Why agrivoltaism in france ?
French agriculture is facing a number of challenges. In order to preserve food sovereignty of the country, it must maintain its competitiveness while reducing its impact on the environment: carbon footprint, water resources, soil life, biodiversity... And this, in a complex geopolitical context, with high volatility in commodity prices.
On the other hand, it must adapt to rapid climate changes that impose more and more frequent climatic hazards. The 6th Report of IPCC projects an increase of 2.4 to 3.5°C worldwide by the end of our century (compared to the pre-industrial era). Hot days will continue to increase, as will violent weather events. Likewise, the water resource is at the heart of concerns, including in France. Agriculture, which is the activity The most consuming of water in France, with 58% of total consumption, is constantly seeking to improve the efficiency of its water use.
In this context, agriculture must constantly evolve and innovate to ensure its sustainability and resilience. Among the variety of existing technological solutions, agrivoltaics is now on the rise to combine renewable energy production and crop protection against the vagaries of the weather.
Agrivoltaics at the service of agriculture
Agrivoltaics consists in installing photovoltaic panels on an agricultural plot. The principle is to produce renewable energy while creating, maintaining or sustainably developing agricultural production. The approach is governed by the APER law: agriculture must remain the main activity on the plot, electricity production being only secondary.
Agrivoltaics therefore aims to create a real synergy between agriculture and energy production. Indeed, while agricultural plots represent an ideal space for recovering the sun's radiative energy, an installation is considered “agrivoltaic” if (and only if) it provides one of the following services to agricultural production:
- improvement of agricultural potential and impact,
- adaptation to climate change,
- protection against hazards,
- improvement of animal welfare.
The panels can thus contribute to protect crops against extreme weather conditions while generating electricity that is generally sold to the grid.
Limiting heat stress
Photovoltaic panels create a microclimate on the plots, which limits extreme temperature variations. The latter decreases at ground level and at plant height during hot weather, while it increases slightly during periods of extreme cold and frost. It is an asset to protect crops from heat stress and promote their development.
Reducing water stress
The shading generated by the panels also maintains better humidity, limits the evaporation of water from the soil and therefore reduces the water stress of crops. For irrigated crops, water savings become possible.
This shading reduces the direct exposure of the soil to sunlight, which decreases water evaporation and maintains moisture in the soil. As a result, irrigation requirements are reduced. This is a significant advantage in the face of climate change, which is imposing more and more hot and dry summers on our regions. In addition, shading limits the drying impact of wind on soils, which can worsen water losses.
By adapting their positioning to the climatic conditions and the needs of the plants, dynamic panels offer rotating and partial shading more effective for crop protection.
Diversifying farmers' incomes
Increasing the attractiveness of the profession is one of the major challenges in the agricultural sector, which sees its number of farmers decrease year by year. Diversifying income offers an additional key to the sustainability of farms. There are a variety of models. It is important to compare in order to make an informed choice.
For example, some developers offer a fixed annual remuneration and a variable portion indexed to the turnover of the agrivoltaic power plant. This is the case of TSE, which offers operating contracts, including rent, for 40 to 50 years. There are also power plant projects financed by farmers.
In any case, one rule prevails: for the project to be qualified as agrivoltaics, it must be avoided that it undermines the Rural lease or agricultural activity.
Participate in the energy transition
As a reminder, agriculture emits approximately 21% of national emissions of greenhouse gases (GHG) and produced directly or indirectly 20% of the country's total renewable energy production : biomass, solar energy, wind energy and biogas (source ADEME). The agricultural sector therefore has an important role to play in the energy transition.
Photovoltaic systems adapted to agricultural projects
An agrivoltaics project must take into account the specific constraints and needs of farmers. There is therefore a diversity of solutions, fixed or dynamic, with different shade heights to adapt to any type of project: breeding (with shaded areas for the comfort of animals), field crops, viticulture, arboriculture...
Fixed solar shades
More economical and simple to set up than dynamic systems, these shades are tilted in a fixed orientation that maximizes the solar energy production over the year (generally to the south, for the northern hemisphere). However, these panels provide consistent shading in a given area. Therefore, they are not suitable for all cultures. They are better suited to the growth of plants that are sensitive to excess light and heat (e.g. salad or radish, raspberries or blueberries, aromatic plants such as basil, etc.).
Since the inclination of these panels is fixed, rain always seeps into the same place and causes soil erosion. In addition, the passage of agricultural machinery can be more difficult with this system.
Dynamic solar shades
Installed on agricultural plots, dynamic panels such as Trackers follow the course of the sun from east to west to maximize energy efficiency. The shadow then turns on the plot. Some developers offer a agroclimatic management which favors the plant at certain key stages of its development.
The solar modules can also be tilted to encourage the passage of agricultural machinery or to allow plants to take advantage of the rain.
Sunflower trackers
In the field of dynamic shades, solar trackers or “sunflowers” automatically orient the panels according to the Sun's trajectory. Depending on the time of day and the year, they adapt along the east-west and north-south axes. These technologies are mostly used in livestock farming and are not well suited to field crops. Indeed, the passage of agricultural machinery is limited around the structures. Moreover, their concrete foundations question the reversibility of the project at the end of operation. Today, few projects are being developed and references are lacking.
The shades installed in height
In agriculture, structures equipped with psolar rings in height tend to develop. Indeed, they facilitate the Passage of tractors and agricultural equipment, optimizing the cultivated area. For example, TSE has developed an innovative system: The agricultural canopy. This system of rotating panels with a small footprint, arranged at a height of 5 m and a width of 27 m, is particularly suitable for field crops. Equipped with trackers, the panels automatically tilt according to the path of the Sun. The concept was also designed to be reversible, so as not to become a brake in the event of transfer of farms or changes in practices.
Some shade models, fixed or dynamic, can be adjusted to a height adapted to viticulture, and even arboriculture. In viticulture, solar shades help to regulate the sun and the temperature around the vines. An asset to limit the risks of water stress! In arboriculture, panels protect trees against hail in order to limit the loss of yield and market value of fruits.
In fish farming, solar shades protect fish from thermal stress and limit variations in water temperature in case of extreme heat.
Vertical bifacial solar panels
Located on a north-south axis, the vertical bifacial solar panels capture the sun's rays optimally at the beginning and end of the day, during peaks in electricity consumption. These panels also produce energy from both sides, which offers better energy efficiency.
At the scale of an agricultural farm, the advantage of this system is to limit the loss of UAS (useful agricultural area) thanks to their small footprint and their vertical position which facilitates the passage of equipment. On the other hand, the shade can be very heterogeneous within the same plot, with some areas shaded for a long time and others very little.
Thanks to tailor-made inter-row spacing, agricultural equipment can circulate without difficulty.
To conclude
Agrivoltaics is not only about combining agriculture and energy production; it is also about mutually reinforcing these two activities to guarantee sustainable, resilient, and economically viable agriculture while participating in the energy transition.
Although technical and regulatory challenges remain, the various agrivoltaic solutions already offer a range of choices adapted to a variety of agricultural projects.
