Inverter Generator - Quiet Power

Inverter generators (IG) combine conventional generator and inverter technologies to create a "best of both worlds" generator to produce clean power with less noise and better fuel economy. IGs are smaller, lighter and quieter than conventional generators. They are more fuel efficient and potentially produce cleaner power as well. Inverter generators do not require a battery bank and are typically less expensive per watt than an comparable inverter setup with the requisite battery bank to power it. The combination of clean power, low noise and fuel economy of an IG is unmatched by either conventional generators or inverters.

Westinghouse
WPro8500

The primary components of a conventional generator are the engine and alternator that produces alternating current (AC). An IG adds a direct current (DC to AC) power inverter to the mix. An inverter generator engine spins an alternator to create variable frequency AC power. The frequency varies with engine speed and the engine runs at the lowest speed required to produce the power for the load. The variable frequency AC power is sent to a rectifier that converts the AC to DC. Next, the DC goes to the inverter where it is inverted back to AC at a constant 60Hz. Finally stable 60Hz electricity is sent to the plug receptacles on the generator. Small loads are where IGs outperform conventional generators in fuel economy and noise reduction. The IG engine runs very slowly with small loads, lights, electric blankets or box fans because these devices do not consume large amounts of power. The IG engine will increase speed to match the load and will run much faster when running microwaves, coffee pots or electric skillets. With large loads, IGs will consume near equal amounts of fuel as conventional generators because it is required to run the larger loads. However, expect IGs to provide significant fuel savings when running smaller loads for extended periods of time.

Inverter generator power quality depends on the inverter technology used. Because an IG uses a DC to AC inverter to produce stable AC power, all the characteristics that apply to inverters also apply to IGs. Inverters produce either pure sine wave or modified sine wave power. Choose an IG that matches the requirements of the appliances that will be plugged into the generator. Space heaters and incandescent lights work well with modified sine waves, however appliances with motors or employ computerized components will probably work better with a pure sine wave inverter generator. See this article for more information about pure vs modified sine waves inverters.

Grid Power Sine Wave

One area IGs are less competitive with conventional generators is the large, multi-kilowatt category. Inverter generators have more parts and are more sophisticated. This translates into higher constructions costs in both materials and labor. Once power loads reach much past 3kw, IGs begin to lose their economy advantage. Larger IGs continue to save fuel on lighter loads, however the cost of multi-kilowatt inverters dramatically drives up the cost of the whole package. An IG in the 6,500 watt range doesn't make much sense for a 300 watt load when a 1,500 watt IG is much less expensive. At the same time, a conventional 6,500 watt generator will be much less expensive to purchase as long as it meets noise and power quality requirements of a particular situation. Conventional generators certainly can be engineered to be just as quiet as IGs when both are running multi-kilowatt loads. As for fuel economy, a 6,500 watt IG will use the same amount of fuel as a conventional generator running the same 6500 watt load. There is no free lunch.


Inverter generators have a reputation for great fuel economy as they are much more efficient when running small loads. Inverter generators can use 40% less fuel than a conventional generators running lighter loads. Like conventional generators, IGs run on many fuels however, gasoline and propane models are the most common. Several dual fuel models on the market run on gasoline and/or propane as well. While diesel inverter generators exist, they are not nearly as common. Inverter generators are already more expensive per watt than conventional generators and diesel engines push the disparity even farther. In addition, diesel engines are heavier than gasoline equivalents and do not bring enough benefit to IGs to offset the cost and weight of diesel power plants. Finally, both ethanol free gasoline and propane are commonly available in small, transport safe containers at just about any big box or hardware store. Since IGs are fuel efficient, these small fuel "bottles" are a perfect companion for lightweight portable inverter generators.

At the end of the day, the ultimate selling point for inverter generators is how quiet they are engineered to operate. There are a few reasons people choose an IG over conventional and the reason at the top of most lists is noise level. From tailgating to camping, the last thing people want to hear is an ear splitting generator. Many camp grounds prohibit operating generators after a specified time. If nobody can hear the generator, is it really running? Some inverter generators can operator down into the 45dB range, which happens to be quiet as a whisper. One thing to understand is these readings are typically taken at 23 feet away from the generator and the dB reading taken three feet from the unit will be higher. An inverter running on a large battery bank will be quieter than an IG but the batteries are expensive and will weight a lot more than an IG with 1 gallon of fuel.

Sound levels are typically measured at 23 feet away

Though inverter generators are mostly prolific in the lower wattage category, one feature that has become common is the ability to link two identical inverter generators together to double the power output. The process is straight forward. Connect two units with a parallel kit and have the power of both. This feature allows the flexibility to run a single small unit for lighter loads to conserve fuel but leverage the investment by adding another to run larger loads. Though this configuration is a little more expensive, it has the benefit of providing a backup if one of the units fails out in the field.

A melding of the most desirable qualities of generators and inverters, inverter generators provide clean electricity without the expense and weight of a battery bank. While not silent as standalone inverters, IGs are designed to be some of the quietest operating generators on the market. Combining these qualities with outstanding fuel economy, inverter generators are able to operate in places where neither conventional generators nor standalone inverters make a whole lot of sense. When you need a quiet portable generator, an inverter generator may just what you're looking for.