A power supply system includes a plurality of sweep modules, a defect detecting unit, and a control unit. Each sweep module includes a battery module and a power circuit module. The defect detecting unit detects a defect for each sweep module. The number of sweep modules is greater S (S≥2) than a minimum number of sweep modules required for operation. When the number of defective sweep modules in which a defect has been detected is equal to or less than F (2≤F≤S), the control unit is configured to disconnect the defective sweep modules from a main line and to continuously execute sweep control.