Attached Link: http://www.aelfheim.co.uk/Vue/Demos/Eco-lights.htm

Quote - "*... while you cannot make lights into echo systems*..."

Although indeed lights can not be natively used as ecosystem instances, there is a script that does a workaround on that, on the link above.

But, a warning, both for lights on ecosystems or scattered: that increases render times a lot. For every light you add to a scene, you increase render time a bit. If you have hundreds of lights... that can be a render killer. Unless, you configure these lights to influence nothing on the scene, which I strongly recommend.