Microphotographs of a broken solar cell showing the soldering spots between the bus-bars and the silver-paste fingers.
On the front side of the cell the silver paste fingers are much thinner, as the goal is to extract as much current while shading as little as possible.
On the rear the silver paste is spread much thicker.
I'm not sure about the exact scales here - maybe around 100um for the thinnest features. Will check once my micrometric scale gets here.