Solar charging system

A solar charging system comprising:

• a solar panel;
• an auxiliary battery to which electric power generated by the solar panel is supplied;
• a driving battery for a vehicle;
• a direct current (DC)-DC converter that operates in a first state in which the electric power generated by the solar panel and electric power of the auxiliary battery are supplied to the driving battery, or in a second state in which electric power of the driving battery is supplied to the auxiliary battery;
• and
• a control unit that controls the DC-DC converter, wherein the control unit is configured to:
• operate in a first control mode in which the DC-DC converter is controlled such that a voltage or a state of charge (SOC) of the auxiliary battery is within a first range, or in a second control mode in which the DC-DC converter is controlled such that the voltage or the SOC of the auxiliary battery is within a second range that is wider than the first range;
• and
• operate in the second control mode when solar charging is performed by the solar panel.