Ground Solar Panels: Are Forests and Farmlands Being Sacrificed?

2,000 hectares in the Landes forest, another 1,000 overlooking the Durance valley… Photovoltaic energy, which is booming, reached a historic high in 2025, now covering a significant portion and reducing France’s dependence on fossil fuels during a critical period.

However, there is growing opposition to the increasing number of ground installations on natural, agricultural, or forested lands rather than on already developed areas. “Let’s not fall into the trap,” stated a new national photorevolted coordination early in 2025, which includes the Peasant Confederation and 400 associations and local groups opposing “the industrialization of the countryside.”

On the other hand, solar professionals and public authorities are reassuring, promising that in the long term “less than 1% of the usable agricultural surface” will be utilized for solar.

What is the real situation today? By cross-referencing public and administrative data, especially from IGN and environmental impact studies, we have obtained unique data.

We can reveal that, according to our calculations, by the end of 2025, at least 1,573 ground solar power plants have been built on over 11,400 hectares of land that were once forests (53%) and agricultural plots (41%).

Together, these ground stations represent between 10 and 12 GW of installed capacity and produce nearly a third of the national solar electricity (another third is installed on small and medium roofs, and the last third mainly on large roofs).

11,450 hectares, or 110 km², what does this represent? Grouped together, this would be slightly less than the total surface area of the city of Paris including the Bois de Vincennes. But since solar production is very dispersed, at the country level, it would represent about 126 hectares per department in mainland France, equivalent to two medium-sized farms.

It’s too much, considering these panels could have been installed on buildings rather than replacing forests or agricultural land. However, it remains relatively limited for two reasons: public policies have until recently encouraged prioritizing installations on roofs, and France has long been behind in solar development compared to European objectives.

We calculated these figures ourselves, thanks to meticulous work using aerial surveys from IGN combined with multiple public databases. Neither the Ministry of Ecology nor the Ministry of Industry, nor the administrations have attempted to measure these surfaces, at best only counting the total power connected by region.

Even the electrical network managers, who are necessarily aware of the power and location of each solar installation, group in their statistics all high-power projects, whether they involve solar panels on a logistics warehouse, an old decommissioned factory, or wooded areas. Our data, on the other hand, allow us to realize not only the extent of ground solar, but also where it has been installed in France.

These ground stations, precisely, where are they located? The majority of ground solar installations have been set up on cleared forests. 6,100 hectares have been razed, according to our data. Almost half of this area is in the Landes massif, between the departments of Gironde, Landes, and Tarn-et-Garonne.

For example, the largest ground installation in the country, Cestas, has been active since 2015 on 233 hectares. It is also nearby that the giant Horizeo project, which sparked strong opposition a few years ago, is located. Originally planned on over 1,000 hectares of forests, it was reduced to 700 hectares and moved from forests to agricultural lands, while Engie, one of its financiers, hinted at this during the summer of 2025, without making it official.

Another favored sector by developers is the foothills of the southern Alps, overlooking the Durance valley, between Alpes-de-Haute-Provence, Hautes-Alpes, and Var. There, more than 1,000 hectares of panels have already been built on forests and natural areas.

It is there, around the mountain of Lure, that the first firm oppositions to ground photovoltaic projects emerged. In this department of Alpes-de-Haute-Provence, the rise of projects on natural and forested areas was “concurrent with the reduction in municipal grants,” explains Pierre Honoré, from the Amilure association, opposed to solar on natural and forested lands on the mountain of Lure. Committed to five legal challenges against projects in the area, the association hopes to eventually stop these installations on natural areas.

Now, developers are cultivating other projects, much more ambitious in number and surface, on agricultural lands. The Occitanie region hosts the most projects, with about a hundred installations in Roussillon, between the Pyrénées-Orientales and Aude, covering nearly 700 hectares in total across both departments.

Why there? In addition to high sunshine, these departments, highly vulnerable to heatwaves and droughts, were among the first to tolerate projects on crops. Initially on greenhouses, risking becoming pretext projects. A 2019 survey by DDT, for example, revealed that two-thirds of the photovoltaic greenhouses in this department were not primarily for agriculture.

More recently, this territory of Roussillon has seen the arrival of projects attempting, albeit with difficulty, to coexist agricultural production with vineyards and fruit trees. Further north, in the Lot, there are just fourteen existing installations but with “really an acceleration since 2022,” notes Pierre Dufour, from the local Peasant Confederation. For him, “what has changed is the position of the State and the prefecture putting pressure on elected officials,” urging them to quickly do their part in the deployment of renewables.

To justify the existing installations, public authorities also argue that they are located on previously developed or degraded lands: wastelands. Behind this term, a wide variety of situations are hidden: old airfield runways, decommissioned military bases, landfills, quarries, polluted grounds.

These areas were identified in the 2019 report by the Agency for Environment and Energy Management as preferred sites for solar projects. And that’s exactly what developers have done. Relying on the Cartofriches database, we have counted 900 hectares.

But these sites sometimes reveal extremely sensitive biodiversity issues. After decades of inactivity, these abandoned lands have often become refuges for wildlife and plants. This was already identified in 2023 by the Environmental Authority, which noted in its report that while these sites “may seem appropriate, [they] are often richer than the surrounding agricultural lands, and also pose questions of soil pollution deserving particular attention.”

But even setting aside this specific issue with wastelands, the question remains about the concrete effect on the soils in question. In absolute terms, a large ground solar installation does not have the same impact as the construction of a highway or solid urbanization. However, a ground station still requires leveling of the land, construction work to install piles, sometimes with a concrete base, trenches for wiring, and the construction of a transformer station.

It also necessitates the creation of tracks for fire rescue both inside and sometimes outside the fenced area. And if the plot was covered in trees, they must be cleared and stumped. Then, for the thirty to forty years of operation, the plot will remain closed and fenced, with limited access to small mammals, although grass can quickly regrow between the rows of panels and sheep may come to graze.

This is why almost all ground parks existing by the end of 2025 are indeed counted as land artificialization. According to reports, nearly 20,000 hectares have been artificialized each year. Solar would thus represent since its emergence 3% of the annual share of artificialization in mainland France. An additional consequence, but far behind housing, roads, and other economic activities.

What can we conclude from this current state? In twenty years, the dynamics of the solar sector have largely followed political priorities. This has allowed two-thirds of solar objectives to be achieved outside sensitive areas, with an increased effort towards individual installations and medium-sized roofs.

However, last year, support for residential photovoltaics and roof projects was sharply reduced, while recent obligations to cover parking lots have emerged. This opens the door to a multiplication of large ground projects in the coming years, which are not currently on this map. Will they explode? The answer in our next investigation.

Our work already reveals a crucial lack of public and industrial data collection. As we have learned through our research, a number of major installers invest significant resources to finely map installations and projects themselves. This allows them to have an overview and a capacity to react to any change in political direction, where citizens only have partial, fragmented, and often late information to consider the relevance of projects near them.

Like wind power a decade ago, solar seems to repeat the same mistake of entrusting renewable industrialists with the task of deciding how to manage the energy transition. With the risk of increasing misunderstandings and local oppositions, which, if not heard, might eventually be exploited by the pro-fossil far right against all renewable energy support policies.