As energy demands fluctuate with the seasons, could seasonal thermal energy storage (STES) be the key to balancing the winter-summer electricity gap? And can we make it economically viable soon? In the 12th edition of our symposium, we focus on the pivotal role of STES in driving decarbonization across Switzerland and Europe. Stakeholders from academia, industry and utility will dive into the latest challenges and innovations as we explore how STES can impact sustainable and resilient energy systems in the future. Attendees can look forward to an engaging mix of expert presentations, interactive workshops, and dynamic discussion panels. The symposium is designed to unite major figures in the field of STES, fostering the exploration of important subjects and facilitating the initiation of valuable collaborations.