A solar cell system for vehicles and a control method thereof, wherein even when a change of electric power generated from a solar cell is high, the variable voltage devices and the constant voltage devices selectively distribute the electric power according to the electric power without changing voltage. Accordingly, energy efficiency can be improved, the number of components can be reduced without using a voltage converter, and energy conversion loss can be decreased. Further, electric power generated from the solar cell is used for ventilation, air purification, cool and warmth, and convenience devices of a vehicle. Thus, a driver is provided with a controlled environment when riding on the vehicle. Accordingly, the present invention can meet a driver's requirements for the utilization of convenience devices and can provide a comfortable interior environment.