In this study has been demonstrated an example of energy planning of the Croatian islands. A Special emphasis is placed on achieving self-sufficiency of the Croatian islands. The study aims to show how all of the 49 inhabited Croatian island can meet its energy demand from locally available renewable energy sources instead of depending to the power system of the Republic of Croatia. In the first part of the study we strive to analyze the Croatian islands themselves, the geographical location an population density. We strive as well to describe the technologies with whom we try to achieve energy self-sufficiency of the Croatian islands. Then, based on data from previous studies that have been done for the islands of Krk, Unije and Lošinj in the North Adriatic, and Mljet, Lastovo and Korčula in southern Adriatic data is been calculated for all the inhabited Croatian islands. Also in the study has been made an energy projection of electricity consumption by 2050, which takes consideration of following trends in energy efficiency measures as well as the advancement of technology. To prove energy self-sufficiency of the Croatian islands, it is necessary to assess and calculate the energy potential of self-renewable energy sources. It has been also made projections of potential for solar photovoltaic power plants and wind farms, taking into account some parameters of the current legislative situation in the Republic of Croatia. In the third part of the study, a computer program “EnergyPLAN“ has been used for calculating energy systems of virtual power plants, which applies to all inhabited islands in Croatia as a whole. He also analyzed the scenario of the results and analysis of the use of renewable energy sources with the objective of achieving self-sufficiency of the island.