To filter out a minimal amount of sunlight, use sheer curtains as a window covering. Sheers are inexpensive and easy to install. They come in many sizes or you can custom make your own. Measure the window and cut the sheers to twice the width. The length depends on how much below the window you want to cover but add about three inches to the top and bottom for a hem. These also only provide a minimum amount of privacy so use them in a space that you don't mind that your home is visible to those outside. Due to the see-through nature of sheer curtains, drapery lining should not be used.