Bat activity patterns during the deployment of a ground-mounted photovoltaic farm in a Mediterranean agricultural landscape: an exploratory multi-stage study
This exploratory study in central Italy reveals that bat activity patterns during the deployment of a ground-mounted photovoltaic farm are taxon-specific and spatially structured, showing no significant differences across construction phases within the facility but lower activity at the site compared to agricultural references in early seasons and higher activity along the illuminated perimeter in late summer.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
The world is shifting its energy sources, moving away from fossil fuels that warm the planet and toward renewable power that does not. Among these new technologies, solar energy is growing faster than almost any other, with vast fields of panels being installed across farms and open landscapes to capture sunlight. While this transition is essential for the climate, it brings a new set of questions about how these massive installations interact with the natural world. One group of animals is particularly important to watch: bats. These mammals are vital to healthy ecosystems because they eat vast numbers of insects, helping to control pests that damage crops and spread disease. Because they fly at night and rely on sound to navigate, they are sensitive to changes in their environment. When a large solar farm is built, it changes the landscape, the wind patterns, and the availability of food. Scientists need to understand if these new energy fields become empty zones where bats avoid flying, or if they can be managed in a way that allows both clean energy and wildlife to thrive.
In central Italy, researchers set out to answer these questions by watching a specific solar farm as it was built and began to operate. The site, located in a farming region near the town of Montalto di Castro, covers about 70 hectares and holds enough panels to generate 37 megawatts of power. To understand what was happening to the local bat population, the team placed sensitive recording devices in the air, listening for the high-pitched calls bats use to find their way and catch insects. They did not try to catch or handle the animals; they simply listened. The study was designed to catch the story at three different stages: before any construction began, while the ground was being cleared and the panels were being installed, and finally, when the farm was running and producing electricity. They also compared the activity inside the solar farm to nearby fields that were still being used for traditional farming, and they paid special attention to the edges of the site where security lights were installed.
The listening took place over three years, from 2023 to 2025. In the beginning, before the solar farm existed, the researchers recorded the bats in the grassy fields that would soon become the solar array. As construction started the following year, they returned to the same spots to see if the noise and activity of building had scared the bats away. When the farm opened in early 2025, they listened again. They found something surprising: during the late summer months, the amount of bat activity inside the solar farm did not change significantly from the time before construction, through the building phase, and into the early days of operation. The bats were still there, flying around the panels just as they had before the ground was broken. This suggests that for the types of bats that use this open landscape, the mere presence of the solar farm did not immediately drive them away during the summer.
However, the story changed when the researchers looked at the early part of the season, from May to June, and compared the solar farm to the nearby agricultural fields. During these months, the solar farm was noticeably quieter. In both 2024 and 2025, fewer bats were detected inside the solar array than in the neighboring farmland. This difference was not the same for every type of bat. Some species, like the common pipistrelle, showed much lower activity inside the solar farm than in the fields. Others, such as the Savi's pipistrelle and the Myotis group, showed no clear difference between the two places. This tells us that the solar farm does not affect all bats in the same way. Some species seem to avoid the open space under the panels, perhaps because they prefer the edges of fields or the shelter of trees and bushes that are less common inside the array. The solar farm might be missing the specific features these bats need to hunt or travel comfortably.
The most striking difference appeared at the very edge of the solar farm in the summer of 2025. The researchers placed a recorder along the perimeter fence, where security lights were turned on at night. Here, the bat activity was dramatically higher than anywhere inside the solar farm. The area around the fence was buzzing with life, particularly for the three most common types of pipistrelle bats and the Savi's pipistrelle. These bats seemed to be drawn to the light, likely because the lights attracted insects, creating a rich buffet for the bats to feed on. Inside the dark, open space of the solar array, however, the activity remained low. The researchers could not say for certain if the light itself was the only reason for this difference, as the fence also provided a physical structure that bats often use as a guide while flying. But the pattern was clear: the edge of the site was a hotspot for activity, while the center was not.
This study highlights that the impact of solar farms on wildlife is complex and depends on who you ask. For some bats, the solar farm is just another open space they can use, but for others, it is a place they avoid, especially during certain times of the year. The fact that the perimeter lights attracted so many bats suggests that how a solar farm is lit and managed matters greatly. While the lights created a feeding ground for some species, they might also be pushing away other bats that are afraid of the light. The researchers emphasize that this was a single site, and the landscape around it was already changing with many other solar farms being built nearby. To truly understand how to build solar energy that supports nature, more monitoring is needed across different types of farms and landscapes. The goal is to find ways to design these facilities so they can produce clean energy without forcing wildlife to choose between a safe home and a place to eat. By listening carefully to the bats, scientists are learning that the path to a green future requires paying close attention to the small details of how we build and manage our energy systems.
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