Surely you have seen some of the videos on YouTube that show to add sun rays to the image.
I have blended following image from 4 exposures using luminosity masks. Sun was poking though the clouds, but even after I closed aperture to F22, sun beams were not prominent enough.
Here is a small re-cap on how to add fake sun rays.
To simplify the next step, I recommend putting a black layer with 70% opacity under your layer with lights - that way it will be easier to see what's going on.
The trick here is to place center of zoom to where your source of light is. Smart object will let you modify filter settings so play with it until you get best results.
Here you have some kind of sun rays. If there are enough of rays, you can just duplicate the layer 3-4 times or run more Radial blurs on top to make rays sharper.
If you were not lucky and rays turned out too short, here is what you can do. You would have to rasterize you smart object first to be able to paint on top.
You can see how you can push this effect even further with carefully and creatively placed brush spots.
Now, this results in much better sun rays, but they still look kind of fake.
Here is how to make them much more realistic.
Wrap all your rays into a group, create Lights luminosity mask and set it on the group.
Better, right? With just 1 luminosity mask.