Impact of Agrivoltaics on berry ripening: preliminary results for the white cv. Encruzado

Abstract

Mediterranean viticulture faces increasing risks from extreme heat and drought due to climate change, often leading to unbalanced grape composition and accelerated ripening. Agrivoltaic systems (AV), integrating viticulture with photovoltaic energy generation, may attenuate these effects through adaptive shading while enhancing land-use efficiency. This study, part of the Agrivoltaic pilot project at the Instituto Superior de Agronomia (Lisbon), in partnership with GALP, evaluates the 2025 season effects on the Portuguese white variety Encruzado. The vineyard is trained in a vertical shoot positioning system and spaced 2.5 m between rows and 1.0 m between vines, oriented north–south. The AV structure consists of 288 solar panels mounted 4–5 m above ground with a single-axis solar tracking system providing variable shading (~40% at solar noon). Three treatments were compared: Control (C, full sun), PVI (panels over interrow), and PVR (panels over row). Berry composition was monitored weekly from veraison until harvest. Harvest date was defined at a target of approximately 20° Brix. At the beginning of the ripening period, shaded treatments exhibited a significantly lower °Brix (PVI: 9.8 ± 1.3; PVR: 10.3 ± 1.3) than C (12.1 ± 1.1), indicating delayed sugar accumulation which lasted until harvest. In the control, °Brix rose from 12.1 ± 1.1 to 20.2 ± 0.8 over 28 days. Under shading, PVI and PVR treatments reached comparable °Brix values (20.6 ± 0.7 and 19.3 ± 0.7, respectively) ~21 days later than C. During the ripening period, total acidity decreased from 18.7 ± 1.2 to 5.4 ± 0.9 g/L in C, while shaded treatments maintained slightly higher acidity levels until ~10 days later and then dropped below those values at harvest (PVI: 4.6 ± 0.3; PVR: 4.7 ± 0.4 g/L). Considering pH, no significant differences were observed between treatments at the date control was harvested (PVI: 3.22 ± 0.01, PVR: 3.22 ± 0.02, C: 3.21 ± 0.04). When the PV treatments were harvested pH reached 3.37 and 3.39 for PVI and PVR, respectively. Overall, Agrivoltaic shading reduced grape sugar accumulation rate, inducing a delay of the targeted Brix by approximately three weeks. Furthermore, a slight attenuation of total acidity degradation was observed, particularly at earlier ripening stages. These results are consistent with trends observed in the same experiment, in 2024 for the Viosinho variety (Victorino et al., 2025), indicating that AV can act as a potential adaptation strategy to climate change by delaying berry ripening.

References

Gonçalo Victorino, Jorge Ricardo-Da-Silva, Joaquim Miguel Costa, Carlos M. Lopes (2025). Impact of agrivoltaics on berry ripening: preliminary results for the white cv. Viosinho. IVES Conference Series, GiESCO 2025.