in residences and the heating of street canyons caused by concentrated reflections.

Australia and Canada: Flight Safety and US Standards

Australia and Canada prioritize flight safety in their regulations under the supervision of CASA and Transport Canada, respectively. In residential areas, decisions are usually made by local municipalities. Since detailed national standards for urban areas are often lacking, the US SGHAT standards (Sandia National Laboratories) have become the technical benchmark in these countries. This highlights the trend that scientifically based simulations of retinal irradiance have become the global language in glare management.

Limits for PV Glare in Comparison (2026)

Country / Region	Focus	Max. Glare Duration (per Day)	Max. Luminance (cd/m2)	Legal Basis / Standard
Germany	Living Space	30 Minutes	—	LAI Notes
Germany	Infrastructure	—	105 (Exclusion)	FBA Key Issues Paper
Switzerland	Living Space	30–120 Min. (staggered)	—	Art. 32a RPV / BAFU
Austria	Living Space	"Local Standard"	Medical Examination	§ 364 ABGB / MedUni Vienna
United Kingdom	Planning	Traffic Light System	Project-Specific	Planning Permission / Network Rail
USA (FAA)	Air Traffic	—	105 (Exclusion ATCT)	FAA Form 7460-1
Singapore	Facades	Strict Limits	Clustering Analysis	BCA Guidelines

 

Practical Guide: Conflict Management and Technical Solutions

If a complaint arises despite careful planning, calmness is required. In 2026, case law increasingly follows the principle of proportionality: before ordering dismantling or a permanent shading mandate, all reasonable technical mitigation measures must be exhausted.

Strategic Evidence Preservation: The Fact Checklist

Well-founded documentation is the best basis to objectify emotional debates and achieve out-of-court settlements:

• Precise Event Log: Record the date and exact time (from/to). Often, comparing with solar position calculations reveals that the problem occurs only on a few days per year for minutes – information that immediately defuses many conflicts.
• Determination of Physiological Relevance: Which rooms are affected? A brief reflection in a hallway is legally assessed differently than persistent glare in a home office or bedroom.
• Professional Photo Documentation: Take photos directly from the point of incidence (from the neighbor’s perspective). Important: Avoid wide-angle lenses, as they unnaturally reduce the light source and weaken the evidential value.

Technical Intervention: Solutions Instead of Decommissioning

Experience shows: Almost every glare conflict can be physically resolved. The priority is always to preserve the system’s capacity.

• Geometric Fine Adjustment: Often, changing the installation angle or orientation by just a few degrees is enough to deflect the reflection beam out of the neighbor’s critical field of view.
• Structural Shielding: Installing localized glare protection fences or strategic planting can interrupt the direct line of sight without endangering the entire project.
• Surface Retrofit: The most efficient solution is the application of microstructured anti-glare films. These films convert specular (mirror-like) reflection into diffuse scattering. This reduces the luminance immediately below the critical limits, while light transmittance and thus energy yield remain almost fully preserved.

Conclusion

The legal situation regarding PV glare in 2026 is complex but absolutely manageable with modern simulation and measurement technology. Whether the 30-minute rule in Europe or retinal irradiance limits in the USA – the goal remains balancing the global energy transition with individual neighborhood harmony. Those who plan proactively and rely on well-founded documentation in case of complaints secure their investment in the long term.