Many islands face problems in regard to sustainable development, both environmentally and economically. Due to geographical isolation energy is often imported from the mainland. Focusing on local energy use may help islands to identify sustainable strategies and solutions. Islands in transition towards using more renewable energy sources are part of the project “Cradle to Cradle Islands”, funded by the EU Interreg IVb North Sea Region Programme. Energy systems on islands are diverse and linked to each specific location. Opportunities for the development of sustainable energy solutions are often inhibited by institutional, organisational or habitual problems. It is therefore essential to examine islands individually in their context; both in regard to energy use and available resources. This can be used to assess possible energy savings and unused renewable energy sources, and visualise their interaction, the consequences for the environment, as well as the effect on insular economy. Even though islands face different problems, they may inspire each other. In this paper a straightforward tool for examining insular energy systems is presented. The tool has been applied to five different islands in the North Sea Region. The application of the model has facilitated the identification of possibilities for each island to improve the regional development in these areas. Furthermore, a learning process can be identified, which helps to develop renewable energy systems on these islands, while addressing insular development.