Abstract: A material-sparing, reusable stack holding system for supporting and transporting framed photovoltaic or solar thermal flat modules. The system consists of individual molded parts, which form stable and transport-safe pillars or rails, respectively, among one another by means of mechanical cogging and with the frames of the modules by means of a locking connection. To date, only stack holders, in the case of which the solar modules are stacked in horizontal position with the use side facing up (“sunny side”), were known. The system disclosed here makes it possible to stack the modules in horizontal as well as in vertical position. In the case of horizontal stacking, the use side can be arranged facing up or down.