Some generators are wired so that the 120 volt output is split between two outlets on two different circuits, limiting the maximum power available on either circuit to approximately half of the generator’s rated capacity. This can be a problem if you only need to power one large load, since it leaves half of the generator’s total capacity unused. Unfortunately, this limitation isn’t always apparent in the generator sales literature.
Some of the newest Honda and Yamaha generators are equipped with "Inverter Technology" that uses a special high-frequency multi-pole alternator in combination with a microcomputer-controlled AC inverter to deliver constant voltage and line frequency regardless of engine speed or electrical load. The alternator used is much smaller and lighter than traditional designs — For example, Honda claims its inverter-equipped EU3000is model is half the size and weight of its conventional EX3300 model, even though both products have identical power output ratings.
Inverter technology allows the alternator to spin at whatever speed provides the greatest efficiency, because the inverter is capable of maintaining a steady voltage, frequency and waveform regardless of alternator speed. So, engine speed can be automatically reduced under lightly-loaded conditions, reducing noise, fuel consumption and exhaust. It's also very clean power.
Some inverter-type generators also include a "strapping" connection that allows two identical models to be connected together, approximately doubling the power available for operating a single load.