Hi, here is my try using v-ray with GI sun.
I followed this tutorial http://software.asgvis.com/index.php?option=com_docman&task=doc_details&gid=594&Itemid=439&uid=0
I used as primary engine Irradiance Map
And second engine deterministic Monte Carlo GI
Caustics On
Max Photons 100 Multiplier 300 search distance 5,0
Environment
GI: Sky, Sunlight,
Photon Emit Distance 100000
Caustic Subdivs 10000