GLASSXcrystal integrates 4 system components in a functional unit: transparent heat insulation, protection from overheating, energy conversion and thermal storage. A 3-ply insulating glass construction provides excellent heat insulation with an U-value of less than 0.5 W/m2K. A prismatic glass implemented in the space between the panes reflects sun rays with an angle of incidence of more than 40° (in summer, when the sun is high in the sky). On the other hand, the winter sun passes through the sun protection at full intensity. The central element of GLASSXcrystal is a heat storage module that receives and stores the solar energy and, after a time, releases it again as pleasant radiant heat. PCM (Phase Change Material) in the form of a salt hydrate is used as the storage material. The heat is stored by melting the PCM; the stored heat is released again when the PCM cools. The salt hydrate is hermetically sealed in polycarbonate containers that are painted gray to improve the absorption efficiency. On the interior side, the element is sealed by 6 mm tempered safety glass that can be printed with any ceramic silk-screen print.