At the moment , a sun is rendered even when "visible in renderer" is deactivated. The only way to prevent a sun from rendering is to "disable" it.
IMO it would be more efficient if the sun would also NOT render - like sky - when "invisible in render" is set.
It could then be made invisible to renderer through a parent object, which is now not possible.
and so it would make things easier with multiple sun positions and keyframing different lighting setups for different frames...
