The very first agrivoltaic site ofOmbreaone of the first experimental agrivoltaic sites in France, was dismantled at the end of March 2024. After 7 years of operation and scientific feedback, this demonstrator, run in collaboration withAstredhor Méditerranée is now entering its final phase, which is an integral part of the project: dismantling. This phase is designed to prove the reversibility of our installations as well as impact on the agronomic potential of the land. Here's a look back at the challenges, progress and lessons learned from this unique dismantling project.
A look back at our first agrivoltaic website
2017: construction of our first experimental site
Created in 2017 through a partnership withAstredhor MéditerranéeInstitut des Professionnels du Végétal, which supports the horticultural industry, this experimental site located in Hyères (48 photovoltaic panels installed for a surface area of 84m²) protects a plot of peonies planted the same year. The peony is an emblematic crop of the south of France, particularly in the Var region (83), which accounts for almost all French peony production.
This structure was installed with the first version of our dynamic shading solutions. The panels slide, retract and extend by means of a rack-and-pinion transmission (rails with toothed wheels) according to the shade requirements of the peonies. Entirely made of metal, it is anchored to the ground with earth screws, without the need for concrete pouring, thus limiting the structure's footprint.
From 2018: operation & positive agronomic results
Peonies are a relevant first crop to monitor, as they are particularly prone to water stress. In 2018, we therefore set up a differentiated irrigation system on a control zone and a protected zone to monitor the impact of our solutions on peonies' water requirements. This site was equipped with sensors that were later used on all our agrivoltaic sites: a weather station with air and soil temperature and humidity, an anemometer (wind sensor), and a sensor to monitor luminosity (PAR).
Since 2018, the site has seen 4 peony harvests of substantial size and has given us some interesting feedback, of which here are a few lessons:
- Equivalent yield: maintaining the number of flower stems of all qualities under the panels
- Increase in quality: +8% of higher quality flower stems on average between 2020 and 2022 and maintenance of vase life
- Decrease in leaf scorch and delayed senescence
- Lower irrigation needs: -21% average irrigation between summer 2018 and end 2022
Why this dismantling?
From the outset, this site has been designed and monitored on a purely experimental basis. It should enable us to establish the agronomic relevance of our solutions in terms of the contributions they make to crops, but also in terms of their reversibility. It is this latter point that the dismantling is designed to test:
- Impact on soils (biodiversity, structure, compaction, traces of pollution) of dismantling an agrivoltaic structure
- Resilience effect, i.e. the behavior of the crop after a period of dynamic shading
Our aim is simple: to return the plot to its original state and meet the requirements of the law on the Acceleration of Renewable Energy Production (APER). This is what we will try to demonstrate with the post-dismantling studies and monitoring of the soil and peonies.
What the APER law says
The latest decree on agrivoltaics, published in the Journal Officiel on April 9, 2024, sets out the framework for dismantling agrivoltaic structures.
Dismantling operations must include :
- Dismantling of production facilities, including excavation of all foundations and trenches
- Restoring the land, in particular by ensuring that it remains fit for its original purpose
- Reuse, recycling, recovery or, failing that, disposal of demolition and dismantling waste.
- Involvement of the organization responsible for controls to certify that the agronomic qualities of the soil have been maintained.
The dismantling process was designed to meet these requirements.
Dismantling in two stages
First step: securing the site
There are two sources of electricity on this site:
- The AC power supply, the site's main source of power. This is the energy we use to drive the solar panels..
- The direct current generated by the solar panels. Unlike the other sites, this current is not fed into the electricity grid, as the aim of this site from the outset was solely to prove the relevance of shading - and not energy production..
Many issues are at stake at this critical stage in the dismantling process. Ensuring the site's electrical safety, hereafter, the smooth running of the rest of the site. For our maintenance team, this involved cutting off the site's AC power supply in order to make it safe. Another key issue was the decontamination or management of the materials recovered following dismantling of the electrical system (sheaths, cables and other site residues). Limiting the impact of dismantling also means managing waste. For example, we were able to recover and reuse all the sensors and electrical equipment from the switchboards (automatic controllers, circuit breakers, etc.).
Second stage: complete dismantling of the structure
We worked with two companies to dismantle the agrivoltaic structure:
- Foseleva lifting company, to dismantle the above-ground structure and panels. Its team of skilled hoists slung and dismantled the entire structure. The structure was then transported piece by piece to suitable sorting centers:
- The structural steel (tubes, screws, washers, etc.) was taken to a recycling center for reuse.
- The panels were transported to an approved solar panel recycling center.
- Technopieuxa company specializing in screw foundations, was called in to remove the structure from the ground, in particular the earth screws.
One of the main challenges of this stage is to preserve the peonies., which, on the day of dismantling, had already grown by more than 5cm. Every precaution was taken to avoid damaging the existing crop.
What impact will dismantling have on crops and the soil's agronomic potential?
This is the question that our R&D team will be monitoring to answer.
Monitoring the impact on soil quality
This pilot site is one of our sites where soil soil quality is monitored. In particular, we will be monitoring the risk of soil compaction following passage of large dismantling machines, which do not yet exist in the area.
To ensure this monitoring (T0 before dismantling, and T1 more than M+1 after dismantling), the indicators chosen focus on all aspects of soil quality: its physico-chemical quality, in particular its structure, and the detection of potential pollutants, not forgetting the soil's biological quality, with monitoring of microbiological communities. Samples will be taken in the control zone and under panels, in the rows and inter-rows of peonies, as well as in a grassed area close to the plot where the dismantling crane has been installed.
Focus on monitoring indicators :
- Structure monitoring indicators :
- Spade test for rapid diagnosis of soil structural condition
- Penetrometer rod to measure soil resistance to penetration and detect deep settlement
- Bulk density, soil compaction indicator
If these different analyses show a compacted soil, this would pose a problem for future root development, the maintenance of soil life and therefore potentially for the quality of future harvests.
- Microbiology monitoring indicators :
- Measurement of soil granulometry and chemical compounds (carbon, nitrogen, phosphorus, pH, etc.), enabling us to define the type of soil and the environment in which micro-organisms evolve.
- Monitoring of microbial molecular biomass and the fungus/bacteria ratio using extracted microbial DNA, early indicators of the response of soil microorganisms to disturbance.
- Pollution indicators :
- Measurement of contaminants (heavy metals, volatile aromatic compounds, hydrocarbons)
Crop impact monitoring
Finally, the impact of dismantling on crops will also be monitored. Throughout the year, we'll be continuing the same monitoring we've been carrying out on this plot for the past 7 years. This will enable us to compare the same indicators before and after dismantling, in order to establish the precise impact on peonies and thus validate the climatic protection provided by our solution. In particular, we will be monitoring :
- Crop yield and quality (number of flowering and non-flowering stems, stem length and diameter)
- Water consumption
The first results of the various monitoring programs will be available in the coming months. We'll let you know about them, and that'll be an opportunity to take stock of this very first dismantling of an agrivoltaic site!
