Ecological impacts of floating photovoltaics on lake ecosystems: eco-design and research perspectives

Floating photovoltaic (FPV) systems are expanding rapidly. While they could be a solution to land-use conflicts in renewable energy development, their ecological impacts remain poorly understood. A national seminar held in France in June 2025 gathered scientists, public authorities, NGOs, and industry stakeholders to assess FPV deployment potential, ecological risks, and eco-design strategies. This seminar was organized by the French Renewable Energies and Biodiversity Observatory, which aims to reconcile energy transition with biodiversity conservation through knowledge sharing and co-elaboration of technical guidelines. Although the effects of FPV systems on some physical parameters (e.g., light, temperature) have been demonstrated, the consequence on biological process needs to be better understood. Standardized Before-After-Control-Impact (BACI) protocols and long-term monitoring should be prioritized. Integrated quantification of the impacts should be also developed, notably through monitoring of the different trophic levels and of functional indicators (e.g., gas and energy exchanges). Future research projects should then promote interdisciplinary collaborations. In the meantime, FPV projects are developing and guidelines for their eco-design are expected. To this end, the participants reviewed a draft eco-design guide proposing a step-by-step framework: i) site selection and project size, ii) platform design, iii) ecosystem design, and iv) park management. All the stakeholders emphasized the need for early-stage guidance (e.g., choice of the sites) and for scientific-based recommendations supported by real-world examples. They supported the development of a shared and evolving reference document that facilitates dialogue among stakeholder groups.