IN-VEHICLE SOLAR CHARGE CONTROL SYSTEM, IN-VEHICLE SOLAR CHARGE CONTROL METHOD, AND PROGRAM

An in-vehicle solar charge control system includes a path switching unit provided in parallel with the first DC-to-DC converter on an electrical circuit that connects a solar DC-to-DC converter and a first battery and through which electricity having output power flows, and a switching unit controller which switches the path switching unit between a first state in which the output power is supplied to the first battery without being input to the first DC-to-DC converter, and a second state in which the output power is allowed to be input to the first DC-to-DC converter that is switched to the first operating state by a converter control unit.