The purpose is to calculate best orientation for solar hot water and PV systems. The requested direction and elevation above the horizon is the max yield. This is the minimum request (4000+ likes).
In practice, topology, nearby trees and man made structures cast shadows on the panels (for solar hot water and PV systems). The end objective is to calculate 'the solar deduction due to shadows", say in Excel spreadsheet.
This could be done by superposing the direction and elevation of these objects (above the "horizontal plane of the panels") to the requested direction and elevation of the sun above the horizon (say in 1, 5 or 10 degrees horizontal increments).