I'm simulating a poultry farm, and I have to put some shadows on the wall,however, I saw that i can only put shadows on the windows. is this true? or I can put a shadow on a wall? this is my poultry farm in sketch up,but the window that you can see, is polypropylene, it is not glass. How can I assign this material to the window? or it is better not to make advantage of glass, and make polypropylene wall

I'm simulating a poultry farm, and I have to put some shadows on the wall,however, I saw that i can only put shadows on the windows. is this true? or I can put a shadow on a wall? this is my poultry farm in sketch up,but the window that you can see, is polypropylene, it is not glass. How can I assign this material to the window? or it is better not to make advantage of glass, and make polypropylene wallwall?

thank you