PURPOSE: To provide a solar generation system with a battery discharge testing function which is economical because it does not need a spare battery when the discharge test of a battery is performed and, further, facilitates the size reduction and the weight reduction of the system.

CONSTITUTION: Circuits which detect the output voltage and output current of a solar cell 1 and the terminal voltage and terminal current of a battery 2-1 respectively and the discharge control arithmetic circuit 11 are provided. When the discharge test of the battery 2-1 is performed, if the terminal voltage of the battery 2-1 is higher than a predetermined voltage, the output power of a solar cell 1 is larger than the rated load of a load 5 connected to a solar generation system and, further, a commercial input terminal voltage is higher than a predetermined voltage, the discharge test of the battery 2-1 is started.