Sun Protection for Fruit: Dynamic Agrivoltaics Reduces Apple Temperature and Sunburn Damage

Abstract

Heatwaves are a risk to fruit tree yield and production. In this study, a dynamic agrivoltaic system was tested as a solution to protect trees from high temperatures by shading the fruits when irradiance and air temperature peak at their maximum values. The study was completed in an apple dynamic agrivoltaic system in France in 2022 and 2023. The agrivoltaic system was compared to a control without solar panels. The study was initiated in 2022 with measurements of microclimate (incident solar radiation and air temperature) and sunburn damage. In 2023, these measures were complemented with detailed measurements of fruit surface temperature and fruit growth. In 2023, fruit surface temperature was continuously measured for two control and two agrivoltaic trees using type T thermocouples (12 apples per treatment). Fruit diameter of 18 tagged fruit per treatment was monitored weekly. Air temperature at the agrivoltaic trees was lower compared to control trees due to a reduction of 50% in daily incident radiation. Sunburn damage was reduced for agrivoltaic apples in 2022 (control 13% vs. agrivoltaics 2%). In 2023, although there were low sunburn values for both the control and agrivoltaic apples, it was found that agrivoltaic apples were cooler than control apples. The maximal fruit surface temperature reduction during the study was 3.3 °C. Fruit diameter was the same across treatments. Dynamic agrivoltaic systems can be used to reduce apple fruit surface temperature and minimize the risk of sunburn when trees are shaded during periods of high irradiance and temperature.