Charge control system and charge control method

A charge control system comprising:

• a solar panel configured to generate electric power with sunlight;
• a first battery configured to be chargeable and dischargeable;
• a second battery configured to be chargeable and dischargeable;
• and
• a charge control unit connected to the solar panel, the first battery and the second battery, the charge control unit being configured to switch between a first mode and a second mode based on at least a magnitude of the electric power generated by the solar panel,
• the first mode being an indirect charge mode in which a process of charging the first battery with the electric power generated by the solar panel and a process of charging the second battery with electric power stored in the first battery are repeatedly executed depending on a state of charge of the first battery,
• the second mode being a direct charge mode in which the electric power generated by the solar panel is directly charged into the second battery,
• wherein the charge control unit is configured to change the charge mode at timing different from timing at which the magnitude of the generated electric power varies across a first threshold such that the charge control unit selects one charge mode having a higher efficiency of use of the generated electric power than efficiency of use of the generated electric power of another charge mode, when the magnitude of the electric power generated by the solar panel varies across the first threshold at which a relationship, that is whether or not the efficiency of use of the generated electric power in the first mode is higher than the efficiency of use of the generated electric power in the second mode, changes.