Solar panels did more than generate power in a French nectarine orchard: positioned horizontally during frost, they kept buds up to 1.9°C warmer and cut damage to below 10%

A cold spring night can be enough to wipe out the flowers that would have become a season’s fruit. But a study from France has found that solar panels placed above nectarine trees may give a second line of defense, helping keep flower buds warmer when frost settles over the orchard.

Researchers found that nectarine trees growing beneath a dynamic agrivoltaic system had warmer nighttime temperatures during frost events than trees growing without panels. The difference was especially notable inside the flower buds, where temperatures were up to 1.90°C higher under the panels on one of the monitored frost nights.

The study, led by Gerardo Lopez, was published in the AgriVoltaics Conference Proceedings in 2024 following the AgriVoltaics World Conference 2023. Published on May 23, 2024, the paper, titled “Protecting Flowers of Fruit Trees From Frost With Dynamic Agrivoltaic Systems,” examined whether movable solar panels could reduce frost damage in a nectarine orchard in Étoile-sur-Rhône, France.

How solar panels became a frost shield

The experiment focused on a mature ‘Kinolea’ nectarine orchard divided into an agrivoltaic plot covering 1,725 square meters and an adjacent 1,500-square-meter control plot without panels.

The researchers used a dynamic system in which the solar panels could change position. During nights when temperatures fell below 5°C, the panels were moved into a horizontal position above the trees.

The idea was based on how radiation frost develops. On clear, calm nights, the ground and plants can lose long-wave radiation toward the sky, causing temperatures around the plants to fall. The researchers hypothesized that horizontally positioned panels could reduce this heat loss and keep the trees and their flowers warmer.

Flower buds stayed significantly warmer

The researchers monitored air temperatures near the trees, used specialized frost sensors to mimic the temperature of plant organs and, in 2023, placed thermocouples directly inside flower buds.

Across the frost events, the air around the agrivoltaic trees was consistently warmer than in the control area. The study reported increases of between 0.27°C and 0.47°C in nighttime air temperature.

The difference widened when researchers examined the plant organs themselves. Frost sensors showed temperature increases of between 0.25°C and 1.29°C, while the flower buds recorded differences ranging from 1.61°C to 1.90°C on the three monitored frost nights in 2023.

The researchers noted that flower and organ temperatures can fall below surrounding air temperatures, making direct monitoring of plant tissue particularly important when trying to prevent frost injury.

Fewer flowers were damaged

The most significant outcome was observed following the frost period in March 2022. Despite frost during flowering periods in both 2022 and 2023, the frosts in March 6 to 9, 2022, led to flower damage. In the control trees, 35% of flowers showed damages, which is much higher compared to the less than 10% for those flowers exposed to the agrivoltaic system.

Why the finding matters for fruit growers

Spring frosts regularly pose a risk for temperate agriculture because blossoms and developing buds can get frost-burnt due to a decrease in temperatures below certain levels.

Farmers already use several frost-protection methods, including water spraying, heating devices, air movement, chemicals and anti-frost nets. The study suggests that dynamic agrivoltaic systems could provide another option while serving their primary purpose of generating solar energy.

The researchers concluded that agrivoltaics can provide frost protection in addition to their more widely discussed role in helping crops cope with heat and other effects of climate change.

Yet, the study does not show whether agrivoltaics would protect all the orchards from all kinds of frost. Radiation frost was the focus of the researchers, while it is known that management systems offer little help in protecting against advective frost caused by the movement of cold air mass into the area.

Still, the results point to a surprising possibility: the same panels that harvest sunlight during the day could, when repositioned at night, help preserve the delicate flowers that farmers need to turn that growing season into a harvest.