The BigStoreDH project is analyzing the integration of large heat stores into thermal networks in Switzerland. Based on three generic network types that are typical for Switzerland, the integration of storages is simulated and the influence of different storage sizes, weather data, hydraulic integrations of the storage and peak loads is investigated. A main focus is set on the replacement of the still often used fossil-fuel-based peak power. An economic analysis shows that for smaller networks, an economic optimum lays in the range of the existing recommendations for wood heating networks. For large networks and thus also large storage systems, seasonal storages can become attractive due to the decreasing specific costs. The positive effect of large heat storage tanks could also be demonstrated in terms of greenhouse gas potentials and sector coupling. An analysis of the potential of large storage tanks for Switzerland's future heat supply shows similar results: In most scenarios, large heating networks require seasonal storage for optimal future energy supply. Smaller biomass networks, on the other hand, are not part of an optimized future energy supply, regardless of the integrated storage size.