Exemplary systems and methods described herein can be used to secure a rail to a module or the rail to a support using a nut that can be inserted at a desired point of mounting. Another exemplary system describes a flashing to be inserted under a roof shingle, wherein the flashing is secured to a support for a rail or module. Yet another exemplary system describes a clamp that secures a rail or module and is adjustable along the length of a post. Spacers can be added to the post to extend the adjustment range of the clamp.