Dear Mohit,
You can use SAM's parametric simulation feature to run a set of simulations on different weather files. For the power tower model, you may want to check the "Always layout automatically" and "Always optimize" boxes on the Heliostat Field page so that SAM calculates the optimal field layout for each location. On the other hand, if you want to fix the field layout, then you should clear those boxes.
To run a parametric simulation on location, you should add the Location variable to the list of input variables. Before you do that, you will need to download weather files for the locations in India, and then on the Location and Resource page, click "Folder settings" to add the folder that contains the files to the list of folders SAM searches for weather data. That will ensure that your files appear in the list of available input variables for the parametric simulation.
Best regards,
Paul.