Researchers from the University of Seville (US) and the Polytechnic University of Madrid (UPM) have demonstrated that it is possible to grow tomatoes and generate solar energy simultaneously, a key strategy for tackling global water scarcity. The study, carried out in Madrid and Seville during the spring of 2024, evaluated the use of agrovoltaic systems and regulated deficit irrigation to optimise water resources in tomato cultivation. The results show that, although using less water reduces the volume of the harvest, the overall outcome is a more efficient and sustainable process.

This innovative combination aims to reduce the plants’ evaporative demand through the shade provided by photovoltaic panels, enabling a more efficient use of land and water. The research compared three irrigation methods: a control group with full irrigation, a regulated deficit irrigation (RDI) system based on the plant’s water status, and an agrovoltaic (AG) system that applied the same water restriction under solar panels. The study measured variables such as leaf water potential and gas exchange to monitor plant stress at different growth stages. The results indicate that, although the shade from the panels reduces available radiation, the design of the system permits adequate plant development to be maintained at most stages of the crop cycle.

One of the most notable findings is that the deficit irrigation strategy reduced water consumption by approximately 50% compared to traditional irrigation. However, this drastic reduction in water led to a yield decrease of around 20% in the RDI treatment, attributed mainly to severe water stress conditions during the ripening phase. Despite this drop in total tomato production, irrigation water productivity increased significantly in the Seville treatments, demonstrating that more fruit can be obtained for every drop of water invested.

Furthermore, the overall success of the agrovoltaic system was validated by the Land Equivalent Ratio (LER), which combines the efficiency of agricultural and electricity production. The values obtained—1.54 in Madrid and 1.67 in Seville—confirm that combined production is far more efficient than growing tomatoes and generating energy on separate plots. This implies that, although tomato yield decreases under the panels, the system’s profitability and sustainability increase thanks to the generation of clean energy in the same space.

In conclusion, the study highlights that agrovoltaics is a promising tool for the agriculture of the future, although it requires more precise irrigation management to avoid excessive stress. The researchers suggest that combining plant measurements with soil moisture sensors could further optimise these systems. This advance points to the sustainable dual use of land, offering a viable solution to the challenges of climate change and the energy transition.

The study forms part of the Ministry of Science and Innovation and the State Research Agency’s PID2021-122772OB-I00 project, entitled ‘Sustainable vegetable production based on agrovoltaic systems’. It was led by experts from the ETSIAAB at the Polytechnic University of Madrid, CEIGRAM and the ETSIA at the University of Seville. The results are published in the prestigious scientific journal Agricultural Water Management.