Cestas solar power plant was inaugurated in 2015 and is operated by Neoen. It is a giant in the French photovoltaic industry, with 300 MWp of power, 983,500 panels spread over 250 hectares, and annual production capable of powering 240,000 homes (equivalent to the city of Bordeaux). Yet what makes it unique is its layout: panels tilted to just a 5% angle, facing east-west, with reduced spacing between each array. These very specific characteristics make the use of existing cleaning machines impractical.

A customized, carbon-free and smart solution

Faced with this challenge, the teams at Eiffage Énergie Systèmes who have been tasked with maintaining the power station since its construction devised a unique and truly customized technical solution. “As the unusual angle of the modules and the limited space between the rows (1 m to 1.20 m max) meant that we couldn't find a suitable cleaning machine on the market, we decided to design our own autonomous solution that runs without fossil fuels. This rolling arch is equipped with two 6-metre brushes and can clean 12 metres of panels in a single pass," explained Eiffage Énergie Systèmes methods manager Julien Escutenaire. The new machine was tested between 15 and 31 October 2025 and is packed with innovations. It is powered by two batteries recharged by twelve on-board solar panels, eliminating any dependence on fossil fuels. "The two brushes are connected to two sets of sensors that automatically adjust the cleaning pressure and detect uneven surfaces to prevent damage to the panels. In addition, the three-dimensional Lidar laser system analyses the machine's immediate environment in real time and corrects its position, even when the ground is uneven. You simply set the required pressure on the panels, and the machine adapts accordingly," continued Julien Escutenaire. The test phase, which verified the efficiency and speed of the new machine, was very conclusive. The washing machine will therefore be fully operational in June 2026.

For safer and more environmentally friendly maintenance

Six Eiffage Énergie Systèmes maintenance technicians are currently working full-time at the power station. After ten years of use, 400 inverters need replacing. “We spread this ten-year maintenance programme over three winter periods (from October to March) to replace 21 specific parts, including inverters, at a rate of four inverters per day. This phasing means we don’t disrupt the summer season, when the power station is operating at full capacity,” said Julien Escutenaire. At the same time, our experts are looking into the idea of using a flock of 200 sheep to maintain the power station's land in an eco-friendly way. Watch this space!