Headline: Windows of opportunity for catching up in formative clean-tech sectors and the rise of China in concentrated solar power

We analyse the potential for industry entry and catching up by latecomer countries or firms in formative sectors, by deriving a framework that builds on the concept of windows of opportunity for catching up. This framework highlights differences in technological, market, and institutional characteristics between formative and mature sectors, and elaborates how this may affect opportunities for catching up. We apply this framework to the global Concentrated Solar Power sector, in which China has rapidly narrowed the gap to the global forefront in terms of technological capabilities and market competitiveness. We find that the formative nature of the sector resulted in turbulent development of the technological, market, and institutional dimensions, making it more difficult for early leaders to retain leadership, and therefore easier for latecomer firms or countries to catch up. This signals an increased role in early-stage technology development in the next phase of the energy transition.