Emmisive materials are not meant for main source of illumination. Use light objects for the actual illumination, and use emmisive lights for visual effect.
V-Ray, being biased, will do less samples in dark areas, as one usually doesn't see details that well in darker area. Which is why when you have a fully dark night scene you can get these artifacts while in a dyalight render with the same settings you won't see them.
You should be able to place the lights inside the light bulb, but have you assigned a fuly transparent glass material? In Sketchup one usually use a partially transparent material, while in V-Ray the diffuse should be 100% transparent and an reflection layer. (also an refraction layer if you use thick glass)