In 1981, the Germans A. Goetzberger and A. Zastrow proposed combining photovoltaic electricity production with agriculture, in order to resolve land and light use conflicts between these two activities. Plants reach a photosynthetic saturation threshold, beyond which additional light intensity no longer improves their growth. Installing photovoltaic panels above crops makes it possible to optimize this light by leaving it sufficient for the development of the plants, while recovering excess energy not absorbed by them. Natural ventilation of the panels is also ensured so as not to exceed 25°C, beyond which their efficiency decreases by 0.45% /°C. The first tests took place in Japan in 2004. In 2011, a study showed that this system can increase agricultural land productivity by 35 to 75%. This concept is then called “agrivoltaics”.
In Europe, agrivoltaics is progressing slowly, while it is already well developed in Japan with more than 2,000 installations. Europe has a potential of 1,000 GW of agrivoltaic capacity, compared to the 590 GW of EU photovoltaic objectives for 2030. Economically, these facilities allow farmers to meet their electricity needs and resell surpluses. If the income is still insufficient, they can rent the space for the panels to energy companies. Agrivoltaic installations have several advantages, including shading and temperature regulation that promote a microclimate conducive to plant growth. In addition, the recovery of rainwater on the panels and the reduction of evaporation from the floors reduce water needs. They also protect crops from climatic hazards, such as hail or strong winds.
Different types of installations are suitable for different crops. The raised panels are suitable for berries, grapes, salads, and squash, which do not require the use of large vehicles. It seems that these panels also improve the taste of wine. For cereals or deep-rooted plants, vertical panels allow the passage of agricultural machinery such as tractors and combines.
Agrivoltaics also has limitations. Some plants require full access to light in order to grow properly. These installations can also cause accidents when operating agricultural machinery. The installation of panels reduces the usable area of the fields and represents a significant initial cost: The average price of a 100 kWp installation can be estimated between €75,000 excluding VAT and €150,000 excluding VAT. However, electricity generation compensates for losses in agricultural land, and contracts with energy companies can significantly reduce costs. Rentals can bring in 1000 to 1500 €/year per hectare on average.
In 2022, ADEME identified nearly 167 agrivoltaics projects in France, with a total capacity of 1.3 GW. Among them, the agrivoltaic farm of the Domaine Viticole de Nidolères in Tresserre, inaugurated in November 2018, covers 4.5 ha with photovoltaic panels above 17,310 vines. This installation reduces water needs by 20% and produces enough electricity to power more than 650 homes, while avoiding the emission of 3,000 t of CO2. With an initial investment of €4 million and a contract for the resale of electricity generated at €85/MW, the project would reach its profitability threshold in 11 years not to mention the marked improvement in agricultural yields. Other ambitious projects are emerging, such as “Terr'about”, which involves the installation of 450 MWp on 200 ha in Landes.
Law No. 2023-175 of 10 March 2023, relating to the acceleration of renewable energy production, now regulates agrivoltaics in France. It regulates the installation of solar panels on agricultural land, guaranteeing priority to food production, while reconciling the challenges of food sovereignty and energy autonomy. The Afnor Certification “Agrivoltaic Project” label ensures that these installations do not harm crops or contribute to the artificialization of soils. From October 2024, Afnor will also label livestock agrivoltaics projects, allowing animals to benefit from shaded areas and to preserve the grass necessary for their diet in summer.
Image credit: Heliantis renewable energies