Could tracking photovoltaic panels shading mitigate worst climate change effect on grape composition? Example of Merlot vineyard located in the Bordeaux winegrowing area

Abstract

Climate change is a challenge for viticulture today and tomorrow, particularly due to the increases in temperature and potential water stress to which vines are subjected. In addition, there will be an advancement of the various phenological stages (Garcia de Cortázar-Atauri et al., 2016; Mira de Orduña, 2010). Projections for the future highlight the risk of a decline in wine quality due to excess sugar in the grapes, leading to an increase in the alcohol content of wines,  a reduction in acidity, a delay in the ripening of polyphenols and aromas (Arrizabalaga-Arriuzu et al., 2024), the risk of yield losses due to damage caused by sunburn or scalding of the grapes, and the risk of loss of quality and yield due to more frequent periods of water stress, which could prove catastrophic if flowering were affected. The effects of these risks are already commonly observed with the earliest-ripening grape varieties such as Merlot. Among the levers for adapting viticulture to climate change, shading using photovoltaic panels could therefore be an interesting solution by reducing the amount of incident solar radiation received by the vines with the added bonus of producing energy. This system would make it possible, at least temporarily, to return the vines to more favourable conditions, particularly in terms of temperature and water balance, at key stages of their cycle.

One of the objectives of the VitiSolar project presented here is therefore to study the impact of photovoltaic panels placed above the vines on the quality of the grapes. The experimental setup was installed in 2022 on a 12-year-old vineyard plot (Merlot variety) located in the Pessac Léognan appellation. Half of the plot is covered with photovoltaic panels and the other half serves as a control plot in full sunlight. The agri-PV set up consists of photovoltaic panels whose orientation is being adjusted throughout the day, by tracking or anti-tracking, to give priority to wine production over energy production.

Samples of 20 berries were collected at different phenological stages from véraison to maturity in 2023, 2024 and 2025. Total acidity and the concentration of sugars, amino acids and anthocyanins in grapes was measured. The PV treatment led to reduced sugars and anthocyanins content in berries, increased total acidity and higher relative abundance in arginine.

References

Arrizabalaga-Arriazu, M., Gomès, E., Morales, F., Irigoyen, J.J., Pascual, I., Hilbert, G., 2024. Increased temperature, elevated atmospheric CO 2 and water deficit modify grape composition of different ‘Tempranillo’ (Vitis vinifera L.) clones. Acta Hortic. 187–196. https://doi.org/10.17660/ActaHortic.2024.1390.23

García de Cortázar-Atauri, I., Duchêne, E., Destrac-Irvine, A., Barbeau, G., de Rességuier, L., Lacombe, T., … van Leeuwen, C. (2017). Grapevine phenology in France: from past observations to future evolutions in the context of climate change. OENO One, 51(2), 115–126. https://doi.org/10.20870/oeno-one.2017.51.2.1622

Mira de Orduña, (2010). Climate change associated effects on grape and wine quality and production, Food Research International, 43(7).https://doi.org/10.1016/j.foodres.2010.05.001

Acknowledgements

EDF power solutions as a project leader and EDF R&D as deputy. This project was supported by “ADEME”(Environment and Energy Management Agency), “Conseil Régional de Nouvelle Aquitaine” and “European Union”.