A portable generator system provides power to a load source including an engine and a generator. The engine drives the generator to provide a generator alternating current (AC) electrical power output. An energy storage system (ESS) provides an ESS direct current (DC) electrical power output. A first inverter is connected to the generator for receiving the generator AC electrical power output and for providing a DC power output. A second inverter is connected to the first inverter and the ESS for receiving the DC power output from the first inverter and the ESS DC electrical power output for providing an AC power output. A first power mode includes the generator maintaining a first generator power output level corresponding to a specified power requirement of a load source, and the ESS providing an additional first ESS power output level for satisfying the specified power requirement of the load source.