Strategic timing for the decarbonization contributions by China's photovoltaic manufacturers in global energy transition.

Photovoltaic (PV) technology is central to clean electricity and the Sustainable Development Goals. However, China's PV manufacturing industry, which accounts for nearly two-thirds of global capacity, is often criticized for its high carbon emissions. Existing studies typically assign emission responsibility to manufacturers while attributing decarbonization benefits to power generation, overlooking upstream producers' contributions. Here we propose a Producer Decarbonization Contribution framework to quantify these long-overlooked contributions at national and global scales. We show that China's PV manufacturers contribute 31.4%-73.8% of total PV decarbonization in China and 27.9%-45.4% globally. We further identify a strategic timing, defined as the point at which the PV's decarbonization contributions reach their maximum, occurring around 2035 in China under the Announced Pledges Scenario and 2030 globally under the Net Zero Emissions Scenario proposed by the International Energy Agency. These findings suggest maintaining supportive policies for China before 2035, while adopting more stringent measures globally after 2030 to avoid overproduction. The proposed framework that enables adaptive industrial policy design can be extended to other renewable energy technologies.