Generator parallel cables

Just for reference an inverter (whether it is attached to a generator or not) starts with starts with a low power sine wave from something like a digital watch and amplifies it much like an audio amplifier, using a DC power source for the amplifier. To mate two together you have to share one source sine wave between the two to keep them from fighting each other. That is what the extra wire(the one with the banana plugs) is for and why you cannot hook any inverter without a place to input a synchronizing signal into another power circuit. Inverters with the ability to match another circuit are ofter referred to as "Grid Tie" inverters.