Test results and optimization of integrated collector storage with a transparent insulation cover

Transparent Insulation Material (TIM) has been used in integrated collector storage (ICS) prototypes developed at the Fraunhofer Institut für Solare Energiesysteme (ISE). Two prototypes (1st generation) without a second, freeze-protecting circuit, have been investigated under stagnation conditions and with water withdrawal during one year at the ISE outdoor test site (/1/, /2/). No damage due to freezing occurred.