From the h-m-g.com web site:
SkyCalc 2.0 ® operates at three levels of detail:
The first level requires little information from the user, instead relying on extensive defaults to describe the user's skylighting system and building operation.
The second level allows the user to modify any default in order to describe the situation more precisely.
The third level allows the user to enter detailed information about products and schedules such as performance data for specific products or detailed building operation information.
SkyCalc® is a Microsoft Excel-based program with screens similar to what is shown here and can be downloaded for free at http://www.h-m-g.com/downloads.htm.
SkyCalc®, computer-aided daylight design tool, screen