For green transition in BSR, local authorities, SMEs and citizens/interest groups need to raise their capacity - learn new skills how to establish and operate energy communities. For this they need compiled information and good pilot samples to build trust in energy community models that would encourage them to establish more energy communities. StartSun project will tackle the start-up challenge of establishing energy communities by creating the necessary knowledge, documentation and first experience-pilots thus enabling further creation of energy communities in BSR, using the locally available resources, serving its greater energy independence in electricity sector and keeping jobs in the communities. The Baltic Sea Region countries have implemented and interpreted the Electricity Market Directive and the Renewable Energy Directive differently. Citizen energy communities and renewable energy communities are two names for energy communities that have been introduced through the directives. This project aims to overcome the energy community start up gap, providing Start-Up package for establishing energy communities and will pilot six different types of energy communities through research-based methods, and exchange experience between them to strengthen and speed up creation of energy communities in the BSR.