In 2012, Norway and Sweden implemented a common market for tradable green certificates to achieve each country's renewable-energy target. This is the first example of a cooperation mechanism that the EU has suggested to improve the cost efficiency of its renewable-energy policies. We asked investors in 446 planned hydropower projects in Norway what type of barriers may prevent their project from being realized under this scheme, and how likely it is that their project will be realized. Based on a regression analysis we find that the responses to these questions vary systematically with investor, project and process characteristics. We find that investors are concerned with capacity barriers imposed on the market because of the short duration and abrupt termination of the subsidy scheme at the end of 2020. Consequently, the cost efficiency of this and similar schemes can be improved by choosing a better design. Moreover, experienced investors and local landowners without previous experience in the energy sector responded differently to these questions. Local landowners were more optimistic, less concerned with capacity barriers and more concerned with economic barriers than experienced investors were. These observations are interesting given the recent emergence of new investors in the renewable energy sector.