The Helio Lug from Amphenol (AKA the U-Lug)is one of the only grounding lugs listed under UL 2703 (UL Listing - QIMS.E338690
Rack Mounting Systems and Clamping Devices for Flat-plate Photovoltaic
Modules and Panels)
The ULug was developed to provide benefits such as listed hardware capable of accepting 4-12 AWG solid copper conductors, does not require the use of unreliable self-tapping screws, can be used with virtually all racking systems, (0.09 inches (2 mm) to 0.25' (6.35 mm) thick), is a code compliant "first make - last break" grounding system, does not require etching or enlarging most module grounding holes, (0.16" (4mm) to 0.295" (7.5mm)) and also comes with reusable hardware for servicing without replacement
For additional information, please see spec sheet below.