AbstractHigh temperatures occurring during stagnation conditions can be very detrimental to the reliability, durability and safety of solar thermal systems. Various approaches to mitigate the effects to stagnation have been employed in the past, however as collector and system efficiencies improve, and larger solar systems are installed, the need for reliable and cost effective stagnation control schemes is increasing. In this paper, the impacts of stagnation and various approaches to stagnation control are discussed and compared with regard to their features and limitations.