Solar district heating (DH) plants consist of large fields of solar thermal collectors feeding their produced solar heat into block or DH networks in urban quarters, smaller communities, or large cities. The solar collector fields are either installed on free ground or integrated into building-roofs. The plant capacities range up to 50 MWth for the presently largest systems installed. Typically, shares of the solar thermal plant are 10–50% of the total heat supply of the DH system. This chapter presents various types of solar DH systems using practical examples of realized projects, discussing technology, economical feasibility, and future trends.