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On our last project, a ground mounted PV system supported by a post and beam frame, I used Unirac WEEB grounding system (UGC-1) on the Unirac rails. WEEB stands for “Washer, Electrical Equipment Bond.”
The electrical inspector was not familiar with the product or the concept. I showed him the spec sheet from Unirac, which details how the grounding clip creates one electrical path through the mounting rails for the ground. Basically, the ground clip pierces the aluminum finish on the panel frame and the aluminum surface of the mounting rail. With that electrical connection established, a ground wire is run between all of the mounting rails and connected to the grounding electrode system. Keep in mind, that systems should have a continuous grounding path back to the service panel ground bar and cannot be bonded to the neutral or negative conductor of the PV system.
Not all electrical inspectors would accept this method and it is not currently part of the NEC, so it is better to check with them first. Otherwise, it saves a lot of time, effort and materials to use WEEB grounds.
