I am investigating how to optimize a PV array for both tilt angle and row spacing. It seems that tillt is fairly easy to evaluate, but row spacing doesn't seem so simple.

For a limited installation area such as a roof, I can install more panels by placing them closer together, but that can result in self-shading by one row to an adjacent row. This may occur for a limited number of hours, however, and allow an overall increase in annual output even though the self-shading occurs.

Are any of you aware of a study or analysis tool which allows this comparison in order to optimize output versus installation cost?