These or the WEEB* lugs are about the only reliable way of grounding a solar panel in many cases. The often used method of using a self-tapping screw to attach a wire fails more often than not due to the copper-aluminum corrosion. Rated for copper and aluminum wire (CU/AL) #14-#4 AWG, tin plated and UL listed.
Includes a 10-24 x 3/4" stainless screw and a keps nut. *The WEEB grounding system uses a different approach, and is probably better than standard lugs. We sell the WEEB components for IronRidge and Direct Power rail mounts. This, or something similar, is required in the NEC code. For more information on panel grounding, see this Home Power Magazine article on PV system grounds.