I worked on a time dependent solar radiation problem a year ago. You will have to define the intensity and direction as a function of time right under General Settings (where you enable solar radiation).
You will also have to resolve the azimuth and elevation angles into its component vectors to determine the resultant position of the sun in terms of X, Y and Z co-ordinates. The easiest way to accomplish this is using Excel, and basic trigonometry (with your sine and cosine components). The net output should be X, Y, Z and intensity each as a function of time.
You can then input these four tables inside General Settings > Solar Radiation after time dependency has been defined.