Well, i've got the code running (finally) after building the various modules and figuring out the WS2812 module, in Atmel studio 7. The PCB needed a little re-design as I had the RTC chip pins in the wrong order.

The corrected PCB design has been uploaded (rev A11)

Below is a short animation of the test cycle the dawn / sunset cycle.

You can see the three panels (x2 sun facing, x1 opposite horizon) with the three azimuths (the highest are similar for all three panels).

The idea is for the panels to be folded into a triangle and placed inside a frosted housing to help diffuse the light. Some more work could be done on the luminosity calculations to get a better dawn / sunset progression through the range of azimuths.