A parallel inverter system includes a plurality of inverters of an instantaneous voltage control type, an output bus, an active power bus, a phase bus, and controlling devices. The output bus is used for connecting outputs of said plurality of inverters to a load. The active power bus is connected to the plurality of inverters so as to provide an active power sharing reference. The phase bus is connected to the plurality of inverters so as to provide a system phase reference. And, controlling devices control sinusoidal wave references of inverters to have the same phase, the reactive power, and the active power responsive to the active power sharing reference and the system phase reference. The related methods are also discussed.