Solar farming in harmony with viniculture

Either way, solar panels are here to stay, estimated to have surged by an impressive 87% in 2023. This growth brought the world's cumulative solar capacity to greater than the combined electricity consumption of Sweden, Netherlands, Belgium, Finland, the Czech Republic, Austria, Portugal, and Greece.

Only so many panels can fit on rooftops, so many of the biggest installations are on the land. Even six years ago, in 2018, it was estimated that more than 1,300 square kilometres of land worldwide was covered by solar panels. That could put a dent in global food production, unless poor quality land was chosen for solar sites.

However, there is a new impetus to use solar panels to shelter crops and help them in other ways, which can boost food production in some countries.

France is one of the countries leading this initiative.

In the drought-prone Mediterranean areas of the south of France, it is hoped solar panels can enable agriculture to continue in areas that would otherwise be abandoned.

If successful in France, this could be extended to help the more than one-third of southern Europe's population that will face water scarcity if global average temperatures rise to two degrees above pre-industrial levels (they are already 1.2 degrees hotter). 

In Spain, which produces one-third of the EU's fruit, the government has said more than a fifth of land is at high risk of becoming infertile. Italy, renowned for wines and pasta wheat, faced one of its most severe droughts in 2022.

The Sun’Agri project seeks to help grape, fruit tree, and vegetable farmers. Again, Sun’Agri's panels are built over the crops, and are moveable, to provide shade when, for example, too much heat and sunlight threaten the crop. 

Panel movement is controlled automatically by data on the climate and the crop collected by a weather station. Meanwhile, power flows from the panels, which are bifacial in order to catch more sunlight. The system can include anti-frost nets, which also protect the crop from hail.

Apples are not very resistant to water deficits and high temperatures. It has been found that apple trees sheltered by the agrivoltaic system suffered 63% less water stress. Without protection, there can be major apple production losses due to frost, high temperatures, and excessive rainfall, especially from flowering to fruiting.

Just north of the Spanish border, solar panels constructed over newly planted vines made it possible to reclaim 7.5 hectares of the Domaine de Nidolères vineyards, which had been uprooted in 1992 and would otherwise have been abandoned. The vineyards here in the Aspres area were hit hard by climate change, with increasingly severe droughts.

But it is thought possible to double the value of the wine produced under panels, which can restore the vineyard to profitability.

The Sun’Agri project has enabled a 20% reduction in the vineyard’s water consumption and reduced stunted growth and leaf scorch during heatwaves in the summer of 2019.

In hot weather, controlled shading can reduce the temperature of vines as much as five degrees.

The panels can also protect the vines from harmful spring frost during the crucial bud burst phase. They can lengthen the vine growth period as much as 14 days. Wine drinkers can enjoy a better aromatic balance in wines from grapes under panels.

Vine growing was the first agricultural sector to benefit from the Sun’Agri project to deliver green electricity while preserving agricultural yields.

The North of France also has spectacular agri-voltaic projects, such as the three-hectare Brouchy Agrivoltaic Canopy in the historic World War One Somme area. The solar panels are five meters up, so that big agricultural machines can work underneath. The panels can be moved and rotated to shield the crops underneath from hot temperatures and strong sunlight. They include a crop irrigation system that will help reduce water consumption by 30%.

This low-carbon project received €2.7 million in funding from the Innovation Fund, one of the world’s largest investment programmes for net-zero and innovative technologies, financed by the EU Emissions Trading System.

Since 2022, power from the Brouchy panels replaced electricity generation causing 700 tonnes of CO2 equivalent of greenhouse gas emissions per year.

A similar three-hectare project at Amance in north-central France has been generating electricity since last August.

Across the Atlantic, the potential of dual-use agrivoltaics (combining agricultural production and solar energy generation on the same land) is being studied by Rutgers, the State University of New Jersey.

They will examine how vertically mounted bifacial panels work with production of forage crops and beef cattle grazing, and with vegetable growing.

The aim is that farmers can produce more sustainably and profitably without substantially reducing space for growing crops and that agrivoltaics can boost the production of certain shade-tolerant crops.

While sunlight is critical to growing healthy crops, managing how much sun crops receive can be even better.

According to a recent study on a Kenyan farm, crops such as cabbage, lettuce, and eggplant grew up to a third larger under solar panels than those farmed in direct sunlight, while reducing the farm’s energy costs by 50%.

Studies of solar sites worldwide reported excellent yield improvements for certain crops, such as peppers and cherry tomatoes.

A study by University of Arizona researchers concluded that crops under the shade of solar panels could yield two or three times more fruit and vegetables, with apples, pears, berries, and grapes most likely to benefit.

Researchers at Oregon State College discovered that areas beneath solar panels had their own microclimate, with 328% better water efficiency and higher levels of soil moisture throughout the summer. Twice as much grass grew under the panels.

Panels have even been used to create habitats that attract pollinators such as butterflies and bees ("Agricola beekeeping").