Offshore floating photovoltaic: from ecological impact pathways to MSFD criteria

Offshore floating photovoltaics (OFPV) are an emerging maritime renewable energy technology with the potential for large scale deployment, yet their ecological impacts remain poorly understood compared to offshore wind farms. This study develops a process-based framework to align OFPV impact assessment with the Marine Strategy Framework Directive (MSFD). We map potential OFPV impact pathways to relevant MSFD descriptors, categorize OFPV effects across spatial, temporal, and functional dimensions, evaluate the suitability of existing MSFD indicators for OFPV impacts, and identify questions for OFPV research needed to support indicator development. Our analysis highlights that MSFD descriptors D1 (pelagic biodiversity), D2, D4, D5, and D7 are likely to be most affected by OFPV. Of all indicators assessed, 13 lack defined thresholds, while 16 appear useable to evaluate OFPV impacts. Key knowledge gaps persist regarding causal mechanisms, multi-pressure interactions, food web effects, cumulative impacts with offshore wind farms, and appropriate spatial assessment scales. As OFPV deployment accelerates, robust in-situ measurements, routine monitoring, and ecosystem modelling efforts will be essential to ensure their sustainable integration into marine ecosystems.