Trade openness amplifies water-saving benefits of global photovoltaic supply chains

The global photovoltaic (PV) supply chain is often criticized for transferring environmental burdens, yet its net impact on freshwater resources remains unexplored. Using a novel framework integrating life cycle assessment with a dynamic partial equilibrium model, we quantify how international trade and climate policies jointly shape water consumption in PV systems from 2018 to 2030. We find that open trade enables trillion-cubic-meter annual freshwater savings, primarily driven by avoided cooling water in consumer regions (Europe and the Americas). However, trade barriers severely diminish these benefits: under high-tariff scenarios, water savings in 2030 drop to only 32% of those under free trade. Importantly, trade openness amplifies the water-saving effectiveness of climate policies. Our results underscore that maintaining an efficient global PV supply chain is critical not only for climate goals but also for global water security.