Comparing the Technology Trajectories of Solar PV and Solar Water Heaters in China: Using a Patent Lens

China invests more in renewable energy than any other countries, such as in solar energy. The traditional literature maintains that these government-supported industries are more innovative than grassroots industries such as solar or thermal, which leads to debate. This study uses mixed methods, combining qualitative and quantitative approaches to compare the technology trajectories of leading solar water heater (SWH) and solar photovoltaic (PV) firms in China. It concentrates on the following three aspects: trajectories of key technologies, patent citation network, and type of collaboration. Our analyses show that technology trajectories differ significantly between leading SWH firms and PV firms in China. We find that the Chinese SWH firms are core to international knowledge networks, and are following a market-driven innovation mode. In contrast, Chinese PV firms are close to the center of the network and government-driven. Research suggests that grassroots innovation, by doing, using, and interaction (DUI), can create short-term market development models relying on China's traditional industry model, but cannot create a long-term international leading innovation model; only integrated science, technology, innovation modes (STI), and DUI innovation modes tend to result in international leadership in innovation.