We present a new methodology for defining regularly-spaced collector layouts for the purpose of simulating annual system cost in two-axis sun-tracking collector arrays, such as those comprising solar-thermal dish collectors or two-axis tracking PV. We thoroughly consider all layout combinations of aspect ratio, offset, ground-cover-ratio, and rotation. Collector position is optimised to reduce annual shading for a range of collector densities for the site of Barstow, California. Optimal layouts are rectangular in shape for ground cover ratios less than 0.23. Diamond layouts collect up to 1.4% more absolute annual solar energy for higher ground cover ratios. From these results, a correlation for determining optimal array layouts subject to the chosen position-dependent cost function is presented. This approach can be used for design of large arrays of two-axis sun-tracking collectors where collector position and costs proportional to land use affect levelised plant cost. (C) 2014 Elsevier Ltd. All rights reserved.