while reading about lighting with Cycles and wondering about translating some things
from Maxwell i found this very interesting article for Cycles, explaining how to create
an accurate sun intensity model and using kelvin values for emitters via the blackbody
node. While not an add-on i think it could be very useful for some of us.
Just a minor remark: Cycles is not unbiased. The term unbiased is used for renderers that do no simplifications to speed up rendering. An unbiased renderer will have a minimal amount of settings and will always converge toward a result that is as realistic as possible.
Maxwell is an unbiased renderer, but Cycles is a biased renderer that uses methods to simplify the result in order to gain speed. This doesn't mean that Cycles is not a realistic renderer. V-Ray is also a biased renderer, and the physics math behind the light ray calculations is correct, but rendering is sped up by using methods like a light bounce limit, ray tresholds, blurring glossy reflections, noise reduction and other approximations that increase speed at the expense of realism. Using the right settings, a biased renderer can yield very similar results to an unbiased renderer while offering more speed.
The Blender 2.81 master builds now include Intel's AI-powered Open Image Denoiser (OIDN). It's quite impressive what it can already do with a one-sample rendering:
