This topic has a list of rendering extensions & programs for SketchUp:
I use Twilight for rendering. It’s pretty reliable, easy to learn, and can produce some great renders.
Also, check out OctaneRender… I can’t even tell the difference between some of their renders and reality. I think it’s cheaper than V-Ray too and can render complex scenes instantly with hundreds of GPUs on the cloud… or something. OTOY • Brigade
OctaneRender In Action on Vimeo
Here’s a link to the V-Ray for SketchUp forums:
https://forums.chaosgroup.com/forum/v-ray-for-sketchup-forums