A system for mounting a plurality of solar panels on a building and comprising: a plurality of panel mounting brackets each comprising a base to be positioned on the building, and a vertical extension having a proximal end coupled to the base and a distal end vertically spaced apart from the base, wherein the distal end of the vertical extension has a fastener channel therein for receiving a nut; and a plurality of interior mounting clamps each comprising a leg having a proximal end to be coupled to the distal end of the vertical extension of a given panel mounting bracket, and a distal end, wherein a hole extends vertically through the leg for receiving a bolt, the bolt and the nut for coupling the proximal end of the leg to the distal end of the vertical extension, a first lateral arm coupled to the distal end of the leg on a first side thereof for securing a first solar panel to the given panel mounting bracket, the first lateral arm having a first thickness (T 1), and a second lateral arm coupled to the distal end of the leg on a second side thereof opposite the first side for securing a second solar panel to the given panel mounting bracket, characterised in that the second lateral arm has a second thickness (T 2) less than the first thickness. a plurality of panel mounting brackets each comprising a base to be positioned on the building, and a vertical extension having a proximal end coupled to the base and a distal end vertically spaced apart from the base, wherein the distal end of the vertical extension has a fastener channel therein for receiving a nut; and a base to be positioned on the building, and a vertical extension having a proximal end coupled to the base and a distal end vertically spaced apart from the base, wherein the distal end of the vertical extension has a fastener channel therein for receiving a nut; and a plurality of interior mounting clamps each comprising a leg having a proximal end to be coupled to the distal end of the vertical extension of a given panel mounting bracket, and a distal end, wherein a hole extends vertically through the leg for receiving a bolt, the bolt and the nut for coupling the proximal end of the leg to the distal end of the vertical extension, a first lateral arm coupled to the distal end of the leg on a first side thereof for securing a first solar panel to the given panel mounting bracket, the first lateral arm having a first thickness (T 1), and a second lateral arm coupled to the distal end of the leg on a second side thereof opposite the first side for securing a second solar a leg having a proximal end to be coupled to the distal end of the vertical extension of a given panel mounting bracket, and a distal end, wherein a hole extends vertically through the leg for receiving a bolt, the bolt and the nut for coupling the proximal end of the leg to the distal end of the vertical extension, a first lateral arm coupled to the distal end of the leg on a first side thereof for securing a first solar panel to the given panel mounting bracket, the first lateral arm having a first thickness (T 1), and a second lateral arm coupled to the distal end of the leg on a second side thereof opposite the first side for securing a second solar panel to the given panel mounting bracket, characterised in that the second lateral arm has a second thickness (T 2) less than the first thickness.