Back when I first became a photographer, light leaks were considered a bad thing. We mounted large hoods on the lens of our camera to prevent solar flare from ruining our shots.
Boy, how things have changed. One cannot stroll Pinterest photography boards without seeing photos with light leaks, sun spots and lens flare streaks. They can be pretty when used carefully.


These photos were all shot late in the day with the sun just outside the frame. A nice golden glow lights the picture and the sun, just off to to top, created streaks in the bottom shot and circles in the top. The shape of the lens flare depends on the angle at which the harsh light is entering the lens.


The photo below was taken on a larger scale, however the sun off to the left still created a light leak that looks good.
Set ups like these are great for portraits. Just remember to have an additional source of light to cast on the subjects face, so it won’t get lost in shadows. A reflector works nicely for this.