Use the Sun + Shadows tool to study the effects of the sun's path on your projects.
The first step for accurate shadow studies is to set your project location.
Once you've set your location and optionally imported a satellite image, model your project including building context, and shading elements like louvers and trees.
Turn shadows on in the Sun + Shadows menu at the top of the application (you can also enable shadows, as well as adjust shadow intensity, in Visual Styles):
From here, you can adjust the time of day and day of year. The default year is shown as 2000 - don't worry, this doesn't affect the accuracy of the sun shading study.
You can also toggle the Sun Editor from the Sun + Shadows menu (or use shortcut DR), which provides a graphical display of the sun's location in space:
The Sun Editor will move with the camera, so you may have to adjust your zoom level and/or camera orientation to get the widget in a position that makes sense relative to the design you're studying.
Grab the circular grip to move the sun along its path and effectively adjust the time of day.
Adjust the time of year from the Sun + Shadows menu. Doing so will adjust the angle and orientation of the graphical sun path based on the time of year.