NOVELTY - The system (1) has an input terminal (IN2) and an output terminal (OUT2) equipped with a direct current-direct current (DC-DC) converter (103). Sum total voltage is output by voltage of electrical storage cells (C1-Cn) e.g. secondary batteries, to the DC-DC converter in an electrical storage cell group, without contributing to input. A balance circuit (101) is connected to an electrical storage module (102). Each voltage of the electrical storage cells is equally maintained by the balance circuit. Load current (ILoad) flows through a load (104).    USE - Power source system for use in a solar energy power generation system in an electronic device. Can also be used for an electrical storage source.    ADVANTAGE - The sum total voltage is output by voltage of the electrical storage cells such as secondary batteries, to the direct current-direct current converter in the electrical storage cell group, without contributing to the input, thus reducing loss generated with switching by low-voltage of the input-output voltage of the DC-DC converter, and noise, relieving voltage-resistant conditions calculated with respect to devices such as capacitor and coil, and hence utilizing a small device of low-voltage as components such as input-output capacitor, that accounts for a large ratio in size and weight of the DC-DC converter, and the coil, and reducing size of the converter, eliminating a power converter device equipped with the balance circuit, and dispersion in the voltage produced by charging/discharging in the capacitor connected in series by applying high voltage to the capacitor, and improving conversion efficiency.    DESCRIPTION OF DRAWING(S) - The drawing shows a circuit block diagram of a power source system. '(Drawing includes non-English language text)'    Electrical storage cells (C1-Cn)    Load current (ILoad)    Input terminals (IN1, IN2)    Output terminals (OUT1, OUT2)    Power source system (1)    Balance circuit (101)    Electrical storage module (102)    DC-DC converter (103)    Load (104)