In 2010, researchers tested solar panels with white lines; the modified surfaces were up to 26 times less attractive to polarotactic insects

Somewhere close to you, a mayfly is about to make the most disastrous choice in her very short lifetime. She has lived underwater as a nymph until now, and in the few hours she has as an adult, her only mission is to find water and lay eggs. So she uses her instincts to detect the glimmering horizontally polarized light reflecting from a flat dark surface, which is exactly how her kind has been identifying their breeding sites over millions of years. She detects it; she lands and lays her eggs. Only she doesn’t land on a lake; she has landed on a piece of tempered glass on top of a solar panel, and her eggs will soon be baked under it.

As stated in a 2010 study titled “Reducing the Maladaptive Attractiveness of Solar Panels to Polarotactic Insects,” published in the journal Conservation Biology, polarized light pollution is a common occurrence.

The optical illusion nobody saw coming


And here is the kicker: while solar panels were not created with the intention of deceiving insects, their effect is nearly flawless. Dark, smooth, glass-like surfaces reflect light horizontally, and this particular type of reflection is precisely the one that about 300 species of insects living in water use to find their way around, including mayflies, stoneflies, caddisflies, horseflies, and more.

The scientists who conducted the study published in Conservation Biology, led by Gábor Horváth, claim that solar panels polarize light up to 100% in some cases, which means that they are even more appealing to these insects than natural lakes that polarize only up to 30-70%. In behavioral ecology, this kind of mistake is called an ecological trap: animals choose one habitat because it resembles another, but it is less suitable. And it is no wonder that this term was created exactly for such cases.

Why this hits different

Already, utility-scale solar power plants occupy tens of thousands of acres of land in states like California, Texas, and Nevada. These solar farms usually are located near canals, reservoirs, and wetlands: places where insect species are already flying around, searching for a place to breed. Fewer breeding cycles among these insects likely won't stay just a bug problem. Mayflies and caddisflies belong to the lowest part of the food chain in freshwater systems; these insects are food for fish, birds, and bats. Less noise made by bugs upstream may mean less noise for fishing downstream.

The fix is pretty simple

The good news is the same scientists discovered a solution that comes at very little cost, and this is a true head-scratcher. They applied simple white, non-reflective grid lines or borders over the top of a solar panel that disrupted the signal enough to throw off the insects, but not enough to have an adverse impact on the energy output from the panel.

The study also found that panels with white partitions were 10-26 times less attractive to insects than black panels with no changes made, which is an incredible drop when compared to the limited design modification. The researchers calculated that the white lines could cut into panel efficiency by about 1.8 percent based on how much of the panel's surface area the lines cover, which is "a rounding error" most engineers would point out.

The industry still hasn't fully caught up, but we can still focus on the bigger picture

The slightly critical part follows: after sixteen years, the use of white-gridded panels is still not commonplace in most solar projects, large-scale or otherwise. Since then, the concept has been continually advanced with further studies. A 2019 study titled “How to disguise evolutionary traps created by solar panels,” in the Journal of Insect Conservation, notes that the width and spacing of white lines is important, and the fix can be fine-tuned even further without compromising too much power output.

A 2020 PLOS ONE study titled “Bioreplicated coatings for photovoltaic solar panels nearly eliminate light pollution that harms polarotactic insects,” showed that almost all horseflies and mayflies avoided microtextured surfaces copied from the surface of rose petals, and, notably, these bioreplicated textures were found to improve light-harvesting in the panels rather than hurt it, meaning the insect-deterring effect came at no cost to efficiency.

The science behind it exists. The manufacturing change is negligible. The problem is, insects are not present on a shareholder report, and therefore they may not be an incentive for solar companies to bother. However, this may not be a reason not to have solar power at all; it is still one of the cleanest tools we have. It's a case of thorough construction, rather than hasty construction. Adding a few painted lines on a panel is a small price to ask for an industry that promises to be a lot more sustainable.