A solar module mounting system having - a base support, mountable on a substrate, in particular on a roof, with a base plate on which at least two base support retaining walls are arranged extending opposite and parallel to one another, a free space being formed between the base support retaining walls and the base support retaining walls forming a bracket support receptacle together with the base plate, - a bracket support with a holding arm which transitions on an end side into a mounting area and which is detachably connectable to the base support, the bracket support retaining walls in the mounted state forming outer surfaces facing inner surfaces of the base support retaining walls, said outer surfaces having a distance from one another which approximately corresponds to a distance of the inner surfaces of the base support retaining walls, wherein - the mounting area has a mounting block with an approximately cuboidal based shape, with tongues projecting therefrom, with the two vertical bracket support retaining walls for mounting on the base support retaining walls, and a horizontal plate and an upper horizontal plate which extends parallel to the horizontal plate, the horizontal plates (42, 48) connecting the bracket support retaining walls to each other, and the horizontal plate being located, with respect to the cross section, at the lower end between the vertical bracket support retaining walls facing the base support and forming the tongues which project laterally with respect to the bracket support retaining walls, the horizontal plate extending in the same plane as the tongues, - the base support retaining walls extend vertically and respectively have, in their inner surfaces facing one another, multiple accommodation grooves running parallel at different distances to the plane of the base plate, - in their mounted state, the bracket support retaining walls respectively have on their outer surfaces facing the base support retaining walls one of the tongues adapted to the accommodation groove of the base support retaining walls, the tongues being arranged on the end of the mounting block facing the base plate in the mounted state of the support bracket. - the horizontal plate and the upper horizonal plate each have a through opening, - a safety clamp is formed by threads in the through openings and a screw screwed into and supported on the base plate of the base support. - a base support, mountable on a substrate, in particular on a roof, with a base plate on which at least two base support retaining walls are arranged extending opposite and parallel to one another, a free space being formed between the base support retaining walls and the base support retaining walls forming a bracket support receptacle together with the base plate, - a bracket support with a holding arm which transitions on an end side into a mounting area and which is detachably connectable to the base support, the bracket support retaining walls in the mounted state forming outer surfaces facing inner surfaces of the base support retaining walls, said outer surfaces having a distance from one another which approximately corresponds to a distance of the inner surfaces of the base support retaining walls, wherein - the mounting area has a mounting block with an approximately cuboidal based shape, with tongues projecting therefrom, with the two vertical bracket support retaining walls for mounting on the base support retaining walls, and a horizontal plate and an upper horizontal plate which extends parallel to the horizontal plate, the horizontal plates (42, 48) connecting the bracket support retaining walls to each other, and the horizontal plate being located, with respect to the cross section, at the lower end between the vertical bracket support retaining walls facing the base support and forming the tongues which project laterally with respect to the bracket support retaining walls, the horizontal plate extending in the same plane as the tongues, - the base support retaining walls extend vertically and respectively have, in their inner surfaces facing one another, multiple accommodation grooves running parallel at different distances to the plane of the base plate, - in their mounted state, the bracket support retaining walls respectively have on their outer surfaces facing the base support retaining walls one of the tongues adapted to the accommodation groove of the base support retaining walls, the tongues being arranged on the end of the mounting block facing the base plate in the mounted state of the support bracket. - the horizontal plate and the upper horizonal plate each have a through opening, - a safety clamp is formed by threads in the through openings and a screw screwed into and supported on the base plate of the base support.