Abstract: The invention relates to a modular, self-supporting mounting system for mounting an arbitrary number of flat modules (170) on flat roofs, wherein the modular, self-supporting mounting system comprises at least one base element for mounting a single flat module (170), wherein the base element comprises the following: a first and second module strut (110) disposed in parallel next to each other; a first and second front module support (120) having a first length, wherein a first end of the first front module support (120) is attached to a first area (111) of the first module strut (110), and wherein a first end of the second front module support (120) is attached to a first area (111) of the second module strut (110); a first and a second rear module support (130) having a second length, wherein a first end of the first rear module support (130) is attached to a second area (112) of the first module strut (110), wherein a first end of the second rear module support (130) is attached to a second area (112) of th