Journal of Insect Conservation

, Volume 20, Issue 4, pp 663–675 | Cite as

Polarized light pollution of matte solar panels: anti-reflective photovoltaics reduce polarized light pollution but benefit only some aquatic insects

  • Dénes Száz
  • Dávid Mihályi
  • Alexandra Farkas
  • Ádám Egri
  • András Barta
  • György Kriska
  • Bruce Robertson
  • Gábor Horváth


Photovoltaic solar panels represent one of the most promising renewable energy sources, but are strong reflectors of horizontally polarized light. Polarized light pollution (PLP) associated with solar panels causes aquatic insects to prefer to oviposit on panels over natural water bodies, with potential to negatively impact their global populations as solar energy expands. We evaluate the hypothesis that anti-reflective coatings (ARCs) used to increase the energy efficiency of solar panels will reduce the amount of PLP they reflect, and their attractiveness to aquatic insects. We created artificial test surfaces that mimicked the optical properties of coated and uncoated solar panels and exposed them to wild populations of polarotactic mayflies (Ephemeroptera), horseflies (Tabanidae) and non-biting midges (Chironomidae) used as indicators of PLP. We evaluated the reflection-polarization properties of test surfaces from four different angles of view and under sunny and overcast skies in the visible and ultraviolet parts of the spectrum. Matte (i.e. ARC-coated) sunlit solar panels were strong sources of horizontally polarized light only when the sun was afront and behind, in contrast to uncoated panels which exceeded common polarization-sensitivity thresholds for aquatic insects from all four viewing directions. As predicted by these polarization patterns, horsefly numbers and water-seeking behaviors were significantly reduced by ARCs. Under overcast skies, both matte and shiny (i.e. uncoated) panels were insect-detectible sources of PLP. Matteness modestly reduced the degree of polarization of reflected light, but not sufficiently such that fewer chironomids were attracted to them. Mayflies actually preferred matte panels under overcast skies. ARCs are most likely to reduce PLP and benefit aquatic insects under sunny skies and when used in conjunction with white non-polarizing gridding, but may actually exacerbate the severity of their negative effects under overcast conditions. Consequently, even current ARC technology has a role to play in aquatic insect conservation, but strategic deployment of solar panels away from water bodies and temperate regions may trump these benefits.


Aquatic insect Mayfly Chironomid Horsefly Anti-reflective coating Photovoltaics Polarization Solar panel Polarized light pollution Polarotaxis Polarization vision Visual ecology 



This work was supported by the grant NKFIH PD-115451 (Studying the polarotaxis of aquatic arthropods and complex optical ecological traps in the aspect of conservation biology) received by Ádám Egri from the Hungarian National Research, Development and Innovation Office. Alexandra Farkas was supported by a grant from the Templeton World Charity Foundation, Inc. (TWCFI). The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of the TWCFI. Many thanks to Csaba Viski (Szokolya, Hungary), who allowed our experiments on his horse farm. We are grateful to the Danish firm, Sunarc Technology, which provided us with the matte glass panes used in anti-reflective photovoltaic solar cells. We are grateful to Miklós Blahó for his assistance in the field experiment in Szokolya. The authors have no conflict of interest to declare. We are grateful to two anonymous reviewers for their constructive and positive comments.

Supplementary material

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Supplementary material 1 (DOC 1691 kb)


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Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  • Dénes Száz
    • 1
  • Dávid Mihályi
    • 1
  • Alexandra Farkas
    • 1
    • 2
  • Ádám Egri
    • 1
    • 2
  • András Barta
    • 1
    • 3
  • György Kriska
    • 2
    • 4
  • Bruce Robertson
    • 5
  • Gábor Horváth
    • 1
  1. 1.Environmental Optics Laboratory, Department of Biological Physics, Physical InstituteEötvös UniversityBudapestHungary
  2. 2.Danube Research InstituteMTA Centre for Ecological ResearchBudapestHungary
  3. 3.Estrato Research and Development Ltd.BudapestHungary
  4. 4.Group for Methodology in Biology Teaching, Biological InstituteEötvös UniversityBudapestHungary
  5. 5.Division of Science, Mathematics and ComputingBard CollegeAnnandale-on-HudsonUSA

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