Influence of agrivoltaic systems on the thermal comfort of dairy cows in a tropical climate

In this study, we evaluate the influence of an agrivoltaic system on the thermal comfort of dairy heifers in a tropical climate. The research was conducted between July and August 2025 in south-eastern Brazil. During 12 consecutive days, two pasture systems were assessed: an open pasture system (OPS) and an agrivoltaic system (AGV). In the AGV, 36 photovoltaic panels were arranged across three paddocks (12 panels/ paddock). Microclimate variables such as air temperature (AT), relative humidity (RH), black globe temperature (BGT), and wind speed (WS) were assessed by sets of autonomous sensors. In the OPS, a set of sensors were installed at the center of the paddock, and in the AGV, a set of sensors were installed in full sun and the shaded areas beneath the panels. With these data, we calculated the black globe–humidity index (BGHI) and radiant thermal load (RTL). All analyses were performed in R using Generalized Mixed Models, with days and hours included as random effects. All microclimatic variables were lower (p<0.001) in the AGV (AT: 22.1 ± 0.9; BGT: 24.4 ± 1.8; WS: 1.4 ± 0.09) compared with the OPS (AT: 23.01 ± 0.9; BGT: 28.8 ± 1.2; WS: 1.6 ± 0.1), except for RH (AGV: 50.4 ± 3.9; OPS: 48.7 ± 3.3). Additionally, the lowest mean (± SE) values of bioclimatic indicators were recorded in the AGV (BGHI: 70.1 ± 0.8; RTL: 487.2 ± 7.4) than in the OPS (BGHI: 74.6 ± 0.9; RTL: 574.2 ± 8.1). In the OPS, BGHI exceeded the heat-stress threshold for cattle (>74 units) during 62% of measurements, indicating a challenging thermal environment. In conclusion, the agrivoltaic system provided a more comfortable thermal environment for pasture-based dairy production compared with the open pasture system, demonstrating its potential to mitigate heat stress in tropical climates.