To effectively use solar battery power generation by taking the total output value as an output value under reference solar radiation intensity when the output value of a solar battery is lower than the output value under the reference solar radiation intensity, and taking the output of the power source other than the solar battery as zero when the output value of the solar battery is higher.

Reference solar radiation current under reference solar radiation intensity corresponds to solar battery output current under mean annual solar radiation quantity in global solar radiation quantity, and output current corresponds to a current value consumed by a load including a loss in one day. Real solar radiation solar battery current is real solar battery current varying every moment, and commercial supplementary current is difference between the reference solar radiation current and the solar battery current under real solar radiation current. For example, when the remaining capacity of a storage battery is A1 at time T1, the remaining capacity becomes A2 at time T2, going through A3, and returns to the remaining capacity of A1 at time T2 on the next day through A3. When the remaining capacity is B1 at time T1, the storage battery is fully charged during a time zone T1-T2, and held for one day. The remaining capacity, going through B2 to B3, returns to such a condition as to be higher than A1 and lower than B1 at time T1.