A solar power system may include rails, solar modules, and a plurality of clamps to secure the solar modules to the rails. An end clamp may be partially disposed inside a rail at an end of the rail. The end clamp may secure a solar module to the rail by coupling to the frame of the solar module. The end clamp may include a fastener that may be tightened to engage the end clamp and secure the solar module by holding it on top of the rail. The end clamp may establish an electrical grounding connection between the frames of the solar module and the rail.