The start-up Sun’Agri, a subsidiary of the Sun’Air group, has developed the agrivoltaism technique and conducted experiments on agricultural test sites. The goal is to combine the production of crops and energy within the context of global warming.

What is dynamic agrivoltaism ?

Dynamic agrivoltaism consists of using the adjustable panels for protecting the crops. The panels are managed according to the type of crop and its needs.

The dynamic agrivoltaic systems (DAV) are installed above the crops and they provide interim shade. The panels act as a tool for the protection and adaptation of the crops in the face of climate change, thus optimising production in terms of quality, while maintaining high yields, by:

• Limiting excess solar radiation and extreme heat: The adjusted shade can reduce the temperature of the crops under DAV by up to – 4°C during heat waves and maintain better relative humidity; the apical leaves do not curl up and photosynthetic activity can continue;
• Reducing the risk of frost: with an average temperature difference of a few degrees when 0°C is approaching in the spring, the DAV thermal cover makes it possible to avoid very harmful episodes of frost, particularly during the period of budburst;
• Improving the non-water stress level while reducing irrigation: the irrigation applications are, on average, 30% less compared with the reference zone, as well as there being a reduction in the actual water consumption and significant periodic spells of water stress (+63% observed during a heat wave).
• Producing to a more uniform quality of the yield: Fruits with unchanged firmness and size, controlled colouring and less sweet fruit;
• And, of course, generating electricity.

Sun’Agri now has some forty ongoing projects, ranging from fruit trees to grape vines and market gardening

We met Damien Fumey, plant modelling researcher, who became part of the Sun’Agri programme in 2019 and is in charge of the Sun’Agri R & D unit. A team of some twenty researchers and 4 PhD students are currently working on the research programme (Sun’Agri3). As far as Inrae is concerned, 7 laboratories, including GEO, are taling part in the project.

Damien gave us more details about these issues:

“Up to now we have had fixed and adjustable shutters, but without smart steering, so it was not of much use. We also had photovoltaic greenhouses covered 100% with panels, which were not of much interest either, because nothing could be produced underneath them”. And he continued, “Dynamic agrivoltaics is revolutionary because it allows for the protection of the crop and the production of electricity at the same time”.

The panels are installed above the crops, at a height of more than 4.50 metres. These are bifacial panels (they capture the light on both sides) and the shutters can be moved by + or – 90°. The farmer must control the solar panels and the shade can vary by 10 to 90%.

According to Damien “We give the farmer the possibility of growing his or her crops by providing protection against the heat waves and solar radiation, which is too high for the plant”. And he adds, “The volumes of irrigation water applied are 30% lower because episodes of plant water stress are avoided”.

Another advantage of these tilting panels: “They protect the farmer against frost by positioning the panels horizontally, especially at night”. This produces a greenhouse effect which will conserve the heat radiated by the soil.

With the MySunAgri app, the farmer can monitor at all times the agronomic data collected from the plot and the louvre control strategy. They can also include additional weather data of their choice as well as alerts.

These panels are connected to a control system using meteorological data that allows for solar radiation to be calculated in real time, which is linked to an agronomic growth model for the plants, thus allowing the farmer to be able to estimate the plant’s needs in terms of light and irrigation. These input data originate from a meteorological station with a rain gauge, anemometer and pyranometer and sensors in the soil and close to the plant.

“These sensors will enable us to configure all our models and control the plant’s water status”, explained Damien. The solar panels are managed in a way to ensure that the plant has as little water-stress as possible. For each installation, a non-protected testing site is compared to a site with protected crops.

At the present time, irrigation and shading experiments are being carried out. “We will soon be able to let the farmer know much water to apply according to the shade and the type of crop”, explains Damien. The four PhD students are currently working on this topic and the tool should be ready within two years.

Sun’Agri has more than forty projects in operation. The different crops under experimentation are as follows: apple trees, grape vines, tomatoes, maize.

The farmers who decide to take part in the research are those affected by climate change, who need protecting against the heat waves, hail or even the frosts. The dossier is submitted to the government and two or three years will elapse from the time it is presented to the time it takes shape. 

The farmer does not receive any rent but s/he can take part in the financing of the project. And the electricity is fed back into the national grid. The guarantee, not least for the farmer, is that his or her production is protected.

The programme is subsidised by the state in an amount of 20 million Euros.

Wine-growing was the first agricultural sector to benefit from the dynamic agrivoltaics solution in terms of area

Experimental data for vines under panels of different sizes were obtained in 2018 and 2019 on the Montpellier SupAgro campus, supplemented by a history of experiments from INRAe in Pech Rouge carried out on a fixed device since 2016.

At the same time, the introduction of an experimental device in Piolenc in 2019 (Grenache grape variety planted in 2000) provides many results that can be analysed by the Vaucluse Chamber of Agriculture (CA84) and INRAE.

Young vine plants were planted in the Nidolères estate (Tresserre) in 2018, over 7.5 ha, above which the first AVD demonstrator was installed over 4.5 ha monitored agronomically by the Pyrénées-Orientales Chamber of Agriculture (CA66).

The objectives of this smart-controlled dynamic agrivoltaic installation: 7800 panels representing the electricity consumption for 650 homes per year. Even more than the generation of electricity, the main aim of this installation is to mitigate the effects of  global warming.

And the first viti-voltaic plot in the world has just produced its first grape harvest. “This was a perfectly acceptable yield more or less in line with what we expected. This installation offers good protection, whether in winter against the freezing temperature or in summer when we can organise around 2 to 5 hours of shade per day for the vines, according to requirements. More importantly, this gives a crop with a lower alcohol content and higher acidity, according to our research carried out on the white wines. And evaporation is reduced by 25%”, enthused Pierre Escudié, the owner of the Nidolères vineyard in Tresserre (Pyrénées-Orientales).

“By comparing our readings with those of the reference vine, we lose one degree of alcohol under the panels and we gain half a degree of acidity”, explained Pierre Escudié

“During this initial exercise we have managed to achieve a good balance between wine production and the generation of photovoltaic energy. This year we produced enough energy to supply 650 homes with electricity for twelve months. This represents a slight decline in electricity production, while the algorithms developed with INRAE control the orientation of the sunlight received by the plants, in particular by offering maximum sunlight in the spring at the key moments of budburst and flowering,” adds Damien from Sun’Agri, who runs some forty projects. This will include the setting-up of a second plot in the Nidolères vineyard.  

Author : Fleur Martin, Irrigazette with the participation of Damien Fumey, Sun’Agri