Small Aircraft; High Wing; 1 Eng; Fixed Gear
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 6
Confusion; Distraction
Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Flight Crew Executed Go Around / Missed Approach
Environment - Non Weather Related; Human Factors
I was the Controller in Charge position (CIC) listening to Local (LC); Ground Control (GC); and Clearance Delivery (CD). The Local Controller (LC) was located on the south side of the tower; I was on the opposite side of the tower watching LC's sequence via the STARs radar display.  The sun was directly in our face at the time which makes it difficult to visually acquire aircraft on final; especially small aircraft. Aircraft X was told to land on Runway 34R; Aircraft X acknowledged his clearance to land Runway 34R. Aircraft Y was cleared to land Runway 34L. Aircraft Y acknowledged his clearance to land Runway 34L. Aircraft X was ahead of Aircraft Y for the parallel runway. Aircraft Y initiated a go-around; as I went to do the paper work and find out why Aircraft Y went around; the LC and I noticed that Aircraft X had exited the runway and was in between Runway 34L and 34R indicating that he had landed on Runway 34L (the wrong runway). I called NORCAL to verify that was the reason Aircraft Y initiated a go-around; and it was. I suggest that all aircraft be required to turn on their landing lights during periods of difficult visual condition to include sun glare.
RNO Tower Controller in Charge; CIC; reported due to sun glare blocking controller's view of final; traffic landed on wrong runway resulted in traffic executing a go around.