A flat roof racking system configured for receiving solar panels having electrically conductive frames, the racking system comprising substantially parallelly disposed panel support structures, spacer bars and retaining and grounding clips pairs, each panel support structure comprises a first end, a second end, a top member having a first channel section connected to a second channel section and two ends, and a bottom member having a channel section and two ends. The first and second channel sections are disposed in a plane but at an angle from one another and each end of the bottom member is fixedly connected to an end of the top member such that the top member is configured to make a first tilt angle at the first end with the bottom member and a second tilt angle at the second end with the bottom member.