An output power adjusting method is applied on an inverter. The inverter includes a capacitor to store direct current (DC) electricity provided by a photovoltaic (PV) module. At least the DC electricity provided by the PV module is converted into alternating current (AC) electricity. Determine whether a power value of the AC electricity exceeds a power threshold. When the AC electricity exceeds the power threshold, the inverter works in a continuous mode. When the AC electricity does not exceed the power threshold, the inverter works in a discontinuous mode where the PV module charges the capacitor. In the discontinuous mode, determine whether a voltage on the capacitor exceeds a reference voltage, and when the voltage on the capacitor exceeds the reference voltage, the DC electricity provided by the PV module and DC electricity in pulses provided by the capacitor are converted to the AC electricity.