Research on the evolution of China's photovoltaic technology innovation network from the perspective of patents

Photovoltaic (PV) technology, as a low-carbon energy technology, is crucial to mitigating climate change and achieving sustainable development. China has the largest total number of PV technology patents in the world, but the lack of core technologies has restricted the further innovative development of China's PV industry. Therefore, it is necessary to clarify China's current PV technology accumulation to better catch up with key technology areas. To clearly describe the structural characteristics of China's PV technology innovation network, this study uses China's patent PV technology data over the past 20 years from the Incopat global patent database and analyses the structural characteristics of the network from the perspectives of one-mode and two-mode networks, using method of social network analysis (SNA). The results show that 1) the leading PV enterprises have basically formed relatively stable internal collaborations and that the scale of innovation network development has expanded rapidly, with very strong stamina; 2) with the development of China's PV industry, many innovative PV techniques have been developed by leading enterprises in the field of innovation and research and development (R&D) of PV technology, and among patent applicants with strong collaboration, kinship collaboration with investment relationships is dominant; 3) provinces participating in PV technology innovation are increasing significantly, the network is more influenced by leading nodes, and the eastern coastal provinces are pioneers in the innovation and R&D of PV technology; and 4) PV technological innovation collaboration between patent applicants and cities has changed from local collaboration to cross-regional collaboration, high-value areas are basically concentrated in the eastern coastal region of China, with scattered spatial characteristics, and cross-regional collaboration presents a "triangular" spatial structure, with the Yangtze River Delta, Pearl River Delta, and Beijing-Tianjin-Hebei as cores. The conclusions can provide patent information support for scientific research on energy conservation and emission reduction to achieve low-carbon goals, and can also provide reference for policy formulation of renewable energy development and green development strategies.