Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. to a large extent driven by governmental support. Various policies that can broadly be categorized as technology push, demand pull or systemic constitute a policy mix for renewable energies. Our goal is to gain insights on the influence of this policy mix on the intensity and organization of inventive activities within the technological innovation systems for wind power and photovoltaic in Germany since the 1980s. We examine the effect of different instruments on the size and structure of co-inventor networks based on patent data. Our results indicate notable differences between the technologies: The network size for wind power is driven by technology push and systemic instruments, while in photovoltaic demand pull is decisive for network growth. The instruments complement each other and form a consistent policy mix. The structure of the networks is driven by demand pull for both technologies. Terms of use: Documents inSystemic instruments increase interaction especially in the wind power network and are complementary to demand pull in fostering collaboration.

We analyze the evolution of the international collaboration network in photovoltaic research. Using data on scientific publications for the period 1980-2015, we apply social network analysis to trace the evolution of the global network of countries and national research networks of organizations. Our objective is to identify the determinants of countries' international research embeddedness by looking at national policies and structural properties of the national research networks. We observe a steady increase of publications and collaboration within the global research network. While there is a small group of countries that remains central throughout all years, several countries emerge and catch up while others lose their relative position.We find that cohesion and connectedness of the national system positively affect research output as well as international embeddedness, whereas centralized systems are less embedded. Policy, especially demand side instruments, has a positive effect on publication output and embeddedness.

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