An attachment system for a solar panel racking system is provided. The attachment system comprises a rail, a nut and a fastener. The rail includes a receiver to releasably receive the nut. The receiver has an arcuate channel and a retainer. The nut has an arcuate portion sized and dimensioned to be receivable within the arcuate channel, and a flange for releasable engagement with the retainer. Upon receipt of the arcuate portion within the arcuate channel, the flange releasably engages the retainer to releasably engage the nut within the receiver. The fastener secures the nut within the receiver and thereby secures the rail to the structure. The arcuate channel assists in the releasable engagement between the nut and the rail by assisting in cooperatively orienting and positioning the nut to guide the nut into the receiver.