Identifying technological sub-trajectories in photovoltaic patents

This paper proposes a search strategy for photovoltaic patents which allows to distinguish the photovoltaic system into sub-trajectories. Identifying and analyzing sub-trajectories is of particular importance for understanding micro patterns of technological change. The proposed search strategy is modular and replicable. It performs similar to leading benchmark search strategies but allows to distinguish three cell sub-trajectories and two system components. Descriptive analysis reveals that inventive activity differs between sub-trajectories. The market dominating silicon wafer cell sub-trajectory shows hardly any patented inventive activity. Country comparison reveals that Asian countries focus on the emerging cell sub-trajectory. The USA focus on the established thin-film sub-trajectory and inventive activity in Germany focuses on module components. While the proposed search strategy allows for a fine-grained analysis of inventive activity in photovoltaics, the empirical assessment of sub- trajectories in general can increase understanding of technological change and can be used to implement policy interventions at a microtechnological level.