Eiffage Builds Carbon-Free Cleaning System for Cestas Solar Plant

Eiffage Énergie Systèmes has developed a customized, carbon-free photovoltaic panel washing system designed specifically for the operational constraints of the Cestas solar power plant in Gironde, France. The solution addresses the challenges of maintaining one of Europe’s largest photovoltaic installations while eliminating fossil fuel use and reducing operational risk.

Adapting maintenance to an atypical plant layout
Commissioned in 2015 and operated by Neoen, the Cestas solar power plant has an installed capacity of 300 MWp and comprises 983,500 photovoltaic panels spread across 250 hectares. The installation generates enough electricity to supply approximately 240,000 households annually, equivalent to the city of Bordeaux. Unlike conventional photovoltaic parks, the panels are mounted at a shallow 5% tilt, arranged in an east–west orientation, with inter-row spacing limited to between 1 m and 1.20 m.

These design characteristics significantly restrict access for standard commercial cleaning equipment, making conventional panel-washing machines unsuitable for use on site.

A purpose-built, autonomous cleaning platform
To overcome these constraints, Eiffage Énergie Systèmes teams responsible for the plant’s maintenance since construction designed and engineered a dedicated cleaning system. The result is an autonomous rolling arch equipped with two six-metre rotating brushes, capable of cleaning a 12-metre panel width in a single pass.

The machine operates entirely without fossil fuels. It is powered by two onboard batteries that are continuously recharged via twelve integrated photovoltaic modules, enabling carbon-free operation during cleaning cycles.

Intelligent sensing and adaptive control
The cleaning system incorporates multiple sensor technologies to protect the photovoltaic modules while maintaining cleaning efficiency. Pressure sensors automatically regulate brush contact force and adjust in real time to surface irregularities, preventing mechanical stress or damage to the panels.

A three-dimensional LiDAR system continuously scans the immediate environment, allowing the machine to correct its trajectory and maintain alignment even on uneven terrain. Operators define target pressure parameters, and the system dynamically adapts its behavior throughout operation.

Validation and deployment timeline
Testing was conducted between 15 and 31 October 2025 to validate cleaning efficiency, operational speed, and system reliability. Following successful trials, the machine is scheduled to enter full operational service in June 2026, supporting routine cleaning of nearly one million photovoltaic panels.

Supporting long-term, low-impact plant maintenance
Six Eiffage Énergie Systèmes technicians currently carry out full-time maintenance at the site. In parallel with panel cleaning, the plant is undergoing a multi-year refurbishment program involving the replacement of approximately 400 inverters. This work is phased across three winter seasons, from October to March, to avoid disruption during peak summer generation periods.

Additional initiatives under consideration include the use of managed grazing, with a planned flock of approximately 200 sheep to maintain vegetation across the site, further reducing mechanical intervention and environmental impact.

By combining site-specific engineering, autonomous operation, and renewable power, the newly developed cleaning system demonstrates how photovoltaic maintenance can be adapted to complex installations while supporting decarbonized operations.

www.eiffage.com