In 2023, scientists placed ultrasonic microphones at 12 Midwest solar plants to see how bats responded. 3 years later, the recordings revealed about 50% more calls above the panels than nearby fields, suggesting the sites were attracting activity

When researchers set up ultrasonic microphones at solar farms across the Midwest, they wanted to find out how bats were responding to the growing presence of renewable energy infrastructure. What they recorded over two years was unexpected.

During May and June, bat calls above the solar facilities were about 50% higher than those over nearby agricultural fields, as per a report. The increase was particularly noticeable around dusk, when bats emerge to feed.

The recordings suggested the bats were not simply avoiding farmland during planting season. Instead, the solar sites appeared to be attracting more bat activity.

Researchers monitored 12 solar plants and nearby farms

The study was carried out during 2023 and 2024 at 12 commercial solar plants across the Midwest, as per The Pulse report. Each solar facility was paired with an active agricultural farm nearby, giving researchers a comparison within the same landscape.

Ultrasonic recording units were installed to capture the echolocation calls bats use to navigate and locate prey. The microphones operated during the warmer months, allowing researchers to compare bat activity around the solar facilities with activity over neighboring crop fields.

The results showed a clear seasonal difference. During May and June, weekly bat call levels above the solar sites averaged around 50% higher than over the nearby agricultural fields. Activity peaked around dusk, when bats typically emerge to feed.

The bats were not simply escaping the fields

The timing of the increase was important. Spring planting turns large areas of farmland into bare ground. Tractors disturb the soil, while agricultural activity and chemical treatments can temporarily leave fields with fewer plants and insects.

If bats were simply leaving the farms because of that disturbance, researchers might have expected the solar sites to serve as an alternative place to fly.

But the recordings showed something more specific. Across the weekly monitoring of all 12 sites, bat activity was never higher on the agricultural farms, as per The Pulse report. That pattern suggested the bats were not simply moving away from tractors. They were showing greater activity around the solar installations themselves.

Different bat species responded differently

The recordings also showed that the response was not identical across species. Hoary bats recorded higher call levels over the solar sites during most of the monitoring period.

Big brown bats showed a different pattern. Their activity increased inside the solar sites during the first third of the season before leveling off.

Silver-haired bats showed no clear difference between the two environments, with call levels remaining similar across the sites, as per The Pulse report.

Even with those differences, the overall weekly results showed consistently greater bat activity at the solar facilities than at the neighboring farms.

Native plants may explain why the solar sites attracted bats

The researchers linked the seasonal difference to what was growing underneath the panels. All 12 monitoring sites used an “ecovoltaic” design. Instead of relying on typical gravel or turf grass, the solar facilities incorporated restored native prairie grasses and wildflowers. That vegetation was especially important in May and June.

While surrounding farmland was being tilled and temporarily left as bare ground, the native plants at the solar sites were blooming and supporting insect populations. That gave the solar facilities something the freshly worked fields did not: plant cover and a source of food during an important spring period.

The solar sites therefore appeared to function as temporary feeding areas when nearby agricultural land offered fewer resources for foraging animals.

The recordings show activity, not exactly what the bats were eating

The ultrasonic microphones provide useful evidence about where bats were active, but there is an important limitation. Acoustic monitoring records bat calls. It does not directly prove that the animals were successfully hunting insects at the solar sites.

Researchers would need more work examining specific echolocation calls and insect numbers to determine exactly how the bats were using the facilities.

So the recordings do not establish that the solar plants were directly increasing feeding success. They do show that bat activity was higher above the ecovoltaic solar sites than over the nearby crop fields during the early growing season, as per The Pulse report.

Solar farms can also become part of the landscape

The findings offer a different look at how renewable energy infrastructure can interact with the surrounding environment.

In this case, the combination of solar panels and restored native vegetation created conditions that coincided with greater bat activity during May and June, when nearby agricultural fields were being prepared for planting.

The recordings do not prove that bats were feeding more successfully at the solar sites, but they reveal a clear seasonal pattern in where the animals were active.

As solar development expands across rural areas, the study highlights why what grows beneath and around the panels can be an important part of understanding their ecological impact.